ii Genetics of quality and yield related traits in spring wheat (Triticum aestivum L.) under terminal heat stress conditions By Shadab Shaukat M.Sc. (Hons.) Agri. 2011-ag-563 A thesis submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHELOSOPHY IN PLANT BREEDING AND GENETICS DEPARMENT OF PLANT BREEDING AND GENETICS FACULTY OF AGRICULTURE UNIVERSITY OF AGRICULTURE, FAISALABAD PAKISTAN 2018
192
Embed
Genetics of quality and yield related traits in spring wheatprr.hec.gov.pk/jspui/bitstream/123456789/9514/1... · Principal/Project Director, Sub campus Burewala-Vehari, University
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
ii
Genetics of quality and yield related traits in spring wheat
(Triticum aestivum L.) under terminal heat stress conditions
By
Shadab Shaukat
M.Sc. (Hons.) Agri.
2011-ag-563
A thesis submitted in partial fulfillment of the
requirements for the degree of
DOCTOR OF PHELOSOPHY
IN
PLANT BREEDING AND GENETICS
DEPARMENT OF PLANT BREEDING AND GENETICS
FACULTY OF AGRICULTURE
UNIVERSITY OF AGRICULTURE, FAISALABAD
PAKISTAN
2018
iii
iv
v
vi
vii
This humble effort is
Dedicated
To
My Beloved
PARENTS
viii
ACKNOWLEDGEMENTS
All praise is due to Allah, The Compassionate, and The Merciful, Who gave me
opportunity to complete this work. In addition, with all humility and reverence, I present my
regards before the Holy Prophet (P.B.U.H) for whose sake this universe was created.
I am highly indebted to my supervisor Prof. Dr. Abdus Salam Khan,
Principal/Project Director, Sub campus Burewala-Vehari, University of Agriculture
Faisalabad, and Co- supervisor Dr. Makhdoom Hussain, Wheat Research Institute, AARI,
Faisalabad who extended their guidance and assistance generously and tried to remove the
difficulties faced during these studies. In short, this would have been impossible without their
valuable support and criticism.
I like to express my humble gratitude to Dr. Muhammad Kashif, Assistant
Professor, Department of Plant Breeding and Genetics and Dr. Nisar Ahmed, Associate
Professor, Center of Agricultural Biotechnology and Biochemistry, University of
Agriculture, Faisalabad for their proper guidance and valuable comments at various
occasions.
I am also thankful to Prof. Dr. Kulvinder Gill, Washington State University,
Pullman, USA, for training to learnt different bioinformatics and biotechnological tools and
techniques for wheat improvement. I am obliged to USPCAS-AFS, for providing funds to
avail this opportunity of visiting Washington State University, Pullman USA.
I have no words to express my feelings to my affectionate parents, loving brothers,
sister and brother in law especially to my father Shaukat Ali and brothers Dr. Rizwan
Shukat, Dr. Irfan Shaukat, Imran Shaukat, and Dr. Aftab Shaukat for being there every
time for me, for their encouragement and for their deep loves and care.
Good friends are blessings of ALLAH ALMIGHTY. I shall ever pride on having very nice,
co-operative and sincere friends, seniors and class fellows who shared many of my tough
hours during my stay at university. May Allah give them long, prosperous and happy life!
Shadab Shaukat
ix
x
LIST OF TABLES
Table No. TITLE Page No.
2.1 Reduction (%) in Various Wheat Traits under Heat Stress Conditions
8
2.2 Change in Total Crop Duration Due to Rise in Temperature 10
2.3 Chemicals, metabolites, and hormones involved in plant stress responses
17
2.4 Trait wise summary of literature review 19-20
3.1 List of wheat genotypes used in the screening experiment 21-25
3.2 List of selected lines and testers 29
3.3 List of crosses for line × tester mating design 30
3.4 Morpho–physiological and quality traits studied under normal and heat stress conditions
32
3.5 Crossing plan for line × tester mating design 40
3.6 Analysis of variance for line × tester 40
4.1 Mean sum of squares of all screened traits under normal and heat stressed conditions
42
4. 2 Mean data of some traits studied in 120 wheat genotypes under normal conditions
44-46
4. 3 Mean data of some traits studied in 120 wheat genotypes under heat stressed conditions
48-50
4.4 Cluster Centroids for eleven variables under Normal (N) and Heat Stressed (H) conditions
59
4.5 Principal Component Analysis of eleven traits under normal conditions
64
4.6 Eigenvectors of eleven traits under normal conditions 64
xi
4.7 Principal Component Analysis of eleven traits under heat stressed conditions
65
4.8 Eigenvectors of eleven traits under heat stressed conditions 65
4.9 Correlation among indicators under normal conditions 69
4.10 Correlation among indicators under heats stressed conditions 70
4.11 Mean square values of line × tester analysis for various traits under normal conditions
75
4.12 Mean square values of line × tester analysis for various traits under heat stressed conditions
76
4.13 Estimation of genetic components of variation under normal and heat stress conditions
77
4.14 Proportional Contribution of Lines, Testers and their Interaction under normal and heat stress conditions
78
4.15 Estimation of General Combining Ability Effects of parents for Agronomic, Physiological and quality Traits under Normal Conditions
81
4.16 Estimation of General Combining Ability Effects of parents for Agronomic, Physiological and quality Traits under heat stress Conditions
82
4.17 Specific combining ability estimates of Cell Membrane thermostability under normal and heat stress conditions
83
4.18 Specific combining ability estimates normalized difference vegetation index at vegetative stage under normal and heat stress conditions
86
4.19 Specific combining ability estimates of normalized difference vegetation index at grain filling under normal and heat stress conditions
89
4.20 Specific combining ability estimates of canopy temperature at vegetative stage under normal and heat stress conditions
92
4.21 Specific combining ability estimates of canopy temperature at grain filling stage under normal and heat stress conditions
95
4.22 Specific combining ability estimates of relative water contents under normal and heat stress conditions
97
xii
4.23 Specific combining ability estimates of plant height under normal and heat stress conditions
100
4.24 Specific combining ability estimates of flag leaf area under normal and heat stress conditions
103
4.25 Specific combining ability estimates of peduncle length under normal and heat stress conditions
106
4.26 Specific combining ability estimates of spike length under normal and heat stress conditions
109
4.27 Specific combining ability estimates of fertile tillers per plant under normal and heat stress conditions
112
4.28 Specific combining ability estimates of days to heading under normal and heat stress conditions
115
4.29 Specific combining ability estimates of days to maturity under normal and heat stress conditions
117
4.30 Specific combining ability estimates of spikelets per spike under normal and heat stress conditions
120
4.31 Specific combining ability estimates of grains per spike under normal and heat stress conditions
123
4.32 Specific combining ability estimates of 1000-grain weight under normal and heat stress conditions
125
4.33 Specific combining ability estimates of grain yield per plant under normal and heat stress conditions
128
4.34 Specific combining ability estimates of protein under normal and heat stress conditions
131
4.35 Specific combining ability estimates of moisture under normal and heat stress conditions
133
4.36 Specific combining ability estimates of ash under normal and heat stress conditions
135
4.37 Specific combining ability estimates of gluten under normal and heat stress conditions
137
4.38 Specific combining ability estimates of starch under normal and heat stress conditions
139
4.39 Specific combining ability estimates of test weight under normal and heat stress conditions
142
xiii
LIST OF FIGURES
Fig. No. TITLE Page No.
2.1 Heat stress incidence, plant response and adaptation strategies 7
2.2 Major effects of high temperature on plants 10
4.1.1 Mean performance of lines and testers for cell membrane thermostability under both normal (NOR) and heat stress (HS) conditions
52
4.1.2 Mean performance of lines and testers for normalized difference vegetation index at vegetative stage under both normal (NOR) and heat stress (HS) conditions
53
4.1.3 Mean performance of lines and testers for canopy temperature at vegetative stage under both normal (NOR) and heat stress (HS) conditions
54
4.1.4 Mean performance of lines and testers for relative water content under both normal (NOR) and heat stress (HS) conditions
55
4.2.1 Dendogram of different traits under normal conditions 60
4.2.2 Dendogram of different traits under heat stress conditions 61
xiv
List of Appendix
Appendix TITLE Page No.
I Mean data of Morpho–physiological and quality traits studied in lines, testers and their crosses under normal conditions.
172-174
II Mean data of Morpho–physiological and quality traits studied in lines, testers and their crosses under heat stressed conditions.
175-177
xv
List of Abbreviations
Abbreviations Full Name
GCA General Combining Ability
SCA Specific Combining Ability
CMT Cell Membrane Thermo-stability
NDVIV Normalized Difference Vegetation Index at vegetative stage
NDVIG Normalized Difference Vegetation Index at grain filling stage
CTV Canopy Temperature at vegetative stage
CTG Canopy Temperature at grain filling stage
RWC Relative Water Content PH Plant height FLA Flag leaf area
PL Peduncle length
SL Spike length
FTP Fertile tillers per plant
DTH Days to heading
DTM Days to maturity
SPS Spikelets per spike
GPS Grains per spike
TGW 1000-grain weight
GYP Grain yield per plant
PRO Protein MOI Moisture contents ASH Ash GLU Gluten
STR Starch
TW Test weight
WRI Wheat Research Institute, Faisalabad
AARI Ayub Agricultural Research institute, Faisalabad
HT Heat trial (Experiment coding for genotypes)
IPCC Inter-Governmental Panel on Climatic Change
PCSIR Pakistan Council of Scientific and Industrial Research
RVU Rapid Visco Units
RVA Rapid Visco Analyzer
PCA Principal Component Analysis
Fig Figure
xvi
ABSTRACT
Wheat crop is a basic staple food in many of countries all over the world. To overcome the need and supply gap of food it is necessary to improve wheat yield against different stresses such as heat stress. This study was performed to enhance the knowledge about genetics of heat tolerance in wheat using different agro-morphological parameters for screening of wheat. Line × tester mating design was used to access the genetic variability of wheat for combining ability against normal and heat stressed conditions. One hundred twenty genotypes were sown in research area of Wheat Research Institute (WRI) of Auyb Agriculture Research Institute (AARI) Faisalabad during growing season of 2014-15 in field and tunnel, which was covered during grain filling stage to provide high temperature stress. Ten lines and five testers were selected after proper screening by using different screening parameters such as cell membrane thermostability, normalized difference at vegetative stage, canopy temperature at vegetative stage and relative water content. The selected lines and testers were crossed in Line × Tester mating fashion. In next growing season (2015-16), parents along with their F1 hybrids were sown in triplicated randomized complete block design (RCBD) under normal and tunnel conditions. Data were recorded for both normal and heat stressed conditions for following traits i.e. cell membrane thermostability, normalized difference at vegetative stage, normalized difference at grain filling stage, canopy temperature at vegetative stage, canopy temperature at grain filling stage, relative water content, plant height, flag leaf area, peduncle length, spike length, number of fertile tillers per plant, days to heading, days to maturity, spikelets per spike, grains per spike, thousand grain weight, grain yield per plant and other quality traits like protein , moisture contents, starch, ash, gluten and test weight. Combining ability as used to investigate genotypes with best GCA and SCA. These parameters can help breeders in wheat crop improvement. All traits in this study showed dominance type of gene action under both normal and heat stressed environments. Results showed that the parents V-12103, Miraj-08, Faislabad-08, V-12082, Millat-11 and Chenab-2000 were good general combiner for grain yield and quality traits under both normal and heat stressed conditions. Among different crosses, V-13013 × ND643, SW89.52277 × Chenab-2000 and V-13013 × V-12082 showed better performance for grain yield and quality related traits that can be used in further breeding program for improvement of grain yield and quality parameters of wheat.
Chapter 1 INTRODUCTION
Wheat (Triticum aestivum L.) belongs to Poaceae family and is one of the oldest cereal crops
cultivated on large scale. It has been domesticated about 8000 years ago. Wheat is a staple
food of different nations (North Africa, West Indies and Europe) across the globe. It is grown
globally and is consumed by 33% of the world population (including Pakistan) because of its
nutritional importance; range of enduse products and especially for its storage qualities.
Wheat is utilized in bread making. Wheat grains contain most of the essential components
such as carbohydrates (60 to 80%), moisture (12%), fats (1.5 to 2%) and proteins (8 to 15%)
as reported by Anjum et al., (2005).
Wheat fulfils 21% caloric requirement and 20% protein requirements of 4.5 billion people
and mostly these people belong to developing countries as reported by Braun et al. (2010).
About 36% of world population consume wheat on daily basis and it is grown under wide
range of climates and soils. According to FAO report of 2015, wheat was sown on an area of
220 million hectares with global production of 690 million tonnes, having average grain yield
of 2700 kg ha-1. Wheat crop is well adapted in temperate climates where annual rainfall
remains within 30-60 cm, latitudes from the range of 30 to 60° N as well as 27 to 40° S.
Wheat crop is grown mostly all around the world, with its genetically diverse genotypes that
show compatibility to grow in diverse environmental conditions (FAO, 2015).
Wheat contributes 9.6 % in the value addition of agriculture and 1.9% in GDP of Pakistan.
Area under wheat cultivation has been decreased from 9224 thousand hectares (2015-16) to
9205 thousand hectares (2016-17), which shows a decrease of 1.9%. The production of wheat
in 2016-2017 was 25.750 million tonnes, which is 0.5% higher than last year (Anonymous,
2016-17). Pakistan has all the favorable conditions of soils, irrigation water and climate but
crops yield is far less than the major wheat growing countries due to many reasons.
Biotic and abiotic stresses are major crop yield limiting factors worldwide. Different
scientists may define heat stress in different ways. According to Wahid et al. (2007), “Heat
stress is a function of the magnitude and rate of temperature increase, as well as the duration
2
of exposure to the raised temperature.” Heat stress can also be described as “the increase in
temperature above a threshold level for the duration of time which is sufficient to cause
irreversible damage to plant growth and development” (Hall, 2001).
The causes of lower yield of wheat in our country are temperature variations, poor
understanding about variety selection and shortage of good quality seed and unavailability of
advance technology, late sowing, irrigation problems, heat and drought stress. Among all
these stresses, heat stress is the main hazard to crop yield especially at the reproductive stage
(Hall, 2001).
Increase of ambient temperature is causing climate change, since the start of this century.
According to forecast of global climatic model, the rise of average ambient temperature will
lie between 1.8 to 5.8°C at the end of this era (Anonymous, 2007). Heat stress can be caused
by increase of temperature that can cause hazards for crop productivity that also disturb
cropping pattern. Over the previous thirty years, constant increase of the global temperature
has resulted in significant decrease in yield of many crops. Additionally, results forecast that
frequent occurrence of heat waves also effects in yield reduction (Pittock, 2003). Rising
global temperatures and gradual increase of frequent heat waves are expected to have same
negative properties on this normal climatic system in the tropics as well as on the subtropics.
It has been reported that mean temperature is rising up to 0.3°C per decade globally (Jones et
al., 1999). It is expected that temperature will increase approximately 1°C and 3°C above the
normal temperature by years 2025 and 2100, respectively (Wahid et al., 2007). Climate
resonance is the ability to survive in different climatic stresses. There is need of Crop
resilience against different environmental stresses. Crops with higher plasticity from
emergence to their maturity are considered resilient against different environmental stressed
conditions. Climate vulnerability threatens food security systems of Pakistan. Rainfed areas
of Pakistan are more exposed to the effects of climatic instability due to extreme variation of
climate. In the recent years, high variability in the rainfall and increased temperature has
been observed in rainfed areas.
Taxonomically wheat is classified in two groups such as winter wheat and spring wheat. In
winter wheat, plant experience cold winter temperature before heading starts (Curtis, 2002)
3
whereas spring wheat (which is grown in Pakistan) requires little bit higher temperature.
Plant have their mechanism for stress regulation in the form of gene expression that results in
alteration in protein synthesis that control different biological functions. Role of gene
expression in different stresses and response mechanism has limited knowledge and has not
yet been explained properly because of multiple functions of some of the genes (Bray, 2002).
In stressed environments, plants have their defense mechanism of cell turgor maintenance.
Successful key for adaptation to climate change is through efficient plant breeding strategies.
