Grain Yield And N Use Efficiency Of Direct-Seeded Rice Under Different N Management Practices Aimed To Reduce N Input

The objective of this study was to determine whether integrated N management strategies can be used to increase yield and N use efficiency (NUE) of direct-seeded rice. Field experiments were conducted in the Chengdu Plain in China. Super hybrid, ordinary hybrid and inbred rice were grown under four N management practices, namely N0 (zero N), N1 (fix-timing N management), N2 (reduced basal N combined with SPAD-based N management [SBNM]), and N3 (no basal N fertilization combined with SBNM). Although total N application rate was 13%-40% lower under N2 and N3 than under N1, grain yield under N2 and N3 was equal to that under N1. Rice grown under N2 and N3 had higher NUE than under N1. Super hybrid rice had 11% higher grain yield than ordinary hybrid and inbred rice. The higher grain yields of super hybrid rice were attributed to higher biomass, larger panicle size and lower temperatures during grain filling period. Our results suggest that it is feasible to improve grain yield and NUE by growing rice under SBNM with a reduced basal N application rate, and that breeding cultivars with large panicle size may be an effective approach to achieve high yield in direct-seeded rice production.