Inheritance of yield, yield components, quality and drought resistance characteristics of cotton (Gossypium hirsutum L.) under water stress conditions

Aim: Since drought is one of the most important environmental stress in agriculture, developing new cultivars with improved yields under drought stress conditions is an important goal of plant breeding. This study aimed to determine suitable parent and hybrid combinations that will serve as a source for the development of new cotton varieties tolerance to stress conditions. In addition this research was also carried out to examine the inheritance of yield, yield components, fiber quality characteristics and some physiological parameters in cotton under drought stress conditions and determined tolerance/sensitivity levels of genotypes by means of drought indices. Material and Method: In this study Harem2, May344, Fiona, BA1010, GC555, Zeta2, MS30/1, Tamcot Sphinx and 15 hybrid populations created by hybridization according to the line tester mating design was used as plant material. This experiment was carried out in split plot under RCBD arrangement with three replications. The water levels were kept in main plot whereas genotypes in subplot. Seeds of the 23 entries per replication and treatment were planted in single row plot. There were 70 cm and 15 cm distance between row to row and plant to plant respectively. This experiment was conducted using normal irrigation (100%) and giving stress at 50% reduced irrigation. Result: According to line tester analysis, plant height, number of monopodial branches, seed cotton weight per boll, ginning out turn, 100 seed weight, fiber fineness, fiber length, fiber strength, fiber elongation, uniformity ratio, chlorophyll content and leaf relative water content traits was controlled by the additive gen effect. On the other hand, while the time of first boll opening, number of fruiting branches, height/node ratio, number of bolls per plant, seed cotton yield and canopy temperature was determined by non-additive gen effects. While BA1010 cotton cultivar's GCA was detected superior than other genotypes in terms of yield and important yield compenents such as number of fruiting branches, number of bolls per plant height/node ratio, relative water content of leaves; Fiona were found to be the parent showing the best GCA for ginning out turn and fiber quality characteristics. Negative heterosis was observed for plant height, fiber fineness, fiber elongation and leaf relative water content, while positive heterosis for other investigated properties. For SCA, Harem2 x Zeta2 and BA1010 x MS30/1 genotypes stood out in terms of yield and yield compenents and Fiona x MS 30/1 hybrid combination in terms of quality parameters. It was determined that STI, MP, GMP and HM indices which was calculated by evaluating the yields under optimum and stress conditions together had a significant correlation with the yield under both conditions. It was also determined that Harem2 x Zeta2 and GC555 x MS30/1 genotypes reached high yields under both conditions but their stability was low, GC555 cultivar and BA1010 x MS30/1 hybrid combination had high yield capacity under stress conditions, but their yield capacity was limited and more stable in terms of yield when environmental conditions improved. Conclusion: It was concluded that it would be more appropriate to make single plant selections in the future (F5-F6) generations due to the presence of non-additive genetic effects in yield and yield compenents such as the number of fruit branches, height/node ratio, and number of bolls per plant and seed cotton yield. Also Harem2 x Zeta2, GC555 x MS30/1 and BA1010 x MS30/1 hybrid combinations should be transferred further generations. Key Words: Cotton, Drought Stress, Gene Effects, Heterosis, Drought Indices