It is very important to select optimum sowing time along with those varieties that gives
maximum yield in all environmental conditions. If there is any fluctuation in environmental
factors from normal range, it will limit crop productivity and ultimately final yield will be
reduced. Environmental stresses give rise to various physical and physiological hindrances in
the plant growth and development. The decline in wheat production is impressively owed to
various climatic variations.
A global population of 9 billion (in 2050) will be fed by wheat. Thus 70 to 100% increase in
its supply is desired to cope this future scenario (Godfray et al., 2010). Extensive cultivation
of crop with high yield is required to assure food security of future (Parry et al., 2011;
Reynolds et al., 2011). Temperature rise upto 30°C at anthesis may cause the reduction of
seed set even if there are differences among cultivars (Dawson and Wardlaw, 1989). Change
in environmental temperature is the major limiting factor in in crop productivity in different
crop growing seasons. Lobell et al. (2008) reported that 3 to 17% of the loss in yield
followed by 1°C rise in temperature in north and west zones of India and Pakistan, due to
global warming. High temperature can cause reduced crop yield, short life cycle, compact
biomass, decrease in the number of grains/spike, reduction in the grain weight and test
weight, all of these eventually result in decrease in grain yield and are threatening to food
security for wheat (the most important staple food in Pakistan). Cell membrane
thermostability is an indicator for screening of wheat varieties against heat stress (Ibrahim
and Quick, 2001). High temperature can cause damage to cell membrane integrity, influence
primary photosynthetic process, which ultimately results in changes in lipid composition and
protein denaturation (Wahid et al., 2007). Local climatic conditions and rise of temperature
due to global warming is the key problem for breeder to enhancing the yield potential of crop
4
(Semenov et al., 2014). Wheat is more delicate to cold (Frost) and hot (Heat stressed)
conditions at reproductive stage (Alghabari et al., 2014; Vara Prasad and Djanaguiraman,
2014). Relative water content osmotic potential, water potential, and grain yield are the most
important indicators of heat tolerance in wheat (Ram et al., 2017). Relative water content
could be used as efficient selection measure for various stress resistance mechanisms (Rad et
al., 2013). Heat stress during generative (reproductive) stage as well as grain-filling stage of
wheat imposes several threats to wheat productivity. Scientists predicted that due to climatic
changes there was increase in temperature which caused the wheat yield reduction range upto
20 to 30 % (Rosegrant and Agcaoili, 2010). In Pakistan, wheat plants exposed to high
temperature mostly face the decrease yield. Terminal heat stress is one of the main problem,
which occur during grain filling period and causes reduction of crop productivity from 10 to
15%.
For development and improvement of different genotypes, plant breeders exploit available
genetic resources of wheat. Newly developed genotypes will depict resistance mechanism
towards biotic and abiotic stresses via wheat breeding through hybridization and other
combination of desirable genes. Primary requirement for developing new varieties in wheat
is to investigate and utilize the available genetic material (which has diversity and potential).
Such genotypes should have the potential to be adapted to different environmental extremes
with high yield. For the development of tolerant cultivars, selection of superior genotypes is a
basic step for the production of different desirable genetic combinations. Suitable
information is required for the selection of genotypes, based on the nature of genes, which
control the expression of selected traits.
Screening of wheat genotypes is mainly based on diverse agro-morphological, physiological
as well as quality parameters that can perform better in heat stressed conditions. Exploitation
of many physiological traits is however yet needed. Yield loss and poor quality of grains
resulted by high temperature stress in wheat is the consequence for heat stressed conditions at
the time of grain-filling stage. The investigation was aimed with the main objective of
cataloguing of different wheat genotypes for normal as well as terminal heat stressed
environments. Wheat genotypes possessed potential differences under both heat stress and
5
normal conditions and their inter-relationship with different traits towards heat stress will be
very helpful to evolve heat tolerant genotypes.
Wheat breeders adopted several biometrical techniques that are required for the productive
wheat breeding programe. Line × Tester mating technique developed by Kempthorne (1957)
provide data for early generations based information on genetic tools involved in trait
expression. Present studies were planned to explore the heat tolerant genotypes having best
traits that results better in high temperature stress conditions and to investigate genetic nature
of these traits by mating them in suitable design according to line × tester mating technique.
Combing ability was also studied in these wheat genotypes. The line × tester mating design is
best one as a beneficial breeding approach that gives statistical information about genetic
mechanism and combining ability of these traits. These heat tolerant genotypes after proper
evaluation could be used to develop heat tolerant cultivars.
Heat stress at grain filling stage disturbs grain maturity as well as grain weight which
eventually causing deterioration of quality and grain yield (Khan et al., 2007; Wahid et al.,
2007). According to an estimate increase of 1°C temperature causes 3-10% loss in grain yield
of wheat (You et al., 2009) and approximately 40% of wheat (36 million hectares) grown in
temperate environment is facing terminal heat stress (Reynolds el al., 2011). Series of
experiments were conducted to evaluate the hypothesis that heat stress has impact at different
growth and developmental stages (vegetative and grain filling) in wheat with respect to
quality traits as well.
This research was planned to evaluate and identify heat tolerant wheat genotypes based on
different morphological, physiological and qualities evaluation.
The objectives of the study were following:
1. To assess variability by screening under terminal heat stress and to select superior/tolerant
wheat genotypes from available germplasm.
2. To find out the genetics of terminal heat stress tolerance to design proper screening
method for future breeding programs.
3. To evaluate the genetic behavior of selected desirable genotypes for future breeding
strategies.
6
Chapter 2 REVIEW OF LITERATURE
Plants respond differently in different environmental stresses by displaying the induction of
complete set of molecular changes. These changes are then depicted in the morphology of
plant, which ultimately manifest the stress responses. The outline of review of literature is as
follows,
2.1. Global scenario of temperature increase
2.2. Response of plant to heat stress
2.3. Genetic variability
2.4. Heat tolerance studies in wheat
2.5. Cell Membrane Thermostability (CMT)
2.6. Canopy Temperature (CT)
2.7. Normalized Difference Vegetation Index (NDVI)
2.8. Relative water content (RWC)
2.9. Effects of heat stress on morphological and physiological traits
2.10. Terminal heat stress in wheat
2.11. Genetics of heat tolerance
2.12. Combining Ability
2.13. Correlation
2.1. Global scenario of temperature increase
As reported by Inter-Governmental Panel on Climatic Change (IPCC), universal average
temperature of this world is rising via 0.3oC each decade (Houghton et al., 1990). It clearly
indicates an increase of 3oC than the present value by the year of 2100, which will lead to
extensive warming across the globe. Exposure adoptability of this supraoptimal temperature
for long time period to plants exerts heat stress and induce permanent damage in crop growth
and development. Heat stress condition created by 10 to 15oC increased the temperature
beyond the normal level. Increasing temperature causes limitation in plant productivity. It is
need of the present day to explore the causes and impacts of heat stress on plants. Patterns of
plant growth changes quickly and continuously due to rise of ambient temperature as
7
reported by Porter, 2005. Some relevant literature interrelates the impact of heat stress on
wheat plant (Fig. 2.1).
Fig. 2.1. Heat stress incidence, plant response and adaptation strategies (Akter and Rafiqul
Islam, 2017).
2.2. Response of plant to heat stress
Plants respond to different stress by different mechanisms such as avoidance, acclimatization
and resistance. Long-term interaction of high temperature to severe situations plants
experience catastrophic breakdown in cellular organization. Alteration in geographical
distribution caused by heat stress and crop maturity on early basis (Schoffl et al., 1999;
Howarth, 2005; Porter, 2005) that cause reduction of global yield reduction (Hall, 2001).
Impact of heat stress on yield related morphological traits were discussed in Table 2.1.
8
Table 2.1. Reduction (%) in Various Wheat Traits under Heat Stress Conditions (Sareen et
al., 2012) Trait Heat stress
Plant height 6.5
Productive tillers -31.1
Days to heading 10.1
Days to anthesis 10.1
Days to maturity 10.7
Grain filling duration 11.3
Number of grains per spike 3.3
Grain weight per spike 16.8
Thousand grain weight 14.1
Grain yield 26.4
2.3. Genetic variability
Genetic variation is a pre- basic requirement for successful running of crop improvement that
mainly depends upon its magnitude for desired heritability of desired traits as studied by
Kahrizi et al., 2010. In this world with increasing population, there is demands to enhance
the agricultural production under stressed conditions. Heat stress is a major problem in wheat
due to late harvesting of cotton and rice. There is the need of varietal development that has
not only the capability to avoid, escape and tolerance against different stress but also have the
potential that give more grain yields in heat stressed conditions.
In world, wheat is grown in different climatic regimes because to its broader range of
farming pattern have many harms for yield. High temperature stress is main hazard to wheat
cultivation. Plant breeder have great opportunity to investigate yield and other yield related
traits for the selection of parents that should provide best cross combinations for the
development of wheat varieties with better yield, environments especially in heat stress
conditions. A huge number of researchers investigated line × tester mating design for
9
understanding about the nature of gene action in better way. Wheat have wide range of
variations in genetic material across the world for different parameters like yield and its
components. Previous studies supported the breeders to run effective breeding programmes,
so they can improve multi-diverse gene pool (genetic material) that can accommodate
universally with improved yield. Ambreen et al., (2002) and Singh and Paroda, (1985)
detected variations in wheat genetic pool.
2.4. Heat tolerance studies in wheat
High temperature stress is a major limiting factor at the grain-filling stage for wheat yield in
many countries especially in some of the West Asian and North African countries. Among
different stresses to plant, heat stress accounts for 40% contribution in different
environmental stresses. Shpiler and Blum (1991) concluded that number of spikelets/spike
also reduce with reduction in number of kernels/spike in wheat crop. Wheat has an
association of heat stress with reasonable increase in temperature beyond the model level for
the photosynthetic action and less than ideal temperature for performing plant respiration. In
wheat, major yield decrease was observed because of 10 to 15°C increase in environmental
temperature during the stage of grain filling as reported by Chowdhury and Wardlaw, (1978)
and Weigand and Cuellar (1981). Heat stress is a factor that limit productivity in temperate
environment during anthesis and grain filling (Reynolds et al, 1994) (Table 2.2). Some
scientists suggested that production and survival of tillers depends on the genotype, spacing
and other agronomic practices, that influence the environmental factors, especially air
temperatures in stressed environments (Kirby et al., 1985; Longnecker et al., 1993). Heat
stress have impact on plants (Fig. 2.2). Environment is also associated with the physical and
other genetic aspects along with their agronomic performance. In order to achieve this goal,
wheat breeders utilize different screening phenotypic characters like plant biomass and plant
potential for tillering as described by Ortiz-Ferrara et al., 1993.
10
Table 2.2. Change in Total Crop Duration Due to Rise in Temperature (Tripathy et al., 2008)
Rise in Temperature (°C) Reduction in Wheat Duration (Days)
1 6
2 12
3 21
4 27
5 32
Figure 2.2. Major effects of high temperature on plants (Hasanuzzaman et al., 2013).
11
2.5. Cell Membrane Thermostability (CMT)
In heat stress, ions leakage and movement of organic solute across the membranes occur, that
interrupts photosynthesis and respiration (Christiansen, 1978). CMT is the measure of
electrolyte leakage from the leaves. It is an efficient tool for screening of wheat germplasm
against heat stress (Shanahan et al., 1990). Under heat stress, there was an association
between thermo-tolerance with respect to cell membrane stability (CMS), as estimated by
electrical conductivity method and the rate of reduction in grain weight per spike. Thermo-
tolerance as cell membrane thermostability (CMT) has shown positive association in seedling
and grain filling stage for plant survival in field under stress conditions. Negative association
between reduction in grain weight per ear (RGWPE), and cell membrane thermostability
(CMT) at seedling and flowering stages was observed (Fokar et al., 1998). Recombinant
Inbred Lines (RIL) differ significantly for cell membrane stability and biomass for yield and
other related traits under heat stressed and normal conditions. Cell membrane stability
remained positively correlated with biomass and yield under heat stress. No correlation was
observed for yield with biomass under non-heat stress environment. Blum et al., (2001)
studied cell membrane stability and yield and found significant correlations across the
different wheat lines. Any type of stress occurrence in plants firstly targeted cell membranes
and if plant retain integrity and stability under stress conditions, that is fit against stresses.
Bajji et al., (2001) concluded that organic acids present in durum wheat reduce the pH of leaf
tissues specifically when treated with Poly Ethylene Glycol (PEG). Different protocols and
procedures for the assessment of electrolyte leakage have been reported in literature for the
development of heat tolerant wheat cultivars. Cell membrane thermostability was measured
by electrolyte leakage method (Sullivan and Ross, 1979).
Durum wheat have higher cell membrane thermostability in comparison to bread wheat.
Severe heat stress causes denaturation of membrane proteins and melting of lipids in
membranes that cause rupture of cell membrane and ultimately cellular contents are lost.
Heat stress or water stress alone are not as dangerous as their interaction of heat and drought
cause severe damage of cell membrane stability (Kaur et al., 2008). Yildirim et al., (2009)
investigated different developmental growth stages in different genotypes of spring wheat. It
was noticed that membrane stability and relative injury give almost similar pattern of results
during three growth stages (seedling, stem elongation and early milk stage). In GS71,
12
correlation between grain yield and membrane stability was highly significant. Cell
membrane thermostability (CMT) practice on flag leaf in spring wheat plants in thermo-
tolerant lines resulted in significant increase in the wheat yield (Shanahan et al., 1990).
Decrease in thermo-stability of cell membrane reduce the growth and development of wheat
plants up to 70%. They also studied that heat shock of 2 hours at 42°C caused the highest
accumulation of H2O2. The highest (72%) cell membrane stability (CMS) was observed at
vegetative stage when temperature outside was about 25°C. Similarly, thermo-stability was
decreased in CMT during pollination stage, milking stage, dough stage and seed maturing
stage respectively. Strong positive association was recorded for grain weight/spike and cell
membrane stability in heat stress (Kumar et al., 2012).
Different changes in cellular membrane during germination of wheat seeds under heat stress
showed that rise in temperature caused significant increase in electrolyte level and proline
content. Cell membrane thermostability results also showed that wheat seeds have higher
electrolyte leakage under heat stress (Al-Jebory 2013). Shanahan et al., (1990) explored
electrolyte leakage method as phenomena of heat tolerance in spring wheat that was based on
CMT values of different genotypes, which were grouped as Heat Tolerant (HT) and Heat
Sensitive (HS). Accumulative response of Faislabad-2008, Lasani-2008, Sussui and AARI-
2011 performed better results in terms of proline accumulation, better antioxidant response
mechanism, Photosynthates stem reserves (PSR), Membrane Stability Index (MSI) and grain
yield under both stress and non-stress environments. Khan et al., (2013) observed lowest
membrane stability index in Faislabad-2008. It was also observed that cell membrane
thermo-stability showed two groups of gene action that control CMT are additive-
dominance-epistatic of major genes and additive-dominance-epistatic of polygenes. Low
damage percentage shown in Parula × Blue Silver depicted high value of CMT (Ullah et al.,
2014). The highest membrane Stability Index (MSI) and better osmotic adjustment for more
proline accumulation was observed in AS-2002 but Inqalab-91 showed best MSI. Heat stress
caused 75% and 40% yield reduction at anthesis and milking stage respectively (Khan at al.,
2015). Electrical conductivity was used as baseline of cell membrane thermostability for
identification of tolerant genotypes in wheat against heat stress. Bala and sikder (2017)
worked on wheat, evaluated cell membrane thermostability test under high temperature
13
conditions and concluded that strong positive relationship was observed in membrane
stability and grain weight/spike in high temperature stress tolerance conditions.
2.6. Canopy Temperature (CT)
Organ temperature depression and grain yield showed strong positive correlation with
canopy temperature depression. While canopy temperature depression and Organ
temperature depression showed positive correlation with the FLA index. Canopy temperature
depression was studied by Ayeneh et al., (2002) and observed higher association with days to
anthesis and days to maturity. Durum wheat is cooler than bread wheat during heat stress
conditions while canopy temperature depression is positively correlated with grain yield
components like, spike yield and grain numbers per spike. Grain yield, harvest index, and
spike numbers are higher in bread wheat than durum wheat. Canopy temperature and harvest
index have non-significant correlation in durum wheat. CT values have positive correlation
with grain yield, spike yield and grain number per spike (Bilge et al., 2008).
