Growth analysis of perennial plants: the relative production rate and its yield components

A new formulation for plant growth analysis, called the relative production rate, is proposed for use in the study of perennial plants. The new measure and its yield components are similar to current growth analysis, but use the annual increment of growth, rather than total accumulated growth, as the basis for assessing performance. The relative production rate removes accumulated past growth of the perennating structure, a major determinant of relative growth rate, and acts independently of tree size as a measure of the vigour of growth. The multiplicative yield components of this relative production rate also provide better insight into the current morphological and physiological features of the tree than the standard growth analysis formulations. Examples are given using Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and red pine (Pinus resinosa Ait.) plantations to illustrate the methodology proposed.