Genetic variability studies for yield and fruit fly resistance in bitter gourd (Momordica charantia L)

Abstract

A study was undertaken in the Department of Plant Breeding and Genetics, College of Agriculture ,Vellayani during the period 2009-2010 to assess the genetic variability for different yield attributes and resistance to fruit fly in bitter gourd and to identify high yielding genotypes tolerant to fruit fly. To attain these objectives field and laboratory experiments were carried out simultaneously. Of the 29 genotypes evaluated IC-45341 was the early flowering and bearing type. Madhurai local was the genotype having maximum number of fruits per plant. Priya and Bharanikkavu local had maximum fruit length and girth respectively. Kanakakunnu local had maximum fruit weight and yield per plant. Kallukuthiavila local and Madhurai local were the long duration and short duration genotypes respectively. Priyanka had maximum protein content. Changanassery local -1 had maximum TSS, fruit colour and phenol content. IC- 68296 had maximum total sugars, reducing and non reducing sugars. Madhurai local had minimum incidence of fruit fly. Analysis of variance revealed significant differences for all the characters. Genotypic and phenotypic coefficients of variation were high for yield per plant, individual fruit weight, number of fruits per plant, fruit length, fruit girth, protein content, total sugars, reducing sugars, non reducing sugars, fruit colour, crude fibre content, phenol content and incidence of fruit fly. High heritability coupled with high genetic advance were noticed for all characters except days to first harvest, duration and water content which had high heritability and low genetic advance. Correlation studies revealed that out of the 13 significant phenotypic correlation coefficients of yield, twelve were positive and one was negative. Significant and positive correlations were obtained for yield with days to first male and female flower opening, days to first harvest, fruit bearing period, fruit length, fruit girth, individual fruit weight, duration, flesh thickness, incidence of fruit fly, protein content and water content. Significant negative correlations were obtained for incidence of fruit fly with phenol content and number of fruits per plant. Protein content, water content, phenol content and flesh thickness of immature, half mature and full mature fruits had significant correlation with incidence of fruit fly. Path coefficient analysis revealed high direct and positive effects of days to first male flower opening, fruit weight and duration on yield. D2 analysis grouped the 29 genotypes into seven clusters. Individual fruit weight contributed maximum to total divergence followed by flesh thickness, duration, fruit girth and protein content. High yielding genotype, Kanakakunnu local, was grouped into cluster I where as fruit fly resistant genotypes Madhurai local and Changanassery local – 1 were grouped into cluster V and VI respectively. This emphasizes scope for further improvement by selecting donor parents from these clusters. Selection indices revealed that Kanakakunnu local had maximum index value and Madhurai local had minimum index value. Kanakakunnu local, Changanassery local-1 and Madhurai local were identified as potent donors for appropriate breeding program for improving fruit yield and quality character like resistance to fruit fly. As per the techniques and rating system of Nath (1966) the percentage of fruit damage was minimum in Madhurai local and Changanassery local-1 under both natural screening and artificial screening. So these two genotypes were rated as resistant/highly resistant genotypes.