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 (r_p) > 0.79, P < .001], winter injury (r_p > 0.89, P < .001), and turfgrass texture (r_p > 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.

中文翻译：

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明尼苏达州多年生黑麦草间隔植物苗圃对草坪草和种子生产区的预测能力

草坪型多年生黑麦草 ( Lolium perenne L.) 的成功取决于足够的草坪草质量和经济的种子产量。在大多数育种计划中，间隔植物是选择的初始单位，其中相关个体的观察决定了用于进一步测试的优良种质的选择。因此，间隔植物必须能够预测种子生产和草坪草生长环境。本研究调查了标准（三株植物 m ^-2）和竞争性（23 株植物 m ^-2) 间隔植物苗圃作为关于两个草地环境的选择环境，以及对几个关键性状应用新的图像分析技术。在明尼苏达州的两个地点测试了种子生产、草坪草和两种间隔植物生长环境。在2017年和2018年和种子生产性状测定草坪草品质性状的2018自动图像分析进行测定是能够在对冠锈病两个位置（预测传统视觉评分值柄锈菌coronata病菌lolii）严重性[Pearson相关（r _p ) > 0.79, P  < .001]、冬季损伤 ( r _p  > 0.89, P  < .001) 和草坪质地 (r _p  > 0.88，P  < .001）。增加间隔植物之间的竞争改变了植物表型，并提高了营养生物量、冠锈病严重程度、种子产量以及某一位置的草坪草质量的准确性。增加对遗传颜色、可育分蘖和小穗数等几个性状的竞争没有任何好处。尽管竞争性设计并非对所有性状都有用，但从实用的角度来看，竞争性设计使用的空间更少，并且通常使束状草的测量和观察更容易。