Effect of pulsing on post harvest life and quality of tuberosecut spikes cv. Prajwal
Homraj Sahare, Alka Singh*, B. K. Dhaduk and S. L. Chawla
Department of Floriculture & Landscape Architecture, ASPEE Collegeof Horticulture and Forestry, Navsari Agriculture University
Navsari, Gujarat-396450
*Corresponding author:[email protected]
ABSTRACT
The present investigation was conducted to study the effect of
growth regulators and antioxidants viz., Thiadizuron(TDZ),
Benzyl adenine (BA), Gibberellic acid (GA3), α-lipoic acid,
CaCl2, BA, along with 15% sucrose as a pulse treatments on
post harvest quality and life of tuberose cut spikes.
Treatments of pulsing with 100mg/l TDZ and 50mg/l α-lipoic
acid +15% sugar significantly improved per cent floret
opening, number of opened florets at one time, vase life and
decreased floret abscission up to 12 days as compared to
control (7 days). Further, similar pulsing treatments improved
physiological parameters like water uptake (ml), retained
higher spikes fresh weight (%) and total dissolved solids in
petals, decreased electrolyte leakage in petals tissue and
exhibited excellent overall quality as compared to control.
Key words: Tuberose, Thiadizuron, GA3, α-lipoic acid,CaCl2, floret
opening, vase life
INTRODUCTION
Tuberoses cut spikes are highly popular owing to its
sweet fragrance, sturdiness and compact floret arrangement.
However, there are frequent price gluts and fluctuations in
the Indian markets. Tuberose cut flowers are also perishable
in nature with vase life of 5-6 days. Further, postharvest
problem of incomplete floret opening is observed in tuberose
cut spikes. Improvement in post harvest quality and vase life
in tuberose spikes with sucrose as pulsing has earlier been
suggested. In addition to sucrose, chemicals like α lipoic
acid, CaCl2, Thiadizuron, GA3, citric acid, etc in preservative
solution have been known to delay senescence and improve
postharvest quality in cut flowers (Halevy and Mayak, 1981,
Singh et al., 2008, Macnish et al., 2010). Further, inclusion
of growth regulators in the sucrose pulse solution have been
known to improve postharvest quality of cut flowers like
gladiolus, tuberose, rose etc. Hence, the research work was
carried out to study the effect of pulsing treatments
constituting of some growth regulators, antioxidants along
with sugar on flower quality in terms of floret opening,
abscission and vase life in tuberose.
MATERIALS AND METHODS
The experiment was conducted at the Department of
Floriculture and landscape Architecture, ASPEE College of
Horticulture and Forestry, NAU, Navsari Gujarat, during 2010 -
2011. The fresh tuberose cut spikes were harvested at early
morning hours when lower most two florets opened and then
basal part of stem kept in bucket containing water. The
maximum and minimum laboratory day and night temperature
fluctuated between 20 -250C and 17- 200C, respectively during
the course of investigation. The experiment was laid out in
the completely randomized design consisting of seven
treatments including control viz., T1- GA3 100 mg/lit + Sucrose
15%, T2-TDZ 100 mg/lit + Sucrose 15%, T3- BA 100 mg/lit +
Sucrose 15%, T4- α Lipoic acid 50 mg/lit + Sucrose 15%, T5-Cacl2
100 mg/ lit + Sucrose 15%, T6-Sucrose 15%, T7-Control (with
distilled water). The treatments were repeated thrice and 10
spikes were used in each treatment.
RESULTS AND DISCUSSION
All treatments as pulse improved water uptake and fresh
weight retention in the tuberose cut spikes as compared to
untreated (control). Fresh weigh retention and water uptake
was higher in the pulsed cut spikes over control as recorded
at different interval throughout the vase life period (Fig. 1,
and 2).
Significantly maximum total water uptake (82.45 ml) and
higher per cent fresh weight retention (95.00 %) was observed
in 100 mg/l TDZ +15% sucrose pulse treatment which was followed
by 50 mg/l α-lipoic acid + 15% sucrose treatment (77.25 ml, 91
%) at 6th DAT as compared to control that recorded minimum
total water uptake and per cent fresh weight (41.32 ml and
72.00 %, respectively), as shown in Table 1. Further, higher
total dissolved solids (12.62 0Brix) in petal tissue was also
observed in 100 mg/l TDZ +15% sucrose (T2) treatment which, was
followed by 50 mg/l α- lipoid acid +15% sucrose (T4,
12.180Brix) , 100 mg/l GA3 +15% sucrose i.e. T1 (11.570Brix) and
100 mg/l CaCl2 i.e. T5 (11.370 Brix) treatments (Table 1).