CT calculated by using IR thermometer that estimate CT and Area Under Canopy
Temperature Depression Progress Curve (AUCTDPC). Genetic variation was shown for spot
blotch resistance with heat stress tolerance. AUCTDPC was found to be associated parameter
for both stresses that can be used for the further screening program and for selecting of stress
tolerant varieties in humid environmental conditions (Rosyara et al., 2008). Karimizadeh and
Mohammadi (2011) studied positive and significant correlation among grain yield per plant,
mean productivity, stress susceptibility index, geometric mean productivity, stress tolerance
index and canopy temperature depression. They concluded that more effective selection
criteria is CT for identification of high yield genotypes under both irrigated and rainfed
conditions. Their results showed that mean value of canopy temperature depression changed
at Zadoks Growth Scale 69 stage with the range of 3.3 to 5.3oC. Leaf chlorophyll content and
canopy temperature showed high significant correlation. Canopy temperature showed high
correlation with width of leaf under all environmental conditions. Grain yield show positive
correlation with canopy temperature in both normal and late sown plants, which showed that
canopy temperature always has a role in grain yield of wheat.
14
Mohammadi et al., (2012) also reported strong association between crop yield and canopy
temperature depression against different drought and high temperature conditions.
Genotypes having high CTD numbers showed significant correlation with high Chlorophyll
Content (CHL) values. CTD showed negative correlation with yield under drought. Epure et
al., (2017) used canopy temperature depression (CTD) and Chlorophyll Content (CHL) for
estimation of drought resistant winter wheat lines and concluded that CTD or CHL alone are
not an effective screening approach but CTD and CHL in combination along with yield
provide an effective screening approach against stress. Canopy temperature depression is
main character that is used by a breeder to select best wheat lines against tolerance to heat as
well as drought stress. The effect of stimulation to heat stress was studied with maximum
crop canopy temperature. Webber et al., (2017) studied gain for the negative effects of heat
stress on net change, remobilization of non-structural carbohydrates (NSC) to grains during
grain filling increased and measured vibrant to ensuring yield during high temperature
stresses.
2.7. Normalized Difference Vegetation Index (NDVI)
In heat stress conditions, plants are provided with the ability to maintain their chlorophyll
content with NDVI and showed a significant association with crop yield. Normalized
difference vegetation index is a good aided tool for screening parameters in heat stress.
Cossani and Reynolds (2012) reported characterization of some favorable group of alleles
against heat stress. Heat stress caused the reduction in days taken to heading of wheat plant.
Combined effect of drought and heat stress caused reduction of grain productivity of the
plants by 60% and 40% respectively. Negative inter-relationship was found between the
yield and days taken to heading, canopy temperature at grain-filling, days to maturity.
Lopes and Reynolds (2012) evaluated the capability of genotypes to stay green with their
designated modification of genotypes toward stress with the aid of NDVI. Normalized
difference vegetation index (NDVI) is a strong tool to study stay green in plants. Maximum
NDVI value was observed at 220 kg/ha. Furthermore, positive association was observed
between NDVI and grain yield at booting stage then grain filling and maturity stage (Sultana
et al., 2014). Normalized Difference Vegetation Index (NDVI), Normalized Difference
15
Water Index (NDWI) and Water Index (WI) are positive significantly correlated with the
biomass and grain yield of triticales. Water index is a best parameter to monitor water stress
in triticale as compared with the NDVI and NDWI (Munjonji et al., 2017). Plants performed
better in heat stressed environments with high yield. Wheat plant showed early biomass
(estimated by NDVI), more grain filling rates and low canopy temperatures. Correlation
between leaf respiration and leaf temperature was reported to be associated negatively with
yield under high temperature during anthesis and grain filling stage. Leaf respiration
increases as temperature increases and plant grows. Pinto et al., (2017) investigated heat
tolerant lines having genetic diversity for morphological (leaf respiration) and physiological
traits in the context of heat tolerance.
2.8. Relative water content (RWC)
At anthesis stage of plants, water stress was artificially applied and results showed that RWC,
chlorophyll and mineral concentration of K and Na produce some differences among
resistance and susceptible genotypes. Reduction in plant vigor was observe reduction of
RWC in crops under drought stressed conditions (Arjenaki et al., 2012). Water stress have
more influence on different morphological traits such as variation in grain yield, variation in
biomass, variation in number of spikes and variation in relative water contents as compared
to other physiological traits (Ghatak et al., 2017). Different Normalized relative canopy
temperature based plant model values were recognized in their study to evaluate and forecast
relative water contents, canopy water content and grain yield.
Elsayed et al., (2017) worked on remote sensing and thermal imaging to study the grain yield
of wheat and estimation of water status under different irrigated conditions during growth of
wheat plant. Interaction between genotype × environment showed that the grain yield of plant
reduction was significant under the influence of water stress. Terminal heat stress and water
stress conditions showed significant decline in grain yield. It was concluded that osmotic
potential, water potential and grain yield are the most important traits indicating tolerant
wheat genotype (Ram et al., 2017). Claussen (2005) confirmed that close link exists between
relative water contents (RWC) and Proline. Stressed conditions causes lowering the osmotic
potential in response to osmolytic maintenance of turgor pressure. According to Carceller et
16
al., (1999) increase in contents of proline follow the decrease in RWC in water stressed
leaves.
2.9. Effects of heat stress on morphological and physiological traits
The effect of heat stress on varieties that encountered high temperature resulted in low starch
synthesis that leads to the reduction in 1000-kernel weight and relatively increased protein
contents. Glutenin to gliadins ratio was also reduced as discussed by Blumenthal et al.,
(1995). Exposure to heat stressed environment after 50% anthesis caused extensive decline in
the harvest index and grain yield in wheat. However, exposure at 82 days after sowing
increased spikes dry weight. Therefore, at mid anthesis time fertilization of grain and setting
of grain was maximum visible at ambient temperature (Ferris et al., 1998). Exposure of heat
and drought stress before the onset of filling of grain caused decrease in the grain filling
time, decreased 1000-kernel weight and grain weight also. Less influence was observed in
harvest index of nitrogen from dry matter harvest index that resulted in higher protein content
(Gooding et al., 2003).
High temperature at shooting stage directly cause significant yield loss and decrease in
number of grains. Results of Balla et al., (2009) revealed reduction of glutenin to gliadin
percentage plus un-extractable polymeric protein with increase of protein contents in wheat.
Majoul et al., (2003) studied that protein significantly decreased after heat treatment due to
glucose-1-phosphate adenyl transferase that plays a role in synthesis of starch. Heat stress
responses the process of grain weight reduction. 17% changes were monitored in the proteins
of mature grain of wheat under heat stress. Radmehr et al., (2004) revealed that all of the
genotypes had no sink constraint. Different chemical, metabolic, and hormonal changes are
involved in plants to respond against different stresses (Table 2.3). On the other hand, source
restriction exhibited 0 to 34% change by some genotypes in favorable normal conditions and
5.7 to 41.2% change under terminal heat stressed conditions. It means 6% more changes due
to the effect of heat stress. Khan et al., (2004) observed that plants with early sowing gave
higher yield of wheat. He also observed gradual decrease in yield with late planting. Peduncle
length of wheat is a significant morphological characteristic that has positive desired correlation
17
for early maturity. For the development of early maturing wheat cultivars, the plant breeders
should have to select such desired plants with a superior peduncle length and high yield.
Table 2.3. Chemicals, metabolites, and hormones involved in plant stress responses.
Compounds Stress response References
ROS Biotic and abiotic stress (Wang et al., 2009)
H2O2 Drought, heat, chilling, and salinity (Gong et al., 2001, Savvides et al.,
2016)
H2S Abiotic stress (Jin et al., 2017)
Strobilurin Abiotic stress (Diaz-Espejo et al., 2012)
NOSH-aspirin Abiotic stress (Antoniou et al., 2014)
NaHS Heat stress (Christou et al., 2014, Min et al., 2016)
2.10. Terminal Heat stress in wheat
Studies showed that early maturing genotypes possess greater kernel weight and higher grain
formation period, so early maturing genotypes have the ability to tolerate heat stress in a
better way than long duration genotypes. Sandeep et al., (2000), reported significant
correlation between genotypes and date of planting with respect to cell membrane
thermostability. Change of sowing time reduced plant height, heading and maturity days,
spikelets/spike, grains/spike and yield of grains as results of two average sowing extremes
(Mahboob et al., 2005). Likewise results for grain yield of wheat crop also greatly decreased
due to sowing in latter days (which cause terminal heat stress) as described by Arain et al.,
(2002.)
2.11. Genetics of heat tolerance
Different proteins like heat shock proteins (Hsps) and other enzymes of antioxidants have
great importance in facing heat stress among plants. Under high temperature stress,
upregulation of numerous enzymatic as well as non-enzymatic antioxidants as well as
stability maintenance of cell membrane, different compatible solutes synthesis with hormonal
18
variabilities occurs (Asthir 2015). In heat stressed conditions, plants collect diverse range of
metabolites like antioxidants, osmo protectants, heat-shock proteins (Hsps) and metabolites
from different pathways as studied by Bokszczanin and Fragkostefanakis 2013. Several
reports have recognized the availability of heat-tolerant genes among them various are
quantitative trait loci (QTL) (Rodriguez et al., 2005). Membrane fluidity in heat tolerance
was explained by mutation analysis as well as transgenic and physiological studies. For
example, a soybean mutant deficient in fatty acid unsaturation showed strong tolerance to HT
(Pastore et al., 2007).
2.12. Combining Ability
Combining ability is the ability of a parent to transmit desirable performance to the resultant
hybrid after crossing (Sprague and Tautum, 1942). It has two types (i) general combining
ability (GCA) and (ii) specific combining ability (SCA). The GCA refers to the relative
performance of individuals, in a similar group of organisms, when crossed with a
heterogeneous tester. The SCA refers to the progeny performance resulting from a particular
cross as related to the performance of other particular crosses of a similar nature (Sprague
and Tautum, 1942).
2.13. Correlation
Correlation studies are useful for understanding the stress tolerance as yield traits can be used
as subordinate criteria for selection in wheat to improve yields in different stressed
environmental conditions. Gupta et al. (2001) observed positive correlations of physiological
and yield traits at both booting and anthesis stages, whereas negative correlations was also
seen leaf canopy temperature with grain yield per plant. Bahar et al., (2011) reported
significant negative correlation of canopy temperature depression (CTD) with grain yield
(GY). From results presented by (Jatoi et al., 2012) showed higher correlation was observed
under stressed whereas under non-stressed environments it showed weaker correlation among
traits. Positive correlation observed by some physiological and yield related traits with
relative water content and stomatal conductance showed negative correlation with all yield
traits under stressed conditions. Dhanda and Munjal (2012) described positive correlation of
19
cell membrane thermostability observed with grain yield in bread wheat. Bhutto et al., (2016)
reported that plant height showed significantly positively correlation with spikelets per spike,
number of tillers per plant and grains per spike. Azimi et al., (2017) observed positive
significant correlation of late sown (cause terminal heat stress) wheat for grain yield with all
other yield contributing traits among genotypic at phenotypic components of variation.
Table 2.4. Trait wise summary of literature review
Trait Literature Remarks
Cell Membrane Thermostability
Bala and sikder, (2017) Strong positive relationship between membrane stability and grain weight/spike in high temperature stress was reported.
Khan at al. (2015) Heat stress caused 75% and 40% yield reduction at anthesis and milking stage respectively.
Ullah et al. (2014) Less damage percentage in cross (Parula × Blue Silver) depicted high value of CMT was investigated.
Al-Jebory (2013) Cell membrane thermostability resulted wheat seeds have higher electrolyte leakage under heat stress.
Kumar et al. (2012) Strong positive association was observed for grain weight/spike and cell membrane stability in heat stress.
Yildirim et al. (2009) Different developmental growth stages in different genotypes of spring wheat were explored.
Blum et al. (2001) Significant correlations was recorded for cell membrane stability and wheat yield.
Canopy Temperature (CT)
Epure et al. (2017) Concluded canopy temperature depression or Canopy Chlorophyll Content alone are not effective screening approach but combined with yield provide an effective screening approach against stress.
Mohammadi et al. (2012) Strong association between crop yield and canopy temperature depression against different drought and high temperature conditions was found.
Cossani and Reynolds, (2012)
Negative inter-relationship between the yield and days taken to heading, canopy temperature at grain-filling, days to maturity was explored.
Karimizadeh and Mohammadi, (2011)
CTD for identification of high yield genotypes under both irrigated and rainfed conditions was reported.
Bilge et al. (2008) CTD values have positive correlation with grain yield, spike yield and grain number per spike
Ayeneh et al. (2002) Canopy temperature depression and Organ temperature depression showed positive correlation with the FLA index
20
Normalized Difference Vegetation Index (NDVI)
Munjonji et al. (2017) Water index is a best parameter to monitor water stress in triticale as compared with the NDVI and Normalized Difference Water Index
Pinto et al. (2017) Heat tolerant lines having genetic diversity for morphological (leaf respiration) and physiological traits in the context of heat tolerance.
Sultana et al. (2014) Positive association was observed between NDVI and grain yield at booting stage then grain filling and maturity stage
Lopes and Reynolds, (2012)
Evaluated the capability of genotypes to stay green with their designated modification of genotypes toward stress with the aid of NDVI.
Relative Water Contents (RWC)
Elsayed et al. (2017) Remote sensing and thermal imaging to study the grain yield of wheat and estimation of water status under different irrigated conditions during growth of wheat plant
Ghatak et al. (2017) Evaluation of different relative canopy temperature based plant model values and forecasted relative water contents, canopy water content and grain yield was done.
Ram et al. (2017) Osmotic potential, water potential and grain yield are found to be the most important traits indicating tolerant wheat genotype
Arjenaki et al. (2012) Reduction in plant vigor was observed with respect to reduction of RWC in crops under drought stressed conditions
Claussen, (2005) Close link exists between relative water contents (RWC) and Proline
Carceller et al. (1999) Increase in contents of proline follow the decrease in RWC in water stressed leaves was reported
21
Chapter 3 MATERIALS AND METHODS
3.1 Collection of germplasm and experimental conditions
The germplasm was collected from Wheat Research Institute, AARI, Faisalabad. The
germplasm comprised of following 120 genotypes (including some standard varieties):
Table 3.1: List of wheat genotypes used in the screening experiment
Entry # Name Parentage/Pedigree 1 HT1 QUAIU #1/4/PFAU/SERI.1B//AMAD/3/WAXWING
Selected lines and testers along with their crosses were sown using randomized complete
block design replicated thrice in the field and tunnel during the crop season 2015-16 with
sowing date of Nov 20, 2016. The gross plot size was kept two rows six meter each, distance
between rows was 30 cm while a net plot size of two rows of five meter each were harvested
to record data for grain yield. Normal agronomic and cultural practices were applied to the
experiment throughout the growing season.
32
3.3.2. Data recording
Data were recorded for the following plant parameters of selected plants.
Table-3.4: Morpho–physiological and quality traits studied under normal and heat stress conditions
Serial No. Trait 1 Cell Membrane Thermo-stability (CMT)
2 Normalized Difference Vegetation Index at vegetative stage (NDVIV)
3 Normalized Difference Vegetation Index at grain filling stage (NDVIG)
4 Canopy Temperature at vegetative stage (CTV)
5 Canopy Temperature at grain filling stage (CTG)
6 Relative Water Content (RWC)
7 Plant height (cm)
8 Flag leaf area (cm2)
9 Peduncle length (cm)
10 Spike length (cm)
11 Fertile tillers per plant
12 Days to heading
13 Days to maturity
14 Spikelets per spike
15 Grains per spike
16 1000-grain weight (g)
17 Grain yield per plant (g)
18 Test weight (kg/hl)
19 Protein (%)
20 Moisture content
21 Ash (%)
22 Gluten (%)
23 Starch (%)
33
3.3.3. Cell Membrane Thermostability:
Cell Membrane Thermostability was measured as described in section 3.2.1.
3.3.4. Normalized difference vegetation index at vegetative stage (NDVIV)
Normalized difference vegetation index at vegetative stage noted as described in section
3.2.2.
3.3.5. Canopy temperature at vegetative stage (CTV) (°C)
Canopy temperature at vegetative stage was recorded as described in section 3.2.3.
3.3.6. Normalized difference vegetation index at grain filling stage (NDVIG)
Normalized difference vegetation index at grain filling stage measured as described in
section 3.2.4.
