GENETIC VARIABILITY AND DIVERGENCE STUDIES IN CUCUMBER (Cucumis sativus L.)
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Date
2019-12-16
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Division of Vegetable Science and Floriculture Sher-e-Kashmir University of Agricultural Sciences & Technology of Jammu Main Campus, Chatha, Jammu
Abstract
The present investigation entitled “Genetic variability and divergence studies in cucumber (Cucumis sativus L.)” comprising of 21 diverse local genotypes was carried out at Vegetable Experimental Farm-I, Division of Vegetable Science and Floriculture, FOA, Chatha, SKUAST-J, during the year 2018-2019. The experiment was laid out in Randomized Complete Block Design with three replications. The observations were recorded on various characters namely,days to 50% flowering, days to first female flowering, node number at which first female flower appears, days to first harvest, fruit length (cm), fruit diameter (cm), average fruit weight (g), number of fruits/vine, vine length (m), number of seeds/fruit, 1000 seed weight (g), total soluble solids (◦brix), fruit yield/vine (kg), fruit yield/hectare (q/ha), powdery mildew incidence, fruit fly incidence and organoleptic test.The Analysis of Variance revealed significant differences among the genotypes for all the characters studied.The Phenotypic Coefficient of Variance (PCV) and Genotypic Coefficient of Variation (GCV) were high for number of fruits/vine and fruit yield/vine.High estimates of heritability wererecorded for number of seeds/fruit, fruit yield/vine, average fruit weight, vine length, 1000 seed weight, fruit length, number of fruits/vine, fruit diameter, days to first harvest, days to 50 % flowering, node number at which first female flower appears, total soluble solids and days to first female flowering. High genetic gain as percentage of mean was observed for fruit yield/vine, number of fruits/vine, number of seeds/fruit, node number at which first female flower appears, 1000 seed weight, fruit yield/hectare, fruit length, average fruit weight and fruit diameter.The traits viz. number of fruits/vine,fruit yield/vine gave high heritability, genetic advance and GCV indicating that these are controlled by additive gene action and could be improved by direct selection. In general,genotypic correlations were higher in magnitude than phenotypic ones. Fruit yield/hectare showed negatively significant correlation with days to 50 % flowering while positive significant correlation with days to first harvest and number of fruits/vine. Maximum positive direct effect towards fruit yield/hectare was exerted by days to first female flowering followed by fruit yield/vine, total soluble solids, days to 50% flowering, number of seeds/fruit and number of fruits/vine.
MahalanobisD2 clustering analysis grouped 21 genotypes in to 4 different clusters namely,Cluster I had maximum number of genotypes (16), followed by Cluster II (3 genotypes). Cluster III and IV comprised of one genotype each. Maximum intra cluster distance was observedin cluster I whilemaximum inter cluster distance was found between cluster II and cluster III revealing sufficient genetic diversity for selecting superior and diverse parents for heterosis breeding and improvement programme.Twenty-one genotypes were screened against the incidence of powdery mildew and fruit fly under natural epiphytotic conditions which depicted that minimum powdery mildew incidence was recorded in genotype Cucumber Selection-18 followed by Cucumber Selection-3whileminimum fruit fly incidence was observed in Cucumber Selection-15 followed by Cucumber Selection-18.Genotype namely Cucumber Selection-9 was found to be best for overall acceptabilityon the basis of sensory evaluation based on hedonic scale.
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