Assessment and Improvement of the Global Agro-Ecological Zones Model for Estimation of Rice Productivity in Hokkaido

Abstract

 We assessed possibility of the Global Agro-Ecological Zones (GAEZ) model for applying to rice productivity in Hokkaido, Japan, and improved it in order to simulate rice yield change responding to climate in Hokkaido. Before improving GAEZ model, the simulated yield was almost zero in most of the calculated periods, which means, the original GAEZ model is not applicable to Hokkaido where strengthening cool tolerance of rice variety has been developed. We improved four points: (1) easing temperature requirement, (2) modifying biomass calculation, (3) predicting heading date and (4) predicting cool summer damage due to floral impotency. The improvement of (1) enables GAEZ model to apply for cold regions; but, it did not simulate the observed yield variation. A simulation with combination of (1), (2), (3) and (4) simulated the variation of observed data. Especially, taking account of cool summer damage due to floral impotency and predicting heading date contribute to more accurate simulation of the observed yield variation.