Nitrogen Supply Affects Grain Yield by Regulating Antioxidant Enzyme Activity and Photosynthetic Capacity of Maize Plant in the Loess Plateau

Nitrogen (N) is the most limiting nutrient for maize, and appropriate N fertilization can promote maize growth yield. The effect of fertilizer rates timings on morphology, antioxidant enzymes, grain yield (Zea mays L.) in Loess Plateau China was evaluated. four levels, i.e., 0 (N0), 100 (N1), 200 (N2), 300 (N3) kg ha?1, were applied at two (T1, one-third sowing two-thirds six-leaf stage maize; T2, sowing, stage, eleven-leaf maize). results show that N2 N3 significantly increased plant height, stem leaf dry weight, area index compared with a non-N-fertilized control (N0). net photosynthetic rate, transpiration stomatal conductance, chlorophyll contents lower, while intercellular carbon dioxide concentration higher non-fertilized plants to fertilized plants. activities peroxidase (POD) superoxide dismutase (SOD) but difference between ha?1 not significant; further, isozyme bands POD SOD also changed their activities. Compared control, by 2.76- 3.11-fold 2018, 2.74- 2.80-fold 2019, 2.71- 2.89-fold 2020, there no significant N3. application timing only affected 2018. In conclusion, through optimizing enzyme system, increasing capacity, promoting matter accumulation. Further research necessary evaluate response more cultivars under seasons validate obtained.