Balancing individual trade-offs for population gain: optimizing nitrogen and density secures fresh ear yield in...

Fresh waxy maize is a unique type of maize harvested at the late R3 stage. Both fresh ear yield and weight per ear determine its economic value. Nitrogen (N) application and planting density are the two major agronomic practice factors influencing maize growth and yield; however, optimal values for fresh waxy maize remain poorly defined, particularly in rain-fed areas.

The purpose of the present study was to clarify the effects of planting density and N application rate on fresh ear yield, in addition to dry matter (DM) and N accumulation and partitioning, and to identify the primary drivers of the effects in fresh waxy maize.

A two-year field experiment was conducted in Shanxi province, China, using a split-plot design with three replicates. N application rate (0, 120, 180, and 240 kg ha^-1) was the main factor and planting density (45, 000 and 60, 000 plants ha^-1) was the second factor.

Increasing planting density from 45, 000 to 60, 000 plants ha^-1 imposed a trade-off: it suppressed dry matter (DM) and nitrogen (N) accumulation per plant while boosting total DM and N accumulation at population level. However, the optimal N application rate (180 kg ha^-1) alleviated the negative effects of high planting density (60, 000 plants ha^-1), ensuring that weight per ear was comparable to that under low density (45, 000 plants ha^-1). The combination of 180 kg N ha^-1 and 60, 000 plants ha^-1 achieved the highest fresh ear yield, demonstrating an effective balance between individual performance and population gain. Therefore, the 180 kg ha^-1 N and 60, 000 plants ha^-1 combination is recommended as an efficient management strategy for improving fresh waxy maize productivity and N partial factor productivity.

The findings of the present study provide practical guidance for integrated management of N and planting density in fresh waxy maize to regulate DM, N and yield in the study area and in other regions with similar climatic conditions.