Characterization of rose clover germplasm for flowering traits

Rose clover (Trifolium hirtum All) cultivars with long-season (November through May) forage production and cold tolerance are needed to increase pasture availability during the winter in northeast Texas. More information about the genetic and environmental control of rose clover flowering is warranted, before this trait can be manipulated through plant breeding. The objective of this study was to evaluate the variability for flowering traits in the U.S. Plant Introduction Collection of rose clover. Sixty-six accessions of rose clover, from eight different countries, were evaluated. Observations recorded on individual plants at 4-d intervals included first elongation of internodes, first bud, first flower, first color, full bloom, and mature seed. In general, rose clover behaved as a long-day plant and flowered in photoperiods from 12 to 14h. Thirty-one rose clover lines were identified within the maturity range of 172 to 182 days of the year (DOY) to full bloom, twenty-seven were identified within the maturity range of 162 to 170 DOY to full bloom, only five rose clover lines reached full bloom in less than 162 DOY, and only three took more than 183 DOY. There was a range of 40 d difference in time to reach maturity for the rose clover germplasm studied. Utilizing principal component analysis and cluster analysis, the germplasm was separated into three different maturing groups: early, midseason, and late maturity groups.