Emergence and seedling growth of five forage legume species at various burial depth and two light levels
A field study compared the seedling emergence and structure of five forage legumes (Trifolium repens L., Medicago falcata L., Melilotus suaveolens Ledeb, Medicago sativa L. and Lespedeza davurica Schindler) at five planting depths (1, 2, 4, 6 and 8 cm) and two light levels (full light and shade) on the 21st day after planting. As expected, increaseing depth lowered and slowed seedling emergence. Maximum emergence occurred at 1 and 2 cm depths for all five forage legumes irrespective of light levels; then decreased as the burial depth increased. Improved seedling emergence was also observed under shade compared to full light. Increased sowing depth diminished seedling size by reducing the plant height, biomass, leaf number and size of all five forage legumes. All the morphological traits and seedling biomass were reduced under shade condition except seedling height and cotyledon size. The optimal planting depth for all the forage legumes in this study was 1 to 2 cm. M. falcata, M. suaveolens and M. sativa had high percentage of emergence and better growth from deeper depth or under shade condition.
Key words: Burial depth, forage legume, optimal planting depth, relative growth rate, seedling emergence, seedling mass, seedling morphology, shade.