INTERPLOT INTERFERENCE DISTORTS YIELD ESTIMATES IN SPRING WHEAT

Research in Europe and the USA indicated that interference between plo ts in cultivar trials can distort yield and result in misleading concl usions from yield comparisons. Field trials were conducted at Swift Cu rrent and Saskatoon in 1993 and 1993 to determine if interplot interfe rence is a concern in the wheat growing region of Saskatchewan, Four s pring wheat (Triticum aestivum L.) cultivars, Biggar, Oslo, Genesis, a nd Glenlea, were grown in four-row plots in a diallel competition trea tment design, with the competition treatments applied randomly to each of the eight replications. Generally, yield was distorted from pure s tand yield when flanking plots differed for height. On average, yield was reduced 0.34% per centimeter increase in height of the Banking plo ts, and the reverse occurred when height of the flanking plots was les s. Plots of the short cultivars Bigger or Oslo Banked by the tall cult ivars Genesis or Glenlea yielded less than when Banked by themselves, and the reverse occurred when the tall cultivars were flanked by the s hort cultivars. Interplot interference affected spike density in the s ame fashion, did not significantly affect height, and was inconsistent with regards to kernel weight. It was concluded that when plots diffe r for height, yield distortion can occur in the Saskatchewan wheat gro wing region.