Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Agronomy

Triallel or three-way mating design was carried out among three successive growing seasons (2015, 2016 and 2017) included 5 genotypes as parents belong to (Gossypium barbadense L.), 10 F1{u2019}s and 30 three-way crosses. All these genotypes and crosses were evaluated in a randomized complete blocks design with three replications at Sakha Research Station {u2013} Kafr El Sheikh, Egypt. The results showed that, the mean squares due to genotypes were significant or highly significant for all studied traits. Also, the amount of useful heterosis values over better parent were significant and highly significant for both kind (3 parents and F1 or P) for yield and yield components for the crosses (P1 x P3) x P5 and (P3 x P4) x P1, fiber traits for the cross (P1 x P2) x P3, earliness traits for the cross (P2 x P3) x P4 and for oilseed traits for the cross (P2 x P4) x P1. The results of general combining ability (GCA) effects showed that, Giza 96 (P5) was the best combiner for most studied yield components, fiber quality and earliness traits in both first and scond kind. However, specific combinig ability (SCA) for first kind (dij) showed that the cross cominations D45 for most studied yield components and fiber traits, D35 for most yield components and earliness traits and D24 for oilseed traits had the best significant and highly significant values (useful) for thease traits. Furthermore, SCA for second kind (sik) showed that the cross combination S24 for most studied yield components and earliness traits, cross combination S41 for most studied yield components and oilseed traits and cross combination S53 for most studied yield components and fiber traits had the best significant and highly significant values (useful) for thease traits. While, SCA for theired kind (tijk) showed significant and highly significant values (useful) of the crosses No. 7 for most studied yield components, fiber and earliness traits and cross No. 12 for most studied fiber, earliness and oilseed traits. The results showed that all studied traits were mainly controlled by additive x dominance epistatic variances and some of them were also controlled by additive variance in case of seed index (SI), mean maturity date (MMD) and oil content % (OC %) and additive x additive epistatic variances for the rest of them. Concerning heritability in broad sense, the values were ranged from74.66 % for seed index (SI) to 98.77 % for gossypol content (GC %)

Issued also as CD