DROUGHT STRESS IMPACTS ON WHEAT AND ITS RESISTANCE MECHANISMS

Scarcity of water has been a serious agricultural hindrance to crop productivity since antiquity. Drought-stressed loss in wheat yield likely exceeds losses from all other causes, since both the severity and duration of the stress are censorious. Here, we have reviewed the effects of drought stress on the morphological, physiological, and biochemical attributes along with the growth impacts, water relations, and photosynthesis impacts in wheat. This review also illustrates the mechanism of drought resistance in wheat. Historical drought years in Nepal have been identified and the yield losses were assessed. Wheat encounters a variety of morphological, physiological, biochemical responses at cellular and molecular levels towards prevailing water stress, thus making it a complex phenomenon. Drought stress affects leaf size, stems elongation and root proliferation, imbalance plant-water relations and decline water-use efficiency. Different types of physiological research are ongoing to find out the changes occurs in the wheat plant as a result of drought stress. Morphological changes can be looked through two ways: changes in root system and changes in shoot system such as effects on height, leaf senescence, flowering, and so on. Physiological changes involve changes in cell growth pattern, chlorophyll contents, photosynthetic disturbances, plant-water relations, etc. Biochemical changes occur in different chemical, biomolecules, and enzymes. Plants portray several mechanisms to withstand drought stress which can be classified as Drought escape, Drought avoidance, and Drought tolerance. Selection of wheat genotype that can tolerate water scarcity would be suitable for the breeding program aiming to development of drought tolerant variety under water limited regions.