Evaluation of some physiological parameters, yield and fiber quality traits under drought stress conditions in cotton

This study was carried out to determine the effect of water stress on cotton yield, yield components, some physiological parameters and fiber quality characteristics in three different cotton varieties. The study was carried out in GAP International Agricultural Research and Training Center's experimental area during 2017-2018 cotton growing season. The experimental design was arranged as Split Plots in Randomized Complete Blocks with four replications. The irrigations were applied to the main plots and the varieties to the sub-plots. Considering the two-year data of the study, it was found out that the treatments were significant in terms of all parameters except number of seeds in boll, first picking percentage, fiber reflectance, seed cotton yield and fiber yield. Full irrigation (I 100) treatment had higher values then those of water stress applications. Depending on water stress applied 25,60% yield loss in I 75 and 54% yield loss in I 50 were occurred. As the result of the study with the application of water stress plant height, number of monopodial branches, number of sympodial branches, number of first fruiting branches, number of squaring days, number of flowering days, first boll opening time, number of node, number of bolls, boll weight seed cotton weight per boll, 100 seed weight, chlorophyll content, average single leaf area, leaf relative water content, NDVI value (Normalized Difference Vegetation Index), photosynthesis rate, stomatal conductance and transpiration rate values were decreased, while ginning percentage and canopy temperature values were increased; number of seeds per boll and first picking percentage were not affected. When comparing the results of fiber quality characteristics, with water limitation fiber fineness, fiber length, fiber strength, fiber elongation, fiber uniformity ratio and spinning consistency index decreased, while fiber yellowness and short fiber index values increased, however, fiber reflectance was not effected from water stress. The results also indicated that there were significant differences among varieties in terms of many properties. Stoneville 468 and Kartanesi varieties had superior properties for yield, ginning percentage, water use efficiency and earliness criteria, on the other hand, FiberMax 832 variety had superior values for chlorophyll content and fiber quality characteristics. According to the results of two years study it was determined that water stress negatively affected yield, fiber quality characteristics and many physiological parameters of cotton. In the light of the results of this study it was concluded that water limitation should not be occurred in order to achieve optimum productivity in cotton production. Keywords: Cotton, water stress, physiology, fiber quality parameters