Correction models for intergenotypic competition in winter wheat

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