Effect Of Several Herbicides On Alfalfa-Rhizobiumsymbiotic Nitrogen-Fixation

Alfalfa,which distributes widely in the world and has high economy value in agriculture, is a perennial legume herb and known as"king of herb". Rhizobia-alfalfa association is a high efficient N-fixing system, has been widely applied on the agricultural production. The N-fixing system can reduce application of chemistry fertilizer, and make for protecting the environment and sustainable development of agriculture. However, with the development of human civilization, the destruction, which the environment suffered from, was without precedent in history. Consequently, environmental factors become an important reason for developing potential fully on the agricultural production. In recently years, herbicides are applied widely and also bring tremendous economy benefit. Effect on non-target after application with herbicides is got people's attention as the augment of applying range along with the lucubration in them.Weeds lead to the reduction of output and bad quality of alfalfa, so much as its destruction. Herbicides are widely applied in alfalfa, but they also caused some disbennifit: reducing the ability of rhizobium-alfalfa symbiotic nitrogen-fixation, decreasing the N supply, reducing the output and quality of alfalfa and succeeding crops. The purpose of this paper is to study effect on rhizobium-alfalfa symbiotic nitrogen-fixation by several herbicides. In this study, 8 herbicides (fluoroglycofen-ethyl, acifluorfen, haloxyfop-R-methyl, fluazifop-P-butyl, acetochlor, metolachlor, butralin, trifuralin) were determined on Sinorhizobium melilo in vitro; In greenhouse, the height, fresh and dry weight, nodulation after treatment with 8 herbicides were studied; at the same time, nitrogenase activity, leghemoglobin, total nitrogen content and flavonoid that were associated with rhizobium-alfalfa symbiotic nitrogen-fixation after treatment with 8 herbicides were also studied. The results could be summaried as follows:1. The studies of 8 herbicides on Sinorhizobium melilo in vitro showed that four...