Associations among U.S. locations for orchardgrass production

Thirteen orchardgrass (Dactylis glomerata L.) cultivars were evaluated across 4 years at five US field locations in Kentucky, Pennsylvania, Utah, Virginia, and Wisconsin. The objective was to determine the relationship among the five locations for orchardgrass agronomic performance. Cultivar × environment interaction was identified for dry matter (DM) yield, stand percentage, maturity rating, disease rating, spring regrowth, and fall regrowth. Significant concordance values were moderate to high (τ = 0.46 to 0.84) among the locations, with the exception of Wisconsin, which showed little association with the other locations. These rankings indicated that there was little association among the locations for orchardgrass performance. This was further illustrated by the mean values of the cultivars for each trait. In only a few cases was a cultivar among the highest ranking for a trait at more than one location. Notable exceptions were the generally high DM yield of the cultivars Benchmark Plus and Persist and the high disease resistance of the cultivars Barlegro, Excellate SA, and Harvestar. The results illustrate that orchardgrass cultivar adaptation is region specific within this subset of U.S. production areas.