ASSESSMENT OF HETEROTIC EFFECTS IN F1 HYBRIDS OF COTTON (GOSSYPIUM HIRSUTUM L.)
Keywords:heterosis, heterobeltiosis, yield and fibre traits, upland cotton
The present research was conducted to determine the mean performance of parental lines and heterotic effects in F1 hybrids of upland cotton. Ten parental genotypes were included in the present study CRIS-134, NIAB-78, AA-802, CIM-496, CRIS-534, BH-160, IR-1524, MG-06, IR-3701 and FH-113. All the ten parents were randomly crossed and ten F1 hybrids were developed for evaluation. The experiment was laid-out in a randomized complete block design with four replications. The mean squares from analysis of variance revealed that parents and F1 hybrids differed significantly for their mean performance regarding all the traits studied, except that hybrids were non-significant for staple length. The importance of heterotic effects was evident from the significant mean squares of parents vs. hybrids. Per se mean performance revealed that F1 hybrids performed better over the parents for all the traits due to manifestation heterotic effects. Nonetheless, among the parents, IR-3701 performed better for setting higher number of bolls, producing more seed cotton yield and ginning higher lint%. While among the hybrids, the crosses CIM-534 x AA-802 produced more sympodial branches per plant, formed higher number of bolls per plant and also gave higher seed cotton yield, yet maximum lint% was given by CIM-496 x MG-06 and longer fibre was measured in BH-160 x IR-1524. The parental performance was not reflected in hybrid combinations; therefore potentiality of parents per se may not be taken as granted for expecting similar performance in the F1 hybrids. The heterotic effects of the hybrids revealed that at least three hybrids viz. CIM-534 x AA-802, NIAB-78 x AA-802 and CIM-496 x MG-06 were identified which exhibited relative heterosis above 100% and heterobeltiosis over 80% for bolls per plant and seed cotton yield. The same hybrids also expressed fair amount of heterosis for lint% and seed index. The high heterotic effects for sympodial branches per plant, number of bolls and seed cotton yield absolutely favour the exploitation of heterosis breeding due to the greater number of favourable dominant and over dominant genes involved at many loci.
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