Maize, a cereal crop of global significance, encounters cultivation challenges in the subtropical regions of Guangxi, mainly due to variable rainfall and low soil fertility, exacerbating the effects of drought. This study evaluated the effects of irrigation and nitrogen fertilisation on overcoming these challenges and improving maize growth and yield. Between 2020 and 2021, a split‐plot experiment was conducted. The main plots were assigned to two irrigation treatments: irrigated and rainfed. Within each main plot, subplots were treated with different nitrogen levels (0, 150, 200, 250 and 300 kg ha−1). The results showed that nitrogen levels and water regime significantly impacted several key factors, including the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular carbon dioxide concentration (Ci), photosynthetically active radiation (PAR), carbon‐metabolising enzymes and total carbon (TC) content accumulation. Under drought‐like rainfed conditions, the application of nitrogen, RN300 (rainfed application nitrogen 300 kg ha−1), IN250 (irrigated application nitrogen 250 kg ha−1) significantly enhanced the Pn (10.0%), Tr (3.17%), Ci (3.41%) and Gs (2.6%). Additionally, PAR was significantly influenced by the water regime and nitrogen levels. Under IN250, the capture ratio (Ca) increased (2.36%), while the penetration ratio (Pe) and reflectance ratio (Re) decreased by 13.12% and 46.36%, respectively, compared to RN300. The levels of carbon metabolism enzymes (sucrose phosphate synthase and phosphoenolpyruvate carboxylase) and the TC content were higher under RN300 compared to IN250; however, these differences were not statistically significant. Path analysis revealed that thousand kernel weight had the most significant impact on yield under both water regimes. The effect was stronger under irrigated conditions, with a path coefficient of 0.647, compared to 0.459 under rainfed conditions. Correlation analysis indicated that plant height (0.938), stem diameter (0.906), ear diameter (0.928) and ear length (0.803) were positively correlated with nitrogen levels. In conclusion, maize under IN250 exhibited superior photosynthetic performance and carbon accumulation. This suggests that balanced irrigation and nitrogen management can effectively mitigate the adverse impacts of drought on maize, optimising growth and yield sustainably.

中文翻译：

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灌溉和氮肥对干旱环境中雨水系统光合性能和产量的协同效应


玉米是一种具有全球意义的谷类作物，在广西亚热带地区面临种植挑战，主要是由于降雨量多变和土壤肥力低，加剧了干旱的影响。本研究评估了灌溉和氮肥对克服这些挑战和提高玉米生长和产量的影响。在 2020 年至 2021 年期间，进行了一项分裂地实验。主地块被分配到两种灌溉处理：灌溉和雨养。在每个主样地内，用不同的氮水平（0、150、200、250 和 300 kg ha-1）处理子样地。结果表明，氮水平和水分状况显著影响净光合速率 （Pn）、气孔导度 （Gs）、蒸腾速率 （Tr）、胞间二氧化碳浓度 （Ci）、光合有效辐射 （PAR）、碳代谢酶和总碳 （TC） 含量积累。在类似干旱的雨养条件下，施用氮、RN300（雨养施氮 300 kg ha-1）、IN250（灌溉施氮 250 kg ha-1）显著提高了 Pn （10.0%）、Tr （3.17%）、Ci （3.41%） 和 Gs （2.6%）。此外，PAR 受水情和氮水平的显著影响。与 RN300 相比，在 IN250 下，捕获率 （Ca） 增加 （2.36%），而穿透率 （Pe） 和反射率 （Re） 分别下降了 13.12% 和 46.36%。与 IN250 相比，RN300 下的碳代谢酶 （蔗糖磷酸合酶和磷酸烯醇式丙酮酸羧化酶） 水平和 TC 含量更高;然而，这些差异没有统计学意义。 路径分析表明，在两种水分条件下，千粒重对产量的影响最显着。在灌溉条件下效果更强，路径系数为 0.647，而在雨养条件下为 0.459。相关性分析表明，株高 （0.938）、茎粗 （0.906）、穗粗 （0.928） 和穗长 （0.803） 与氮素水平呈正相关。综上所述，IN250 下的玉米表现出优异的光合性能和碳积累能力。这表明平衡的灌溉和氮管理可以有效减轻干旱对玉米的不利影响，可持续地优化生长和产量。