Perennial plants provide extensive environmental services and increasing their prevalence on the agricultural landscape is one way to improve sustainability. Direct domestication of intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] as a perennial grain crop is underway, and selection has focused primarily on improving seed size and grain yield. Breeders lack understanding of grain yield and its relationship with component traits in this species. We characterized a large (n = 1,168) spaced plant nursery in St. Paul, MN, and Salina, KS, in 2017 and 2018 for a series of 13 yield component traits. In Year 2 in St. Paul, yield per plant and reproductive tiller number nearly doubled, whereas other yield components, including yield per spike, spikelets per spike, florets per spikelet, and thousand‐grain weight, significantly decreased. Correlation analyses between traits highlighted positive associations of seven traits with grain yield. Structural equation modeling (SEM) revealed that when yield was measured on a yield per spike basis, floret site utilization was the primary contributor to yield, and when measured on a per‐plant basis, reproductive tiller number was the primary contributor. The indirect effects of biomass and maturity traits on both measures of yield were limited. Future work should investigate the predictive ability of reproductive tiller counts in spaced plant and sward environments to inform how breeders assess and select for yield.

中文翻译：

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小花位点的利用和生殖分till数是中型草丛间隔植株谷物产量的主要组成部分

多年生植物提供广泛的环境服务，提高其在农业景观中的流行率是改善可持续性的一种方法。作为多年生谷类作物的中间小麦草（中间薄麦草（寄主）Barkworth＆DR Dewey）的直接驯化工作正在进行中，选择主要集中在提高种子大小和谷物产量上。育种者对谷物产量及其与品种性状的关系缺乏了解。我们的特点大（ñ = 1,168个）于2017年和2018年在明尼苏达州圣保罗和堪萨斯州萨利纳的植物育苗间，进行了一系列13种产量构成性状的研究。在圣保罗的第二年，单株产量和生殖分number数量几乎翻了一番，而其他产量组成部分，包括每个穗的产量，每个穗的小穗，每个穗的小花和千粒重，则显着下降。性状之间的相关性分析突出了七个性状与籽粒产量的正相关。结构方程模型（SEM）显示，以单穗产量为基础来衡量产量时，小花部位利用率是产量的主要贡献因素，而以每株植物来衡量时，生殖分till数量是主要贡献因素。生物量和成熟性状对两种产量指标的间接影响是有限的。