Effect of growth regulators on fruit set and yield of pumpkin (Cucurbita moschata. Poir)

Abstract

An experiment was conducted at the College of Horticulture, Kerala Agriculture University, Vellanikkara during December-April 1983-‘84 to study the effect of six levels of growth regulators viz., alar (100 and 200 ppm), CCC (500 and 1000 ppm) and ethrel (100 and 200 ppm) and of the two different stages of application (four leaf and six leaf stage) on growth, sex-expression, fruit set, yield and quality of two distinct pumpkin genotypes (Cucurbita moschata Poir.) collected from Palghat district of Kerala State. The experiment was laid out in split-plot design with three replications. The effect of plant growth retardant to suppress the luxuriant growth of the crop is further confirmed by the results of the present study. All treatments caused a significant reduction in the length of the main vine and all other vegetative characters under study. There was a drastic reduction in the number of male flowers and an increase in the female flower number, altering an otherwise male dominated sex-ratio of the crop. CCC 1000 ppm was found to be effective in promoting early fruit set and harvest of both the genotypes tried. However there was no significant increase in the number of fruits per plant, average weight of the fruit, flesh thickness and the number of seeds per fruit. CCC treatments followed by alar 200 ppm was found to be the most effective in increasing the yield. Type T1 gave maximum yield with CCC 1000 ppm whereas type T2 responded well to CCC 500 ppm concentration. CCC 1000 ppm however caused a slight reduction in the yield of this genotype. There was also a slight increase in the carotene content with CCC treatments. Type T1 recorded a slight decrease in yield with both ethrel (100 and 200 ppm) treatments. No significant difference was noticed when growth regulator sprays were given at two different stages (four leaf and six leaf) of the crop. The study thus also proved that the response of pumpkin to growth regulators sprays is governed by the genotype and the concentration of the growth regulators used.