DIVERGENCE, HETEROSIS AND GENETIC STUDIES IN CUCUMBER (Cucumis sativus L.)
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Date
2018-04
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K.R.C. COLLEGE OF HORTICULTURE COLLEGE OF ARABHAVI (UNIVERSITY OF HORTICULTURAL SCIENCES, BAGALKOT)
Abstract
The investigation on ‘Divergence, heterosis and genetic studies in cucumber (Cucumis sativus L.)’ was undertaken at Vegetable Science Department of Kittur Rani Channamma College of Horticulture, Arabhavi. Genetic variability and diversity were assessed by evaluating 56 genotypes. Out of 18 characters studied genotypic and phenotypic coefficient of variation was highest for average fruit weight and number of fruits per vine. Fruit yield per vine had significant and positive association with vine length, fruit length and average fruit weight both genotypically and phenotypically. Using estimated D2 values 56 genotypes were grouped into 10 clusters. Intra cluster distance was highest in cluster VIII followed by cluster V. The highest inter cluster distance was noticed between cluster IV and VIII followed by Cluster IV and IX.
Heterosis and combining ability were determined using 12 lines and 3 testers and subjected to line x tester analysis. Among 36 hybrids, maximum positive and significant heterosis over best parent and commercial check was noticed in the hybrids ACS12-51 x POI followed by ACS12-51 x B 19. Lines ACS12-51, ACS12-31 and ACS12-29 were identified as good general combiners and two crosses ACS12-13 x B 19, ACS12-48 x BL were good specific combiners.
Generation mean analysis was carried out for three crosses viz., Cross-I (ACS12-29 x BL), Cross-II (ACS12-31 x B 19) and Cross-III (ACS12-51 x POI). Scaling test revealed that presence of epistasis for most of the traits in crosses. Additive (d) gene effect was found significant in all three crosses for vine length, days to first male flowering, number of fruits per vine, average fruit weight and fruit length. Dominance gene effect (h) was found significant for sex ratio (M:F), number of fruits per vine, fruit yield per vine and pericarp thickness in Cross-I and Cross-III. Additive x additive (i) interaction were significant for number of branches per vine, nodes upto first female flower in all the three crosses, for vine length in Cross-II and Cross-III. Additive x dominance (j) gene effects was significant for pericarp thickness and fruit yield per vine in Cross-I. Dominance x dominance (l) gene effects was significant for vine length, number of branches per vine and fruit length in all three crosses.
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TH630
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