Effect of nitrogen rates on plant growth, seed yield and seed quality of three lines of Brachiaria hybrid grass

Abstract

Improved grasses planted for forage are increasing in demand throughout Thailand due to the increasingnumber of cattle. New varieties are being introduced in response to new demands. Brachiaria grasses, especially the hybrids, are gaining popularity because of their good yields and high quality. However, seed production of the brachiaria hybrids is difficult. The objectives of this experiment were to find out the appropriate rate (0, 20, 40, or80 kg/ha N) of N fertilizer (46-0-0) for growth, seed yield and quality of three lines of brachiaria hybrid (Mulato II,BR02/1752, and BR02/1794). This experiment composed of a field trial and laboratory tests and all were conducted at the Faculty of Agriculture, Ubon Ratchathani University, Thailand from May 2009 to June 2010. The results showed that N fertilizer at 40 kg/ha N was an optimum rate for seed production and growth (tiller number) for all three brachiaria hybrids. BR02/1752 and BR02/1794 produced significantly (P<0.05) higher seed yields than Mulato II. The quality of seeds produced in terms of purity and moisture content was not affected by N fertilization. Dormancy in new seeds was common, but declined over time. However, this seed dormancy could be broken by soaking in sulfuric acid for 10 minutes or passing through an accelerated ageing technique for about three days.