Salicylic Acid-Mediated Enhancement of Photosynthesis Attributes and Antioxidant Capacity Contributes to Yield Improvement of Maize Plants Under Salt Stress

Addressing salinity-induced crop losses is a prime concern of modern agriculture to sustain agricultural productivity, thereby contributing to global food security. The current study explored the potential roles of salicylic acid (SA) in the improvement of maize tolerance to salinity, and evaluated the resultant effects on yield-associated parameters and yield. Our results showed that maize plants grown under salinity alone exhibited severely compromised growth performance, and consequently yield loss, which could be attributed to reduced plant height, decreased photosynthetic efficiency, and elevated levels of the lipid peroxidation product malondialdehyde in maize leaves. On the other hand, foliar application of SA minimized the detrimental effects of salinity in salt-exposed plants, leading to better growth performance and yield when compared with SA-free salt-stressed plants. SA-mediated beneficial effects were particularly evident in the enhancement of photosynthesis-related parameters, including photosynthetic rate, carboxylation efficiency, water use efficiency, and chlorophyll content (SPAD value). Exogenous SA also contributed to the reduction of membrane damage under salinity, as reflected by significantly decreased levels of malondialdehyde in the leaves of maize exposed to salt stress. Furthermore, activities of enzymatic antioxidants like ascorbate peroxidase and catalase in maize leaves were significantly enhanced following SA application in salt-exposed plants, indicating a protective role of SA against salt-induced oxidative stress. Finally, clustering and principal component analysis revealed that the antioxidant capacity and photosynthetic efficiency were intimately associated with the salt and SA treatments. Our findings demonstrate that foliar application of SA is a viable option in alleviating the adverse effects of salinity on growth performance and yield of maize, as well as other economically important crops cultivated in salt-affected areas.