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Background: Inflorescence properties such length, spikelet number, and their spatial distribution across the rachis, are fundamental indicators of seed productivity in grasses and have been a target of selection throughout domestication and crop improvement. However, quantifying such complex morphology is laborious, time-consuming, and commonly limited to human-perceived traits. These limitations can be exacerbated by unfavorable trait correlations between inflorescence architecture and seed yield that can be unconsciously selected for. Computer vision offers an alternative to conventional phenotyping, enabling higher throughput and reducing subjectivity. These approaches provide valuable insights into the determinants of seed yield, and thus, aid breeding decisions. Results: Here, we described SpykProps, an inexpensive Python-based imaging system to quantify morphological properties in unilateral inflorescences, that was developed and tested on images of perennial grass (Lolium perenne L.) spikes. SpykProps is able to rapidly and accurately identify spikes (RMSE < 1), estimate their length (R2 = 0.96), and number of spikelets (R2 = 0.61). It also quantifies color and shape from hundreds of interacting descriptors that are accurate predictors of architectural and agronomic traits such as seed yield potential (R2 = 0.94), rachis weight (R2 = 0.83), and seed shattering (R2 = 0.85). Conclusions: SpykProps is an open-source platform to characterize inflorescence architecture in a wide range of grasses. This imaging tool generates conventional and latent traits that can be used to better characterize developmental and agronomic traits associated with inflorescence architecture, and has applications in fields that include breeding, physiology, evolution, and development biology. [ABSTRACT FROM AUTHOR]

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]

Fine fescues (Festuca L. spp.) comprise a group of five cool‐season grasses used in turfgrass systems under many conditions: strong creeping red fescue (F. rubra L. ssp. rubra Gaudin), slender creeping red fescue [F. rubra L. ssp. littoralis (G. Mey.) Auquier], Chewings fescue [F. rubra L. ssp. commutata Gaudin; syn. F. rubra L. ssp. fallax (Thuill.) Nyman], hard fescue (F. brevipila Tracey), and sheep fescue [F. ovina L.; syn. F. ovina L. ssp. hirtula (Hack. ex Travis) M.J. Wilk.]. Their extensive geographic distribution is a result of adaptation to many different environmental and management conditions especially low‐input sites. This review summarizes the history, production, establishment, management, use, and availability of fine fescues; discusses strengths and shortcomings of fine fescue; identifies knowledge gaps; and provides an outlook toward further research on this group of grasses. Improved cultivars have been developed in recent years that expand the geographic distribution and uses of species but additional efforts to increase seed yield and improve abiotic and biotic stress tolerances are still needed. Expanded use of fine fescue could be achieved through increased sod production of fine fescue, though current research‐based information is limited. Research on fine fescue allelopathy and the contributions of fungal endophytes, both of which could lead to reduced pesticide requirements is important for improved pest management. Future research on fine fescues should focus on implementation and management of new cultivars that possess enhanced abiotic and biotic stress tolerance that will result in fewer inputs and improve the appeal and adoption of these low‐input grasses. [ABSTRACT FROM AUTHOR]