PJB-2018-295
Morphological, Physiological and Biochemical Response of Wheat to Drought and Heat Stress in Arid and Semi-Arid Region: An Overview
Ayman EL Sabagh
Abstract
The Intergovernmental Panel on Climate Change projected that global climate change will have a major impact on climatic sensitive crops like wheat and already projected that 20-30% wheat yield losses will occur by 2050 in developing countries due to 2 to 3°C temperature increase. Since due to changing climate major wheat producing countries have already reported the yield reductions of wheat due to increasing temperatures. Similar to increasing temperature, drought is one of the considerable abiotic factors that impact the crop growth and productivity through changing the morphological, physiological and biochemical processes of the plant. Short and long-term heat stress can significantly affect the growth, yield and quality, particularly when heat stress occurs at sensitive stages. Considering the above important issue, the present review aims to address the adverse impact of drought and heat stress through representing the physiological, agronomical, biochemical responses of wheat under stress condition. The review also tried to imply the survival mechanism of wheat under stress conditions for genetic improvement of wheat, as it is the best indirect selection criteria subjected to select heat and drought tolerance of wheat genotypes. Thus, improvement of grain yield is becoming a widely discussed topic in wheat. Because, grain yield is strongly influenced by ripple effects of environmental stresses during different phases of plant growth. Hence, our aim was to understand and identify adaptive genotypes by evaluation of growth, physiology, and grain yield and quality of wheat under stress environments, and likewise to evaluate the responses of wheat under high temperature and drought stress for adaptability under stress environment. However, there are two ways to mitigate heat and drought stress in wheat, either by developing and practicing improved heat management practices, or by developing and using heat-tolerant cultivars. Several agronomic strategies during critical growth stages, continuous water supply to heat-stressed wheat and time of sowing helped to sustain grain yield. The physiological approaches such as application of exogenous signaling compounds, osmolytes and certain inorganic salts play a significant role in alleviating stress. A significant correlation between grain yield (GY) and stress tolerance indices (STIs) of a genotype is observed when suitable to grow under heat stress conditions. Therefore, correlations between STIs and GY can be used to screen the wheat genotypes that are suitable to grow under stress conditions. Genotypes those are suitable to grow under stress conditions are positively and significantly correlated between GY and each of mean productivity (MP), geometric mean productivity (GMP), yield index (YI), yield stability index (YSI) and relative productivity (RP%) and while, negatively and significantly correlated between GY and stress susceptibility index (SSI) and between GY and tolerance index (TOL). Keywords: Wheat, drought, heat stress, morphological, physiological and biochemical
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