Nitrogen Management Enhanced Plant Growth, Antioxidant Ability, And Grain Yield Of Rice Under Salinity Stress

Salinity is a major abiotic stress limiting crop growth and reducing grain yield. In recent years, little progress was made in salt-tolerant cultivation techniques. Therefore, a controlled experiment was conducted to study the effects of nitrogen management (NM) on growth, antioxidant ability, and yield performance of salt-tolerant rice (Oryza sativa L.) under salinity stress. Three salinity levels (0 parts per thousand as control; 0.75 parts per thousand, 4.3 dS m(-1); and 1.5 parts per thousand, 7.7 dS m(-1)) and four levels of NM (tillering fertilizer/panicle initiation fertilizer = 7:3, 6:4, 5:5, and 4:6) were arranged in this study. Under salinity stress, plant height, tiller number, fresh weight, grain yield, panicle, spikelets per panicle, grain weight, and soluble sugar content in stem were significantly decreased. In contrast, antioxidant parameters of superoxide dismutase, peroxidase, and catalase were significantly increased. Grain filling percentage and sucrose content were slightly changed. Compared to the control, grain yield was reduced by 45.6%, 34.8%, 60.4%, and 46.7% at the ratio of 7:3, 6:4, 5:5, and 4:6 NM at 0.75 parts per thousand salinity level, and 73.5%, 59.7%, 74.8%, and 61.7% at 1.5 parts per thousand salinity level, respectively. The highest yield was generated by 6:4 NM at both the 0.75 parts per thousand and 1.5 parts per thousand salinity level, and the lowest by 4:6 and 5:5. However, NM could obviously alleviate the inhibition effects of salinity stress and improve antioxidant ability of rice. Among them, 6:4 NM performed the best alleviation effects, followed by 7:3 and 5:5 NM. This study suggests that the appropriate NM can effectively alleviate salinity stress and increase grain yield.