Effect of intergenotypic competition on yield assessment in cowpea trials

Study on the effect of intergenotypic competition in cowpea revealed significant differences among cultivars for their competitive ability. Competition caused significant changes in the relative performance of cultivars with regard to the characters studied except pod length and number of seeds per pod. For seed yield, the average competition was the major source of bias in single-row plots. Estimates of the average competition effects and average expected bias for seed yield indicated that an aggressive competitor was over estimated in competition, whereas a poor competitor was under estimated. Negative correlation between yielding and competing abilities of cultivars suggest the need for bordered plots in yield evaluation trials of cowpea. Since pod length and number of seeds per pod were unaffected by competition, they could be beller selection criteria for yield in single-row plots.