A METHOD FOR THE ANALYSIS OF BARLEY KERNEL GROWTH DATA FROM DESIGNED EXPERIMENTS

The growth of kernels at selected positions along the spike of barley was studied using three models: segmented, logistic and Gompertz. The segmented model divides the growth period into three segments: an init ial constant stage, a middle period of 'linear growth', and a final co nstant stage. The identification of a period during which growth is ap proximately linear - the 'linear phase' - was estimated from the curvi linear functions by imposing some criterion to determine the period of 'linear growth' in order that the results were similar to those from the segmented model. From this a model of final growth, growth rate an d duration of growth as a function of kernel position was developed an d fitted to data from four different thinning treatments at five sowin g dates. The model of final growth and growth rate was shown to have a family of gamma functions. The analysis of these models showed that t here were marked interactions between sowing and thinning treatments f or growth rate, less so for grain yield, but there was no substantial interaction for duration.