3.3.7. Canopy Temperature at grain filling stage (CTG) (°C)
Canopy temperature at grain filling stage measured as described in section 3.2.5.
3.3.8. Relative water content:
Relative water content was calculated as described in section 3.2.6.
3.3.9. Plant height (cm)
Height of randomly selected ten plants from three replications of each entry from top (tip of
spike without awns) to bottom. Mean data of these plants was used for future statistical
analysis.
3.3.10. Flag leaf area (cm2)
Flag leaf area calculated as described in section 3.2.7.
3.3.11. Peduncle length (cm)
From selected plants, peduncle length was recorded at maturity from node to base of spike.
Mean data of these plants for peduncle length was used for future statistical analysis.
3.3.12. Spike length (cm)
Spike length was noted from selected mother plants in centimeters (cm) from base to the tip
of spike excluding awns. Average of spike length was used.
3.3.13. Number of tillers per plant
From selected plants, numbers of tillers from each genotypes were recorded at crop maturity
with each replication and mean data was used.
34
3.3.14. Days to heading
Days to heading was counted from date of sowing up to the date when it have more than 50
percent plants with completed heading.
3.3.15. Days to maturity
From selected plants, days taken to maturity recorded as the duration from sowing to
maturity dates when plants were physiologically mature.
3.3.16. Number of spikelets per spike
Number of spikelets per spike noted as described in section 3.2.9.
3.3.17. Number of grains per spike
Number of grains per spike recorded as described in section 3.2.8.
3.3.18. 1000-grains weight (g)
1000-grains weight was measured as described in section 3.2.10.
3.3.19. Grain yield per plant (g)
Grain yield per plant was calculated as described in section 3.2.11.
3.4. Quality Traits
3.4.1. Protein (%)
kjeldahl apparatus (D-40599, Behr Labor Technik, Gmbh-Germany) was used to assess the
nitrogen percentage in the raw samples by following ACCA (2000) method number 46-12.
Accordingly, 2g of moisture free sample (wheat flour) was added in 30 ml of concentrated
H2SO4 and then 5g digestion mixture (K2SO4: FeSO4: CuSo4 at 100:5:10 ratio) was added
and kept for 3-4 hours, until the color was light greenish. Dilution of the digested material
was done in a 250 ml volumetric flask using distilled water. Then 10 ml of dilution from 250
ml volumetric flask was taken and 10 ml alkali (40% NaOH) was added in the distillation
apparatus to get the nitrogen samples of the contents in the form of NH4OH. The ammonia
thus liberated was collected in a beaker containing 10 ml of 4% boric acid solution using
methyl red as an indicator. This resulted in the formation of ammonium borate that was used
for the nitrogen determination in samples. Nitrogen was estimated by titrating the distillate in
the receiver flask against 0.1N H2SO4 till light pink end color. Protein (%) was calculated by
multiplying nitrogen percentage (N %) with factor 6.25 as given bellow:
35
Vol. of 0.1N H2SO4 × 0.0014 × Vol. of Dilution (250 ml) N (%) = --------------------------------------------------------------------------------- × 100 Vol. of distillate taken × Wt. of Sample
Crude protein (%) = Nitrogen (%) × 6.25
3.4.2. Starch (%)
For starch percentage determination, method number 22-08 as described in AACC (2000)
applied. Wheat flour of 3.5grams sample mixed with water (25 ml) for slurry formation.
Rapid visco analyzer (RVA) stirred heated slurry (heated at 60 to 95°C for 6 minutes). Peak
values of viscosity were noted from rapid visco analyzer as they make a curve. Starch
viscosity was indicated by measuring the resistance of slurry (water and flour) in RVA. After
heating slurry, granules of starch make thicker slurry. Highest peak viscosity was observed in
thicker slurry that have more resistance during stirring. Results of RVA during high heating
cycle highest viscosity was observed in rapid visco units (RVU).
3.4.3. Ash
The ash content of raw samples were estimated according to the procedures described in
AACC (2000) Method No. 08-01. 5g of sample was taken in pre-weighted crucibles and
directly charred on flame until there was no fumes coming out. Afterwards sample was
ignited in muffle furnace (MF-1/02, PCSIR, Pakistan) at 550-600oC for 5-6 hours until
grayish white residues were obtained. Ash content after cooling in desiccators was calculated
as:
Wt. of residues (g) Ash (%) = ------------------------------- × 100 Wt. of samples (g)
3.4.4. Moisture
The moisture content of raw samples was determined following method described by AACC
(2000) method No. 44-15A. Accordingly, 5g sample was placed in already weighted china
dish and dried it in a hot air oven (Model: DO-1-30/02, PCSIR, Pakistan) at the temperature
of 105 ± 5oC for 24 hours. The samples were cooled in desiccator. The moisture percentage
was calculated by using following formula.
Wt. of original samples (g) - Wt. of dried samples (g) Moisture (%) = ----------------------------------------------------------------------- × 100 Wt. of original samples (g)
36
3.4.5. Gluten (%)
The gluten content of raw samples was determined by following AACC (2000) method No.
38-12A. Already weighted sample of 10 grams wheat flour of 10 and put in glutomatic
washing chamber on top of the polyester screen. Mix sample and wash samples with salt
solution (2%) for 5 minutes. After washing wet gluten was removed from chamber and then
placed into centrifuge for centrifugation. From top of screen, collected residues were
weighted. The gluten percentage (%) was calculated by the formula given below
Cell Membrane Thermostability plays a vital role for plant stresses. Electrolytes leakage
from cell membranes as results of stresses (e.g. Drought and Heat stress). Heat stress cause
the activation of stress mechanisms in plants. Resistance in plants at protoplast level results
cellular membrane integrity. These electrolyte levels are also affected by degree of hardening
(Stress) in plant species. Cell membranes firstly directed as a result of stress and
sustainability of that integrity under heat stress is major key factor for heat stress in wheat.
Degree of injury to cell membrane was estimated by electrolytes leakage from cell. Cell
Membrane Thermostability (CMT) is therefore, quick and efficient screening technique
against assessment of thermo tolerance. Analysis of variance for CMT was presented in
Table 4.1.1 and Table 4.1.2 which showed significant differences among all genotypes used
for screening experiment under both normal and heat stressed conditions. Genotype HT-120
show maximum value for CMT (69.32) under normal and genotype HT-101 showed
minimum value for trait (42.84) as shown in Fig.4.1.1. In heat stressed conditions genotype
HT-36 show maximum mean value (68.28) whereas genotype HT-109 show minimum value
that is (36.45) shown in Table 4.1.3. Range for CMT tend to decrease little bit in heat
stressed conditions. High temperature stress cause kinetic energy of molecules and their
movements across membranes studied by Savchenko et al. (2002). Higher values of CMT
explained their tolerance against the heat stress as discussed by Bala and Sikder (2017).
These results accordance with the Khan et al., (2013) and Kaur et al., (2008) as they studies
that membrane stability Values decreased with the increase of temperature. Cell membrane
stability by use of electrical conductivity method against screening of tolerant genotypes
against heat stress in wheat reported by Blum and Ebercon, (1981) while CMT is used in
different genotypes for tolerance evaluation to heat stress in various crop plants (Blum,
1988).
52
Fig.4.1.1: Mean performance of lines and testers for cell membrane thermostability under both normal (NOR) and heat stress (HS) conditions
4.1.2.4. Normalized Difference Vegetation Index at Vegetative Stage
NDVI determine the greenness vegetation of that area. This trait related to the green leaf
biomass of plant, chlorophyll content and for the grain yield prediction (Sultana et al., 2014).
Mean performance values were shown in Table 4.1.3 for normal while for heat stress shown
in Table 4.1.4. ANOVA Table 4.1.1 and 4.1.2 major contributing differences among mostly
all genotypes under normal and heat stressed conditions. Depicted mean performance under
normal environment was maximum in genotype HT-83 with value 0.83 whereas minimum in
genotype HT-5 with value of 0.61 (Fig.4.1.2). Under heat stressed conditions genotype HT-5
showed higher vale (0.82) but minimum value was observed by genotype HT-101 with mean
vale of 0.62. Under stressed conditions data showed to decrease in NDVI value at vegetative
stage of plants. Greater NDVI shown at different vegetative growth stages as booting and
heading is the outcome for good health of these plants before entering into the reproductive
stage. Lopes and Reynolds (2012) studied NDVI as efficient screening traits against stresses
that measure capability of plants to stay green which confirm these findings that higher value
of NDVI could be used as detection of heat tolerant wheat genotypes.
53
Fig.4.1.2: Mean performance of lines and testers for normalized difference vegetation index at vegetative stage under both normal (NOR) and heat stress (HS) conditions
4.1.2.5. Canopy Temperature (Vegetative Stage)
Heat stress stimulation cause maximum effects on canopy temperature Epure et al., (2017).
Crop plant with cooler canopies can tolerate stress in an efficient mode than others with
warmer crop canopies (Mohammadi et al., 2012). Under normal and heat stressed conditions
significant differences observed among the all genotypes for CTV. The highest value for
normal climatic conditions was recorded in genotype HT-20 (26.94) while minimum value
was observed in genotype HT-5 (22.10). Under high temperature stress, mean performance
was highest in genotype HT-120 (27.07) but lowest in genotype HT-101 (22.39) as described
in Fig.4.1.3. Ju et al. (2005) also found similar pattern of increased canopy temperature under
stress conditions at vegetative stage as our results showed under heat stressed conditions.
54
Fig.4.1.3: Mean performance of lines and testers for canopy temperature at vegetative stage under both normal (NOR) and heat stress (HS) conditions
4.1.2.6. Relative Water Content
Relative water content provide precise information about the amount of leaf water shortfall
that specify the degree of stress stated under both the drought and heat stress. RWC add the
leaf water potential to the effects of osmotic adjustment as the measurement of plant water
status in stress. In response to the heat and drought stress decrease in RWC for different
plants was reported by Almeselmani et al., (2012); Saxena et al., (2014) and Ramani et al.,
(2017). There were significant differences among genotypes. From mean performance shown
in Table 4.1.1 for normal conditions maximum value observed by genotype HT-59 (74.16)
while minimum scored by genotype HT-5 (51.83) as shown in Fig.4.1.4. High temperature
maximum value for genotype HT-105 (72.80) while minimum in HT-75 (50.61). Ram et al.,
(2017) concluded that with the increase of temperature there were decrease in relative water
content that show as similar kind of findings as has been reported in this case.
55
Fig.4.1.4: Mean performance of lines and testers for relative water content under both normal (NOR) and heat stress (HS) conditions
56
4.1.3. CLUSTER ANALYSIS
Khodadadi et al., (2011), used cluster analysis to study different traits. In this study, 11 traits
and 120 genotypes were used for screening. Genotypes were grouped into five clusters
(Table 4.4) after cluster analysis upon observing dendogram (Fig 4.1.1 and 4.1.2). Clear-cut
differences in dendogram were observed in both normal and heat stressed conditions
indicated variations among genotypes for trait expression in different environments.
4.1.3.1. Normal environment
Cluster from normal environmental conditions shown in dendogram Fig. 4.2.1. Dendogram
of 120 genotypes with five clusters represent that in cluster number one forty genotypes are
present while in second cluster only seventeen genotypes ranked, in third cluster ten
genotypes while forth cluster contain largest group of genotypes as forty four and in last
cluster number five only nine genotypes were present. From these observations it was seen
that cluster one and four maintain more amount of genetic diversity for different traits under
study. Less diversity in cluster five whereas in cluster number three and two have medium
genetic diversity. As we go toward cluster, number five from cluster one there was similarity
level decreases that show lot of diversity of genotypes under study. Genotypes of different
origin grouped in the same cluster designate the existence of some part of ancestral
relationship between genotypes (Sharma et al., 1998).
In cluster, these traits like thousand-grain weight showed maximum value and cell membrane
thermostability with minimum effects. Small amount of diversity for most of traits shown in
the same cluster (Dotlacil et al., 2000). In this cluster only one trait, canopy temperature at
grain filling stage show positive value except that all show negative effects (Table 4.4).
On second cluster, flag leaf area have maximum and canopy temperature at grain filling stage
show minimum value among all traits. All traits show positive effects in this cluster (Table
4.4). Cluster number three depicted highest negative value for thousand-grain weight while
minimum effects observed for canopy temperature at grain filling stage.
57
In third cluster, five traits show negative values are CMT, NDVIG, CTG, FLA and GPS.
While remaining six traits NDVIV, CTV, RWC, SPS, GYP and TGW shown positive values.
In cluster four, the highest peak value observed by CTG followed by RWC and minimum
value was observed for grain yield per plant. All traits showed negative effects.
Fifth cluster maximum value depicted with negative number of normalized difference at
vegetative stage and minimum effects by canopy temperature at grain filling stage. In this
last cluster, all traits have negative values except cell membrane thermostability, canopy
temperature at vegetative stage, relative water contents, and grains per spike.
4.1.3.2 Heat stressed environment
High temperature at the time of grain filling cause severe yield loss in wheat indicated by
Wahid et al., (2007). Similarity index of heat stressed genotypes from clustering resulted a
dendogram by using one twenty genotype in five diverse clusters shown in fig 4.2.2 that
show decrees of similarity index as we move from cluster one toward five. In first cluster
twenty-eight genotypes, second cluster forty, third with ten, thirty-seven in fourth and last
fifth cluster contain only five genotypes. The highest number of genotypes observed in
cluster number two. High estimates of genetic diversity was obtained in clusters two, four
and one whereas cluster number three and five have lesser number of genotypes.
For heat stress in cluster number one highest value for grains per spike and lowest in cell
membrane thermostability followed by flag leaf area. Except canopy temperature at grain
filing stage, relative water contents and thousand grain weight all traits show negative value
(Table 4.4).
In cluster two maximum value by relative water contents followed by thousand grain weight
and minimum effects by normalized difference at grain filling stage followed by grains per
spike. All traits of second cluster show negative values except normalized difference at grain
filling stage, canopy temperature at vegetative stage and grain yield per plant. In cluster
three, all traits show positive values. Maximum value with thousand grain weight and
minimum with normalized difference at grain filling stage.
58
Last fifth cluster highest value shown by grains per spike with minimum normalized
difference at vegetative stage. Except cell membrane thermostability, normalized difference
at grain filling stage, flag leaf area, spikelets per spike and grain yield per plant all other
show positive values.
59
Table 4.4. Cluster Centroids for eleven variables under Normal (N) and Heat Stressed
showed better performance for grain yield and quality related traits.
• Non-allelic interaction found in yield, quality and heat stress tolerance related traits
showed that selection of plants with desirable traits should be delayed until 4th and 5th
segregating generation when allelic combinations are fixed.
146
LITERATURE CITED:
AACC 2000. Approved Methods of the American Association of Cereal Chemists, 10th ed.
Methods 46-12, 22-08, 08-01, 44-15A, 38-12A and 55-10, AACC St. Paul, MN.
Abdelmula, A.A., M.O.M. Jaber and S.M. Gasim, 2011. Differential response of some bread wheat (Triticum aestivum L.) genotypes for yield and yield components to terminal heat stress under Sudan conditions. In: Proceedings of the Tropical (Tropentag2011) Conference; International Research on Food Security, Natural Resource Management and Rural Development, October 5 -7, 2010, University of Bonn (Germany).
Abdullah, M., Aziz-Ur-Rehman, N. Ahmad and I. Rasul. 2007. Planting time effect on grain and quality characteristics of wheat. Pak. J. Agri. Sci. 44 (2): 200-202.
Adel, M.M. and E.A. Ali. 2013. Gene action and combining ability in six parent diallel cross of wheat. Asian J. Crop Sci. 5 (1): 14-23.
Ahmad, Z. and J.K. Srivastava. 1991. Partial diallel analysis for some quality and physiological traits related to productivity in wheat. Golden Jubillee symp. Genetics Res. Edu. Current trends and the next five years, New Delhi, pp 12-15.
Ahmed, N., M.A. Chowdhry, I. Khaliq and M. Maekawa. 2007. The inheritance of yield and yield components of five wheat hybrid populations under drought conditions. Indonesian J. Agric. Sci. 8(2): 53-59.
