ESTIMATION OF TIIE WITHIN PLOT ENVIRONMENTAL VARIANCE IN THE DESIGN II OF NORTH CAROLINA

Abstract

The within plot environmental variance (σ²_WE) is an important variance component to determine heritability and expected gains from selection when different methods of mass and combined selection are under consideration. However, a formula to estímate σ²_WE based only on in the information produced by the evaluation of the families formed according to the  males and females has the same precision as the one North Carolina design II, has not yet been developed. In this study an analysis of the design II making no use of the concept of covariance, is made, finding three unbiased estimators for a o²_WE. It was also found that when males and females occur in the same number, the estimator based on the mean squares for males and females has the same precision as the one based either on the mean square for males or for females. The estimation of the additive variance is discussed as well.