Bridging yield gaps in irrigated lowland rice of Southern Brazil through management optimization and attainable yield analysis

Context and objective Improving rice yield and resource-use efficiency is essential for sustainable crop intensification. This study quantified the magnitude and causes of rice yield gaps in irrigated lowland production systems of southern Brazil. Methods We combined observations from 475 farmer fields collected over five growing seasons (2016–2020) with the process-based crop model SimulArroz and stochastic frontier analysis to estimate potential yield, actual yield, and the contributions of genetic, environmental, and management factors to the overall yield gap. Results Mean potential yield was 16.0 t ha⁻¹ , whereas farmers' actual yield averaged 8.4 t ha⁻¹ , resulting in an overall yield gap of 7.6 t ha⁻¹ . The genetic component (cultivar choice) explained approximately 10% of the total yield gap, whereas environmental effects associated with sowing date accounted for 20%. The remaining yield gap was primarily associated with management, with the resource (46%) and efficiency (24%) yield gap components representing the largest opportunities for improvement. Optimizing sowing date alone could increase regional rice production by 8.4%, equivalent to an additional 0.5 Mt of paddy rice, without expanding cultivated land. Conclusions and significance Management practices remain the main leverage point for narrowing rice yield gaps in southern Brazil. Site-specific optimization of sowing date, nutrient management, and crop establishment can substantially improve productivity and resource-use efficiency, supporting sustainable intensification of irrigated rice production systems.