Abstract: Based on the field experiments using different type rice varieties under different sowing dates and nitrogen application levels, the leaf age and leaf area index (LAI) simulation models were established. A power function was used to describe the nonlinear relationship between leaf appearance and accumulated thermal time after sowing (TTS). The LAI model contained two consecutive phases: at exponential expansion phase (LAI<1.6), LAI increased exponentially with the accumulated growing degree days after sowing (GDD) and was regulated by the nitrogen level; when LAI≥1.6, leaf area expansion was quantified on the bases of specific leaf area (SLA) and green leaf dry weight. SLA was mainly determined by GDD and nitrogen nutrition index, and green leaf dry weight was calculated as the product of its partitioning index and shoot dry weight. Validation of the models using the experiment data with a wide range of ecological and cultivated conditions showed that the two models could accurately simulate the leaf appearance and LAI dynamic under different environments. Thus, the models might be widely adaptable and applicable, which needs only a few and simple parameters.

Key words: rice, leaf age, leaf area index, specific leaf area

摘要： 依据不同类型品种的播期试验和氮肥试验结果，建立了水稻叶龄与叶面积指数(LAI)的模拟模型。叶龄模型采用幂函数描述叶片出生与播后累积热时间(TTS)的关系，TTS的计算定量了温度与出叶速率之间的非线性关系。叶面积指数模拟包括两个阶段:在指数生长阶段，LAI随播后累积生长度日(GDD)呈指数式增长，同时受到氮素营养水平调节；当LAI≥1.6时进入非指数生长阶段，采用比叶面积法模拟，LAI是比叶面积与绿叶干物质量的乘积。绿叶干物质量是绿叶分配指数与地上部干物质量的乘积，比叶面积(SLA)为GDD的函数，同时考虑植株氮素营养因子对SLA的影响。利用生态条件和栽培条件差异较大的试验资料对模型进行了验证。结果表明，模型能较好地模拟不同条件下叶片的出生动态和LAI变化动态，表现出较强的适用性，具有参数少、易确定、简便实用的特点。

关键词: 水稻, 叶龄, 叶面积指数, 比叶面积, 模拟模型