Perennial ryegrass varieties are evaluated in monoculture plots, but in practice are typically sown as combinations of three or more varieties. Monoculture performance is used a predictor of mixture performance, but is questionable, particularly for grazing efficiency traits that interact with the grazing animal. Two field experiments were carried out to examine the production, grazing efficiency and nutritive quality traits of varieties sown in monoculture, and their binary, ternary and quaternary mixtures. Both studies contained two diploid and two tetraploid varieties comprising of only Late heading varieties in Study 1 and combinations of Late and Intermediate heading varieties in Study 2, all managed under cattle grazing with 16 grazing events taking place over two years.

Synergistic effects, defined as a higher performance above that of the component variety mean (based on their respective component monoculture performance), were observed within some mixtures for certain traits although these rarely exceeded that of the best component monocultures. Performance differences attributable to ploidy in monoculture were expressed in the mixtures but differences in the spread of heading date within a mixture had few effects. Differences in grazing efficiency between varieties were also expressed within mixtures but with no consistent evidence of a synergistic enhancement of the cattle’s willingness or ability to graze sward mixtures more effectively. Mixture performance values were within the range of the component varieties for most traits, indicating that monoculture evaluation can be used as a reliable indicator of the performance of perennial ryegrass mixtures.

多年生黑麦草品种在单一养殖区进行评估，但实际上通常以三个或更多品种的组合播种。单种养殖性能可作为混合饲料性能的预测指标，但存在疑问，特别是对于与放牧动物相互作用的放牧效率性状。进行了两个田间试验，以检验单种播种的品种及其二元，三元和四元混合物的产量，放牧效率和营养品质性状。两项研究均包含两个二倍体和两个四倍体变种，仅在研究1中包含后期抽穗变种，在研究2中包含后期和中度抽穗变种的组合，它们均在牛放牧下进行，两年内发生了16次放牧事件。

在某些特性的某些混合物中观察到协同效应，定义为高于组分多样性平均值的较高性能（基于它们各自的组分单培养性能），尽管这些效果很少超过最佳组分单培养。在混合物中表达了归因于单倍体倍性的性能差异，但是混合物中抽穗期分布的差异几乎没有影响。混合物中还表现出了不同品种之间的放牧效率差异，但是没有一致的证据表明牛的意愿或更有效地放牧混合物的能力得到协同增强。大多数性状的混合表现值都在成分品种的范围内，