Drought tolerance and water status of bean plants (Phaseolus vulgaris L.) as affected by citric acid application

Enhancement of drought tolerance of plants is a crucial concern in arid and semi-arid regions. Using safe and environmentally-friendly tools and treatments for this purpose is needed to overcome the problems of water shortage with particular emphasis on sustainable resource management and environmental protection. This study investigated the water status and drought tolerance of beans. Bean plants (Phaseoulus vulgaris L.) were treated with citric acid (0.5, 1, 1.5 and 2 g/L) as a foliar application prior the exposition to drought stress conditions. Physiological changes, such as leaf temperature, relative water content (RWC) and chlorophyll content of leaves, were recorded in response to citric acid application. The results revealed that the water status of bean plants under drought stress conditions was improved by citric acid application, indicated by higher RWC of leaves compared to control plants. The most effective level in this respect was 1.5 g/L. A similar trend was observed with total chlorophyll content of leaves. In addition, plant growth, productivity and quality parameters were significantly improved by application of citric acid compared to control plants. The possible roles of citric acid on water status and drought tolerance of bean plants are discussed.