Effect of pulsing on post harvest life and quality of tuberose cut spikes cv. Prajwal

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