Gibberellic acid and nitrogen efficiently protect early seedlings growth stage from salt stress damage in Sorghum

Salinity one of environmental factor that limits the growth and productivity of crops. This research was done to investigate whether GA₃ (0, 144.3, 288.7 and 577.5 μM) and nitrogen fertilizer (0, 90 and 135 kg N ha^-1) could mitigate the negative impacts of NaCl (0, 100, and 200 mM NaCl) on emergence percentage, seedling growth and some biochemical parameters. The results showed that high salinity level decreased emergence percentage, seedling growth, relative water content, chlorophyll content (SPAD reading), catalase (CAT) and peroxide (POD), but increased soluble protein content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. The SOD activity was decreased by nitrogen. However, the other measurements were increased by nitrogen. The interactive impact between nitrogen and salinity was significant in most parameters except EP, CAT and POD. The seedling length, dry weight, fresh weight, emergence percentage, POD, soluble protein and chlorophyll content were significantly affected by the interaction between GA₃ and salinity. The GA₃ and nitrogen application was successful mitigating the adverse effects of salinity. The level of 144.3 and 288.7 μm GA₃ and the rate of 90 and 135 kg N ha^-1 were most effective on many of the attributes studied. Our study suggested that GA₃ and nitrogen could efficiently protect early seedlings growth from salinity damage.