Exogenously Applied Nitric Oxide Enhances the Drought Tolerance in Hulless Barley

Drought stress is a severe threat to high altitude hulless barley production, which causes oxidative damage, disturbs water relations and photosynthesis, while exogenously applied nitric oxide (NO) has the potential to alleviate these effects. In the present study, the role of NO in improving drought tolerance of hulless barley was evaluated. At the three leaf stage, sodium nitroprusside (SNP), a NO donor, was applied at 50, 100 and 150 μmol l–1 under drought stress, the controls, were kept at full field water capacity without NO treatment. The results showed that drought stress seriously reduced the hulless barley growth and physiological attributes, but NO application alleviated the stress effects. Drought tolerance in hulless barley was strongly related to the maintenance of water content and enhanced capacity of antioxidants, improved stability of cellular membranes and enhanced photosynthetic capacity, plausibly by signaling action of NO. Among the NO treatments, 100 μmol l–1 SNP was the most effective