Effects of Drought, High Temperature, and Nitrogen Application on the Growth, Yield, and Grain Quality of Spring Maize in Northeast China

To clarify the impacts of drought, high temperature, and nitrogen application on the growth, yield, and grain quality of spring maize, the variety "Danyu 405" was used as the test material. Experiments involving drought stress, high temperature stress, and nitrogen addition were conducted during key growth stages such as jointing, tasseling, and flowering. The study systematically revealed the comprehensive effects of drought, high temperature, and nitrogen fertilization on spring maize (variety 'Danyu 405'). In the water-nitrogen interaction experiments, it was found that compared with the control under adequate water conditions without nitrogen, moderate drought combined with nitrogen application at the jointing or tasseling stages increased plant height, barren tip ratio, amino acid content, and crude protein content. However, it significantly suppressed the leaf area index, biomass, hundred-grain weight, and theoretical yield, while reducing grain fat and starch content. Drought at the tasseling stage was particularly detrimental to yield, with an average reduction of 40.8% in theoretical yield. Furthermore, as nitrogen application increased, most yield-related indicators showed a declining trend, while some quality indicators (such as starch) improved, indicating that nitrogen application under drought conditions could enhance certain quality traits while inhibiting yield. In experiments combining temperature and water stress, it was further demonstrated that drought, high temperature, and their combined stress significantly reduced the maximum carboxylation rate of leaves (by 23.3% to 33.2%) and yield. Drought alone reduced yield by 40.0%, while the combined effect of high temperature and drought was less severe than that of drought alone. Additionally, the combined stress significantly altered grain quality, manifesting as increased fat and amino acid content and decreased starch content. The findings provide a theoretical basis for spring maize production in Northeast China to address climate change and optimize water and nitrogen management.