New patented growth promoter technology to enhance early season soybean development and grain yield

OSBURN, R M; DÉNARIÉ, JLC; MAILLET, F; PENNA, C; DÍAZ-ZORITA, MARTÍN; KOSANKE, J W; SMITH, R S

19th North American Conference

Congreso; 19th North American Conference on Symbiotic Nitrogen Fixation; 2004

New soybean growth promoter technology based on the U.S. patents 5,549,718 and 5,646,018 has been developed and field tested.  The natural bacterial promoter compound has been purified, formulated and assayed via HPLC to provide field efficacious concentrations ranging from 0.000001 to 0.001% w/v of the active lipo-oligosaccharide compound (nod factor).  Purified material has been applied as a liquid formulation to soybean seed at the time of planting.  Multi-year field evaluations have demonstrated an early season growth enhancement that includes improved stand, early season vigor, earlier root nodule formation with both applied and indigenous Bradyrhizobium japonicum independent of soil temperature, earlier canopy closure and improved grain yield.  A liquid formulation has been commercialized (OptimizeTM) that utilizes Cell-Tech® as the carrier, and is custom applied on seed at a retail facility to ensure uniform application and grower convenience.  Cell-Tech included as the carrier, with Bradyrhizobium japonicum, ensures sufficient nodulation on fields with or without a history of soybean production.  The liquid formulation is applied to soybeans at the rate of 125 ml/45.4 kg seed.  The material may be combined with compatible fungicides and applied 30 days before planting.  The Optimize formulation in the U.S. has increased plant stand compared to the control from 70.8 to 76.4%, vigor (1 to 9 relative scale) from 4.8 to 6.5, nodulation from 21.1 to 24.4 nodules per plant, decreased days to canopy closure from 70.4 to 67.4, and increased grain yield in 22 trials by 343 kg/ha (10.1%).  Four trials in Argentina in 2003 provided an average grain yield increase of 402 kg/ha (12.2%).