Effect of exogenous ascorbic acid on two sorghum varieties under different types of salt stress

Salinity is a severe environmental factor that has limited the growth and productivity of crops. Ascorbic acid (ASA) is one of the most important plant growth regulators for mitigating salt stress. A controlled experiment was conducted to evaluate the impact of different salt compositions (0, 50 mM NaCl, 50 mM Na2SO4, and 50 mM NaCl+50 mM Na2SO4, designed as S0, S1, S2, and S3, respectively) and different ASA concentrations (0, 284, and 850 mu M) on the seedling growth and physiological attributes of two sorghum varieties (Wadahmed and Tabat). The present study proved significant differences between sorghum (Sorghum bicolor (L.) Moench) varieties under saline conditions at seedling stage and 'Wadahmed' was more tolerant to salinity stress than 'Tabat'. Both types of salt induced a strong decrease in all the parameter measured, including emergence percentage (48.4%), shoot length (42.1%), root length (39.6%), total dry weight (g) (23.5%), chlorophyll (SPAD) (43.5%), and recorded the highest value of soluble protein content, and malondialdehyde (MDA) content when compared with the non-saline treatment. At the S3 salinity level, emergence percentage, shoot and root length, total dry weight, soluble protein content, and MDA content were increased by 850 mu M ASA levels. Our results found that the combination of both salts showed more damage than a single salt treatment. This study indicated that exogenous addition of ASA at an appropriate level can be a useful strategy to promote early seedling growth and improve antioxidant enzymes of sorghum plants grown under different saline types.