COMPARISON OF HARVEST INDEX AND GRAIN STRAW-RATIO WITH APPLICATIONS TO WINTER OILSEED RAPE

To compare the statistical properties of harvest index and grain/straw -ratio their variabilities (expressed by the relative measure coeffici ent of variation), their skewnesses and kurtoses have been compared th eoretically. With regard to variability, the harvest index exhibits a clear superiority (= smaller variability) compared to the grain/straw- ratio. For skewness and kurtosis no such generally valid relationships exist. But, for the range of the empirically most relevant parameter values one obtains approximately equal numerical values for skewness a s well as for kurtosis of harvest index and grain/straw-ratio. Finally , the theoretical results and conclusions have been checked and applie d to the experimental data sets from a field trial with ten European c ultivars/lines of winter oilseed rape.