Akbar, M., A. Rehman, M.H. Chaudhry and M. Hussain. 1997. Prepotency judgment of diallel crosses in F1 generation for wheat improvement. Sci. Int. 47: 303-305.
Akbar, M., J. Anwar, M. Hussain, M.H. Qureshi and S. Khan. 2009. Line × Tester analysis in bread wheat (Triticum aestivum). J. Agri. Res. 47(1):411-420.
Akram, Z., S.U. Ajmal, K.S. Khan, R. Qureshi and M. Zubair. 2011. Combining ability estimates of some yield and quality related traits in spring wheat (Triticum aestivum L.). Pak. J. Bot. 43:221-231.
Akter, N. and Rafiqul Islam M. 2017. Heat stress effects and management in wheat. A review. 547 Agronomy for Sustainable Development 37, 37.
Alghabari, F, M. Lukac, H.E. Jones, M.J. Gooding. 2014. Effect of Rht alleles on the tolerance of wheat grain set to high temperature and drought stress during booting and anthesis. J. Agro. Crop Sci. 200, 36–45.
147
Ali, F., Muneer, M. Rahman, H. Noor, M. Durrishahwar, S.S. Yan. 2011. Heritability Estimates for Yield and Related Traits Based on Testcross Progeny Performance of Resistant Maize Inbred Lines. J. Food Agric. Environ. Res. 9: 438-443.
Ali, Y., B.M. Atta, J. Akhter, P. Monneveux and Z. Lateef. 2008. Genetic variability, association and diversity studies in wheat (Triticum aestivum L.) germplasm. Pak. J. Bot. 40(5): 2087-2097.
Al-Jebory, E.I. 2013. Changes in cellular membrane tolerance due to heat stress during Triticum sativum L. seeds germination. magazin of alkufa university for biology 5(2): 234-239.
Al-Khatib, K., G.M. Paulsen. 1984. Mode of high temperature injury to wheat during grain development. Plant Physiol. 61:363–368.
Almeselmani, M., A. Saud, K. Al-Zubi, F. Abdullah, F. Hareri, M. Nassan, M.A. Ammar and O. Kanbar. 2012. Physiological performance of different durum wheat varieties grown under rainfed condition. Global J. Sci. Frontier Res. 12: 55-63.
Ambreen, A., M.A. Chowdhry, I. Khaliq and R. Ahmad. 2002. Genetic determination for some drought related leaf traits in bread wheat. Asian J. Pl. Sci. 1(3): 232-234.
Anjum, F.M., I. Ahmad, M.S. Butt, M.A. Sheikh and I. Pasha. 2005. Amino acid composition of spring wheats and losses of lysine during chapatti baking. J. Food Comp. Anal. 18: 523-532.
Anonymous. 2007. Climate change 2007: Impacts, adaptation and vulnerability. Working group II contribution to the intergovernmental panel on climate change (IPCC) fourth assessment report Brussels.
Anonymous. 2016-17. Ministry of Finance, Govt. of Pakistan. (http://www.finance.gov.pk/survey/chapter_12/02-Agriculture.pdf).
Antoniou, C., G. Chatzimichail, K. Kashfi and V. Fotopoulos. 2014. P77: Exploring the potential of NOSH-aspirin as a plant priming agent against abiotic stress factors. Nitric Oxide 39: S39.
Anwar, J., M. Akbar, M. Hussain, S. Asghar, J. Ahmad. 2011. Combining ability estimates for grain yield in wheat. Lahore J. Agric. Res. 49: 437-445.
Arain, M.A., M.A. Sial and M.A. Javed. 2002. Influence of different seeding rates and row spacings on yield contributing traits in wheat. Pak. J. Seed Tech. 1: 01-6.
148
Arjenaki, F.G., R. Jabbari, A. Morshedi. 2012. Evaluation of Drought Stress on Relative Water Content, Chlorophyll Content and Mineral Elements of Wheat (Triticum
aestivum L.) Varieties. Intl. J. Agri. Crop Sci. 4 (11): 726-729.
Aslani, F. and M.R. Mehrvar. 2012. Responses of wheat genotypes as affected by different sowing dates. Asian J. Agric. Sci. 4(1): 72-74.
Asthir B. 2015. Protective mechanisms of heat tolerance in crop plants. J. Plant Interact. 10(1): 202-210.
Atiq-ur-Rehman, I. Khaliq, M.A. Chowdhry and R.I. Khushnood. 2002. Combining ability studies for polygenic characters in Aestivum species. Int. J. Argic. Biol. 4: 171-1174.
Awan, S.I., M.F.A. Malik, M. Siddique. 2005. Combining ability analysis in intervarietal crosses for component traits in hexaploid wheat. J. Agric. Social Sci. 1: 316-317.
Aycicek, M. and T. Yildirim. 2006. Path coefficient analysis of yield and yield components in bread wheat (Triticum aestivum L.) genotypes. Pak. J. Bot. 38(2): 417-424.
Ayeneh, A., M.V. Ginkel, M.P. Reynolds and A. Ammar. 2002. Comparison of Leaf, Spike, Peduncle and Canopy Temperature Depression in Wheat under Heat Stress, Field Crops Res. (79): 173-184.
Azimi, A.M., S. Marker and I. Bhattacharjee. 2017. Genotypic and phenotypic variability and correlation analysis for yield and its components in late sown wheat (Triticum
aestivum L.), J. Pharmaco. Phytochem. 6(4): 167-173.
Bahar, B., M. Yildirim and C. Yucel. 2011. Heat and drought resistance criteria in spring bread wheat (Triticum aestivum L.): Morpho-physiological parameters for heat tolerance. Scientific Research and Essay. 6(10):2212-2220.
Bajji, M., K. Jean-Marie and S. Lutts. 2001. The use of the electrolyte leakage method for assessing cell membrane stability as a water stress tolerance test in durum wheat. Plant Growth Regulation. 00: 1–10.
Bakhsh, A., A. Hussain and A.S. Khan. 2003. Genetic studies of plant height, yield and its components in bread wheat. Sarhad J. Agric. 19: 529-534.
Bala, P. and S. Sikder. 2017, Evaluation of Heat Tolerance of Wheat Genotypes through Membrane Thermostability Test, MAYFEB. J. Agri. Sci. 2: 1-6.
149
Balla, K., I. Karsai and O. Veisz. 2009. Analysis of the quality of wheat varieties at extremely high temperatures. In: VIII. Alps-Adria Sceintific Workshop. 27th April – 2nd May 2009, Neum, Bosnia-Herczegovina. 37: 13-16.
Barnabas, B., K. Jager, A. Feher. 2007. The effect of drought and heat stress on reproductive processes in cereals. Plant Cell Environ. 31: 11–38.
Barnard, A.D., M.T. Labuschagne and H.A. Van-Niekerk. 2002. Heritavility estimates of bread wheat quality traits in the western cape province of South Africa. Euphytica. 127: 115–122.
Behl, R .K., H. S. Nainawatee , and K. P. Singh. 1993. “High temperature tolerance in wheat”. In: Intl Crop Sci. Crop Science Society of America, USA.
Bhesaniya, S.V. 2005. Effect of high temperature on biochemical changes in different genotypes of wheat (Triticum aestivum L.). M. Sc. Thesis (Unpublished). Junagadh Agricultural University, Junagadh. Gujarat, India.
Bhutta, M.A., S. Azher and M.A. Chowdhry. 1997. Combining ability studies for yield and its components in spring wheat (Triticum aestivum L.). J. Agric. Res. 35: 353-9.
Bhutto, A.H., A.A. Rajpar, S.A. Kalhoro, A. Ali, F.A. Kalhoro, M. Ahmed, S. Raza and N.A. Kalhoro. 2016. Correlation and Regression Analysis for Yield Traits in Wheat (Triticum aestivum L.) Genotypes. Natural Science. 8:96-104.
Bilge, B., M. Yildirim, C. Barutcular, I. Genc. 2008. Effect of Canopy Temperature Depression on Grain Yield and Yield Components in Bread and Durum Wheat, Not. Bot. Hort. Agrobot. Cluj. 36 (1): 34-37.
Blum, A. 1988. Heat tolerance. In: Plant breeding for stress environments. CRC Press. Inc., Boca Raton, Florida, USA.
Blum, A. and A. Ebercon. 1981. Cell membrane stability as a measure of drought and heat tolerance in wheat. Crop Sci. 21:43-47.
Blum, A., N. Klueva and H.T. Nguyen. 2001, Wheat cellular thermotolerance is related to yield under heat stress. Euphytica. 117: 117–123.
Blumenthal, C., F. Bekes, P.W. Gras, E.W.R. Barlow and C.W. Wrigley. 1995. Influence of wheat genotypes tolerant to the effects of heat stress on grain quality. Cereal Chem. 72: 539-544.
150
Bokszczanin KL and S. Fragkostefanakis. 2013. Perspectives on deciphering mechanisms underlying plant heat stress response and thermotolerance. Front Plant Sci. 4:315– 335.
Borghi, B. and M. Perenzin. 1994. Diallel analysis to predict heterosis and combining ability for grain yield, yield components and bread making quality in bread wheat (Triticum
aestivum L.). Theor. Appl. Genet. 89: 975–981.
Braun, H.J., G. Atlin and T. Payne. 2010. Multi-location testing as a tool to identify plant response to global climate change. In: Reynolds, CRP. (ed.). Climate change and crop production, CABI, London, UK.
Bray, E. A. 2002. Classification of genes differentially expressed during water-deficit stress in Arabidopsis thaliana: an analysis using Microarray and differential expression data. Ann. Bot. 89: 803-811.
Broschat, T.K. 1979. Principal Component Analysis in Horticultural Research. Hort. Sci. 14: 114-117.
Carceller, M., P. Prystupa and J. H. Lemcoff. 1999. Remobilization of proline and other nitrogen compounds from senescing leaves of maize under water stress. J. Agron. Crop Sci. 183: 61-66.
Chaman, S., S.K. Gupta and D.R. Satija. 2005. Genetic architecture for some quality traits in wheat (T. aestivum L.). Indian J. Genet. Plant Breed. 65 (4): 278–80.
Cheema, N.M., M. Ihsan, M.A. Mian, G. Rabbani, M.A. Tariq and A. Mahmood. 2007. Gene action studies for some economic traits in spring wheat. Pak. J. Agri. Res. 20:99-104.
Chen, X.Y., Q. Sun and C.Z. Sun. 2000. Performance and evaluation of spring wheat heat tolerance. J. China. Agri. Uni. 5(1): 43-49.
Chowdhry, M.A. and B. Ahmad. 1990. Combining ability in a seven parent diallel cross of spring wheat. Pak. J. Sci. Res. 42: 18–24.
Chowdhry, M.A., G. Taqi and N.M. Cheema. 1991. Correlation analysis and path co-efficient for grain yield and yield components in bread wheat. J. Agric. Res. 29: 151–8.
Chowdhry, M.A., M. Iqbal, G. M. Subhani and I. Khaliq. 2001. Heterosis, inbreeding depression and line performance in crosses of Triticum aestivum. Pak. J. Biol. Sci. 4: 56-58.
151
Chowdhry, M.A., M.A. Chaudhry, S.M.M. Gilani and M. Ahsan. 2001. Genetic control of some yield attributes in bread wheat. Pak. J. Biol. Sci. (4): 980-982.
Chowdhry, M.A., M.S. Saeed, I. Khaliq and M. Ahsan. 2005. Combining ability analysis for some polygenic traits in a 5 × 5 diallel cross of bread wheat (Triticum aestivum L.). Asian J. Pl. Sci. 4: 405–408.
Chowdhry, M.A., M.T. Mahmood, N. Mahmood and I. Khaliq. 1996. Genetic analysis of some drought and yield related characters in Pakistani spring wheat varieties. Wheat Inform. Ser. 82: 11-18.
Chowdhury, S.I and I.F. Wardlaw. 1978. The effect of temperature on kernel development in cereals. Aust. J. Agric. 29: 205-23.
Christiansen, M.N. 1978. The physiology of plant tolerance to temperature extremes. p. 173-191. In G.A. Jung (ed.) Crop tolerance to suboptimal land conditions. Am. Soc. Agron. Madison. WI.
Christou, A., P. Filippou, G.A. Manganaris and V. Fotopoulos. 2014. Sodium hydrosulfide induces systemic thermotolerance to strawberry plants through transcriptional regulation of heat shock proteins and aquaporin. BMC Plant Biol. 14:42.
Ciuca, M. and E. Petcu. 2009. SSR markers associated with membrane stability in wheat (Triticum aestivum L.). Rom. Agric. Res. 26: 21–24.
Clarke, J.M., R.M. De Pauw, T.M. Townley- Smith. 1992. Evaluation of methods for quantification of drought tolerance in wheat. Crop Sci. 32:728-732.
Claussen, W. 2005. Proline as a measure of stress in tomato plants. Plant Sci. 168:241-248.
Corral, L.R. 1983. Influence of competition on combining ability estimates and subsequent prediction of progeny in wheat (Triticum aesivum L. em Thell). Dis. Abst. Int. B., 43: 3132 B (Pl. Br. Abst., 53: 7921; 1983).
Cossani, C.M. and M.P. Reynolds. 2012. Physiological traits for improving heat tolerance in wheat. Plant physiol. 160: 1710-1718.
Costa, R., N. Pinheiro, A.S. Almeida, C. Gomes, J. Coutinho, J. Coco and A. Costa. 2013. Effect of sowing date and seeding rate on bread wheat yield and test weight under Mediterranean conditions. Emir. J. Food Agric. 25 (12): 951-961.
152
Curtis, B.C. 2002. Wheat in the world. In: Bread Wheat Improvement and Production (Eds. B. C. Curtis, S. Rajaram and H. Gómez Macpherson). Food and Agriculture Organization of the United Nations. Rome, Italy. p. 1–17.
Dalrymple, D.G. 1986. Development and spread of high-yielding wheat varieties in developing countries. Bureau for Science and Technology Agency for International Development Washington. D.C.
Dawson, I.A. and I.F. Wardlaw. 1989. The tolerance of wheat to high temperatures during reproductive growth, Booting to anthesis. Aust J. Agri. Res. 40: 965- 980.
Dewey, J.R. and K.H. Lu. 1959. A correlation and path coefficient analysis components of crested wheat grass seed production. Agron. J. 51: 515-518.
Dhadhal, B., K. Dobariya, H. Ponkia and L. Jivani. 2008. Gene action and combining ability over environments for grain yield and its attributes in bread wheat (Triticum aestivum
L.). Int. J. Agri. Sci. 4(1):66-72.
Dhanda, S.S. and G.S. Sethi. 1998. Inheritance of excised-leaf water loss and relative water content in bread wheat (Triticum aestivum). Euphytica. 104: 39-47.
Dhanda, S.S. and R. Munjal. 2009. Cell membrane stability: Combining ability and gene effects under heat stress conditions. J. Cereal Res. Commun. 37(3): 409-417.
Dhanda, S.S., R. Munjal. 2012. Heat tolerance in relation to acquired thermotolerance for membrane lipids in bread wheat. Field Crops Res. 135:30–37.
Dhayal, L.S. and E.V.D. Sastry. 2003. Combining ability in bread wheat (Triticum aestivum
L.) under salinity and normal conditions. Indian J. Genet. 63: 69-70.
Dias, A.S., A.S. Bagulho and F.C. Lidon. 2008. Ultrastructure and biochemical traits of bread and durum wheat grains under heat stress. Braz. J. Plant Physiol. 20(4): 323-333.
Diaz-Espejo, A., M.V. Cuevas, M. Ribas-Carbo, J. Flexas, S. Martorell, J. E. Fernández. 2012. The effect of strobilurins on leaf gas exchange, water use efficiency and ABA content in grapevine under field conditions. J. Plant Physiol. 169: 379-386.
Dokuyucu, T., A. Akkaya and D. Yigitoglu. 2004. The effect of different sowing dates on growing periods, yield and yield components of some bread wheat (Triticum aestivum L.) cultivars grown in the East- Mediterranean region of Turkey. J. Agron. 3(2): 126-130.
153
Doru-Gabriel, E., M. Becheritu, C. Cristian-Florinel. 2017. Prediction Of Drought Resistant Lines Of Winter Wheat Using Canopy Temperature Depression And Chlorophyll Content Analizis. Agro-life Sci. J. 6:104-111.
