Improvement of Climate Resource Utilization Efficiency to Enhance Maize Yield through Adjusting Planting Density

Abstract

The sustainable high yield of crops is critically important under the current situation of global climate warming. In order to improve regional yield, it is urgent to clarify the limiting factors of local grain yield and change the traditional planting measurements to adapt to the warming climate and make full use of climate resources. Long-term field experiments over seven years from 2014 to 2021 were conducted with the same maize cultivar (i.e., Luyu9105) with seven planting density treatments: 3.0 × 104 (D1), 4.5 × 104 (D2), 6.0 × 104 (D3), 7.5 × 104 (D4), 9.0 × 104 (D5), 10.5 × 104 (D6), and 12.0 × 104 (D7) plants per hectare in Taihe and Hefei, which belong to the southern Huang-Huai-Hai (SHHH) and southeast (SE) maize-producing areas in China. According to the field experiment data, differences in grain yield, ear number, kernel number per spike, and 1000-kernel weight of different treatments were analyzed. The utilization efficiency of climate resources in Taihe and Hefei was calculated using daily solar radiation, mean temperature, and precipitation data. The results showed that Taihe had 7.8% higher solar radiation during the growing season of maize than Hefei, while accumulated temperature ≥10 °C (AT10) was 3.9% lower than Hefei. The grain yields of different planting densities in Taihe were 9.7~23.6% higher than in Hefei. The agronomic optimal planting density (AOPD) was 8.6 × 104 plants ha−1 in Taihe and 8.0 × 104 plants ha−1 in Hefei. Compared to the actual grain yields, when the agronomic optimal planting densities were adopted, the simulated yield increased by 51.3% and 59.6%, respectively. The radiation utilization efficiency, temperature utilization efficiency, and precipitation utilization efficiency in Taihe were 12.9%, 24.6%, and 26.7% higher than the values of Hefei, respectively, and D4 and D5 treatments had significantly higher climatic resource utilization efficiency than D1 and D2 treatment. The grain yield was negatively correlated with accumulated temperature ≥10 °C and positively correlated with solar radiation. The multiple linear regression model among solar radiation, accumulated temperature was ≥10 °C, and grain yield was y = 0.550R−0.562AT10 + 14,593.6 (R = 0.379). Accumulated temperature ≥10 °C was the main climatic factor affecting the grain yield due to the higher occurrence probability of a maximum temperature ≥35 °C. Overall, in the future, increasing planting density and alleviating heat stress may enhance grain yield. These results could provide cultivation measurements with regional characteristics to adapt to the local climate and maximize the utilization efficiency of climatic resources.