HETEROSIS AND COMBINING ABILITY FOR YIELD AND FIBER QUALITY IN COTTON (GOSSYPIUM BARBADENSE L.) USING HALF DIALLEL MATING SYSTEM

Abstract

The present study was carried out at Sakha Agricultural Research Station, Cotton Research Institute, Agricultural Research Center, Egypt, during the two successive seasons 2018 and 2019. Six cotton varieties belong to (Gossypium barbadense L.). Three of them are Egyptian cotton varieties; Giza 89, Giza 93 and Giza 96. The other three varieties are Pima S4, Pima S6 and Suvin. They were crossed in a half diallel mating to produce 15 F1 hybrids in 2018 season. The F1 hybrids and six cotton varieties were growing in 2019 season in a randomized complete blocks design with three replications. The Results showed that the mean squares of the genotypes, parents, crosses and parents versus crosses were significant and highly significant for all studied traits except No. of bolls/plant at parents and micronaire reading at parents versus crosses. The results illustrated that the mean squares of general combining ability (GCA) and specific combining ability (S.C.A.) were significant and highly significant for all studied traits except micronaire reading at specific combining ability (S.C.A.). The parental genotypes Giza 96 and Giza 89 gave significant (desirable) GCA effects for most yield traits. Giza 96 and Suvin exhibit significant and positive (desirable) GCA effects of some fiber properties. The crosses Giza 89 x Pima S4, Giza 96 x Pima S6 and Giza 96 x Suvin recorded significant and positive (desirable) SCA effects for most yield traits, while the crosses Giza 89 x Giza 96, Giza 96 x Suvinand Giza 89 x Suvin showed significant (desirable) SCA effects for some fiber properties. following crosses Giza 89 x Giza 96, Giza 93 x Giza 96, Giza 96 x Pima S4, Giza 96 x Pima S6 and Giza 96 x Suvindemonstrated desirable heterosis relative to mid- and better-parent for most studied yield traits, also the crosses Giza 89 x Giza 96 and Giza 89 x Suvin indicated desirable heterosis relative to mid- and better-parent for some fiber properties. The results indicated that the non-additive of genetic variances were larger than the additive genetic variance with respect to all studied traits except, lint percentage, boll weight, upper half mean and micronaire reading traits. Generally, Giza 96 and Giza 89 could be used in breeding programs for improving high yielding varieties, while Giza 96 and Suvin could be considered as excellent parents for breeding programs to produce new varieties characterized with best fiber properties.