Effect of Ethephon and Nitrogen Fertilizer on Nitrogen Uptake, Nitrogen Use Efficiency and Yield of Summer Maize

Abstract

A field experiment using maize hybrid Zhengdan 958 was conducted to study effect of ethephon (0 and 180 g ha) and nitrogen fertilizer (0, 75, 150, and 225 kg N ha) on summer maize yield and yield components, nitrogen uptake, nitrogen use and SPAD value. The results showed that ethephon significantly decreased nitrogen uptake and N uptake efficiency, whereas markedly increased N utilization efficiency. N agronomic efficiency under ethephon treatment was 32.7%–34.6% more than that under control, and ethephon had no negative effect on maize yield and yield components. With increase nitrogen fertilizer of application, maize yield, yield components and nitrogen uptake were increased, but N uptake efficiency, N utilization efficiency, N partial factor productivity and N agronomic efficiency were decreased. Nitrogen uptake under 225 kg N ha treatment was 68.4%–91.8% more than that under 0 kg N ha. However there was no difference for nitrogen uptake between 225 kg N ha and 150 kg N ha treatments. Significant effect of ethephon × nitrogen was observed on nitrogen uptake, N uptake efficiency and N agronomic efficiency. Ethephon as well as higher nitrogen rate increased SPAD value of ear leaf during grain filling stage, while there was no significant interaction between ethephon and nitrogen fertilizer on SPAD value. Correlation analysis indicated that summer maize yield was significantly positively correlated with nitrogen uptake at silking stage and harvest stage and with SPAD value of ear leaf.