Dotlacil, L., J. Hermuth, Z. Stehno, and M. Maner. 2000. Diversity in European winter wheat landraces and obsolete cultivars. Czech J. Genet. Plant Breed. 36(2): 29-36.
Drikvand, R.. E. Farshadfar and F. Nazarian. 2005. Genetic study of some morpho-physiological traits in bread wheat lines under dry land conditions using diallel crossing. Seed and Plant. 4 (20): 429-444.
El-Hossary, A.A., M.E. Riad, Nagwa, R. Abd El-Fattah and M. A. Hassan. 2000. Heterosis and combining ability in durum wheat. Proc. 9th Conf. Agron., Minufiya Univ. 1(2): 101-117.
Elsayed, S., M. Elhoweity, H.H. Ibrahim, Y.H. Dewir, H.M. Migdadi and U. Schmidhalter. 2017. Thermal imaging and passive reflectance sensing to estimate the water status and grain yield of wheat under different irrigation regimes, Agric. Water Manag. (189): 98–110.
Epure, Doru-Gabriel, M. Becheritu, C. Cristian-Florinel. 2017, Prediction Of Drought Resistant Lines Of Winter Wheat Using Canopy Temperature Depression And Chlorophyll Content Analizis. Agro-life Sci. J. 6.104-111.
F. Álvaro, J. Isidro, D. Villegas, L.F. García Del Moral and C. Royo, 2008 Breeding effects on grain filling, biomass partitioning, and demobilization in Mediterranean durum wheat,” Agron. J. 100: 361–370.
FAO. 2015. FAOSTAT. Online statistical database. (available at http://faostat.fao.org). Farhan, A., Irfan Ahmed, S., Hidayat, U. R., Mohammad, N., Durrishahwar, Muhammad, Y.
K., Ihteram, U. and Jianbing, Y. 2012. Heterosis for Yield and Agronomic Attributes in Diverse Maize Germplasm. Aust. J. Crop Sci. 6: 455-462.
Farooq, J. and I. Khaliq. 2004. Estimation of heterosis and heterobeltiosis of some quantitative characters in bread wheat. Asian J. Pl. Sci. 3(4): 508-511.
Farooq, J., I. Khaliq, M. Akbar, M. Kashif and S. Mahpara. 2013. Hybrid vigor studies for different yield contributing traits in wheat under normal and heat stress conditions. Comun. Sci. 4: 139-152.
Farooq, M., H. Bramley, J.A. Palta, K.H.M. Siddique. 2011. Heat stress in wheat during reproductive and grain-filling phases. Crit. Rev. Plant Sci. 30, 491-507.
154
Farshadfar, E., F. Rafiee and H. Hasheminasab. 2013. Evaluation of genetic parameters of agronomic and morpho-physiological indicators of drought tolerance in bread wheat (Triticum aestivum L.) using diallel mating design. Aus. J. Crop Sci. 7: 268-275.
Farshadfar, E., Ghanadha, J. Sutka and M. Zahravi. 2001. Generation mean analysis of drought tolerance in wheat (Triticum aestivum L.). Acta Agron. Hung. 49: 59-66.
Ferris, R., R.H. Ellis, T.R. Wheeler and P. Hadley. 1998. Effect of high temperature stress and anthesis on grain yield and biomass of field-grown crops of wheat. Ann.Botany.82: 631-639.
Fokar, M., A. Blum, and N.T. Nguyen. 1998. Heat tolerance in spring wheat. II. Grain filling, Euphytica, 104: 9–15.
Fonseca, S. and F.L. Patterson. 1968. Hybrid vigour in seven parental diallel cross in common wheat. (Triticum aestivum L.) Crop Sci., 8: 85-88.
Foulkes, M. J., J. W. Snape, V. J. Shearman, M. P. Reynolds, O. Gaju and R. S. Bradley. 2007. Genetic progress in yield potential in wheat: recent advances and future prospects. J. Agric. Sci. 145,17–29
Freeman, G.F. 1919. Heredity of quantitative characters in wheat. Genetics. 4: 1-93.
Gami, R.A., C.J. Tank, S.S. Patel, R.M. Chauhan and H.N. Patel. 2011. Combining ability analysis for grain yield and quality component traits in durum wheat (Triticum durum
Desf.). Res. on Crops, 12 (2): 502-504.
Ghatak, A., P. Chaturvedi and W. Weckwerth, 2017. Cereal Crop Proteomics: Systemic Analysis of Crop Drought Stress Responses towards Marker-Assisted Selection Breeding. Front. Plant Sci. 8:757.
Godfray, H.C.J., J.R. Beddington, I.R. Crute, L. Haddad, D. Lawrence, C. Toulmin. 2010. Food security: the challenge of feeding 9 billion people. Sci. 327: 812–818.
Golparvar, A.R., A. Ghasemi-Pirbalouti and H. Madani. 2006. Genetic control of some physiological attributes in wheat under drought stress conditions. Pak. J. Bio. Sci., 9: 1442-1446.
Golparvar, A.R., O. Lotfifar and S. Mottaghi. 2011. Diallel analysis of grain yield and its components in bread wheat genotypes under drought stress conditions. Plant. Prod. Tech., 11(1): 51-61.
155
Gong, M., B. Chen, Z.G. Li, L.H. Guo. 2001. Heat-shock-induced cross adaptation to heat, chilling, drought and salt stress in maize seedlings and involvement of H2O2. J. Plant Physiol. 158: 1125-1130.
Gooding, M.J., R.H. Ellis, P.R. Shewry and J.D. Schofield. 2003. Effects of restricted water availability and increased temperature on the grain filling, drying and quality of winter wheat. J. Cereal Sci., 37: 295–309.
Gorjanovic B. M., M. M. N., N. Sad, Kraljevic-Balalic. 2007. Inheritance of plant height, spike length and number of spikelets per spike in durum wheat. Plants Genet Breed 112: 27–33.
Gorjanovic, B. and M.K. Balalic. 2005. Inheritance of plant height and spike length in wheat. Genetika, 37: 25–31
Gouda, K., U. Kage, H.C. Lohithaswa, B.G. Shekara. 2013. Combining Ability Studies in Maize (Zea Mays L.). Molecular Plant Breed., 3(14): 116-127.
Griffing,. 1956. Concepts of general and specific combining ability in relation to diallel crossing system. Aust. J. Biol. Sci. 9: 463-493.
Gupta, N.K., S. Gupta and A. Kumar, 2001. Effect of water stress on physiological attributes and their relationship with growth and yield of wheat cultivars at different stages. J. Agron. Crop Sci., 186: 55-62.
Guttieri M. J., J.C. Stark, K. Brien, E. Souza. 2001. Relative sensitivity of spring wheat grain yield and quality parameters to moisture deficit. Crop Sci. 41:327–335
Hakim, M.A., A. Hossain., J.A.T.D. Silva, V.P. Zvolinsky and M.M. Khan. 2012. Yield, protein and starch contents of twenty wheat (Triticum aestivum L.) genotypes exposed to high temperature under late sowing conditions. J. Sci. Res.. 4(2): 477-489.
Hamada, A. A.; H. L. Hendawy and M. A. H. Megahed, 2002. General and specific combining ability and its interactions with two plant densities for yield and yield components, protein content and total carbohydrates in bread wheat. Annals of Agric. Sci., Moshtohor, 40(2): 803 – 829.
Haq, W., M, Munir and Z. Akram. 2010. Estimation of interrelationships among yield and yield related attributes in wheat lines. Pak. J. Bot., 42: 567-573.
156
Harer P. N. and D. R. Bapat, Line × tester analysis of combining ability in grain Sorghum. J Maharastra Agric Univ. 1982; 7:230-232.
Hasanuzzaman, M., K. Nahar, M.M Alam, R. Roychowdhury and M. Fujita. 2013. Physiological, biochemical, and molecular mechanisms of heat stress tolerance in plants. Int. J. Mol. Sci. 14, 9643–9684.
Hasnain, Z., G. Abbas, A. Saeed, A. Shakeel, A. Muhammad, M.A. Rahim, 2006. Combining ability for plant height and yield related traits in wheat (Triticum aestivum L.). J. Agric. Res. 44: 167-1175.
Hassan G, F. Mohamma, S. S. Afridi and I. Khalil. 2007. Combining ability in the F1 generations of diallel cross for yield and yield components in wheat. Sarhad J Agri. (4): 937-94.
Heidari, B., A. Rezai, and S.A.M.M. Maibody. 2006. Diallel analysis for the estimation of genetic parameters for grain yield and grain yield components in bread wheat. J. Sci. Techno. Agricul. Natural Res., 10 (2): 121-40.
Hossain, A., M. Sarker, M. Saifuzzaman, J.A. Teixeira da Silva, M.V. Lozovskaya and M.M. Akhter. 2013. Evaluation of growth, yield, relative performance and heat susceptibility of eight wheat (Triticum aestivum L.) genotypes grown under heat stress. Int. J. Plant Prod., 7(3): 615-636.
Houghton, J.T., G.J. Jenkin and J.J. Ephramus. 1990. Climate change: the IPCC Scientific assessment Cambridge University Press, New York
Howarth, C.J. 2005. Genetic improvement of growth and survival at high temperature In: Ashraf, M., Harris, P.J.C. (Eds.), Abiotic Stresses: Plant Resistance through Breeding and Molecular Approaches. Howarth Press Inc., New York, pp. 277-300.
Hussain, M., A.S. Khan, I. Khaliq, and M. Maqsood. 2012. Correlation studies of some qualitative and quantitative traits with grain yield in spring wheat across two environments. Pak. J. Agri. Sci., 49(1): 1-4.
Ibrahim, A., and J.S. Quick. 2001. Genetic control of High temperature tolerance in wheat as measured by membrane thermal. Crop Sci., 41:1405–7.
Iftikhar, R., I. Khaliq, M. Ijaz and M.A.R. Rashid. 2012. Association analysis of grain yield and its components in Spring Wheat (Triticum aestivum L.). J. Agric. and Environ. Sci. 12: 389-392.
157
Ijaz, U., Smiullah and M. Kashif. 2013. Generation means analysis for five physiological traits of bread wheat under rainfed condition. Universal J. Plant Sci. 1: 21-26.
Inamullah, F. Mohammad and G. Hassan. 2005. Genetics of important traits in bread wheat using diallel analysis. Sarhad J. Agric., 21: 617–622.
Iqbal, M.M., 2007. Combining ability analysis in wheat. Pakistan Journal of Agricultural Sciences 44, 1-5.
Islam, M. A., N. C. Barma, D. M. A. Hakim, and D. K. R. Sarker. 2011. Genetic Variability and Selection Response of heat tolerance through Membrane thermostability in Spring wheat (Triticum aestivum L.) ”. Bangladesh J. Pl. Breed. Genet., 23(2):15- 22.
Ivanovska, S., C. Stojkovski, L. Marinkovic. 2000. Inheritance mode and gene effect on spikelets number per spike in wheat. Macedonian Agri. Rev., 47(1/2):1–8.
Jag, S., L. Khant and R.P. Singh. 2003. Winter and spring wheat: An analysis of combining ability. Cereal Res. Com., 31: 347-354.
Jain S. K. and E. V. D. Sastry. 2012. Heterosis and combining ability for grain yield and its contributing traits in bread wheat (Triticum aestivum L.). RRJAAS, vol. 1, pp. 17–22, 2012.
Jatav, M., S.K. Jatav and V.S. Kandalkar. 2014. Combining ability and heterosis analysis of morpho-physiological characters in wheat. Ann. Plant Soil Res., 16: 79-83.
Jatoi, W.A., M.J. Baloch, M.B. Kumbhar and M.I. Keerio. 2012. Heritability and correlation studies of morpho-physiological traits for drought tolerance in spring wheat. Pak. J. Agri. Agril. Engg. Vet. Sci. 28: 100-114.
Jin, Z., Z. Wang, Q. Ma, L. Sun, L. Zhang, Z. Liu, D. Liu, X. Hao and Y. Pei. 2017. Hydrogen sulfide mediates ion fluxes inducing stomatal closure in response to drought stress in Arabidopsis thaliana. Plant Soil. 419: 141-152
Jones, P.D., M. New, D.E. Parker, S. Mortin, I.G. Rigor. 1999. Surface area temperature and its change over the past 150 years. Rev. Geophys., 37, 173–199.
Joshi, S.K., S.N. Sharma, D.L. Singhania and R.S. Sain. 2004. Combining ability in the F1 and F2 generations of diallel cross in hexaploid wheat (Triticum aestivum L. em. Thell). Hereditas. 141:115-121.
158
Ju, C.Z., Z.S. Wu, W.L. Quan and M. Fang. 2005. Effect of fertilization on the canopy temperature of winter wheat and its relationship with biological characteristics. Acta Ecol. Sin. 25(1): 18-22.
Kahrizi, D., K. Cheghamirza, M. Kakaei, R. Mohammadi, and A. Ebadi. 2010. Heritability and genetic gain of some morphophysiological variables of durum wheat (Triticum
turgidum var. durum). African J. Biotech. 9:4687-4691.
Kapoor, E., S.K. Mandal T. and Dey. 2011. Combining ability analysis for yield and yield contributing traits in winter and spring wheat combinations. J. Wheat Res., 3(1): 52-58.
Karimizadeh, R. and M. Mohammadi. 2011, Association of canopy temperature depression with yield of durum wheat genotypes under supplementary irrigated and rainfed conditions, Aust J Crop Sci., 5(2):138-146.
Kashif, M. and I. Khaliq. 2004. Heritability, correlation and path coefficient analysis for some metric traits in wheat. Int. J. Agric. Biol., 6(1): 138-142.
Kaur, V., R.K. Behl, T. Shinano and M. Osaki. 2008. Interacting Effects of High Temperature and Drought Stresses in Wheat Genotypes under Semiarid Tropics- An Appraisal, TROPICS, 17(3): 225-234.
Kempthorne, O., 1957. An introduction to Genetic Statistics. John willy and Sons, Inc., New York.
Khaliq, I., N. Parveen, M.A. Chowdhry. 2004. Correlation and Path Coefficient Analyses in Bread Wheat. Int. J. Agrıc. Bıo., 6(4):633–635.
Khan F.U. and F. Mohammad. 2016. Application of Stress Selection Indices for Assessment of Nitrogen Tolerance in Wheat (Triticum Aestivum L.), J. Anim. Plant Sci. 26(1): 201-210.
Khan, A.A., N.C.D. Barma, M.M. Hasan, M.A. Alam and M.K. Alam. 2014. Correlation study on some heat tolerant traits of spring wheat (Triticum aestivum L.) under late sowing conditions. J. Agric. Res. 52(1): 11-23.
Khan, A.S. and A. Rizwan. 2000. Combining ability analysis of physio-morphological traits in wheat (Triticum aestivum L.). Int. J. Agri. Biol., 2(1): 77-79.
Khan, A.S., M. Khan, R. Kashif and T.M. Khan. 2000. Genetic analysis of plant height, grain yield and other traits in wheat (Triticum aestivum L.). Int. J. Agric. Biol. 2: 129-132.
159
Khan, M. F., Khan, M. K. and Mushtaq, Kazmi, 2004. Genetic variability among wheat cultivars for yield and yield components under the agro-ecological condition of district rawalakot azad Kashmir, Pakistan. Sarhad J. of Agric., 20 (3): 391-394
Khan, M.A., N. Ahmad, M. Akbar, A. Rehman and M.M. Iqbal. 2007. Combining ability analysis in wheat. Pak. J. Agric. Sci., 44: 1-5.
Khan, M.K.R. and A.S. Khan, 1999. Graphical analysis of spike characters related to grain yield in bread wheat (Triticum aestivum L.). Pak. J. Bio. Sci., 2: 340-343.
Khan, N.I. and M.A. Bajwa, 1989. Potential of hybrid wheat in Punjab. Sarhad J. Agri., 5: 381-386.
Khan, S., U., Jalal-Ud-Din, A. Gurman, R. Qayyum and H. Khan, 2013. Heat Tolerance Evaluation of Wheat (Triticum aestivum L.) Genotypes Based on Some Potential Heat Tolerance Indicators, J. Chem. Soc. Pak., 35(3): 647-653.
Khan, S.U., J.U. Din, A. Qayyum, N E. Jan and M.A. Jenks, 2015. Heat Tolerance Indicators In Pakistani Wheat (Triticum Aestivum L.) Genotypes, Acta Bot. Croat., 74 (1): 109–121.
