作物临界氮浓度稀释模型研究述评

A review on the crop critical nitrogen concentration dilution model and its application

作物临界氮浓度是作物达到最大生长的植株最小氮浓度。临界氮浓度随地上部植株干物质积累量增加而下降,可以用幂函数模型N_(c)=a×W_(max)^(-b)表示。已建立了数十种作物临界氮稀释模型,根据作物收获器官的特点,分为收获籽粒、收获鲜果实、收获块根块茎和收获地上部营养体4类,不同类型临界氮浓度稀释模型在模型参数和氮素诊断应用方面各有特点。临界氮浓度稀释模型除了植株临界氮浓度-植株干重这一典型形式外,还有器官临界氮浓度-器官干重、植株临界氮浓度-器官数量指标(叶片干重、茎鞘干重、LAI、叶面积持续期)等形式。因此,提出评价选择临界氮浓度稀释模型类型的基本原则。由于不同气候条件、不同作物类型,甚至同一作物不同品种的生育特性、氮素营养特性和干物质生产力差异很大,建立某一大类作物甚至某一种作物在各个气候区域的通用模型是困难的,应以一定生态区域某一作物特征相近品种类型作为建模基本单元。作物临界氮浓度稀释模型的应用包括计算氮营养指数(NNI)进行氮素营养诊断,计算临界氮积累量、亏缺量和氮肥需要量,预测作物产量和品质等。分析了以植株干物质重驱动的氮素稀释模型的局限性,指出最大植株干物质重的增加在本质上是作物发育进程的度量,临界氮浓度的概念提供了在某个生育时期确定植株适宜氮浓度的科学方法。提出首先进行区域和品种类型划分,通过田间试验确定作物不同生育期的临界氮浓度,进而建立以生育进程驱动的临界氮浓度动态模型的研究技术路线。

The crop critical nitrogen concentration is the plant minimum nitrogen concentration for the crop to reach the maximum growth.The critical nitrogen concentration decreases with the increase of the dry matter accumulation of the aboveground plants,which can be expressed by the power function model of N_(c)=a×W_(max)^(-b).Critical nitrogen dilution models for dozens of crops have been established.According to the characteristics of crop harvest organs,they are divided into four categories:harvesting grains,harvesting fresh fruits,harvesting roots and tubers,and harvesting aboveground stems and leaves.Different types of critical nitrogen concentration dilution models have their own characteristics in terms of the parameters and nitrogen diagnostic applications.In addition to the typical form of the critical nitrogen concentration of the plant-the dry weight of the plant,the critical nitrogen concentration dilution model also has the critical nitrogen concentration of the organ-the dry weight of the organ,the critical nitrogen concentration of the plant-the quantitative index of the organ(leaf dry weight,stem and sheath dry weight,LAI,leaf area duration)and other forms.The basic principles for selecting the type of critical nitrogen concentration dilution models are proposed.Because the growth characteristics,nitrogen nutrition characteristics and dry matter productivity of different crop types,and even different varieties of the same crop under different climatic conditions are greatly different,it is difficult to establish a general model for a certain category of crops or even a certain crop under various climatic regions and therefore a certain type of crop with similar characteristics in a certain climate region and certain cultivation mode should be used as the basic unit for building the models.The applications of crop critical nitrogen concentration dilution model include the calculation of nitrogen nutrition index(NNI)for nitrogen nutrition diagnosis,calculation of critical nitrogen accumulation,deficit and nitrogen fertilizer requirements,and prediction of crop yield and quality.The limitations of the nitrogen dilution model driven by plant dry matter are pointed out that the increase in the maximum plant dry matter weight is essentially a measure of the process of crop development.The concept of critical nitrogen concentration provides a scientific method to determine the appropriate nitrogen concentration at a certain growth stage.A research technical route of“the climate zoning,cultivation method selection and varieties classificationdetermination of the critical nitrogen concentration at different growth stages through experiments-establishment of a dynamic model of critical nitrogen concentration driven by growth process”is proposed.