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Turf‐type perennial ryegrass (Lolium perenne L.) success depends on adequate turfgrass quality and economical seed yield. In most breeding programs, spaced plants are the initial unit of selection in which observations of related individuals dictate the selection of superior germplasm for further testing. Therefore, spaced plants must be predictive of seed production and turfgrass growing environments. This study investigated the effectiveness of standard (three plants m−2) and competitive (23 plants m−2) spaced‐plant nurseries as selection environments with respect to two sward environments as well as applying a novel image analysis technique for several key traits. Seed production, turfgrass, and the two spaced‐plant growing environments were tested at two locations in Minnesota. Turfgrass quality traits were measured in 2017 and 2018 and seed production traits were measured in 2018. Automated image analysis was able to predict the traditional visual scoring values at both locations for crown rust (Puccinia coronata f.sp. lolii) severity [Pearson's correlation (rp) > 0.79, P <.001], winter injury (rp > 0.89, P <.001), and turfgrass texture (rp > 0.88, P <.001). Increasing the competition among spaced plants altered the plant phenotype and improved accuracy for vegetative biomass, crown rust severity, seed yield, and, at one location, turfgrass quality. There was no benefit of increasing competition for several traits such as genetic color, fertile tillers, and spikelet number. Although the competitive design was not useful for all traits, pragmatically, the competitive design used less space and often made measurements and observations easier for bunch‐type grasses. [ABSTRACT FROM AUTHOR]

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 (rs = 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 (rs = 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. [ABSTRACT FROM AUTHOR]