Resistance/Tolerance Mechanism under Water Deficit (Drought) Condition in Plants

Abstract

Drought is a shortfall of water availability sufficient to cause loss in yield. Agricultural drought is a situation where the moisture supply is inadequate to meet the requirement of the crop. To cope with the drought, resistant/tolerant plants initiate defense strategies against water deficit, which are categorized as morphological and physiochemical/biochemical mechanisms. Plant drought tolerance involves changes at whole-plant, tissue, physiological and molecular levels. Manifestation of a single or a combination of inherent changes determines the ability of the plant to sustain itself under limited moisture supply. Drought escape, drought avoidance, phonological flexibility are the main attributes in morphological mechanisms and it can be achieved by early growth vigour, reduced leaf area, high degree of leaf rolling, vigorous root system, epicuticular wax deposition, presence of awns, hairiness etc. Osmotic adjustment, osmoprotection, antioxidation and scavenging defense system have been the most important physiochemical/biochemical bases responsible for drought tolerance. Cell tissue and water conservation, antioxidant defense, cell membrane stability, compatible solutes and plant growth regulators mainly contributes in above said physiochemical/biochemical mechanisms