Exogenous salicylic acid ameliorates waterlogging stress damages and improves photosynthetic efficiency and antioxidative defense system in waxy corn

Salicylic acid (SA) is an endogenous growth regulator. It is vital for the growth and development, photosynthesis, disease resistance, and abiotic stress tolerance of plants. This study aimed to investigate the effects of exogenous SA on photosynthetic characteristics and antioxidant system in the four-leaf-stage waxy corn inbred seedlings SY-MY13 (waterlogging-resistant) and SY-XT1 (waterlogging-sensitive) under waterlogging stress. Waterlogging stress negatively influenced the morphology, plant height, biomass, photosynthetic characteristics, and chlorophyll content of waxy corn seedlings, obstructing their growth and development. SY-MY13 exhibited better growth and photosynthesis than SY-XT1 under waterlogging, this was due to SY-MY13 possessed excellent scavenging ability to reactive oxygen species (ROS). However, the application of exogenous SA could not only reduce the accumulation of ROS and regulate the activities of antioxidant enzymes but also improve photosynthesis in leaves and promote the growth of seedlings. Hence, the results revealed that the potential of SA as a promising exogenous growth regulator mediated physiological and photosynthetic adaptation of waxy corn seedlings under waterlogging stress, which might prove helpful for other plants suffering from waterlogging stress.