Efficient root system in legume crops to stress environments

Abstract

Food grain legumes are very important as source of protein in many parts of the world. Climate change may bring about increased aridity to extend areas of the world. Thus it is important to evaluate the effects of elevated CO2 in association with other stress factors, namely high temperature and water deficit. Water is a pre-requisite for plant growth. Water is taken up by the plants via its roots, transported to its leaves, and lost to the atmosphere as vapors. This continuum involves retention and movement of water within the soil, proliferation of root system in the soil and uptake of water by the plants in relation to evaporative demand. In this chapter we will refer to some research on managing root system development and structure of leguminous plants for efficient water use under drought stress. Most of food grain legumes are usually grown in marginal areas under rainfed conditions and their yields are fairly low. There is genetic variation existing among different legume species. The total root length beneath cool-season food legume crops could be about five to 10 times smaller than that below same area of cereal crops. Deeper root system and larger root dry mass could be associated with better avoidance to soil water limitation in drought tolerant legume than in drought-sensitive ones. The effectiveness of root traits in improving drought avoidance may vary depending on growth environment, e.g., moisture status of the soil. Although the importance of root traits in drought avoidance is well-recognized, other plant mechanisms for coping with drought stress are not well understood in food legumes. Case studies on managing root systems of soybean, faba bean and chickpea for efficient water use under drought conditions are reviewed.