However, a very low total dissolved solid (5.370 Brix) was
observed in control (T7). Higher water uptake and per cent
fresh weight in all pulse treatments might be due to the
normal condition of the petal cells and maintained high level
of carbohydrates as indicated by total dissolve solids in
petals. The higher intake of the sugars in the petal cells is
known to enhance water uptake due to osmotic pull in cut
flowers (Ho and Nicholus, 1975). Further, delayed senescence
with pulse treatments (Indicated by enhance vase life, Table
2) also contributed to increase in total water uptake and
fresh weight retention. Thidiazuron (TDZ, N-phenyl-N_-l,2,3-
thiadiazol-5-ylurea) being a non-metabolizable phenyl-urea
compound with strong cytokinin like activity (Mok et al., 1982)
is known to improve and maintain carbohydrates supply from
leaves to floral organ, necessary for maintaining the flower
metabolism (Reid et al., 2002). α-lipoic acid being an anti-
oxidant and anti-ageing agent as a free radical scavenger,
(Sen and Packer 2000) consequently delayed senescence
(indicated by enhanced vase life) that, further contributed to
increase in total water uptake and spike fresh weight
retention. GA3 has been known to enhance the liposomal
permeability of the cell membrane to glucose (Wood and Pleg,
1974), hydrolyse starch, fructans and sucrose into glucose and
fructose molecules and also known to be involved in
mobilization of stored food, increase water uptake and water
retention capacity in some plant tissues (Toa – Hanzhi et al.,
1995). Similarly, other scientists have also reported
beneficial effects of pulsing with sucrose in combination with
other chemicals on water uptake and fresh weight retention in
tuberose cut spikes (Uthairatanakij et al., 2007, Waithaka et al.,
2001).
Pulse treatments significantly influenced per cent floret
opening, number of florets opened at one time in tuberose cut
spikes and floret abscission (Table 2). Maximum per cent of
floret opening (Fig. 3) and number of opened florets per spike
at one time (82.00 and 7.00, respectively) were observed in
100 mg/l TDZ +15% sucrose treatment, that was at par with
treatment 50 mg/l α- lipoid acid + 15% sucrose (80.67%, 6.00,
respectively) and followed by 10 mg/l GA3 and minimum in
control (55.67%, 2.00). Total number of florets abscised per
spike was also minimized (2.00-2.33 number) in 100 mg/l TDZ or
50 mg/lα- lipoid acid or 100 mg/l GA3 along with 15% sucrose
pulsed cut spikes as compared to control that showed maximum
number of florets abscission per spike (8.00). Floret opening
in general is known to be influenced by petal turgidity,
intact and stabilized cell membrane (Torre et al., 1999) and the
up-regulation of optimum metabolic activities with readily
available carbohydrates (Halevy and Mayak, 1981). Thus,
maintained higher water uptake, petal-sugar status (high TDS
per cent) and improved membrane integrity due to reduced
electrolyte leakage and fresh weight retention with pulse
treatment of TDZ, α-lipoic acid, GA3 and BA in combination with
sucrose improved floret opening percentage. Further, improved
floret opening percentage (as indicated by longer vase life)
along with delayed abscission and senescence and increased
vase life, contributed to increase in number of opened florets
per spikes at one time in the pulsed tuberose cut spikes. Van
der Meuler et al. (2001) and Waithaka et al. (2001) have also
reported influence of carbohydrate content on floret opening
in tuberose and gladiolus. Further, evidence suggests TDZ can
regulate endogenous cytokinin biosynthesis and metabolism and
improve floret opening in cut iris flowers (Macnish et al.,
2010). The stress conditions may promote abscission and
senescence by stimulating the biosynthesis of endogenous
ethylene in some flower species (Borochov et al., 1982.). Thus, α-
lipoic acid being an anti-oxidant and anti-ageing agent as a
free radical scavenger (Khanna et al. 1999) consequently delayed
abscission. Inclusion of TDZ in vase water has been found to
reduce ethylene-mediated flower abscission and senescence on
phlox and lupin stems (Sankhla et al., 2005). Further, master
regulatory role of GA3 on flower development is known well
(Weiss 2000) that may have influenced floret opening and
abscission as earlier observed in gladiolus (Singh et al., 2008).
Similar beneficial effects on improved floret opening have
been reported in gladiolus with α-lipoic acid + sucrose (Sen
and Packer, 2000) and in iris with TDZ, GA3 and sucrose
(Macnish et al., 2010).
