Determination of heritability of high temperature resistance in cotton (Gossypium hirsutum L.)

Objective: It was aimed to determine the effect of heat stress on genotypes, to estimate the heritability for traits studied, to determine suitable parents and promising hybrids under heat stress. Material and Methods: Twenty hybrid populations, obtained by crossing the parents of 4 lines and 5 testers according to line x tester, and their parents were used as material in the study. The experiment was carried out in Randomized Complete Block Design with 4 replications as heat stress and control. Heat stress was created via a plastic tunnel during 50% flowering period under field conditions. Results: Heat stress significantly affected the seed cotton yield per plant, boll number, boll weight, boll shedding rate, ginning out-turn, 100-seed weight, fibre fineness, canopy temperature and SPAD values. Genotypic differences were significant for all traits studied under heat stress, and additive gene effects were higher for boll opening days, plant height and 100-seed weight, whereas non-additive gene effects were higher for yield and fibre quality traits. Heterosis and heterobeltiosis values were generally positive for boll weight and seed cotton yield per plant, but negative for boll shedding rate. Conclusion: It was concluded that single plant selection for yield and fibre quality traits should be postponed to F5-F6 generations in breeding studies under heat stress. May-455 and FH-142 genotypes were the most suitable parents, and May 455 × AGC-375, Gloria × FH-142, May-455 × FH-142 and Fiona × FH-142 hybrid combinations were promising genotypes that can be used in further breeding studies. Keywords: Heat stress, shedding rate, gene action, ability effects, heterotic patterns