Grain yield adjusting efficiency in common bean genotypes

The objective of this study was to verify the efficiency of using the plant stand covariate to adjust the average grain yield of common bean genotypes. Sixteen years of experiments were considered. In all years, the genetic treatments were randomized in field in a completely randomized block design. The main variable grain yield and the covariate plant stand per observation unit were evaluated. The information was submitted to analysis of variance and covariance. In approximately half of the trials (43.75%), the mean square of treatments was significant in both analyses, indicating the small improvement of the model when plant stand was included as a covariate. This information is confirmed by estimate of covariate efficiency, since in just two years (2017 and 2015) the adjustments were effective (268 and 203%, respectively). In addition, an association was observed between the average grain yield and adjustment efficiency of-0.60. Thus, the covariate was useful in years when the genotypes showed low productive performance, possibly caused by adverse environmental conditions. These conditions are responsible for plants heterogeneity number in the observation units.