Abstract:

Aims Our objective was to develop a simulation model of grain starch formation in rice plants by analyzing the dynamic patterns of carbon assimilation and translocation under varied environmental factors and genetic types.
Methods We used field experiments involving different eco-sites, growing seasons, cultivar types and nitrogen rates in developing a model of grain starch accumulation.
Important findings The model proposed that the rate of grain starch accumulation was determined by (a) carbon availability restricted by source and (b) carbon accumulation rate restricted by sink. Carbon accumulation rate restricted by sink was dependent on the potential starch accumulation rate and the interaction of influencing factors: temperature, water, nitrogen conditions within plants and the ability of carbon translation into starch. Carbon availability in grains restricted by source was the sum of carbon assimilation from the photosynthetic organs and remobilization from the vegetative organs after anthesis. Photosynthetic product transported to grain directly after anthesis exhibited a logarithmic relationship to post-anthesis growing degree days. Post-anthesis carbon remobilization from the vegetative organs included remobilization from leaves and stems. Testing of the model with independent datasets involving different years, eco-sites, varieties and nitrogen rates indicated values of RMSE of 3.61% and 4.51% and R²of 0.994 and 0.959 for starch accumulation and content, respectively. Results showed that the model could predict accumulation and content of grain starch in rice under different cultivated conditions, which provides a quantitative tool for quality prediction and regulation.

Key words: carbon accumulation, carbon translocation, grain, rice, simulation model, starch