Efficacy Of Glyphosate And Nicosulfuron Herbicides And Their Effect On Growth And Yield Of Soybean (Glycine Max L.)

Abstract

Weeds are a serious constraint to agricultural production in the tropics with more devastating effects felt in developing countries where farmers have no access to herbicide and resort to manual weeding. Glyphosate is the commonest herbicide on the Ugandan market, however, recently, glyphosate is under scrutiny. There is need to provide alternative to glyphosate which means bringing newer formulations, but prior efficacy trials are needed before recommendation. A field experiment was conducted at Makerere University Agricultural Research Institute, Kabanyolo between December 2019, and March 2020 to evaluate the efficacy of Nicosulfuron and Glyphosate in soybean. The experiment was set up in a completely randomised block design with treatments including Glyphosate IPA salt 41% SL 60ml/20L of water was as a pre-emergence herbicide while Nicosulfuron 40g/L Oil Dispersion (OD) was applied once at 1.5L/ha (60ml/20L of water) and a control that was not weeded. Results showed that Nicosulfuron had significantly (p<0.05) lower broad leaf weed density and dry matter, and higher grain yield than the glyphosate and un-weeded control. Treatments with Nicosulfuron gave the lowest in weed biomass (1.358kg) while the un-weeded control gave the highest biomass (2.487kg). Treatments with Nicosulfuron reduced broad leaf weed species compared to the glyphosate and the control. Soybean pod yield in Nicosulfuron treatments was higher (0.194kg) than that in glyphosate treatments (0.133kg) while the control treatment gave the lowest yield (0.063kg). Nicosulfuron considerably effectively controlled broad leaf weeds to a higher extent than glyphosate but the reverse was true for blade weeds. Soybean growth and development was generally better for Nicosulfuron treatment compared to glyphosate. Nicosulfuron seems like a good alternative for glyphosate herbicides and can be used for weed control to replace Glyphosate, however, more research should be conducted on how to reduce the phytotoxicity.