Khodadadi, M., M.H. Fotokian and M. Miransari. 2011. Genetic diversity of wheat (Triticum
aestivum L.) genotypes based on cluster and principal component analyses for breeding strategies. Aust. J. Crop Sci., 5:17-24.
Khodarahmpour, Z., R. Choukan, M.R. Bihamta, E.M. Hervan. 2011. Determination of the best heat stress tolerance indices in maize (Zea mays L.) inbred lines and hybrids under Khuzestan province conditions. J. Agric. Sci. Tech., 13:111-121.
Kirby, E.J.M., M. Appleyard and 0. Fellowes. 1985. Variation in development of wheat and barley in response to sowing date and variety. J. Agric. Sci. 104: 383-396.
Knobel, H. A., M.T. Labuschange and C.S. Derenter. 1997. The expression of heterosis in the F1 generation of a diallel cross of diverse hard red winter wheat genotypes. Cereal Res., Comm. 25: 911-915.
Koumber, R.M., I.M.A.EL-Beially and G.A.EL-Shaarawy. 2006. Study of genetic parameters and path coefficients for some quantitative characters in wheat under two levels of nitrogen feretilizer . Al-Azhar J. Agric. Res.(43): 99-122
Kraic, F., J. Mocak, T. Rohacik and J. Sokolovicova. 2009. Chemometric characterization and classification of new wheat genotypes. Nova Biotech. 9: 101-106.
160
Kraljevic-Balalic, M., D. Stajner and O. Gasic. 1982. Inheritance of grain proteins in wheat. Theor. Appl. Genet. 63:121-124
Krystkowiak, K., T. Adamski, M. Surma and Z. Kaczmarek, 2008. Relationship between phenotypic and genetic diversity of parental genotypes and the specific combining ability and heterosis effects in wheat (Triticum aestivum L.). Euphytica, 165: 419-434.
Kumar, A. and S. Sharma. 2007. Genetics of excised-leaf water loss and relative water content in bread wheat (Triticum aestivum L.). Cereal Res. Commun. 35: 43-52.
Kumar, A., V. Mishra, R.P. Vyas and V. Singh. 2011. Heterosis and combining ability analysis in bread wheat (Triticum aestivum L.). J. Plant Breed. Crop Sci., 3(10): 209–17.
Kumar, N., B.S. Khatkar and R. Kaushik. 2013. Effect of reducing agents on wheat gluten and quality characteristics of flour and cookies. Annals Univer Dunarea de Jos of Galati - Food Tech 37(2):68–81.
Kumar, R. R., S. Goswami, K.S. Sharma, K. Singh, K.A. Gadpayle, N. Kumar, G.K. Rai, M. Singh and R.D. Rai. 2012. Protection against heat stress in wheat involves change in cell membrane stability, antioxidant enzymes, osmolyte, H2O2 and transcript of heat shock protein. Int. J. of Plant Phys. and Biochem. 4(4), 83-91.
Kumar, S. and D.K. Ganguli. 1993. Heterosis and inbreeding depression in bread wheat. In heterosis breeding in crop plants–theory and application: short communications: symposium, Ludhiana, India; Crop Improvement Society of India: 62-63.
Larik, A.S., A.R. Mahar, A.A. Kakar and M.A. Shafkh. 1999. Heterosis, Inbreeding Depression and Combining Ability in Triticum Aestivum L. Journal of Plant Genetics, 25, 455-450.
Li, L.Z., D.B. Lu and D.Q. Cui. 1991. Study on the combining ability for yield and quality characters in winter wheat. Acta Agric. University Henanensis, 25: 372–8.
Lobell, D.B., M.B. Burke, C. Tebaldi, M.D. Mastrandrea, W.P. Falcon and R.L. Naylor. 2008. Prioritizing climate change adaptation needs for food security in 2030. Science 319: 607–610.
Longnecker, N., E.J.M. Kirby and A. Robson. 1993. Leaf emergence, tiller growth, and apical development of nitrogen-deficient spring wheat. Crop Sci. 33: 154-160.
161
Lopes, M.S. and M.P. Reynolds. 2012. Stay-green in spring wheat can be determined by spectral reflectance measurements (normalized difference vegetation index) independently from phenology. J. Exp. Bot. 63: 3789–3798.
Lysa, L.L. 2009. Identification of the genetic controlling system of the protein content in the grain of winter wheat. Cytol. Genet. 43:258-261.
Mahantashivayogayya K, R. Hanchinal and P. Salimath. 2010. Combining ability in dicoccum wheat. Karnataka J. Agri. Sci., 17(4): 781-786
Mahboob, A.S., M.A. Arain, S. Khanzada, M.A. Naqvi, M.U. Dahot and N.A. Nizami. 2005. Yield and quality parameters of wheat genotypes as affected by sowing date and temperature stress. Pak. J. Bot., 37(3): 575-584.
Mahmood, N. and M.A. Chowdhry. 2002. Ability of bread wheat genotypes to combine for high yield under varying sowing conditions. J. Genet. Breed., 56: 119–25.
Majeed S., M. Sajjad, S. H. Khan. 2011. Exploitation of non-additive gene actions of yield traits for hybrid breeding in spring wheat. J. Agric. Social Sci., 7: 131–135.
Majoul, T., E. Bancel, E. Triboi, J.B. Hamida and G. Branlard. 2004. Proteomic analysis of the effect of heat stress on hexaploid wheat grain: characterization of heat-responsive proteins from total endosperm. Proteomics 4(2): 505-513.
Malik, M. F.A., S. Iqbal and S. Ali. 2005. Genetic behavior and analysis of quantitative traits in five wheat genotypes. Journal of Agriculture and Social Sciences 1(4): 313-315.
Maqbool, R., M. Sajjad, I. Khaliq, A. Rehman, A.S. Khan and S.H. Khan. 2010. Morphological diversity and traits association in bread wheat. J. Agric. Environ. Sci. 8: 216-224.
Mather, K.V. and J.L. Jinks. 1982. Introduction to biometrical genetics. Chapman and Hall Ltd., London.
Meena, B.S., and E.V.D. Sastry. 2003. Combining ability in bread wheat (Triticum aestivum
L.). Ann. J. Bio. 19(2): 205-208.
Menon, U. and S.N. Sharma. 1997. Genetics of yield determining factors in spring wheat over environments. Indian J. Genet. 57: 301-306.
Min, Y., B.P. Qin, W. Ping, M.L. Li, L.L Chen, L.T. Chen, A.Q. Sun, Z.L. Wang and Y.P. Yin. 2016. Foliar application of sodium hydrosulfide (NaHS), a hydrogen sulfide
162
(H2S) donor, can protect seedlings against heat stress in wheat (Triticum aestivum L.). J. Integr. Agric. 15: 2745-2758.
Mishra, P. C., T. B. Singh, D. P. Nema, 1994. Combining ability analysis of grain yield and some of its attributes in bread wheat under late sown condition. Crop Res. Hisar. 7(3):413–423.
Mishra, P.C., T.B. Singh, O.P. Singh and S.K. Jain. 1994. Combining ability analysis of grain yield and some of its attributes in bread wheat under timely sown condition. Int.
J. Trop. Agric., 12: 188–194.
Mohammad, F., H. Deniel, K. Shahzad and H. Khan. 2001. Heritability estimates for yield and its components in wheat. Sarhad J. Agric. 17(2): 227-234.
Mohammadi M., R. Karimizadeh, N. Sabaghnia and M.K. Shefazadeh. 2012, Effective application of canopy temperature for wheat genotypes screening under different water availability in warm environments, Bulgarian J. Agric. Sci. 18 (6): 934-941.
Mohsen A. A. A., S.R. Abo-Hegazy and M.H. Taha. 2012. Genotypic and Phenotypic Correlations among Grain Yield and Yield Components In Ten Egyptian Bread Wheat Genotypes. Egypt Journal of Plant Breeding. 15(5):43-58.
Mossua, A.M. and A.A. Morad. 2009. Estimation of combining ability for yield and its components in bread wheat (Triticum aestivum L.) using Line x Tester analysis. Minufiya J. Agric. Res., 34 (3), 1191-1205.
Muller, J. 1991. Determining leaf surface area by means of a wheat osmoregulation water use: the challenge. Agric. Meterolo. 14: 311-320.
Munir M., M. Chowdhry and T.A. Malik. 2007. Correlation Studies among Yield and its Components in Bread Wheat under Drought Conditions. Inter. J. Agric. Bio. 1560–8530/09–2–287–290.
Munjonji L., K.K. Ayisi, B. Vandewalle, I. Dhau, P. Boeckx and G. Haesaert. 2017. Yield Performance, Carbon Assimilation and Spectral Response of Triticale to Water Stress, Expl. Agric., 53 (1), 100–117.
Nasri, R., A. Kashani, F. Paknejad, S. Vazan and M. Barary. 2014. Correlation, path analysis and stepwise regression in yield and yield component in wheat (Triticum aestivum l.) under the temperate climate of Ilam province, Iran. Ind. J. Fund. Appl. Life Sci. 4(4): 188-198.
163
Nawaz, A., M. Farooq, S.A. Cheema and A. Wahid. 2013. Differential response of wheat cultivars to terminal heat stress. Int. J. Agric. Biol. 15: 1354‒1358.
Nazari, L. and H. Pakniyat. 2010. Assessment of drought tolerance in barley genotypes. J. Appl. Sci. 10: 151-156.
Nisar, A., M. A. Chowdhry, I. Khaliq and M. Maekawa. 2007. The inheritance of yield and yield components of five wheat hybrid populations under drought conditions. J. Agri. Sci., 8 (2): 53-59.
Noorka, I. R. and S. Tabasum 2015. Dose-response behavior of water scarcity towards genetical and morphological plant traits in spring wheat (Triticum aestivum L.) Pak. J. Bot. 47(3):1225-1230.
Ortiz-Ferrara, G., R. Rajaram and M.G. Mosaad. 1993. Breeding strategies for improving wheat in heat- stressed environments. p. 24-32. In D.A. Saunders and G.P. Hettel (ed). Wheat in heat stressed environments: Irrigated, Dry Areas and Rice-Wheat farming systems. UNDP/ARC/BARI/CIMMYT, Mexico.
Ozakan, H., T. Yagbasanlar and I. Gene. 1997. Genetic analysis of yield components, harvest index and biological yield on bread wheat under medetiterranean climatic conditions. Rachi, 16: 49-52.
Packer, D. J. 2007. Comparing the Performance of F1 Testers Versus Their Inbred Line Parents in Evaluating Experimental Sorghum R and B Lines in Testcrosses. Vol. Master of science plant breeding: Brigham Young University.
Padhar, P. R., R.B. Madaria, J.H. Vachhani and K.L. Dobariya. 2010. Combining ability analysis of grain yield and its contributing characters in bread wheat (Triticum
aestivum L. em. Thell) under late sown condition. Intl. J. Agrl. Sci., 6(1): 267-272.
Parry M. A., M.P. Reynolds, M.E. Salvucci, C. Raines, P.J. Andralojc, X-G. Zhu, G.D. Price, A.G. Condon, R.T. Furbank. 2011. Raising yield otential of wheat. II. Increasing photosynthetic capacity and efficiency. J. Exp. Bot. 62: 453–467.
Pask, A., A.K. Joshi, Y. Manes, I. Sharma, R. Chatrath G.P. Singh. 2014. A wheat phenotyping network to incorporate physiological traits for climate change in South Asia. Field Crops Res. 168:156–167.
Pastore, A, S.R. Martin, A. Politou, K.C. Kondapalli and T. Stemmler. 2007. Unbiased cold denaturation: low- and high-temperature unfolding of yeast frataxin under physiological conditions. J Am Chem Soc. 129:5374–5375.
164
Pierre, C. S., J. Crossa, Y. Manes and M.P. Reynolds, 2010. Gene action of canopy temperature in bread wheat under diverse environments. Theor. Appl. Genet. 120: 1107–1117.
Pinto, R. S., Molero G. and Renyolds M. P., 2017, Identification of Heat Tolerant Wheat Lines Showing Genetic Variation in Leaf Respiration and Other Physiological Traits, Euphytica, 213:76.
Pittock, B. 2003. Climate Change: An Australian Guide to the Science and Potential of Impacts. Department for the Environment and Heritage, Australian Greenhouse Office, Canberra, ACT.
Porter, J.R. 2005. Rising temperatures are likely to reduce crop yields. Nature, 436: 174.
Powers, Leroy. 1944. An expansion of jones theory for the explanation of heterosis. Amer. Nat., 78: 275-280.
Przuli, N. and N. Mladenov. 1999. Inheritance of grain filling duration in spring wheat. Plant Breed 118:517-521.
Qari, M.S., N.I. Khan and A.G. Khan. 1986. Combining ability analysis for yield and yield components in spring wheat diallel crosses. Pakistan J. Agric. Res., 22: 95–9.
Quarrie S.A., J. Stojanovic and S. Pekic. 1999. Improving drought tolerance in small-grain cereals: A case study, progress and prospects. Plant Growth Regulation. 29: 1-21.
Rad, M.R.N., M.A. Kadir, M.R. Yusop, H.Z. Jaafar and M. Danaee. 2013. Gene action for physiological parameters and use of relative water content (RWC) for selection of tolerant and high yield genotypes in F2 population of wheat. Austr. J. Crop Sci. 7: 407-413.
Radmehr, M., G.A.L. Aeyneh and A. Naderi. 2004. A study on source-sink relationship of wheat genotypes under favorable and terminal heat stress conditions in Khuzestan. Iranian J. Crop Sci. 6(2): 101-113.
Rahim, M.A., A. Salam., A. Saeed and A. Shakeel. 2006. Combining ability for flag leaf area, yield and yield components in bread wheat. J. Agric. Res. 44(3): 175-180.
Rahman, M.A., N.A. Siddquie, M.R. Alam, A.S.M.M.R. Khan and M.S. Alam. 2003. Genetic analysis of some yield contributing and quality characters in spring wheat (Triticum aestivum L.). Asian J. Plant Sci., 2: 277–282
165
Rajara, M.P. and R.V. Maheshwari. 1996. Combining ability in wheat using line × tester analysis. Madras Agric. J., 83: 107–110.
Ram K., R. Munjal, Sunita and N. Kumar. 2017. Combine Effects of Drought and High Temperature on Water Relation Traits in Wheat Genotypes under Late and Very Late Sown Condition, Int. J. Curr. Microbiol. App. Sci. 6(8): 567-576.
Ramani, H.R., M.K. Mandavia, R.A. Dave, R.P. Bambharolia, H. Silungwe and N.H. Garaniya. 2017. Biochemical and physiological constituents and their correlation in wheat (Triticum aestivum L.) genotypes under high temperature at different development stages. Int. J. Plant Physiology and Biochemistry. 9(1): 1-8.
Rasul, I., A.S. Khan and Z. Ali. 2002. Estimation of heterosis for yield and some yield components in bread wheat. Int. J. Biol. Sci. 4(2): 214-216.
Rebetzke, G.J., A.G. Condon, R.A. Richards and G.D. Farquhar. 2003. Gene action for leaf conductance in three wheat crosses. Crop Pasture Sci. 54: 381-387.
Reynolds, M. P., M. Belota., M. I. B. Delgado, I. Amani and R. A. Fischer. 1994. Physiological and morphological traits associated with spring wheat yield under hot, irrigated conditions. Aust. J. Pl. Physiol. 21: 717-730.
Reynolds, M.P, D. Bonnett, S.C. Chapman, R.T. Furbank, Y. Manès, D.E. Mather, M.A.J. Parry. 2011. Raising yield potential of wheat. Overview of a consortium approach and breeding strategies. J. Exp. Bot. 62: 439–452.
Richards R. A., 1996. Defining selection criteria to improve yield under drought. Plant Growth Regulation. 20: 157-166.
Rodriguez M, E. Canales, O. Borras-Hidalgo. 2005. Molecular aspects of abiotic stress in plants. Biotechnol Appl. 22:1–10.
Rong, G.Z., L.Q. Xie and J.T. Gu. 2001. Heredity study on grain protein content of different type winter wheat varieties. Journal of Agricultural University of Hebei 24:9-12.
