Predictive ability of perennial ryegrass spaced-plant nurseries for turfgrass and seed production swards in Minnesota

Turf-type perennial ryegrass (Lolium perenne L.) success depends both on
adequate turfgrass quality and economic seed yield. In most breeding
programs, spaced plants are the initial unit of selection in which
observations of related individuals dictate selections of superior
germplasm for further testing. As such, spaced plants must be predictive
of both seed production and turfgrass growing environments. This study
investigated the effectiveness of both standard (3 plants m-2) and
competitive (23 plants m-2) spaced-plant nurseries as selection
environments with respect to two sward environments as well as employed 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 severity (rp > 0.79, P < 0.001),
winter injury (rp > 0.89, P < 0.001), and texture (rp
> 0.88, P < 0.001). Increasing competition in between spaced
plants altered 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. While the
competitive design was not useful for all traits, from a feasibility
standpoint the competitive design took up less space and often made
measurements and observations much easier for bunch-type grasses.