Optimal Planting Density for Maximizing Maize Yield in China: A Meta-Analysis

This study examined the yield response of maize to plant density in China using a boundary-line method based on metadata (2,783 data points) gathered from 157 recent studies during 2000–2017. The optimal planting density for maximum yield was found to be 8.5 ×104 plants ha–1 in Northeast China, 9.3 ×104 plants ha–1 on the North China Plain, 10.5 ×104 plants ha–1 in Northwest China, and 8.0 ×104 plants ha–1 in Southwest China. Compared to current practices, optimizing planting density resulted in a 13% to 20% improvement in potential grain yield for these major maize regions of China. Across regions, the planting density at maximum yield was similar for spring-planted (9.2 ×104 plants ha–1) and summer-planted maize (9.3 ×104 plants ha–1) systems, although maximum yield was 7% greater for the spring-planted maize system. For different productivity environments, high-yielding plots achieved a maximum yield of 18.2 Mg ha–1 at a planting density of 11.6 ×104 plants ha–1, while general productivity plots obtained 39% lower grain yield at a 19% lower planting density (9.4 ×104 plants ha–1).