Manipulation of sex expression in bitter gourd (Momordica charantia L.) by plant growth regulators

Abstract

Bitter gourd is considered among the most important medicinal and nutritional vegetable of family Cucurbitaceae. Owing to more male and less female flowers production there is always pragmatic reduction in its yield, which is a stumbling block in the production of bitter gourd. In order to fully exploit its potential and to circumvent barrier in production system of bitter gourd this project was formulated. The project was divided into two studies, study-1 is seed priming for 12 hours while, study-2 is foliar application of four plant growth regulators (PGRs), Ethephon (2-chloroethyl phosphonic acid), Maleic hydrazide (MH), GA3 and CPPU [N-(2-chloro-4-pyridyl)-N-phenylurea] at two leaf stage, along with Faisalabad long and Jaunpuri varieties of bitter gourd in order to evaluate their effect on growth, sex expression and yield. During 1st study, Ethephon at 500 mg L-1 positively affected morphological (vine length, number of primary branches, and number of nodes per unit length of vine), floral (number of days of male and female flowers, total number of male and female flowers and sex ratio), fruit (number of fruits per plant, single fruit weight, fruit length, fruit diameter, average fruit weight per vine, fruit yield per hectare) biochemical (total chlorophyll contents of leaves, reducing, non reducing and total sugars of fruit, total phenolic contents of fruit, super oxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activities of fruit and fruit soluble solids) and seed attributes (number of seeds per fruit and 1000 seed weight) in Faisalabad long cultivar of bitter gourd. Similarly, during foliar application, Ethephon at 500 mg L-1 revealed maximum length of main stem and number of primary branches, while, GA3 at 100 mg L-1 revealed maximum number of nodes per unit length of vine (nodes m-1) and reduction in inter-nodal distance in Faisalabad long. Furthermore, in floral and fruit attributes, Ethephon at 500 mg L-1 in variety Faisalabad long performed better as compared to all other PGRs. However, in biochemical attributes, Ethephon at 500 mg L-1 showed the most significant results of total chlorophyll contents, non reducing sugars and total sugars. Reducing sugars were maximum with foliar application of CPPU at 500 mg L-1 in Faisalabad long. Maximum total phenolic contents were revealed through foliar spray with GA3 at 100 mg L-1 in Faisalabad long. SOD, CAT and POD activities were maximum with MH at 100 mg L-1 in Faisalabad long. While, GA3 at 150 mg L-1 in Jaunpuri cultivar showed maximum fruit soluble solids. Regarding seed quality attributes, maximum number of seeds per fruit and 1000 seed weight was observed when foliar application of GA3 and Ethephon at 200 and 250 mg L-1 in cultivar Faisalabad long. In a nutshell, Ethephon at 500 mg L-1 significantly affected growth, sex expression and fruit yield of Faisalabad long cultivar of bitter gourd.