一个新的养分效应数学模型

A New Mathematical Model for Nutrient Effect

在养分效应研究中，多采用二次抛物线模型，从容（1991）在米氏方程的基础上提出一个改进抛物线模型，这两种模型都是对称性模型，也即是把养分正负效应的速率视为相同，而大多数实际情形并非如此．本文建立了一个反映养分效应普遍现象的非对称性模型，两个应用实例表明新模型较之原来的模型无论在拟合度（残差平方和）还是在生物学意义方面都具有明显的优越性．

The quadratic parabola model has been widely used in studying nutrient effect．Based on the Mitsherlich's equation,Cong（1991）proposed a modified model.However,these model are all symmetric model,i.e.rates of the positive and negative effects of nutrient are considered as the equality.In practice,this is always not true.A nonsymmetric model was proposed to describe the relationship between the nutrient ontent and yield in this paper.The results obtained from it was used in the two examples indicated that the model proposed here is obviously an advantage in both fitting degree and biology implications compared with quadratic parabola model.