**2. Physiological changes during drought stress**

During drought, Water scarcity occurs generally because of absence of water in the soil. But Physiological drought caused both lack of water in the soil, and also occurs when excess water is present in the soil. Thus, physiological drought is a situation where the plant cannot receive water [15, 16]. The responses of plants to water stress are diverse and may involve the contribution of various defense mechanisms or modification of physiology, morphology, anatomy, biochemistry, as well as short and long-term developmental and growth related adaptation processes [17].

