Plant Density and Crop Yield

Abstract

In investigations into the relationship between mean plant density and crop yield, an inverse power response curve has often been used. In this paper the theoretical properties of a family of these curves are examined, including situations where two or more such relationships are being compared. Methods of fitting these response models are given. When response curves are fitted to experimental data it is usually desirable to summarize the data as briefly as possible and this leads to a search for parameter invariance. A formal scheme for analysing data by looking for invariance of parameters of the response curves is proposed and methods are given for fitting the various constrained models that this involves. These methods are illustrated in two examples.