Nitric Oxide Protects Photosynthetic Capacity Inhibition by Salinity in Indian Mustard

The potential of nitric oxide (NO) was studied individually or in combination for the alleviation of 100 mM NaCl stress in mustard (Brassica juncea L.). Salinity generally decreased photosynthesis and growth characteristics. The individual application of NO at 50 μM and 100 μM promoted and enhanced the photosynthetic efficiency and growth, but under salinity stress the application of 100 μM NO was proved more efficacious than 50 μM in alleviating salt stress by limiting the accumulation of NaCl content of ions and reducing oxidative stress. However, application of high (150 μM) concentrations of NO showed inhibitory results in the presence of 100 mM NaCl. These results indicated that the application of NO at 100 μM alleviates the salt-induced decrease in photosynthesis mainly through decreasing chlorophyll degradation or by increasing PS II efficiency, rubisco activity and net photosynthesis along with growth.