Effect of growth regulations on flower and fruit drop in chilli (Capsicum annuum L.)
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Date
2000
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Department of Plant Physiology, College of Agriculture, Vellayani
Abstract
Investigations were carried out at the Department of Plant Physiology,
College of Agriculture, Vellayani during December 1999 to March 2000 to
find the effect of growth regulators viz. IAA, NAA, Triacontanol and GA in
controlling flower and fruit drop in chilli var. ', Jwalasakhi. IAA, NAA and GA
were used at concentrations of 10, 20, 30 and 40 ppm while Triacontanol
was used at 1,2, 3 and 4 ppm. Two controls were also provided, one with
distilled water spray and the other with no spray. Two sprays of growth
regulators were given, one at 20 days after transplanting and the other at 40
days after transplanting. The effect of these growth regulators on
morphological, growth, physiological, biochemical and yield parameters were
also studied.
The growth regulators produced considerable variation with respect to
intensity of flowering, flower drop, fruit set and fruit drop. The flower
production was increased upto 45.5 per cent with IAA 30 ppm. IAA 40 ppm
was most effective in reducing the flower drop by 48.06 per cent increasing
the fruit set by 69.18 per cent when compared to control (water spray). NAA
30 ppm induced earliness in flowering (23.17 days) and GA at 40 ppm
showed the maximum plant height (38.93 cm).
The plants treated with GA 40 ppm showed the maximum leaf area
(478.04 cm2 plant"! ) and leaf area index (0.23). NAA 20 ppm recorded the
highest specific leaf weight (l.30 g m-2)and IAA 30 ppm, the maximum leaf
area ratio (l.08 m-2 g-l). The plants sprayed with Triacontanol 2 ppm showed
the highest crop growth rate (2.24 g m-2 day-I), relative growth rate (0.033
mg g-l day' l ) and root-shoot ratio (0.69). Highest net assimilation rate (0.75
mg cm-2 day-I) was seen in plants sprayed with IAA 20 ppm.
Significant influence of growth regulators was observed In the
physiological and biochemical parameters studied. The highest photosynthetic
rate (28.09 11 mol m-2 s-l) was seen in plants sprayed with IAA 40 ppm. GA
20 ppm recorded the highest transpiration rate (0.74 milli mole m-2 s-l).
Stomatal conductance was maximum (78.0 milli mole m-2 s-l) in control
plants followed by Triacontanol 1 ppm with a value of 70.9 milli mole m-2 s-l.
IAA 30 ppm had a significant role in increasing the photosynthetic pigments
viz., chlorophyll-a content (0.54 mg g fresh weight" 1), chlorophyll-b content
(0.80 mg g fresh weight-I) and total chlorophyll content (1.13 mg g fresh
weight"! ). F oliar sprays of Triacontanol 4 ppm produced the highest protein
content (1.65 mg g-l) in leaves and GA 40 ppm recorded the highest
carbohydrate content (112.50 mg g-l). The proline content of leaves was
. more in Triacontanol 2 ppm sprays. The highest reducing sugar content (9.68
g glucose 100 g-l )of ripe fruits was seen in NAA 20 ppm, carotenoid content
of 2.69 mg 100 s' in IAA 40 ppm sprays and the capsaicin content of 67.52
11 gram gram=! was recorded in IAA 10 ppm treated plants.
Significant effect of growth regulators was seen in the yield parameters
also. The maximum fresh weight (66.11g plant-I) and fruit yield (l83.66g
planr l ) was seen in IAA 20 ppm sprays. The fruit yield was 42.6 per cent
when compared to contro!' Triacontanol 3 ppm recorded the highest dry
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weight (13.22g planr ! ) and germination percentage (87.16) of seeds. The
number of fruits per plant (48.83), thousand seed weight (4.62 g) and harvest
index (0.77) was maximum in foliar sprays of IAA 40 ppm. The maximum
fruit length (7.87cm) was recorded in Triacontanol 2 ppm while NAA 40 ppm
showed the maximum breadth (1. 76 cm) of the fruits.
Correlation studies indicated significant positive association of fruit
yield with number of fruits per plant, harvest index and root shoot ratio. In
terms of net income and benefit-cost ratio, foliar sprays of Triacontanol
1 ppm was the most remunerative. An additional expenditure of Rs. 1210 per
hectare towards the growth regulator showed 51 per cent more yield over
control and thus a greater benefit-cost ratio (1.51).
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