Kura clover growth and development during the seeding year

Information on Kura clover (Trifolium ambiguum Bieb.) development in the seeding year would be useful in developing new cultivars with greater seedling vigor and establishment. Our objective was to study herbage and root biomass accumulation and seedling development of Kura clover following spring and summer planting. Field experiments were conducted on a fine-silty over sandy, mixed Typic Hapludoll and on a sandy, mixed, Udorthentic Haploboroll. Spring seeded Kura clover had rhizome initials (≤3 cm) 63 d after planting and some spring seeded plants had rhizomes which were 20 cm long with leaves by the end of October. Secondary rhizomes had developed on primary rhizomes of some plants by 98 d after seeding. Summer planted Kura clover plants developed rhizome initials about 100 d after planting but had no rhizomes longer than 3 cm. Pink nodules were observed about 56 d following spring planting and about 42 d after summer planting. Contractile growth was observed about 35 and 46 d after spring and summer planting, respectively. Herbage and root dry weight accumulated at a linear rate following spring and summer plantings until growth was reduced in the fall. By October of the seeding year, spring planted kura clover had average herbage yields of 1672 kg ha^-1 and below-ground mass of 2733 kg ha^-1 with 10% of the below-ground mass consisting of rhizomes. Endura had greater average whole plant and herbage yields than Rhizo, but root yields were similar for the two entries. Since Kura clover seedlings partition a significant amount of dry matter to the root system, increased seedling vigor might be achieved by selecting for increased herbage accumulation.