INTERGENOTYPIC COMPETITION IN BIBLENDS OF SPRING WHEAT
Wheat (Triticum aestivum L.) breeding programs evaluate germplasm sources and/or segregating progenies comprising a mixture of genotypes. If intergenotypic competition is operating, then performance of mixtures of genotypes may not be indicative of the performance of its pure line components. Our objective was to measure and quantify intergenotypic competition in 1:1 mixtures of eight spring wheat cultivars representing both tall and semidwarf classes. The 28 possible 1:1 biblends plus the eight uniblends were evaluated in a replicated trial in 2 yr at Bozeman, Montana. Grain yield, test weight, and grain protein concentration were measured. Analysis of variance showed the eight cultivars differed as uniblends and for average performance in biblends for all three measured traits. Interactions, deviations of biblends from average performance of the two uniblend components, were detected for test weight and grain protein concentration in the first year and for grain yield in the second year and for grain protein concentration when combined over years. Intergenotypic competition reduced grain yield of biblends compared to uniblends in the second year but not in the first year. Grain protein concentration and test weight did not show a proportionate change in response to the reduced grain yield. General mixing effects isolated for each cultivar showed competitive ability could not be delineated on the basis of height class.Key words: Wheat, Triticum aestivum L., mixtures, competing ability