Heterosis, combining ability and gene action studies in early cauliflower (Brassica oleracea var. botrytis L.)
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Date
2012-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present investigation in a 7x7 half diallel of cauliflower (Brassica oleracea var. botrytis L.) including 21 F1s and 7 parents was undertaken with a view to estimate the extent of genetic variability, correlation, path analysis, manifestation of heterosis, general and specific combing ability effects and genetic components of variance indicating different type of gene effects. The experiment was laid down in randomized block design with 3 replications at the vegetable research centre of GBPUAT&T, Pantnagar during cropping season of 2010 and 2011. The observations were recorded on 17characters namely Plant height(cm), plant diameter(cm), number of leaves per plant, leaf length(cm), leaf width(cm),days to curd initiation, days to 50 per cent curd initiation, days to curd maturity, gross plant weight(g), marketable weight(g), net curd weight(g), curd diameter(cm), curd depth(cm), stalk length(cm), curd index (cm2 ), harvest index (%) and curd yield (q/ha). The data were subjected to appropriate statistical analysis.
The analysis of variance revealed highly significant differences among genotypes for all the attributes under study. High heritability coupled with moderate genetic advance as per cent of mean was recorded for the plant height indicating importance of additive gene action controlling this character.
The F1 cross INB-21-2 X PCF-84 was best heterotic combination for gross plant weight, marketable curd weight, net curd weight, curd diameter, curd depth, curd size index and curd yield per hectare (q) over better parent. PG-3 X PES-1 was best heterotic cross over standard parent. Other combinations showing significant values for all type of heterosis were INB-21-2 X PCF-27, PG-3 X PCF-84, PCF-27 X PES-1 and INB-21-2 X PES-1.The findings of present investigation revealed that the parent PG-3 (stalk length), INB-21-2 (days to curd initiation and days to curd maturity), PCF-27 (plant height, days to curd initiation, days to 50 per cent initiation, days to curd maturity, gross plant weight, marketable curd weight, net curd weight, curd diameter, curd depth, curd index, harvest index and curd yield), PES-1 (leaf length, leaf width, days to curd initiation, days to 50 per cent curd initiation, days to curd maturity, gross plant weight, marketable curd weight, net curd weight, net curd weight, curd depth, curd index, harvest index and curd yield), PCF-108 (plant height, plant diameter, number of leaves per plant, leaf length, leaf width and stalk length) and DC-98-4-2 (plant diameter, curd diameter and days to 50 per cent curd initiation) were promising donor based on general combining ability. The crosses INB-21-2 X PCF-84 and PG-3 X PES-1 showed maximum sca effects hence, these crosses may be advanced to recover desirable segregants for the improvement of yield and yield contributing characters
Result on the genetic component of variance showed the preponderance of non additive genetic variance and over dominance for all the characters and the value of (KD/KR) indicated the presence of dominant alleles in excess for all the traits. Preponderance of dominance variance for most of the traits needs to be exploited for the development of improved cauliflower cultivars.
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Thesis-PhD
Keywords
heterosis, combining ability, gene action, cauliflowers, horticulture, Brassica oleracea var. Botrytis, path analysis, correlation, yield components