Genetic diversity and variation in North American orchardgrass (Dactylis glomerata L.) cultivars and breeding lines

Abstract

Orchardgrass (Dactylis glomerata L.) is a high quality forage grass naturalized to temperate climates. Used extensively in hay and grazing agriculture, hundreds of orchardgrass cultivars have been released over the past 50 years. However, progress in yield and other agronomic characteristics in orchardgrass cultivars has occurred slowly and often inconsistently. One cause of the slow progress could be a lack of genetic diversity among orchardgrass cultivars, or an over‐abundance of diversity within cultivars. With an emphasis on North American cultivars, this study assessed the genetic diversity within and among 52 orchardgrass cultivars, breeding lines and accessions. Genetic similarity within cultivars ranged from 52 to 71%, similar to values from wild‐land, unselected accessions. Populations from Wisconsin and Missouri breeding efforts that resulted from two cycles of genotypic recurrent selection were included as checks. Neither group of selection populations exhibited more within‐population similarity compared to the wild‐land accessions (ecotypes) and cultivars. Genetic differentiation was detected only for the selection populations and several cultivars and breeding lines that had a tendency to originate from eastern Asian germplasm and have late flowering times. These results indicated an abundance of genetic variation within the orchardgrass cultivars, but a paucity of genetic differentiation among cultivars.

Agronomic and genetic diversity in intermediate wheatgrass (Thinopyrum intermedium)

“…Xie et al. () reported tentative and unsupported groupings in 52 cultivars and breeding lines of orchardgrass. Last et al.…”

“…AFLP analysis by Tuna et al (2004) suggested a high level of gene flow among natural orchardgrass populations in the Thrace region of Turkey. Xie et al (2014) reported tentative and unsupported groupings in 52 cultivars and breeding lines of orchardgrass. Last et al (2013) reported a high degree of gene flow leading to low genetic distance among individuals and populations between two Swiss ecotype populations of orchardgrass that were less than 100 km apart.…”

Genetic Variation for Dry Matter Yield, Forage Quality, and Seed Traits Among the Half‐Sib Progeny of Nine Orchardgrass Germplasm Populations

“…More recent public orchardgrass germplasm improvement work in the United States focused on the development of nonflowering populations (Casler et al, 2013, 2014), with little documentation of other objectives. While a number of commercial cultivars from private programs are available in North America, much of this is based on the recycling of older cultivars rather than the incorporation of novel germplasm (Xie et al, 2014a). The work reported in this paper complements ongoing efforts to identify and develop new sources of orchardgrass germplasm for use in temperate agriculture (Robins et al, 2012a; 2012b).…”

Variation and Correlations among European and North American Orchardgrass Germplasm for Herbage Yield and Nutritive Value

“…Paiute). However, cultivar performance under different or stressed conditions has been inconsistent [9], possibly due to a lack of uniformity in orchardgrass cultivars [10,11] or the unpredictability of appropriate environmental conditions in field settings [12]. Improving forage production and quality under abiotic stresses are objectives in orchardgrass breeding and genetics programs throughout the world (e.g., [13]).…”