Effect of hydrogen sulfide and hydrogen peroxide on growth, yield and nutrient content of broccoli plants grown under saline conditions

Salt stress is one of the most damaging abiotic stresses and is likely to worsen in arid and semi-arid regions under climate change, limiting plant production and reducing crop yields. This study was conducted in an open field in the desert under a saline environment, saline soil (9.68 dS.m- 1) and saline irrigation water (7.12 dS.m- 1), to evaluate the protective effects of H2O2 and H2S on broccoli, two levels of H2O2 (1, and 2 mmol. L-1), and two levels of sodium hydrosulfide (NaHS), H2S donor (0.1 and 0.2 mmol. L-1). Foliar application of either H2O2 or H2S was effective in mitigating the adverse effects of salt stress on growth and yield of broccoli. Chlorophyll (a and b), carotenoids, and APX were significantly increased in plants sprayed with H2S compared to those sprayed with H2O2, while SOD, POX, and CAT activities were greater in plants sprayed with H2O2. The largest decrease in malondialdehyde (MDA), H2O2, and Na accumulation was observed in plants treated with 0.2 mmol. L-1 H2S. Broccoli yield, nutritional content, and cell membrane stability index (CMSI) were increased with foliar treat-ments, all foliar treatments yielded larger and heavier broccoli heads than untreated plants. However, plants sprayed with 0.2 mmol. L-1 H2S showed the most promising results, significantly enhancing broccoli yield pa-rameters in terms of head fresh weight (24.5%), head dry weight (19.2%), and head diameter (17.7%), and nutritional content such as vitamin C (16.8%) and total soluble solids (9.9%), as well as, leaf nutrient content in terms of N (21.2%) and K (15.6%), with decreasing sodium content by 20.3%. The results suggest that foliar spraying of H2O2 and H2S could be an effective physiological method to mitigate abiotic stress and improve plant growth and yield.