Enhancing maize high-density population uniformity and yield through timely drip irrigation after sowing

Uneven crop stands arise from natural variations in emergence time, which are influenced by different irrigation measures applied post-sowing. In the pursuit of high-yielding maize populations, the emergence rate and uniformity of maize stands are critical factors. This study investigates the effects of different irrigation methods and drip irrigation at various days after sowing on the emergence uniformity and yield of summer maize. The experiment consisted of six treatments: drip irrigation on the 0th, 3rd, 6th, 9th, and 12th days after sowing (DAS0, DAS3, DAS6, DAS9, and DAS12), and sprinkling irrigation (SI) on the 0th day after sowing (SI0). Agronomic traits, ear characteristics, harvest yield, and indices of population uniformity were evaluated at critical growth stages. Results indicated that timely drip irrigation (DAS0–3) significantly increased the emergence rate and number of harvestable ears by 9.57% (8,621.61 plants ha^–1) and 10.54% (8,017.05 ears ha^–1) compared to the SI treatment. Treatment with DAS0–3 resulted in a significant increase of 13.50% in ear length and 24.85% in kernel weight per ear compared to the SI treatment. Maize populations subjected to delayed drip irrigation (DAS6–12) demonstrated a progressive decline in quality throughout the growth period. At the silk stage, the uniformity of plant height and ear height decreased by 47.19 and 44.85%, respectively, compared to the DAS0–3 treatment. Furthermore, at harvest, the uniformity of dry matter accumulation and leaf area index (LAI) was reduced by 28.24 and 41.83%, respectively, relative to the DAS0–3 treatments. Correlation analysis reveals that the uniformity of kernel weight per ear is most significantly associated with yield, as indicated by a correlation coefficient of 0.90^**. The yield in the DAS0–3 treatments was significantly higher than that in the SI treatment by 23.71%. The yields of the DAS6–12 treatments were notably lower than those of the DAS0–3 treatments, ranging from 13.18 to 23.97% lower, and were comparable to those observed in the SI treatment. The suboptimal implementation of drip irrigation technology has prevented it from realizing its full potential to increase crop yields. Each day’s delay in initiating drip irrigation after the third day post-sowing reduces yield by an average of 0.32 Mg ha^–1 Timely drip irrigation following maize seeding significantly enhances emergence rate and population uniformity, increases the number of harvestable ears and kernel weight per ear, ultimately leading to higher final yields. Applying drip irrigation for seedling emergence within 3 days after sowing can better realize its yield-increasing potential.