Investigation the role of nitric oxide on drought tolerance of mung bean (Vigna radiata L.)

Drought is one of the most important adverse environmental factors that limits crop production. Nitric oxide (NO) as a signaling molecule contributes in plant response to environmental stresses. Therefore, in order to investigate the effects of NO on drought tolerance of mung bean (cv. Partow), a field experiment was done in the south of Tehran in 2015. The study was conducted as a randomized complete block design with 9 treatments and 4 replications. In this experiment, sodium nitroprusside (SNP) solution was used as NO donor. Treatments included control, drought stress, seed treatment, foliar application at the vegetative stage, foliar application at the reproductive stage, seed treatment + foliar application at the vegetative stage, seed treatment + foliar application at the reproductive stage, foliar application at the vegetative and reproductive stages, and seed treatment + foliar application at the vegetative and reproductive stages. Results showed that due to the drought stress, antioxidant enzymes activities such as superoxide dismutase, catalase, and ascorbate peroxidase, as well as malondialdehyde (MDA) and proline concentrations were increased but the relative water content (RWC), chlorophyll value, leaf area index (LAI), and seed yield decreased. However, application of SNP by further increasing the activity of antioxidant enzymes and proline accumulation, reduced the MDA content while improving the RWC, chlorophyll value, LAI, and eventually the seed yield under drought stress. Among SNP application treatments, seed treatment + foliar application at the vegetative and reproductive stages was the most effective, although it was not significantly difference from the other treatments including SNP foliar application at the reproductive stage. According to the findings of the study, application of NO may be recommended as a useful tool for improving drought tolerance of mung bean.