Performance of hard red spring wheat cultivar mixtures

The effects of cultivar mixing on yields and production requirements have not been thoroughly understood in hard red spring wheat (Triticum aestivum L.) production. The objective of the present study was to investigate if HRSW cultivar mixtures could achieve yield and/or grain protein advantages, reduce the incidence of leaf rust (Puccinia triticina Erikss.), or reduce lodging compared with single cultivars. Field experiments arranged in randomized complete blocks were conducted in five site-year environments during 2008-2010 in the Red River Valley region of Minnesota. Three pairs of HRSW cultivars ('Faller' and 'Glenn', 'RB07' and 'Bigg Red', and 'Rush' and 'Traverse') were chosen for compatibility in plant height and maturity and contrasting characteristics in grain yield, grain protein, leaf rust susceptibility, and lodging resistance. Each environment contained three replications of the three pairs of component cultivars and the 3:1, 1:1, and 1:3 mixtures of each pair. Regression analyses were conducted to examine the possible advantages or disadvantages of the mixtures in comparison to their corresponding pure lines. Disease pressure and wind damage were mild in years that the trials were conducted. Grain yield, protein content, leaf rust severity, and lodging responded linearly to cultivar mixing. The inverse relationship between grain yield and grain protein was unchanged by cultivar mixing. Therefore, no benefits or penalties were attributable to cultivar mixing in HRSW under the conditions of the present study. Future trials may need to include mixtures composed of more than two component cultivars grown under more extreme conditions.