【摘要】 根据作者近年对水稻发育光温反应的研究,本文综合出积温法在描述作物发育与温度关系上存在的问题。第一,积温法假设作物发育速度与温度间呈线性关系,而实际上为非线性。第二,积温法假定作物发育对昼、夜温反应相同,而实际上发育存在明显的温周期现象,即对昼温和夜温有不同的反应。第三,积温法假设作物发育对温度的敏感性是恒定的,而实际上感温性可能随生育阶段而变化。彻底克服这些缺陷,需要建立分别包含昼温和夜温效应的、分阶段的非线性模型。但考虑到若仅利用田间试验数据往往难以准确估计这类模型的参数,人们仍可能偏爱积温法。于是,本文提出了改进积温法预测精度的可行途径。更多还原

【Abstract】 The thermal time approach has widely been used in crop growth modelling and crop management and breeding practices. The thermal unit required for a crop to fulfil a developmental phase, however, varies strongly among years or among locations, ever for occasions where no photoperiod effect occurs. This indicates that the thermal time approach has no biologically theoretical basis. Based on recent findings on photothermal responses of rice development, the author summarized in this paper three problems of the thermal time approach in describing the effect of temperature on crop development. First, the thermal time approach assumes that the relationship between crop development rate and temperature is linear, whereas the actual response of the development rate to temperature is bell-shaped nonlinear. Secondly, the thermal time approach uses the mean daily temperature, assuming no difference in the impact of day and night temperature on crop development, whereas the actual effect of day and night temperature is often strongly different, showing an apparent phenomenon of thermoperiodism. Thirdly, the thermal time approach assumes that sensitivity of response of crop development to temperature does not change during a developmental period, whereas the temperature sensitivity may vary strongly with developmental stage. To thoroughly overcome these problems of the thermal time approach, it is necessary to develop a detailed stage-specific nonlinear model in which effects of day and night temperature on development rate are accounted for separately. However, since it is often difficult to accurately estimate parameters of this type of detailed nonlinear models only based on data offield experiments, the thermal time approach may still be preferably used. In this paper, several possibilities to improve the accuracy of the thermal time approach were proposed.更多还原