Planting Strategy Optimization Can Increase Maize Yield by Delaying Leaf Senescence and Improving Photosynthetic Capacity

This study aimed to investigate the effects of different planting density and row spacing configurations on maize corn yield, leaf photosynthetic parameters, and senescence characteristics; to reveal the purpose of the physiological mechanism of row density interaction regulatsving maize yield; and to clarify the optimal planting combinations for optimizing population structure, delaying leaf senescence, and improving light energy utilization efficiency. In doing so, this study provides a theoretical basis and technical guidance for increasing corn yield, the sustainable development of the maize industry, and improved yield production in Shanxi Province. An experiment was conducted with a two-factor randomized block design, with three planting densities of 60,000 plants/hm2 (D1), 67,500 plants/hm2 (D2), and 75,000 plants/hm2 (D3) in the main area and four-row spacings of 40 + 40 cm, 40 + 80 cm, 50 + 50 cm, and 80 + 80 cm in the secondary area. The maize kernel yield, leaf photosynthetic parameters, malondialdehyde content, and anti-aging key enzyme activities were measured in 2023 and 2024. The results show that with the increase in planting density, the net photosynthetic rate of maize leaves gradually decreased, and the transpiration rate gradually increased. At the same time, too high or too low density will accelerate the aging of maize leaves, which is manifested by the increase in MDA (malondialdehyde) content and the decrease in SOD (superoxide dismutase) and CAT (catalase) activities. The best row spacing configuration performance is 40 + 80 cm, which is conducive to the ventilation and light transmission of maize plants, improves the efficiency of light energy utilization, slows down the aging of plant leaves, and thus promotes maize growth, development, and yield enhancement. The interaction effect between two intercropping maize factors significantly affects corn yield, with a medium density of 67,500, where 6000 is the most effective. Thus, 67,500 plants/hm2 combined with a row spacing of 40 + 80 cm significantly increases corn yield. This combination obtained the highest net photosynthesis, SOD, and CAT of 24.33 µmol·m−2·s−1, 32.54 U·mg−1 and 1038.99 U·g−1, and the lowest transpiration rate and MDA content of 3.47 mmo·m−2·s−1 and 108.95 µmo·L−1, resulting in the highest maize yield of 13,916.46 kg/hm2. In summary, a density of 67,500 plants/hm2 and 40 + 80 cm row spacing is the best combination, improving light energy utilization efficiency, delaying the leaf senescence process, and increasing the yield, which can provide a theoretical reference for the planting pattern of maize in Shanxi Province.