AIR-TEMPERATURE VARIATIONS AND RICE PRODUCTIVITY IN BANGLADESH - A COMPARATIVE-STUDY OF THE PERFORMANCE OF THE YIELD AND THE CERES-RICE MODELS

Potential increase in air temperature due to climatic change and inter -annual climatic variability and its impacts on crop productivity is o f major concern to crop scientists. A number of physically-based model s have been developed and applied to estimate crop-environment relatio nships. In the present study the performance of two such models (the Y IELD and the CERES-Rice) are discussed. These two models are used to e stimate bore rice productivity under normal and abnormal climate scena rios in Bangladesh. This study finds that bore rice productivity at My mensingh predicted by the YIELD is higher than the prediction by the C ERES-Rice. Productivity estimates for Barisal by these two models are almost identical. Assumptions of non-identical management practices, d ifferent soil characterization procedures, different methods for calcu lation of dry matter production by these two models and the range of d iurnal temperature variations played an important role in productivity estimates. The YIELD model predicted the lengths of the growing seaso n under the normal and abnormal thermal climate conditions and they ar e to be shorter than the lengths predicted by the CERES-Rice model. Th e YIELD model's assumption of higher threshold temperature and a relat ively simple relationship between phenology and air temperature has pr oduced such estimations (shorter growing season). The complex data req uired by CERES-Rice may be an impediment for its extensive use. If inp ut data for the CERES-Rice is not available, the YIELD model can be co nsidered as a possible tool for various applications in crop-environme nt relationships. (C) 1998 Elsevier Science B.V. All rights reserved.