Effect of Nitrogen Supply Methods on the Gas Exchange, Antioxidant Enzymatic Activities, and Osmoregulation of Maize (Zea mays L.) Under Alternate Partial Root-Zone Irrigation

Increasing drought stress resistance by exploiting crops’ potential is crucial for agricultural sustainable development. Alternate partial root-zone irrigation (PRI) shows some benefits in coping with drought stress, but there is limited information on physiological mechanism of crop in response to nitrogen supply patterns under alternate PRI. Therefore, we designed a rainproof-pond study to determine the effects of nitrogen supply methods on the physiological characteristics of maize (Zea mays L.) under alternate PRI. Two nitrogen fertilizer supply methods, including alternate nitrogen supply (AN) and conventional nitrogen supply (CN), were applied with alternate furrow irrigation (AI) and conventional furrow irrigation (CI), respectively. In addition, AIAN was applied in two ways, namely AIANS (supply of N fertilizer and irrigation water in a synchronized manner) and AIAND (supply of N fertilizer and irrigation water in a separate manner). Compared to CICN, AICN and AIANS enhanced leaf water use efficiency with a significant increase in transpiration rate, while photosynthetic rate was comparable. Also, compared to AIAND, the AIANS positively affected the most measured physiological characteristics. Greater leaf relative water content, chlorophyll and soluble protein content, and the activities of peroxidases and superoxide dismutase enzymes were found in AIANS and AICN. Moreover, the contents of malondialdehyde, proline, and soluble sugar decreased which can be attributed to enhanced root vitality in AICN and AIANS. Alternate furrow irrigation combined with conventional nitrogen supply or alternate synchronized nitrogen supply enhances the drought tolerance of maize by improving photosynthesis, antioxidant defense system, and osmoregulation.