Adequate seed production is essential for cultivar success in perennial ryegrass turf and forage industries, but improvement is limited by the complexity of yield components and low‐rank correlations between selection and production environments. This study examined seed yield components among 20 perennial ryegrass entries in both spaced plantings (selection environment) and swards (production environment) at two locations in Minnesota. Competitive (23 plants/m²) and non‐competitive (3 plants/m²) spaced‐plant nurseries were tested. Competitive spaced‐plant total yield was highly correlated with sward yield (r_s = 0.64 and 0.66, p < 0.01) at both locations, whereas the non‐competitive environment showed no correlation. Structural equation modelling (SEM) was used to explore the indirect and direct relationship of fall vegetative growth, winterkill, and yield components on total seed yield in all environments. Fertile tiller number (spikes plant⁻¹/m⁻²) exhibited both strong direct and indirect influence on total seed yield in all environments. However, the importance of fertile tiller number in the SEM was reduced with increased plant competition. The SEM showed that both weight per spike and seed yield per spike influenced total yield in spaced plants; however, neither consistently predicted total sward yield. The ratio of these two traits (g seed spike⁻¹/g spike⁻¹) gave an index of fertility that was easy to measure and had a superior correlation with sward yield at two locations (r_s = 0.81 and 0.54, p < 0.05) when spaced plants were under competition. Results suggest that increasing competition in spaced plantings and selecting for spike fertility may more accurately identify superior plant material compared to lower competition environments.

中文翻译：

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多年生黑麦草产量构成要素与间隔植物和草皮种子产量的关系和影响

足够的种子产量对于多年生黑麦草皮和牧草行业的品种成功至关重要，但产量的复杂性以及选育和生产环境之间的低相关性限制了种子产量的提高。这项研究检查了明尼苏达州两个地点的间隔种植（选择环境）和草地（生产环境）的20个多年生黑麦草条目中的种子产量组成。对竞争性（23株/ m ²）和非竞争性（3株/ m ²）的间隔苗圃进行了测试。竞争性植株总产量与草皮产量高度相关（r _s  = 0.64和0.66，p <0.01），而非竞争性环境则没有相关性。使用结构方程模型（SEM）来探讨在所有环境下秋季营养生长，防寒和产量成分与种子总产量之间的间接和直接关系。在所有环境中，肥力分till数（穗植物^-1 / m ^-2）对总种子产量表现出强烈的直接和间接影响。但是，随着植物竞争的加剧，可育分number数在SEM中的重要性降低了。该SEM结果表明，每株穗重和每株穗粒产量都影响间隔植物的总产量。但是，都没有一致预测总的草皮产量。这两个性状的比率（g穗穗^-1 / g穗^-1）提供了一个易于测量的育性指标，并且与两个位置的草皮产量具有更好的相关性（r _s  =  0.81和0.54，p  <0.05 ），当间隔植物处于竞争状态时。结果表明，与较低竞争环境相比，间隔种植中竞争的加剧和穗粒肥力的选择可能更准确地鉴定出优良的植物材料。