Investigation of hybrid populations of cotton (Gossypium hirsutum L.) genotypes with different maturation periods under restricted irrigation conditions

Aim; The study focused on determining the performance of the hybrid combinations and estimating the heritability of the traits examined under normal and water shortage conditions. It was also aimed to determine the selection criteria that can be used in drought tolerance breeding and to identify suitable parents and promising combinations. Material and Methods: The hybrid combinations and parents formed by crossing Bomba, Özbek 100, May 455, Ramses, Bir 949 and Fiona varieties with different maturity groups and water stress tolerant varieties Şahin 2000, Eva, Sahra and Sasha according to the line × tester mating design were used as materials. The study was carried out under both full irrigation and 25% of full irrigation conditions in 2023 in Nazilli Cotton Research Institute in Randomized Complete Blocks Design. Result; Water shortage significantly and adversely affected seed cotton yield, plant height, number of interboğumes, plant height/boğume ratio, number of sympodial branches, boll number, boll weight, boll retention rate, seed weight, ginning out-turn, fiber yield, stomatal density, chlorophyll content, cuticle thickness, fiber length and fiber fineness. Non-additive gene effects were higher in the inheritance of all traits under deficit irrigation conditions. Conclusion; Bir 949 and Sahra cultivars were found to be the most suitable parents in terms of the traits examined. Similarly, Bomba × Şahin 2000, Bomba × Sasha, Ramses × Eva, Ramses × Şahin 2000, Ramses × Sasha, Ramses × Sahra, Bir 949 × Sasha, Bir 949 × Sahra, Fiona × Eva and Fiona × Sahra hybrids were found to be the most promising combinations. It was concluded that it would be useful to apply bulk or modified bulk method in these hybrid combinations. Keywords: Cotton, Deficit irrigation, Combining ability, Yield, Fiber quality parameters