BREEDING FOR HARD RED WINTER-WHEAT CULTIVARS ADAPTED TO CONVENTIONAL-TILL AND NO-TILL SYSTEMS IN NORTHERN LATITUDES

Conservation tillage in the Great Plains of North America has increased in recent years, in part, to control soil erosion, increase soil water storage and reduce production costs. No-till production is recommended for winter wheat (Triticum aestivum L.) in northern latitudes for the purpose of trapping snow and protecting the crop from freezing temperatures. A 5 year field study was conducted at four North Dakota locations from 1984-85 through 1988-89 to determine if significant cultivar x tillage interactions existed for grain yield of winter wheat. Fourteen hard red winter wheat cultivar were planted in both conventional-till and no-till systems. Significant cultivar x tillage interactions were obtained for grain yield from both a weighted analysis across all environments and from individual analyses of 12 of the 16 environments in which wheat survived under both tillage systems (P < 0.05). Regression of cultivar yield on mean environment yield produced b values that varied little between conventional till and no-till for 10 of the 14 cultivars. The top five yielding cultivars were the same for both tillage systems and had b values > 1.0. Although the cultivar x tillage interaction may be a result of differential winter survival rather than tillage per se, this study suggests that selection for winter wheats with superior yield performance can be conducted under either no-till or conventional-till systems.