Seeding rates of Ubon Stylo (Stylosanthes guianensis) affect plant population density, growth and dry matter yield

Abstract

Agronomic characteristics of Ubon Stylo (Stylosanthes guianensis; var. vulgaris x var. pauciflora) were studied during the establishment period while evaluating the effects of four seeding rates (5, 10, 15 and 20 kg/ha) of Ubon Stylo seed (95% germination rate) on the population density of emerged plants, growth vigor (measure of plant height every three weeks), dry matter (DM) yield and botanical composition (proportions of Ubon Stylo and weeds) at a cutting 98 days post-seeding. Seeding rates were achieved with a calibrated seeder. Significant differences were found between seeding levels for density of emerged plants, which Increased from 18 to 89 per square meter upon Increasing seeding levels from 5 to 20 kg/ha. There was no significant Interaction of seeding level x week post-seeding on plant height. Increments In height with time followed either a quadratic or a logarithmic pattern at the different seeding levels; heights of 80 cm being reached at the 10 to 20 kg/ha levels. Seeding level also affected (P<0.05) DM yield and botanical composition. A relative Increase of 47% (2,900 kg/ha DM) resulted from increasing the amount of seed used from 5 to 10 kg/ha. The proportion of Ubon Stylo in the harvested biomass at the four successive seeding rates was 61, 84, 84 and 87%. In conclusion, the use of 10 kg/ha of Ubon Stylo seed resulted in satisfactory establishment of this legume in terms of the characteristics evaluated of density and composition of the plant population, plant height and forage yield.