The Use of the Jip-Test to Investigate the Role of Nitric Oxide in Alleviation Drought Damage to Photosystem II in Salviaofficinalis L

Although the significance of nitric oxide (NO) in inducing a plant defence response in response to drought has been well established, the specific involvement of NO in photosynthetic performance has not been well investigated. Here, we used chlorophyll a fluorescence analysis using the JIP-test as a biomarker to investigate the effect of sodium nitroprusside (SNP, 0, 25, and 50 M) on the performance and behavior of PS II in Salvia officinalis L. under drought stress (100% of field capacity (FC), 75% FC, 50% FC, and 25% FC). The results showed that drought stress, especially 25% FC, increased fluorescence intensity in the OK, OJ, OI, and OP phases and induced J-band and G-band peaks, indicating a disturbance in electron transfer from the water-evolving complex and reaction centres to electron receptors in PS II (Q A and Q B ), as well as electron receptors in PS I. However, leaf-applied SNP diminished the fluorescence intensity in drought-stressed plants by improving the efficiency of the water-evolving complex and reaction centres and increasing the electron transfer from Q A and Q B to PS I. Therefore, using the JIP-test as a non-invasive and sensitive method of assessing the impacts of drought stress and SNP as a NO donor under field conditions can be highly valuable and efficient. Furthermore, SNP might be an excellent candidate for potential application as a chemical in agriculture due to its positive effects during drought stress.