Agronomic Performance of Timothy Germplasm from Forage and Turf Sods under Two Harvest Managements

number of dead corms per plant by up to 93% and decreases living corm mass by up to 29% (Peters, 1958). Cultivated timothy (Phleum pratense L.) is an important grass for Harvesting frequently, up to three or four cuts per year, hay production in temperate North America. It is underutilized in and season-long competition in a timothy–alfalfa (Medmanagement-intensive rotational grazing systems because of its poor icago sativa L.) mixture reduces persistence of timothy persistence when frequently defoliated. The objective of this study was to compare families selected for forage yield under frequent cultivars (Casler and Walgenbach, 1990; Smith et al., defoliation, families derived from old turf sods, and cultivars for agro1973). Cultivars with earlier heading tend to be more nomic performance under frequent and infrequent harvest managepersistent under frequent harvests, but earliness does not ments (four vs. two harvests per year). Forage timothy was generally guarantee persistence (Casler and Walgenbach, 1990). superior to turf timothy for most traits. Forage selections averaged Partly because of the long history of breeding timothy 9.4 and 4.9% higher forage yield compared with cultivars under infrein North America and perhaps because of its excellent quent and frequent harvest managements, respectively, indicating that reputation as a highly cold-tolerant grass for hay producselection for higher forage yield under frequent harvest improved tion, it has been extensively planted throughout the forage yield under both harvest frequencies. There were differences north-central and northeastern USA and eastern Canamong the four types of turf (golf course fairways and roughs, cemeterada. Urbanization, resulting in the sale and development ies, and lawn/roadways), but these differences were not closely related to mowing height or frequency, perhaps because of the small sample of farmland, has led to the conversion of many timothy size. Some turf collections ranked high for net herbage accumulation hay fields to turf sods, including lawns, golf courses, and under frequent harvesting, but most turf collections were also characcemeteries. Timothy plants survive in many of these turf terized by a high frequency of regrowth panicles under either or both areas, despite more than 35 yr of frequent mowing. harvest frequencies. Timothy germplasm from old turf sods may have Because of the genetic heterogeneity that exists within value in developing new timothy cultivars with improved tolerance timothy cultivars and ecotypes, these remnant populato frequent defoliation and efforts should continue to gather and tions of timothy represent germplasm that may have evaluate collections from a range of turf types and locations. undergone natural selection for tolerance to frequent defoliation. Many factors contribute to changes in swards under T imothy was the first cool-season forage grass intrograzing, including treading, manure and urine deposiduced to North America by European colonists in tion, soil fertility, climate change, diseases, insects, and the 18th century (Berg et al., 1996). It is the most imporseed banks (Charles, 1964; Watkin and Clements, 1978). tant forage grass in Scandinavia (Jönsson et al., 1992) However, Watkin and Clements (1978) suggested that and has the longest history of formal breeding activity the frequency of defoliation may be the most important of all the cool-season grasses bred in both Europe and factor causing changes to plant populations and/or North America (Casler et al., 1996). Over 150 named sward structure of pastures. The objective of this study cultivars have been bred in North America or imported was to evaluate and compare the agronomic perforfrom other countries (Alderson and Sharp, 1994; Lawmance of three types of timothy germplasm under frerence et al., 1995; GRIN, Germplasm Resources Inforquent and infrequent harvest managements. The germmation Network, www.ars-grin.gov/npgs/, verified 16 Apr. plasm included timothy families derived from old turf 2005). sods, timothy families derived from plants selected for Timothy cultivars are well adapted to hay manageforage yield under frequent harvesting, and timothy culment practices on the basis of relatively infrequent hartivars. vests. Timothy reproduces vegetatively by corms, swollen culm bases just beneath the soil surface. Individual corms MATERIALS AND METHODS are biennial, so long-term persistence of timothy depends The germplasm for this study derived from three sources: on continual production of new corms (Childers and Hanforage selections, turf collections, and commercial cultivars. son, 1985). Frequent harvesting of timothy increases the A total of 450 timothy plants were selected from 19 600 plants evaluated by Casler (2001), the entire population originating from 489 accessions that represented 23 countries. These plants M.D. Casler, USDA-ARS, U.S. Dairy Forage Research Center, Madison, WI 53706-1108. Research supported by the USDA-ARS and were selected for high forage yield, low second-harvest panicle the College of Agricultural and Life Sciences, Univ. of Wisconsindensity, and survival for 3 yr (1994–1996) under a frequentMadison. Received 15 Nov. 2004. Corresponding author (mdcasler@ harvest management. In July 1997, plants were removed, split wisc.edu). into four ramets, and transplanted into a polycross block in a randomized complete block design with four replicates at Published in Crop Sci. 45:1990–1996 (2005). Arlington, WI. The crossing block was maintained weed free Plant Genetic Resources by the use of pre-emergence herbicides and hand weeding doi:10.2135/cropsci2004.0659 (Falkner and Casler, 1998). © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA In June 1996, timothy plants were collected from old turf 1990 Published online August 26, 2005