Study on Predictions of Phenological Phases of Winter Wheat-comparison between Beta and Sine Models

Temperature is one of the most important elements that determine plant growth, development and yield. Accurate temperature response is thus a prerequisite to successful crop system modeling and proper managerial decisions. Results from many previous studies showed that the predictions of developmental stages were better with non-linear temperature response function compared to linear ones. In this study, three non-linear models including two versions of Beta models and a Sine model using only three cardinal temperatures, namely the minimum, the optimum and the maximum temperatures were commonly introduced which were derived from a series of long-term field experiments on winter wheat conducted in thirty sites in Henan Province, China. Model evaluation for winter wheat was based on a set of four-year independent data. The simulated results showed that no significant improvement in the prediction of the developmental stages using the Sine model was found as compared to two Beta models and the Sine model generally produced a more reasonable set of cardinal temperatures than the two Beta models. In general, there was no much difference among the three models and it just mean that the three cardinal temperatures used in simulating the developmental stages must agree with the corresponding model.