Growth of white clover ecotypes, cultivars, and germplasms in the southeastern USA

Naturalized populations, or ecotypes, of white clover (Trifolium repens L.) are found in many southeastern U.S. pastures, often persisting despite adv erse environmental and cultural conditions. Our objective was to compare th e growth, morphology, and vegetative persistence of white clover ecotypes ( small- to medium-leaf) with selected cultivars (large-leaf) and improved ge rmplasm under grazing in four southeastern states. Seed or stolons of white clover ecotypes were collected primarily from grazed pastures in spring 19 94 in Louisiana, Mississippi, Alabama, and Georgia, and increased by interc rossing. Plots of seven ecotype collections, 'Osceola','Regal', 'Louisiana S-1','Grasslands Huia','Grasslands Prestige', Brown Loam Synthetic No. 2 ge rmplasm, and Southern Regional Virus Resistant germplasm were established i n October 1995 in each state. Plots were stocked continuously with cattle ( Bos taurus) (5-cm stubble) from January 1996 to January 1998. Stolen length and axillary bud viability, and number of stolen apices, rooted nodes, and seedlings were measured every 3 mo. Stolen length of the ecotypes usually exceeded that of the cultivars and germplasm at all locations, particularly in the winter and spring. By the end of the experiment, the ecotypes also exhibited greater stolen branching than the cultivars and germplasm (1580 v s. 320 branches m(-2)). Superior vegetative growth of the ecotypes was attr ibuted to a greater proportion of the stolen nodes being both branched and rooted, particularly during the summer. White clover ecotypes represent a v aluable source of germplasm to incorporate into breeding programs or to dev elop directly into more persistent cultivars.