Evaluation of the Drought Stress Effects on Cotton Genotypes by Using Physiological and Morphological Traits

Drought stress is the major environmental factor that negatively impacts cotton yield throughout the world. Thus, there is a need for a protocol to offer new opportunities for improving drought tolerance in cotton. By understanding the correlation between yield and morphological traits (root length, shoot length, root/shoot ratio), and physiological traits (relative water content (RWC), electrolyte leakage percentage (EL %), membrane stability index (MSI %), Chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a/b ratio, chlorophyll stability index (CSI)), we can develop efficient screening method able to screen large amounts of plant material in the shortest time possible. In the current study, 21 cotton genotypes (6 parents and their 15 F1 crosses) were evaluated under two irrigation treatments i. e. , 100 % ETc, 1269 mm/season (normal) and 60 % ETc, 761 mm/season (drought). The morphological and physiological traits were studied. Also, correlation between yield and physiological and morphological traits were determined. The results revealed high significant difference among genotypes for all the studied physiological and morphological traits under normal and drought treatments. Although all studied traits in all genotypes were significantly affected by drought but some genotypes such as Tamcot C. E. x Deltapine, Giza 90x (Giza 90X Australian) and Giza 80x Deltapine showed drought tolerance by maintaining the highest values of root length, shoot length, root/shoot ratio, RWC, MSI, Chlorophyll a, b, total chlorophyll, chlorophyll a/b ratio, CSI and lowest values of EL % under drought stress. Yield was correlated with each of the morphological and physiological traits under normal and drought conditions. Therefore, it could be concluded that the morphological and physiological traits could be used as selection criteria for high yield under drought stress.