Significant influence of pulse treatments on electrolyte
leakage in petal cells and vase life of tuberose cut spikes
was observed (Table 2). The maximum vase life (12 days) and
minimum electrolyte leakage on 5 DAT (25-26 %) was recorded in
tuberose cut spikes pulsed with 100 mg/l TDZ +15% sucrose (T2)
treatment and 50mg/l α- lipoid acid +15% sucrose (T4)
treatments. These treatments were at par and followed by with
treatments 100 mg/l GA3+15% sucrose (T1, 11.67 days, 27.43%),
whereas control cut spikes recorded minimum vase life (7.33
days) and high electrolyte leakage in petal cells (43.19%) on
5 DAT. The leakage of ions is known to coincide with the
decrease in water content of the flower petals and senescence
(Singh et al., 2008). Imbalance of water in cut flowers has been
known to lead early breakdown of plasma membrane which release
the leaches into the interspaces of plant tissue (Bhaskar et al.,
2006). Sucrose has known to stabilize selective permeability
of cell membrane. α- lipoic acid being antioxidant play vital
role in scavenging of membrane-damaging reactive oxygen
species (ROS) and thus, stabilized cell membrane system and
decreased leakage of ions. Further, antioxidant property of
TDZ (Tang and Newton, 2005) and α- lipoic acid (Parker and
Tritschler, 1996) contributed in stabilized cell membrane
structure and thus reduced electrolyte leakage in the petal
tissue. Thus, enhanced vase life of tuberose cut spikes in
these treatments can be attributed to continued and increased
water uptake in the cut spikes, higher retention of fresh
weight and high petal sugar status. Further, reduced water
stress due to high water uptake (Table 1), well established
and stabilized membrane integrity and cellular structure as
indicated by maintained lower electrolyte leakage ultimately
delayed petal senescence and increase the longevity in pulse
treated tuberose cut spikes with TDZ, α-lipoic acid, GA3,
calcium chloride and BA along with sucrose. TDZ being a
phenyl-urea compound and non metabolizable in nature with
strong cytokinin like activity, is known for its remarkable
effects in preventing leaf yellowing and delaying senescence
in tulip and chrysanthemum (Ferrante et al., 2002). Further,
delayed senescence with TDZ has been associated with improved
carbohydrate supply from leaves to floral organs for
maintenance of floral metabolism (Reid et al., 2002). Beneficial
effects of pulsing on vase life in different cut flowers viz.,
with TDZ in tuberose (Uthairatnakij et al., 2007), in iris
(Macnish et al., 2010) and along with GA3 in gladiolus (Singh et al.,
2005) have been reported.
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Figure 1: Effect of pulse treatments on per cent fresh weight
of tuberose cut spikes
Figure 2: Effect of pulse treatments on water uptake in
tuberose cut spikes recorded at different intervals
Figure 3: Effect of pulse treatments on percent per cent bud
opening in tuberose cut spikes
Table 1 Effect of pulse treatments on total water uptake, percent fresh weight and per cent floret oepning, maximumnumber florets opened per spikes at one time of tuberosecut spikes cv. Prajwal
Treatment
Totalwateruptake(ml)
Freshweight of
spike at 6th
at day (%)
Totaldissolvedsolids
(0Brix) at6th DAT
T1-(GA3100 mg/l+15% Sucrose) 63.22 88.00 11.57
T2-(TDZ 100 mg/l +15% Sucrose) 82.45 95.00 12.62T3-(BA 100 mg/l +15 % Sucrose) 67.73 87.00 9.36T4-( α-Lipoic acid 5
mg/l+15%Sucrose)77.25 91.00 12.18
T5- (CaCl2 100 mg/l+15% Sucrose) 67.44 84.00 11.37T6 - (Sucrose 15 %) 56.41 85.00 6.53T7- (Control) 41.32 72.00 5.37S Em + 0.80 1.02 0.12
CD 2.44 3.10 0.38CV% 2.14 2.06 2.18
Table 2 Effect of pulse treatments on total number of florets
abscissed per spikes, electrolyte leakage, total
dissolved solids and vase life of tuberose cut spikes
cv. Prajwal
Treatment
Floretopening
at6th day(%)
Florets
opened/
spikeat onetime
Floretsabscised/spikes
Electrolyte
Leakage(%)
Vaselife
(days)
T1 -(GA3100 mg/l +15%Sucrose) 72.00 4.67 2.33 27.43 11.67
T2 -(TDZ 100 mg/l+15% Sucrose) 82.00 7.00 2.00 25.20 12.00
T3 -(BA 100 mg/l+15 %Sucrose) 76.00 4.00 3.33 30.17 11.67
T4- (α-Lipoic acid 50mg/l+15% Sucrose) 80.67 6.00 2.00 26.20 12.00
T5-(CaCl2 100mg/l+15% Sucrose) 72.67 4.00 3.00 29.89 11.33
T6 -(Sucrose 15 %) 77.33 3.00 4.00 31.57 8.33T7- (Control) 55.67 2.00 8.00 43.19 7.33 S Em + 1.24 0.13 0.18 0.21 0.28CD 3.76 0.38 0.54 0.65 0.85CV% 2.91 4.98 8.76 1.27 4.60