Eco-physiological responses of desert and riverain legume plant species to extreme environmental stress

Abstract

Abstract Drought and heat events frequency and severity are expected to increase in the near future as responses to global warming, influencing crops productivity and human diet as result in the increasing soil aridity and area affected by drought. It is becoming increasingly important to find new crop plants or genotypes of crops that have adaptation strategies to water loss at extreme arid conditions. It was hypothesized that growth and development of plants are affected differently by drought stress, depending on their nature habitats whether desert or riverain. In this current research, we compared the changes in physiological behavior between desert and riverain legume plants, as response to drought stress at two levels of water regimes. Rates of transpiration were highly correlated to radiation. Transpiration increases with the increase in photosynthetic active radiation (PAR) at both levels of water regimes. Highest photosynthesis (pn) and transpiration (E) were achieved in R. minima at both low water regime and high PAR (1250). The super oxide dismutase (SOD), catalase (CAT), phenyl ammonia lyase (PAL) and peroxidase activities were higher in Rhynchosia minima. Drought stress induced significant accumulation of total sugars, flavonoids, saponins, proteins and phenolics. The higher photosynthesis rate, higher flavonoids and phenolics content and stronger activity of protective enzymes were the important physiological reasons for the drought resistance of Rhynchosia minima.