Correction models for intergenotypic competition in winter wheat

Single-row plots (SRP) are often used in early generation selection. For wheat, in such trials, it has already been demonstrated that inter-plot competition leads to highly biased estimations of grain yield. An experiment including one SRP trial and one reference 6-row-plot trial were conducted over two consecutive years in order to compare two statistical models for correcting competition effects. The neighbourhood covariate model relying on plant height proved to be more efficient than the more general producer-competitor model. It provided significant improvement in yield estimation, slightly greater using height measured at heading than using final height as covariate. Moreover, relative efficiency of selection in SRP when corrected for competition effects always reached about 85%, whatever the intensity of competition. The neighbouring covariate model based on plant height should be used for routine analysis of single-row-plot trials.