Physiological responses of grain legumes to stress environments

Abstract

Abiotic stresses adversely affect growth and productivity and trigger a series of morphological, physiological, biochemical and molecular changes in plants. Drought, temperature extremes and saline soils are the most common abiotic stresses that plants encounter. Globally, approximately 22% of the agricultural land is saline, and areas under drought are already expanding and this is expected to increase further as a result of changing climates. Often crops are exposed to multiple stresses, and the manner in which a plant senses and responds to different environmental factors appears to be overlapping. Legumes are often grown as a secondary crop in arid and semi-arid regions under poor edaphic and receding soil moisture conditions. Most food legumes have a long history of domestication almost as long as cereals, and during this time they have been subjected to conscious and unconscious selections for better adaptation to environmental condition as well as better seed yield. In general, during their ontogeny crops face a number of abiotic stress viz., excessive and/or low soil water stress, soil salinity stress, high as well as low temperature stress. It has been well documented that crop yields would be greater in many cropping regions if more water were available.