Chapter 8 - Heavy metals, water deficit, and their interaction in plants: an overview

Abstract

The concurrent occurrence of more than one abiotic stress in plants is a regular consequence in natural field environment. The heavy metals and deficiency of water are two different abiotic stress factors that affect plant system by their single or simultaneous existence. In recent times, due to the industrial revolution, the contamination of agricultural soil by different heavy metals has increased drastically. For plants, some of the heavy metals are considered as essential nutrients in microquantities, which help in plant growth and development, whereas some are considered nonessential and show a visible toxic effect even at low concentration. Water deficit is a condition of inadequate supply of water in plants due to limited water availability that results in damaging effects in plants. Both of these stresses, that is, metal and water deficit, when combined to a certain level, result in some consequences in plants that might have responses similar to that of individual stress, or these responses might completely differ from that of single stress. Previous relevant literature suggested that plants have unique and sometimes complex responses against different abiotic stress combinations that cannot be directly compared with those of individual stress effects. At present, very few reports are available on mutual and interactive effects of metal and water-deficit stress in plants. Hence, it is essentially required to analyze numerous stress responses in different plants to understand the underlying mechanism of interaction and develop resistant varieties against various stresses but maintaining high yields. This chapter reviewed the articles related to different abiotic stresses’ interaction with plants, specifically heavy metal and deficiency of water; with an attempt to elucidate the morphological, physiological, and biochemical effects on the plants. We have discussed the combined metal and water-deficit stress to understand the responses of plants against these two stresses individually and in combination.