Optimized agronomic management practices narrow the yield gap of summer maize through regulating canopy light interception and nitrogen distribution.

Optimizing the canopy nitrogen (N) distribution by matching the available light resources to construct a light-N matching canopy structure of summer maize is important to improve yield and narrow the yield gap (YG). A field experiment with four integrated agronomic management practice systems [a control treatment (T1), an improved management system (T2), a super high-yield management system (T3), and an optimized management system (T4)] was conducted at Da Wenkou Town, Tai'an, China, from June to October in -2018–2020 to study the canopy light and N distribution and photosynthetic N use efficiency of summer maize. The results showed that optimized integrated agronomic management practices could coordinate canopy light and N distributions to increase the yield, thus narrowing the YG between T1 and yield potential by 1.9–5.2 Mg ha-1. In addition, the T4 treatment intercepted more radiation by adjusting the leaf area. Furthermore, the leaf N content of T4 in the middle canopy was significantly increased. The coordination of canopy light and N distributions of T4 was increased significantly, which was conducive to maximizing the use of N and solar radiation and increasing photosynthetic N use efficiency significantly by 9.4–41.4%, compared to that of T1. As a result, the yield of T4 was increased by 37.0% compared to that of T1. And T4 narrowed the YG by 3.4 Mg ha-1. Therefore, the T4 was the best choice for achieving a high-yield and high-efficiency production of summer maize in this study. • Optimized agronomic management improved leaf nitrogen vertical distribution. • Optimized agronomic management increased canopy light interception. • Optimized agronomic management narrowed yield gap by regulating canopy structure. [ABSTRACT FROM AUTHOR]