Cotton is a precious commodity that offers raw material to the textile industry. This crop is grown in tropical and sub-tropical regions of the world. Abiotic stresses exerts negative impact on cotton production, but water scarcity has the worst impact. It is rising due to current situation, in which global warming is producing a decrease in precipitation while an increase in evapo-transpiration is causing an agricultural drought. Thus, it is a difficult task for cotton breeders to identify cotton lines that can respond to areas with limited water supplies without lowering yields and might be utilized as suitable parents in a breeding program to produce drought-tolerant indices. The primary objective of this research was the estimation of drought tolerance indices in upland cotton under water deficit conditions. For this purpose, fifty accessions of upland cotton were assessed for their ability to tolerate the water stress under three conditions, namely control, 50% FC, and 75% FC. These genotypes showed significant variations based on morpho-physiological and biochemical characteristics. At control conditions, these genotypes exhibited enhanced growth and better performance. Whereas, the behavior of some indices under 75% FC showed less growth as compared to control, while under the 50% FC highly significant reductions were observed among genotypes. The genotypes that are resistant to drought and those that are susceptible were found using the K-means cluster and biplot analysis. In terms of performance, the genotypes namely Cyto-515, CIM-595, FH-142, and IR-3701 exhibited relatively better in all the treatments and low excised leaf water loss, high relative water contents, chlorophyll contents, free proline contents, and peroxidase activity were observed to be useful selection criteria for drought resistance. These identified genotypes namely, Cyto-515, CIM-595, FH-142, and IR-3701 may be grown in water deficit areas of the country to assess their potential, could be used in breeding programs for development of germplasm suitable for water stress conditions.

Soil salinity is increasing due to several factors such as climate change and areas with uneven rainfall. This increase in level of salinity compelled the cotton breeders to develop a new germplasm that exhibit the suitable for salty soil. This study aimed to determine the salt tolerance of 50 accessions of Gossypium hirsutum in hydroponic conditions having three levels of NaCl, i.e., 0 mM, 150 mM, and 200 mM. The experiment was carried out in a completely randomized design with a factorial arrangement. Morphological, physiological, and biochemical attributes were estimated in these genotypes. The Na⁺/K⁺ ratio was determined by dry digestion method. Salt-susceptible and -tolerant genotypes were identified by biplot and cluster analysis. The genotypes showed significant differences for morphophysiological and biochemical parameters. In control, Cyto-515 showed enhanced growth with shoot length (30.20 cm), root length (20.63 cm), fresh shoot weight (2.34 g), and fresh root weight (0.93 g), while under 150 mM and 200 mM salinity levels, MNH-992 had the maximum root length (15.67 cm) and shoot length (24.67 cm). At a 150 mM salinity level, maximum levels of antioxidants were found in Kehkshan and CIM-595, while at a 200 mM salinity level, AA-703, CIM-595, and Kehkshan showed maximum values of antioxidants. The highest Na⁺/K⁺ ratio was observed in VH-363 and FH-114, while Kehkshan had lowest Na⁺/K⁺ ratio. The biplot analysis revealed that Kehkshan, CIM-595, VH-330, Cyto-178, MNH-992, and Cyto-515 were widely dispersed and distant from the origin, and exhibiting variability for morphophysiological and biochemical traits under the salt stress. In terms of performance across the treatments, accessions MNH-992, Kehkshan, Cyto-515, and CIM-595 performed significantly better. Peroxidase activity, proline contents, H₂O₂ determination, and Na⁺/K⁺ ratio were shown to be useful for the salt tolerance selection criteria. The potential of such salt tolerant accessions (MNH-992, Kehkshan, Cyto-515, and CIM-595) could be assessed after planting in salt affected areas and could be used in breeding programs for the development of diverse salt tolerant new genotypes of upland cotton.