Rosegrant, M.W. and M. Agcaoili. 2010. Global food demand, supply and price prospectus to 2010. International Food Policy Research Institute, Washington, D. C. USA.
Rosyara, U.R., D. Vromman and E. Duveiller. 2008. Canopy temperature depression as an indication of correlative measure of spot blotch resistance and heat stress tolerance in spring wheat. J. Plant Pathol. 90(1): 103-107.
166
Saadalla, M. M., J. F. Shanahan and J. S. Quick. 1990. Heat tolerance in winter wheat.II. Membrane thermostability and field performance. Crop Sci. 30:1248-1251.
Saeed A, Chaudhry MA, Saeed N, Khaliq I, Johar MZ. 2001. Line × tester analysis for some morpho-physiological traits in bread wheat. Int. J. Agric. Biol., 3: 444-447.
Said, A.A. 2014. Generation mean analysis in wheat (Triticum aestivum L.) under drought stress conditions. Annals Agri. Sci. 59: 177-184.
Sairam R. K., G.C Srivastva and DC Saxena 2000. Increased antioxidant activity under elevated temperature: a mechanism of heat stress tolerance in wheat genotypes. Biologia-Plantarum (Czech Republic.) 43(2):245-251.
Sairam, R.K. and G.C. Srivastava. 2001. Water Stress Tolerance of Wheat (Triticum
aestivum L.): Variations in Hydrogen Peroxide Accumulation and Antioxidant Activity in Tolerant and Susceptible Genotypes. J. Agron. Crop Sci. 186: 63-70.
Sajnani, D.N. 1968. Studies of hybrid vigour and combining ability in wheat diallel crosses. Diss. Absts. 28(68): 4641 B.
Sakin, M.A., C. Akinci, O. Duzdemir and E. Donmez. 2011. Assessment of genotype x environment interaction on yield and yield components of durum wheat genotypes by multivariate analyses. Afr. J. Biotech. 10: 2875-2885.
Saleem, S.A. and S.A. El-Sawai. 2006. Line × tester analysis for grain yield and its components in bread wheat. Minufiya J. Agri. Res. 31(1):75-87.
Saleem, U., I. Khaliq, T. Mahmood and M. Rafique. 2006. Phenotypic and correlation coefficients between yield and yield components in wheat. J. Agric. Res., 44:1-6.
Sandeep, K., M. Singh and R.S. Verma. 2000. Studies on heat tolerance in wheat genotypes. Gujrat Agri. Uni Res. J.26 (1): 16-22.
Sanjeev, R., S. Prasad and M.A. Billore. 2005. Combining ability studies for yield and its attributes in Triticum durum. Madras Agric. J. 92(1-3):7-11.
Sareen, S., B.S. Tyagi, V. Tiwari and I. Sharma. 2012. Response Estimation of Wheat Synthetic Lines to Terminal Heat Stress Using Stress Indices. J. Agri. Sci. 4: 97 – 104.
Sarkar, D.D., D.J. Joardar and M. Hossain, 1987. Combining ability analysis in wheat. Envir.
and Ecol., 5: 808–19.
167
Savchenko, G.E., Klyuchareva, E.A., Abrabchik, L.M. and Serdyuchenko, E.V. (2002). Effect of periodic heat shock on the membrane system of etioplasts. Russ. J. Plant Physiol., 49: 349–359.
Savicka M, Skute N (2012). Some morphological, physiological and biochemical characteristics of wheat seedling Triticum aestivum L. organs after high-temperature treatment. Ekologija 58(1):9-21.
Savvides, A., S. Ali, M. Tester, V. Fotopoulos. 2016. Chemical priming of plants against multiple abiotic stresses: Mission possible? Trends Plant Sci. 21: 329-340.
Saxena, J., Minaxi and A. Jha. 2014. Impact of a phosphate solubilising bacterium and an arbuscular mycorrhizal fungus (Glomus etunicatum) on growth, yield and P concentration in wheat plants. CLEAN – Soil, Air, Water, 42: 1248–1252.
Schoffl, F., R. Prandl and A. Reindl. 1999. Molecular responses to heat stress. In: Shinozaki, K., Yamaguchi-Shinozaki, K. (Eds.), Molecular Responses to Cold, Drought, Heat and Salt Stress in Higher Plants. R.G. Landes Co., Austin, Texas, pp. 81–98.
Semenov M.A, P. Stratonovitch, F. Alghabari, M.J. Gooding. 2014. Adapting wheat in Europe for climate change. Journal of Cereal Science 59, 245–256.
Senapati, N., S.K. Swain and N.C. Patnaik. 1994. Genetics of yield and its components in wheat. Madras Agric. J., 81: 502–4.
Shah, S. M. A., M. S. Swati, T. Shahzad and I.H. Khalil. 2004. Heterosis for yield and related traits in spring wheat. Sarhad J. Agi. 20(4): 537-542.
Shahab, S., H. Mehdi, S.H. Mehdi, M. Mani and K.M. Seyed. 2011. Genetic Study of Some Agronomic Traits in Maize Via Testcross Analysis in Climatic Conditions of Khuzestan-Iran. World Appl. Sci. J. 15: 1018-1023.
Shahid M., F. Mohammad, M. Tahir. 2002. Path coefficient analysis in wheat. Sarhad J. Agrirc. 18: 385-388.
Shahzad, K., Z. Mohy-ud-din, M.A. Chowdhry and D. Hussain, 1998. Genetic analysis for some yield traits in (Triticum aestivum L.) Pakistan J. Biol. Sci., 1: 237–40.
Shanahan, J. F., I. B. Edwards, J. S. Quick and J. R. Fenwick. 1990. Membrane thermostability and heat tolerance of spring wheat. Crop Sci. 30: 247-251.
Sharma, J. R. (2006). Statistical and biometrical techniques in plant breeding. New Delhi. India: New age international.
168
Sharma, P.K., P.K. Gupta, and H.S. Balyan, 1998. Genetic diversity in a large collection of wheats (Triticum spp.). Ind. J. Genet. Pl. Breed. 58(3): 271-278.
Sheikh, S. and I. Singh, 2000. Combining ability analysis in wheat plant characters and harvest index. Intl. J. Tropic. Agri. 18(1):29-37.
Shpiler, L., and A. Blum. 1991. Heat tolerance for yield and its components in different wheat cultivars. Euphytica. 51: 257-263.
Shushay, W., Abrha, H. Z., Zeleke and Gissa, D. W. 2013. Line × tester analysis of maize inbred lines for grain yield and yield related traits. Asian J. Plant Sc. Res. 3(5): 321-342.
Sial, M.A., M.A. Arain, S.K.M.H. Naqvi, M.U. Dahot and N.A. Nizamani, 2005. Yield and quailty paramertes of wheat genotypes as influenced by sowing dates and high temperature stress. Pak. J. Bot. 37(3): 575-584.
Singh, A., A. Kumar, E. Ahmad and J.P. Jaiswal, 2012. Combining ability and gene action studies for seed yield, its components and quality traits in bread wheat (Triticum
aestivum L. em Thell.). Electronic J. Plant Breed., 3(4): 964-972.
Singh, H. 2002. Genetic architecture of yield and its associated traits in bread wheat. PhD Thesis, Rajasthan Agriculture Univ., Bikaner, Rajasthan, India
Singh, H., S.N. Sharma and R.S. Sain, 2004. Heterosis Studies for Yield and Its Components in Bread Wheat over Environments. Hereditas, 141: 106-114.
Singh, H., S.N. Sharma, and R.S. Sain, 2011. Combining Ability for Some Quantitative Characters in Hexaploid Wheat (Triticum aestivum L. em. Thell). Procedings of 4th International Crop Science Congress, Brisbane, 26 September-1 October 2004.
Singh, I. and R. S. Paroda. 1985. Partial diallel analysis for combining ability in wheat. Indian J. Genet. 45: 492–498.
Singh, K., S.N. Sharma and Y. Sharma, 2011. Effect of high temperature on yield attributing traits in bread wheat. Bangladesh J. Agril. Res. 36(3): 415-426.
Singh, R.K., and B.D. Chaudhary, 1979. Biometrical Methods in Quantitative Genetic Analysis. Kalyani Publishers, New Delhi.
169
Singh, R.M., L.C. Prasad, M.Z. Abdin, A.K. Joshi, 2007. Combining ability analysis for grain filling duration and yield traits in spring wheat (Triticum aestivum L. em. Thell.). Genetics Molec. Bio., 30: 411-416.
Singh, S.K., 2003. Gene action and combining ability in relation to development of hybrids in wheat. Farm Sci. J., 12 (2):118–21.
Singh, S.P., L.R. Singh, S. Devendra and K. Rajendra. 2003. Combining ability in common wheat (Triticum aestivum L.) grown on sodic soil. Progressive Agri., 3: 78-80.
Singh, S.P., M. Singh H.K. Yadav, 2006. Diallel analysis for seed yield and its component traits in Cuphea procumbens. Genetika. 38(1):9-22
Singh, V., R. Krishna, S. Singh and P. Vikram, 2008. Combining Ability and Heterosis Analysis for Yield Traits in Bread Wheat (Triticum aestivum). Indian J. Agric. Sci., 82: 56-63.
Skider S., Ahmed J U., Hossain T., 2001. Heat Tolerance and Relative Yield Performance of Wheat Varieties under Late Seeded Conditions. Indian J. Agric. Res. 35(3):141-148.
Spiertz, J.H.J., R.J. Hamer, H. Xu, C. Primo-Martin, C. Don and P.E.L. Putten, 2006. Heat stress in wheat (Triticum aestivum L.): Effects on grain growth and quality traits. Eur. J. Agron., 25: 8-–95.
Sprague, G.F. and L. A. Tautum, 1942. General Vs Specific Combining Ability in Single Crosses of Corn. American Soc. Agron., 34: 923-932.
Srivastava, M. K., D. Singh, and S. Sharma, 2012. Combining ability and gene action for seed yield and its components in bread wheat (Triticum aestivum L. Em. Thell]. Electronic J. Pl. Bred., 3: 606-611.
Steel, R.G.D., J.H. Torrie and D.A. Dickey. 1997. Principles and procedures of statistics: A biometrical approach, 3rd ed. McGraw Hill Book Co., New York.
Subhani, G.M. and M.A. Chowdhry. 2000. Correlation and path coefficient analysis in bread wheat under drought stress and normal conditions. Pak. J. Biol. Sci. 3: 72-77.
Subhani, G.M., M. A. Chowdhry and S. M. M. Gillani. 2000. Manifestation of heterosis in bread wheat under irrigated and drought conditions. Pak. J. Biol. Sci. 3(6): 971-974.
170
Sullivan, C.Y. and W.M. Ross. 1979. Selecting for drought and heat resistance in grain sorghum. In Mussell, H. and Staples, R (eds) Stress physiology in Crop plants. New York, USA: John Wiley.
Sultana, S. R., A. Ali, A. Ahmad, M. Mubeen, M. Zia-Ul-Haq, S. Ahmad, S. Ercisli, and H. Z. E. Jaafar. 2014. Normalized difference vegetation index as a tool for wheat yield estimation: A case study from Faisalabad, Pakistan. Sci. World J., 8 pages.
Tosun, M., I. Demir, C. Server and A. Gurel, 1995. Line × Tester analysis in some wheat crosses. Anadolu, 5: 52–63.
Tripathy, Rojalin, S.S. Ray and A.K. Singh. 2008. Analysing the Impact of Rising Temperature and CO2 on Growth and Yield of Major Cereals Crops using Simulation Model. Paper presented at Workshop on Impact of Climate Change on Agriculture, 17-18 December, 2009, organised by Space Applications Centre (ISRO) and Indian Society of Remote Sensing, Ahmedabad.
Tsegaye, D., T. Dessalegn, Y. Dessalegn and G. Share, 2012. Genetic variability, correlation and path analysis in durum wheat germplasm (Triticum durum Desf). Agric. Res. Rev., 1(4): 107-112.
Udaykumar, K., M.C. Wali, M. Deepa, M. Laxman and G. Prakash, 2014. Combining Ability Studies for Yield and Its Related Traits in Newly Derived Inbred Lines of Maize (Zea Mays L.). Molecular Plant Breed., 4(8): 71-76.
Ullah, I. 2004. Inheritance of important traits in bread wheat using diallel analysis. PhD. Thesis, KPK Agri. Univ., Peshawar, Pakistan.
Ullah, K., N.U. Khan, S.J. Khan, I.M. Khan, I.U. Khan, S. Gul, Habib-Ur-Rahman and R, Ullah, R.U. Khan. 2014. Cell Membrane Thermo-Stability Studies through Joint Segregation Analysis in Various Wheat Populations. Pak. J. Bot. 46(4): 1243-1252.
Ullah, S., A.S. Khan, A. Raza and S. Sadique. 2010. Gene action analysis of yield and yield related traits in spring wheat (Triticum aestivum). Int. J. Agric. Biol. 12: 125-128.
Usman, M. 1998. Line × tester analysis for combining ability in wheat. M.Sc. Thesis, Deptt. Pl. Br. Genet. Univ. of Agri., Faisalabad.
Vanpariya, L.G., V.P. Chovatia, and D.R. Mehta. 2006. Combining ability studies in bread wheat (Triticum aestivum L.) National J. Plant Improv. 8: (2) 132-137.
171
Vara, P.V., M. Djanaguiraman. 2014. Response of floret fertility and individual grain weight of wheat to high temperature stress: sensitive stages and thresholds for temperature and duration. Funct. Plant Bio. 41; 1261–1269.
Wahid, A., S. Gelani, M. Ashraf and M.R. Foolad. 2007. Heat tolerance in plants: an overview. Environ. Exp. Bot. 61: 199–223.
Wang, Y, Z. Yang, Q. Zhang, J. Li. 2009. Enhanced chilling tolerance in Zoysia matrella by pre-treatment with salicylic acid, calcium chloride, hydrogen peroxide or 6-benzylaminopurine. Biol. Plant. 53: 179 –182.
Wang, Z.Y. and S.Y. Lu. 1991. Genetic analysis of quality and yield characters of wheat. J. of Agri. Uni. Hebei., 14:1-5.
Ward, J.H. 1963. Hierarchical grouping to optimize an objective function. J. Am. Stat. Assoc. 58(30): 236-244.
Webber, H., P. Martre, S. Asseng, B. Kimball, J. White, M. Ottman, G.W. Wall, G.D. Sanctis, J. Doltra, R. Grant, B. Kassie, A. Maiorano, J. E. Olesen, D. Ripoche, E.E. Rezaei, M.A. Semenov, P. Stratonovitch, F. Ewerta. 2017. Canopy temperature for simulation of heat stress in irrigated wheat in a semi-arid environment: A multi-model comparison. Field Crops Res. 202: 21–35.
Weigand, C.L. and J.A. Cuellar. 1981. Duration of grain filling and kernel weight of wheat as affected by temperature. Crop Sci. 21: 95-101.
Yadav, M.S., I Singh, S.K. Sharma, K.P. Singh 1988. Combining ability in bread wheat. (Triticum aestivum L.). Int. J. Trop. Agri. 6:102-105.
Yao, J.B., H.X. Ma, L.J. Ren, P.P. Zhang, X.M. Yang, G.C. Yao, P. Zhang, P. Zhou. 2011. Genetic analysis of plant height and its components in diallel crosses of bread wheat (Triticum aestivum L.). Aust. J. Crop Sci. 5: 1408–1418.
Yildirim, M., B. Bahar, M. Koç and C. Barutçular. 2009. Membrane Thermal Stability at Different Developmental Stages of Spring Wheat Genotypes and Their Diallel Cross Populations, Tarim Bilimleri Dergisi, 15(4): 293-300.
You, L., M.W. Rosegrant, S. Wood and D. Sun. 2009. Impact of growing season temperature on wheat productivity in China. Agricultural and Forest Meteorology. 149: 1009–1014.
Zubair, M., A.R. Chowdhry, I.A. Khan and A. Bakhah. 1987. Combining ability studies in bread wheat (Triticum aestivum L.). Pak. J. Bot. 19: 75–80.
172
Appendix- I. Mean data of Morpho–physiological and quality traits studied in lines, testers and their crosses under normal conditions.
Genotype
CMT NDVIV
NDVIG
CTV CTG RWC PH FLA PL SL FTP DTH DTM SPS GPS TGW GYP PRO MOI STR ASH GLU TW