Inadequate water and nitrogen (N) supplies can limit the productivity of maize. Climate change will likely increase drought in many regions on a global scale. The determination of N fertilizer rates under field drought conditions will be critical toward the reduction of agricultural risk. For this study, drought-resistant/sensitive cultivars were selected as experimental samples. Our results revealed that drought stress reduced the relative water content (RWC) of leaves, which resulted in leaf curling, while decreasing photosynthesis levels and N accumulation. In contrast to those without N treatments, the application of N significantly increased grain yields by 26.8% during the wet year but increased only by 5.4% during the dry year. Under the same N levels, the reduction in yield caused by drought increased with the increased application of N. This was because the application of the N fertilizer translated to increase the leaf area and transpiration, exacerbated the soil water loss and induced a leaf curling state in maize, which had deleterious effects on photosynthesis and N absorption. During the dry year, the yields of drought-sensitive cultivars were even less than those without the application of N. Compared with those of drought-sensitive cultivars, the RWCs of drought-resistant cultivars decreased more rapidly, and they entered the state of leaf curling earlier. Thus, N fertilizer inputs should be reduced, and the extent of N fertilization for drought-sensitive cultivars should be reduced even further.

中文翻译：

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不同田间氮素条件下玉米叶片对干旱胁迫的高效生理和养分利用效率响应

水和氮（N）供应不足会限制玉米的生产力。气候变化可能会在全球范围内加剧许多地区的干旱。确定田间干旱条件下的氮肥用量对降低农业风险至关重要。对于该研究，选择抗旱/敏感的品种作为实验样品。我们的结果表明，干旱胁迫降低了叶片的相对含水量（RWC），从而导致叶片卷曲，同时降低了光合作用水平和氮素积累。与未进行氮处理的作物相比，氮的施用在雨季明显提高了26.8％的谷物产量，而在旱年仅增加了5.4％的谷物产量。在相同的氮水平下，干旱引起的单产下降随着氮素施用量的增加而增加。这是因为氮肥的施用增加了叶面积和蒸腾作用，加剧了土壤水分流失，并导致玉米叶片卷曲，这对光合作用和氮素吸收具有有害作用。在干旱年份，对干旱敏感的品种的产量甚至比不施氮的品种少。与干旱敏感品种相比，抗旱品种的RWCs下降更快，并进入叶片状态。较早地卷曲。因此，应减少氮肥的投入，对干旱敏感品种的氮肥施用量应进一步减少。加剧了土壤水分流失，并导致玉米叶片卷曲，这对光合作用和氮素吸收具有有害作用。在干旱年份，对干旱敏感的品种的产量甚至比不施氮的品种少。与干旱敏感品种相比，抗旱品种的RWCs下降更快，并进入叶片状态。较早地卷曲。因此，应减少氮肥的投入，并进一步减少对干旱敏感的品种的氮肥施用量。加剧了土壤水分流失，并导致玉米叶片卷曲，这对光合作用和氮素吸收具有有害作用。在干旱年份，对干旱敏感的品种的产量甚至比不施氮的品种少。与干旱敏感品种相比，抗旱品种的RWCs下降更快，并进入叶片状态。较早地卷曲。因此，应减少氮肥的投入，对干旱敏感品种的氮肥施用量应进一步减少。抗旱品种的RWCs下降较快，且较早进入叶片卷曲状态。因此，应减少氮肥的投入，对干旱敏感品种的氮肥施用量应进一步减少。抗旱品种的RWCs下降较快，且较早进入叶片卷曲状态。因此，应减少氮肥的投入，并进一步减少对干旱敏感的品种的氮肥施用量。