Patterns of Variation in a Collection of Timothy Accessions

Abstract

Cultivated timothy (Phleum pratense L.) is an important grass for hay production in temperate North America. It is under utilized in management‐intensive rotational grazing systems because of its poor persistence when frequently defoliated. The objective of this study was to evaluate the USDA‐NPGS collection of timothy accessions for agronomic traits, including persistence under frequent defoliation. Unlike previous reports for infrequent harvest systems, diploid and tetraploid species of Phleum were similar in forage yield to hexaploid P. pratense, suggesting their potential value in livestock agriculture. Cultivated accessions tended to have fewer, but larger leaves; longer and narrower panicles with a greater number of smaller seeds; lower survival under frequent defoliation; and higher forage yield than natural accessions. A considerable amount of phenotypic variation among accessions was explained by geographic source of the accessions. Twenty‐one unique phenotypic clusters were formed to account for 50% of the phenotypic variability among accessions, providing the basis for development of a core collection for P. pratense Clusters were highly differentiated on the basis of geographic origin of the accessions, underscoring the potential importance of the relationship between phenotype and geography in hexaploid timothy.

High SSR diversity but little differentiation between accessions of Nordic timothy (Phleum pratense L.)

“…In autotetraploid alfalfa ( Medicago sativa ), even 99.8% of genetic variation in SSR markers was within populations ( Bagavathiannan et al 2010). In timothy, significant differentiation between populations was reported on phenotypic level, although close to 90% of variation was still detected within populations for all traits scored ( Casler 2001). Casler (2001) also found differentiation between varieties and wild populations of timothy for several morphological traits.…”

“…In timothy, significant differentiation between populations was reported on phenotypic level, although close to 90% of variation was still detected within populations for all traits scored ( Casler 2001). Casler (2001) also found differentiation between varieties and wild populations of timothy for several morphological traits. However, population structure observed at phenotypic level is not always reflected at molecular level when neutral markers are used ( Karhu et al 1996).…”

Phenotypic Performance of Timothy Accessions under Irrigated and Nonirrigated Conditions

“…Spearman rank correlations between dry matter yield (DMY), crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), and water-soluble carbohydrates (WSC) and the first three principal components (PC1, PC2, and PC3) measured in three environments at two locations in 2008 and 2009. In contrast to Casler (2001Casler ( , 2005, the accession ´ year interaction was limited to WSC. There also appeared to be a trend for increased IVTD and WSC and decreased NDF under the second-crop Lewiston (August) and dry Tetonia conditions, which is consistent with previous work on forage quality in cool-season grasses under drought (Sheaffer et al, 1992).…”

“…At least for DMY, there was a two to three times difference between the values at the Lewiston (June) environment Table 3. Interaction between timothy genotypes and environmental or management conditions is common in timothy (Surprenant et al, 1993;Bélanger et al, 2001;Casler, 2001) but has never been explored under the more arid conditions of western North America. Lewiston, UT (June) Lewiston, UT (August) Tetonia, ID DMY CP IVTD NDF WSC DMY CP IVTD NDF WSC DMY CP IVTD NDF (Evans and Wilson, 1984;McElroy and Christie, 1986;Buxton and Fales, 1994;Bélanger et al, 2001) and summer regrowth conditions (Ashikaga et al, 2011).…”

Cytogeography of thePhleum pratensegroup (Poaceae) in the Carpathians and Pannonia

“…Within Phleum pratense , hexaploid cytotype (2 n = 6 x = 42) is the most common. This cytotype is native to Europe and Asia, but it is also a widely grown forage grass in temperate regions of the world, including North America (Casler, 2001). Other ploidy levels have been reported rarely from natural habitats, e.g.…”