Determination of Physiological Indices and Some Antioxidant Enzymes of Chard Exposed to Nitric Oxide under Drought Stress

This research was carried out to determine effectiveness of nitric oxide (NO) on some physiological and biochemical reactions, and water use efficiency (WUE) of chard (Beta vulgarisL. var. cicla) under well-watered and drought conditions. NO solutions were prepared with four doses (0, 50, 100, 150 and 200 mu M) of sodium nitroprusside as a nitric oxide donor and exogenously applied on only seeds (s) or together with seed and foliar (sf) of chard under different levels of drought according to 100 (control), 67 and 33% of the water required to reach field capacity. NO mitigated the negative effects of drought stress on fresh and dry weights of leaf and root, chlorophyll content, gas exchange parameters and electrical leakage in all doses, especially for doses of 100 and 150 mu M for both s and sf applications. Higher antioxidant enzyme content was observed with the application of NO especially under well-watered conditions. Mild drought conditions caused a desirable increase on WUE of the chard.