Adaptation and application of soybean phenology model in the north China spring soybean producing area

Accurate prediction of the development is essential for managing production practices such as determination of optimal planting date, choice of appropriate cultivar for a specific site. The phenology model SOYDEV, considering the responses of development to temperature and photoperiod, was adapted in the north China spring soybean producing area. A 2-year cultivar × location field experiment and a 2-year sowing dates experiment were conducted in this area. Using the model, we simulated cultivars designated as early, early-medium, medium and late maturity classes in the north China spring soybean area, which corresponded to maturity groups (MG) MG II, MG III and MG IV and MG V respectively. By holding other parameters constant, a single parameter, the maximum developmental rate at optimum temperature and photoperiod (Rmax), was optimized on maturity group level and the resulting values gave acceptable predictions of phenological stages of R0, R1 and R7 with root mean square errors (RMSE) within 7 days. Cultivar specific optimization of Rmax and photoperiod response parameters improved further the prediction of R0, R1, R3.5, R5 and R7 with RMSE being less than 2 days. It is concluded that the simplified approach for parameter optimization can improve the simulation accuracy for a better prediction of soybean development and be helpful for phenology prediction in the north China spring soybean producing area.