Three-component barley mixtures: Ratio effects in replacement series

Within a species, cultivar mixtures may offer yield and quality advantages if the cultivars have complementary abiotic and biotic stress tolerances. This study was conducted at Botha, Lacombe and Olds, Alberta, from 1992 to 1994 to determine the effect of relative seeding ratios on yield and other traits of 16 three-component barley (Hordeum vulgare L.) mixtures of Virden:Abee:Tukwa all grown at a standard seeding rate of 250 seeds m(-2). Grain yields of these mixtures fell between the yields of the monocrops, with yields of the 20:40:40 and 50:30:20 mixtures being higher than expected based on the weighted mean yields of the monocrops. When stability of yield was measured using ranking or regression analyses, several mixtures had desirable combinations of high yields and good stability with the 20:40:40 and the 40:20:40 mixtures being identified using either method. Test weights, kernel weights, percent thins, protein contents, and disease levels of the mixtures were intermediate to the monocrops; while lodging levels were as low as the best monocrop. As the proportion of any one cultivar in the mixture increased, the traits it brought to the mixture also increased. These mixtures had no yield advantage over growing a high yielding monocrop.