Wheat Responses and Tolerance to Drought Stress

Abstract

Drought is an environmental worldwide problem affecting crop productivity earnestly, and recent climate change has made this status more critical. The projections point out an increase in water request used in agriculture leading to more drought stress. In the future by 2025, about 60% of world peoples may suffer from water scarcity. Adaptation to drought is mainly identified through three mechanisms, i.e., drought tolerance, drought escape, and drought avoidance. Wheat plants are responses to water deficit relative to its growth stage, metabolic activity, and yield potential. Germination, flowering, and grain filling are considered as critical periods for water stress. Exposing wheat plants to drought are adversely affecting phenological development, physiological and biochemical processes, and yield. Increasing water stress degree causes a decrease in shoot elongation of seedlings. Stomatal conductance and photosynthetic rates were reduced when plants exposed to water deficit, which include some signals like ABA accumulation. The photosynthetic system may be damaged under extreme drought condition. In response to water deficit, wheat plants can minimize the deleterious effects by increasing osmotic adjustment through the accumulation of solutes within the plant. The stress plants recorded lowest values of total carbohydrates (TC) and total free amino acids (TAA), while well-irrigated plants obtained the highest values of total soluble sugars (TSS) and total phenols (TP). Proline appears to assist plants in drought tolerance. A gradual increase in proline content is exposing wheat plants to drought degrees compared to its content in well-watered plants. The reduction in photosynthesis under drought stress resulted in reducing the efficiency of biochemical processes, which lead to reduce plant growth and yield. It is supposed that new wheat varieties that have higher water-use efficiency (WUE) and strong grain sink under water deficit condition had more drought tolerance and produced more yielding than other varieties.