ESTIMATION OF GENETIC PARAMETERS USING SIX POPULATIONS IN COTTON (Gossypium barbadense L)

Genetic variance components and type of gene action controlling yield, yield components, and quality characteristics of cotton plants. Therefore, this investigation was implemented at Sakha Agricultural Research Station, Kafr Elshiekh Governorate, Egypt during the summer seasons of 2019, 2020, and 2021 to estimate two cotton crosses, cross I (Giza 92 x Suvin) and cross II (Giza 92 x 10229) using the mean of six populations (P1, P2, F1, F2, BC1 and BC2), and laid down in a Randomized Complete Blocks Design (RCBD) with four replications.. Results revealed that the mean values of the F1 population were better than the respective parents, F2, BC1, and BC2 populations for most studied traits of the two crosses. The significant and positive (desirable) heterosis relative to mid and better-parent for most studied traits in both crosses. Inbreeding depression was significant and positive for most studied yield traits at the cross I, which exhibited highly significant and negative for micronaire reading in cross II. The values of the phenotypic coefficient of variation (PCV) were higher than the values of the genotypic coefficient of variation (GCV) for all the studied traits of both crosses. The dominance gene effect, was higher than additive gene effects for all studied traits in the two crosses except the uniformity index in cross II, indicating the predominant role of the dominant component of gene action in the inheritance of these traits. High heritability in broad-sense estimates (>50%) was detected for all traits studied at the two crosses. The heritability in narrow-sense estimates ranged from 7.74% to 63.76% for the boll weight and uniformity index in cross I. The expected genetic advance under 10 % selection of the individual plants in the F2 generation ranged from 32.31% to 99.12% for seed index and boll weight of cross I, respectively. It could be concluded that dominance and epistatic gene effects played a major role in controlling the genetic variance in most of the studied traits.