Analysis of Yield Constraints and Challenges for Sustainable Production of Dry Direct-seeded Rice in Cool Climates

Dry direct-seeded rice (DDSR) cultivation can eliminate the cost of rice seedling management and transplanting. Its popularity is increasing in Japan; in particular, its area in northeastern Japan increased 4.8× from 2001 to 2021, versus 3.4× nationwide. On the other hand, the yield of DDSR in northeastern Japan tends to be about 10% lower than that of transplanted rice. As DDSR is expected to become more widespread, an analysis of yield constraints is needed to achieve stable rice production. This review focuses on nitrogen uptake patterns and meteorological factors that are closely related to yield formation. For sustainable food production, it is necessary to consider not only improvement in productivity but also the environmental impacts of N fertilizers. Therefore, this review describes a framework for comprehensively evaluating farmers’ profits and the environmental impacts of N fertilization in DDSR. Improvements in leaf development, canopy coverage, and N uptake during early vegetative growth are important for increasing yield. The review also describes a framework for evaluating N fertilizer application methods for DDSR and identifies the most suitable methods.