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Heterosis and Combining Ability Studies in
Sprouting Broccoli (Brassica oleracea var.
italica Plenck)
Khursheed Habib
Prof. Nazeer Ahmed
Ph.D
2011
Broccoli, Combining ability, Correlation,
Gene action, Heterosis, Variability
ABSTRACT
The present investigation broccoli (Brassica oleracea var. italica Plenck) was undertaken to
obtain information on mean performance, association of yield and other characters contributing to
yield, coefficient of variability, heritability, heterosis, combining ability (general and specific)
together with nature and magnitude of gene action through diallel mating design. The set of 45
crosses along with their ten parents were evaluated at Experimental Block of Division of
Olericulture, SKUAST-K, Shalimar, during Rabi 2008 and 2009 in Randomized Block Design with
three replications. The data was recorded on plant height (cm), plant spread (cm), days to central
head initiation, days to central head harvest, central head diameter (cm), central head length (cm),
number of lateral heads, peduncle length (cm), leaf number, leaf area (cm2), main head yield (g),
lateral head yield (g), total head yield (g), total carotenoids (mg/100g), ascorbic acid (mg/100g),
dry matter content (%). Analysis of variance revealed significant differences among the parents and
their crosses for all the characters in the individual as well as in pooled over environment. Mean
values of parents and crosses indicated parents Palam Kanchan, Palam Samridhi and Green Head
and crosses BI-7042-24 x SH-BR-4, Calaberese Amule x SH-BR-4 and SH-BR-1 x SH-BR-4 to be
superior for most of the traits. Coefficient of variability (GCV and PCV) and heritability in broad
scense was moderate to high for lateral head yield, total head yield, lateral head number, main head
yield and total carotenoides. While for rest of the characters it was low. The expected genetic
advance ranged from 0.84 to 30.68 percent. A positive significant correlation existed between main
head yield, head diameter, lateral head yield, lateral head number and plant spread with total head
yield while it was negative for ascorbic acid, total carotenoides and maturity traits. The variance
due to gca and sca were significant for most of the traits studied indicating significance of both
additive and non-additive gene effects in the inheritance of the traits. The estimates of dominance
variance were higher in magnitude than their corresponding additive genetic variances both in the
individual as well as in data pooled over environments for all the characters, indicating
preponderance of non-additive gene action except for days to central head harvest. Estimates of
average degree of dominance also revealed preponderance of over dominance for all the traits. The
estimates of gca effects revealed that among ten parents the genotypes namely Palam Kanchan,
Palam Samridhi and Green Head are found as best general combiners with high gca effects and per
se performance for yield and most of the yield attributing traits and SH-BR-1 for quality attributes.
Among cross combinations, the crosses like BI-7042-24 x SH-BR-4, Calaberese Amule x SH-BR4, SH-BR-1 X SH-BR-4, were found most heterotic with highly significant sca effects and per se
performance and could be exploited for commercial cultivation.