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. T his study was conducted at Botha, Lacombe and Olds, Alberta, from 1992 to 1 994 to determine the effect of relative seeding ratios on yield and other t raits 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 y ields of these mixtures fell between the yields of the monocrops, with yiel ds of the 20:40:40 and 50:30:20 mixtures being higher than expected based o n the weighted mean yields of the monocrops. When stability of yield was me asured using ranking or regression analyses, several mixtures had desirable combinations of high yields and good stability with the 20:40:40 and the 4 0:20:40 mixtures being identified using either method. Test weights, kernel weights, percent thins, protein contents, and disease levels of the mixtur es 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 inc reased, the traits it brought to the mixture also increased. These mixtures had no yield advantage over growing a high yielding monocrop.