Predicting nursery growth and transplanting shock in rice

Seedling growth in the nursery and the magnitude of shock experienced by th e seedlings after transplanting can affect subsequent growth and developmen t of transplanted rice (Oryza sativa). These two processes have not been ad equately represented by rice growth simulation models. In this study, seedl ing growth in the nursery was described with respect to endosperm mobilizat ion, dry matter (DM) distribution and seed size. In addition, the transplan ting shock process was represented describing the crop development and grow th in relation to seedling age at transplanting. These relationships, as tw o sub-models, were incorporated into CERES-Rice, a rice growth model, and t heir performances compared with independent field data. The nursery growth sub-model was also evaluated with another model, RIBHAB. Results of the com parison showed that the nursery growth sub-model, either with CERES-Rice or RIBHAB, closely predicted observed seedling growth. On the other hand, CER ES-Rice overestimated root and leaf DM and underestimated culm DM, while RI BHAB underestimated all the growth traits considered in the evaluation. Tra nsplanting shock period predicted by the sub-model closely mimicked observa tion, whereas CERES-Rice highly overestimated it. It is concluded that the developed nursery growth and transplanting shock sub-models can be incorpor ated into CERES-Rice and other rice growth models for better simulation of those growth processes.