Water stress and its management strategies on rainfed maize: A review

Abstract

Drought (water stress) is one of the most important environmental stresses and occurs for several reasons, including low rainfall, salinity, high and low temperatures, and high intensity of light, among others. Drought stress is a multidimensional stress and causes changes in the physiological, morphological, biochemical, and molecular traits in plants. Water stress is considered as one of the most devastating environmental stresses worldwide as it has rendered large area of agricultural land unproductive around the globe. It is more likely that increasing population and changing climatic conditions will increase water scarcity, which will cause a further decrease in crop productivity in the world. Alterations in rainfall pattern and rising temperature are major causes of drought and have contributed an appreciable decline in maize productivity Current trends of climatic changes will increase water scarcity and will reduce maize productivity by 15- 30%. Globally maize is the third most important crop in the world. The main maize crop is generally grown as rained. In India, approximately 2.4 mha (~ 32.4%) of total maize growing areas is prone to face water or excess moisture stress. Mechanisms involved in plant tolerance to drought follow a general plan: maintaining cell homeostasis in water-deficit situations, which is possible by increasing the water inlet to the cells. Drought avoidance is other common drought resistance mechanism in annual plants. With this mechanism, escape from stress conditions is the main strategy for plant growth under drought conditions. Different strategic characters are improved by numerous biological approaches which enable the plants to escape, avoid, and tolerate the water stress. Screening of germplasm for assessment of tolerant variants, development of tolerant genotypes through conventional breeding, mutation breeding, molecular breeding, and transgenic approaches are possible options which are working and can further be employed for further improvement.