Plant Responses to Drought Resistance: A Review

Abstract

Plants cope up drought stress by stress avoidance, tolerance, or a combination of both to various degrees. Plant groups follow variety of strategies for survival under drought conditions. Some plants try to avoid drought stress by various physiological and biochemical mechanisms. Stress avoidance is the ability to prevent an externally applied stress from producing an equivalent internal stress in the plant, i.e. the ability to maintain high cellular water content even when the external water potential is low. Desiccation postponement is the ability to maintain tissue hydration and Desiccation tolerance is the ability to function while dehydrated. Another category, drought escape comprises plants that complete their life cycles during the wet season, before the onset of drought. These are the only true “drought avoiders.” Stress resistance (hardiness) is the ability to endure an externally applied stress i.e. the ability to survive low external water potential. Stress tolerance is the ability to survive an internal stress, i.e the ability to survive low cellular water content. Hardening (acclimation) is the development of stress resistance, stimulated by subjection to mild and/or gradually increasing stress. Adaptation and acclimation to environmental stresses result from integrated events occurring at all levels of organization, from the anatomical and morphological level to the cellular, biochemical, and molecular level. A plant that is capable of acquiring more water or that has higher water-use efficiency will resist drought better.