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Asian Journal of Plant Sciences

Year: 2003  |  Volume: 2  |  Issue: 6  |  Page No.: 485 - 490

Behaviour of Some Polygenic Characters in Cotton (Gossypium hirsutum L.)

Muhammad Zaffar Iqbal and Muhammad Aslam Nadeem

Abstract

Six quantitative traits were studied by analyzing F1 data derived from a 6 x 6 diallel cross. Two traits i.e., yield of seed cotton and number of bolls per plant showed complete adequacy of additive dominance model. Two characters lint percentage and seed index partially passed the assumption for diallel analysis. Both additive and dominance (non-additive) variations were observed in the diallel cross population for yield of seed cotton per plant, boll numbers per plant, lint percentage and seed index. The magnitude of non-additive genetic components were greater than additive for yield of seed cotton per plant and seed index, whereas the value of additive genetic components were higher than dominance for boll numbers per plant. The substantial contribution to dominance was due to heterogeneity of loci for the four traits analysed in this experiment. The recessive alleles were in excess in the parents for yield of seed cotton per plant, number of bolls per plant, lint percentage and seed index. The operation of over-dominance was estimated for yield of seed cotton per plant and seed index whereas partial dominance was observed for boll number per plant. The lint percentage possessed complete dominance in this set of diallel cross. The ratio of positive and negative alleles at the loci exhibiting dominance were in equal proportion in these parents for yield of seed cotton per plant and number of bolls per plant whereas asymmetrical distribution of negative and positive alleles among the parents was suggested for lint percentage and seed index. The level of dominance was not constant in all loci and it varied in some loci for yield of seed cotton per plant, number of bolls per plant and seed index. The level of dominance at all loci was almost constant for lint percentage. Dominant genes were responsible for the increase of yield of seed cotton per plant, number of bolls per plant, lint percentage and seed index in this material. S-12 had maximum number of dominant genes for yield of seed cotton per plant and lint percentage. The variety LRA-5166 had maximum number of recessive alleles for yield of seed cotton per plant and seed index. The variety CIM240 possessed maximum number of dominant alleles for number of bolls per plant and lint percentage. The genotype Albacala (69)11 have maximum concentration of recessive alleles for boll number per plant and seed index.

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