Abstract:

To determine the suitable combination of tillage and nitrogen (N) rate for synergistic improvement of wheat yield, quality and N use efficiency in Huang-Huai-Hai area, field experiments was conducted from 2018 to 2020 with three tillage practices (rotary tillage, R; deep ploughing, P; subsoiling, B) and four N rates (135 kg/hm², N135, 180 kg/hm², N180, 225 kg/hm², N225, 270 kg/hm², N270) in Zibo, Shandong. The results showed that the grain yield, grain protein content and N use efficiency could be significantly regulated by tillage practice, N rate and the interaction of tillage practice and N rate. Compared with the traditional R or P, B increased the N accumulation amount at anthesis and maturity stages by 1.2%-18.9% and 5.2%-16.3%, respectively. The pre-anthesis N translocation amount and post-anthesis N accumulation amount were increased by 0.8%-70.4% and 5.7%-21.9%, respectively. Additionally, the plant N production capacity and N use efficiency increased by 3.2%-21.1% and 3.7%-40.7%, respectively. Therefore, compared with R or P, the grain yield, grain protein content and grain protein yield under B were significantly increased by 3.7%-40.7%, 3.6%-8.9% and 3.0%-49.9%. Increasing the N rate in a certain range could increase the grain protein content, but reduced the N use efficiency at the same time. In general, the highest grain yield, grain protein content and grain protein yield could be obtained simultaneously by B combined with 270 kg/hm² N rate, and the N use efficiency was higher than other tillage practices with the same N rate. Therefore, in this experimental area, the preferred B combined with 270 kg/hm² could achieve a synergistic increase in wheat yield and quality, while maintaining relatively higher N use efficiency.

Key words: tillage practices, nitrogen rates, grain yield, grain protein content, nitrogen use efficiency