Transferability of recommendations developed for transplanted rice to direct-seeded rice in ORYZA model

Rice (Oryza sativa L.) production is transitioning from a transplanted system to a direct-seeded system, and researchers aim to use current calibrations if possible. However, the ORYZA model calibrated for the transplanted rice has not been tested and validated for direct-seeded rice. This study evaluated the transferability and predictability of ORYZA (v3) in estimating crop yields among different rice cropping systems. Evaluations were performed with inbred and hybrid rice cultivars in the early and late rice-growing seasons in central China. The analysis indicated that the crop parameters calibrated for the direct-seeded rice cropping system could be applied to satisfactorily simulate rice growth and development in the transplanted cropping system. By contrast, crop parameters calibrated for the transplanted rice system required modifications before they could be used for an accurate prediction in the direct-seeded rice system. The modifications were associated with the delay in leaf area development due to transplanting shock. From the results of this study, a framework was proposed to develop crop parameters for direct-seeded rice using experimental data from transplanted rice and vice versa.