Modeling plant nitrogen uptake and grain protein accumulation in rice | 水稻植株氮素吸收与籽粒蛋白质积累模型

Chinese. 目的建立基于生理生态过程的水稻籽粒蛋白质积累模拟模型。方法基于不同地点、品种及施氮水平的田间试验资料，通过解析花前植株氮素吸收与积累、花后氮素吸收与转运的动态特征及定量关系，构建水稻植株氮素吸收与籽粒蛋白质积累的模拟模型。结果水稻籽粒中氮素积累速率取决于源限制下的可获取氮源和库限制下的氮素积累速率；源限制下的可获取氮源取决于营养器官向籽粒转运的氮素和花后植株吸收的氮素，库限制下的氮素积累速率由潜在氮素积累速率及温度、水分和氮素因子效应来综合决定。营养器官中的氮素转运又分为叶片和茎中积累氮素的转运；花前叶片和茎中的相对氮含量随播后生长度日线性增加；花后叶片和茎中的相对氮含量随花后生长度日线性递减；花后吸收的氮素随籽粒重的增加对数递增。利用独立的田间试验资料对所建模型进行了检验，结果显示模拟值与观测值之间具有较好的一致性，其中花前叶片与茎秆氮素吸收量、花后籽粒氮素吸收量、花后叶片与茎秆中氮素转运量的决定系数分别为0.968、0.980、0.974、0.970和0.976，根均方差分别为16.55%、13.24%、9.53%、10.93%和9.29%；籽粒蛋白质含量的决定系数分别为0.930，根均方差分别为7.82%。结论模型对不同栽培条件下水稻植株氮素吸收与转运以及籽粒蛋白质积累具有较好的预测性，为水稻生产中籽粒蛋白质指标的动态预测提供了量化工具。

English. ObjectiveGrain protein content is an important quality index in rice. The objective of this study was to develop a process based simulation model for predicting the content and accumulation of grain protein under different cultural conditions. MethodOn the basis of the field experiments involving different eco-sites, cultivar types and nitrogen rates, the fundamental relationships between grain protein accumulation and environmental and genetic factors were quantified by modeling the processes of nitrogen assimilation and partitioning within plant. ResultThe model proposed that the rate of individual grain nitrogen accumulation was determined by the nitrogen availability restricted by source and nitrogen accumulation rate restricted by sink. Nitrogen availability of individual grain restricted by source was the sum of nitrogen uptake and remobilization from the vegetative organs post-anthesis, whereas nitrogen accumulation rate restricted by sink was dependent on potential nitrogen accumulation rate and interactive effects of temperature, water and nitrogen factors. Post-anthesis nitrogen uptake exhibited a logarithmic relationship to increasing grain weight. Nitrogen remobilization from the vegetative organs was provided from nitrogen accumulated in both leaves and stems. Relative nitrogen contents in leaves and stems pre-anthesis linearly increased with the accumulative growing degree-days after sowing, while those post-anthesis linearly decreased with the growing degree-days. The model was tested using the independent data sets of different years, eco-sites, cultivars, nitrogen rates, and it exhibited a good fit between the simulated and observed values, with the R2 of 0.968, 0.980, 0.974, 0.970 and 0.976, and RMSE of 16.55%, 13.24%, 9.53%, 10.93% and 9.29% for nitrogen uptake amounts of leaf and stem before anthesis, grain nitrogen uptake amount after anthesis, and nitrogen translocation amount of leaf and stem after anthesis, respectively, with the RMSE of 7.82% and R2 of 0.930 for grain protein content, respectively.ConclusionThe simulation model based on nitrogen assimilation and translocation in rice could give a reliable prediction of plant nitrogen uptake and translocation amounts, and grain protein content and accumulation under different cultural conditions, which would provide a quantitative tool for grain quality prediction.