Interactive Effects of Salinity, Drought, and Heat Stresses on Physiological Process and Selection Criteria for Breeding Stress-Resistant Cotton

Abstract

The cotton crop is adversely affected by the combination of salinity, drought, and heat stress during all growth stages in cultivated areas. The negative impacts of salinity together with water scarcity on osmotic stress dramatically increased the sensitivity of reproductive development. After membrane integrity and signaling networks are depressed under stress at the cell level, the metabolic and physiological processes are disrupted in the next stage. The restricted root growth, ion and water uptake, phloem, photosynthetic and respiratory capacity, incompatible hormonal balance, and reduction in yield due to lower boll retention are the most important symptoms. The seed treatments and foliar applications of osmoprotectant and fertilization appear to reduce multiple stress factors in possible climate change conditions. The osmotic adjustment, antioxidative ability, electrolyte leakage in the membrane, and chlorophyll fluorescence are evaluated as selection criteria for improving genotypes. Direct selection of plants with high yield under stress conditions may increase the success of cotton breeding. It is important to know the molecular approaches and gene functions responsible for abiotic stress. In this chapter, the effects of high temperature, salinity, and drought on cotton plants and characteristics associated with tolerance were focused on cotton improvement. The classical breeding methods and molecular approaches should be combined for breeding new cotton varieties.