Abstract
A laboratory experiment was carried out to investigate the relationship between uprooting strength and root length in seminal root of 8 temperate grass species (14 varieties) with emerged seedlings when sown on the surface of yellow paddy field soil and Kuroboku soil under 25℃ and 100% RH. The volume of clod of soil particles, bound by both root and coleorhiza hairs, was measured with a few grass species. The figures were related to the differences in anchoring force of the seedling roots depending on grass species and the soil types. 1. The elongation of the seminal root penetrated into yellow paddy field soil was 4-6 mm per day in orchardgrass, perennial ryegrass and Italian ryegrass as compared to 2-3 mm in tall fescue and smooth bromegrass. All these species were similar within the range of 8-10 g in uprooting strength. Seminal root of Kentucky bluegrass and timothy grew to 2 mm in length and with ca. 4 g of the uprooting strength. 2. The uprooting strength of grass seedlings was closely related to the length of penetrating seminal root (r=0.757, p<0.01). 3. Although seminal root of tall fescue grew longer and grasped larger clod in Kuroboku soil than in yellow paddy field soil, it showed similar to or slightly lower uprooting strength than those in the latter soil. 4. The volume of soil clod and uprooting strength of surface-sown grass seedlings were related to penetrated root length. Three milimeter of seminal root length had an uprooting strength three times as strong as the adhering strength of coleorhiza hairs.
