Combination of suitable planting density and nitrogen rate for high yield maize and their source-sink relationship in Northwest China.

Abstract

Increasing crop yield per unit area by increasing planting density is essential to ensure food security. However, the optimal combination of planting density and N application for high-yielding maize and its source-sink characteristics need to be more clearly understood. A two-year field experiment was conducted combining three planting densities (D1: 70,000 plants ha-1 ；D2: 100,000 plants ha-1 ；D3: 130,000 plants ha-1 ) and three nitrogen rates (N1: 150 kg N hm-2 , N2: 350 kg N hm-2 , N3: 450 kg N hm-2 ). The results showed that increasing planting density significantly increased leaf area index and grain yield, but negatively affected ear traits. The Richards model was used to fit the dynamic changes of dry matter accumulation of maize under different treatments, and the fitting results were good. Increasing planting density increased population yield while limiting the development of individual plants, bringing the period of rapid dry matter accumulation to an early end and accelerating leaf senescence. Appropriate N rate could prolong the period of rapid accumulation of dry matter in maize, increase the 100-kernel weight. Increasing planting density enhanced post-silking dry matter accumulation to a lesser extent, and the source-sink relationship of the maize population gradually developed from sink limitation to source limitation with increasing planting density. The decrease in yield due to the insufficient source strength to meet the sink demand at too high densities was the reason that limited further improvement of the optimal planting density. Appropriate N rate facilitated the realization of yield potential at high density. This article is protected by copyright. All rights reserved.