Modeling of flower bud differentiation development stages and phenophase in castor

Four castor cultivars,Tongbi 5,Tongbi 6,Tongbi 9 and Zhongdong were used to construct the mechanism model of flower bud differentiation development stages and phenophase in castor,based on the principle of crop physiological development time constancy. Temperature sensitivity,photoperiod sensitivity,intrinsic earliness and filling factors were used in the model. The relative thermal effectiveness was calculated by Bate function and photoperiod effectiveness was calculated by Gauss function. The model was examined in different years and sites. The results showed that absolute errors of flower bud differentiation development stages and phenophase were0-5d,and root mean square error was fewer than 3d.