Enhanced Drought Tolerance in Chinese Cabbage (Brassica campestris L.) Seedlings Upon Pretreatment with Exogenous Salicylic Acid

Salicylic acid (SA) is an important signal transduction molecule that helps plants overcome external stress conditions.Drought stress can strongly impact plants during cultivation.In this study, we investigated the effects of pretreating Chinese cabbage seedlings with exogenous SA during drought stress through physiological and biochemical analyses.The study lasted for 39 days, including a period of 23-day during which Chinese cabbage seedlings were pretreated with SA.Plants were pretreated three or six times with SA (10 -4 M) or left untreated (control), and subjected to a 12-day drought period.Leaf samples were harvested before (day 0) and on days 3, 6, 9, and 12 of the drought period.Malondialdehyde (MDA) content, photosynthesis rate, chlorophyll fluorescence, total chlorophyll content, and antioxidant enzyme (catalase, ascorbate peroxidase, glutathione reductase) activities were determined during the drought period.Pretreatment with SA led to enhanced drought tolerance in Chinese cabbage seedlings.Pretreating seedlings six times was found to be more efficacious than three times.SA pretreatment reduced MDA synthesis and prevented leaf rolling and leaf scorching.Additionally, SA pretreatment preserved the photosynthetic apparatus and counteracted the reduced activity of antioxidant enzymes.These results demonstrate that pretreatment with exogenous SA protects Chinese cabbage seedlings from oxidative stress and promotes their growth.We thus conclude that pretreatment with exogenous SA can enhance drought tolerance in Chinese cabbage seedlings.