Effect of Long Term Soybean Monoculture on Soybean Root Rot and Soybean Growth and Development in Pot Experiment

Soybean root rot was the main cause of soybean monoculture obstacle.By pot experiment with soils from soybean monoculture 16 years(S-S…-S),Wheat-Corn-Soybean rotation(W-C-S) and fallow arable layer soils in Hailun Agricultural Ecology Experimental Station,the research was carried to probe the effect of soybean monoculture on soybean root rot and plant growth.Soybean root rot severity,plant height and fresh weight were detected after sowing 20 d;pathogens and Cyst quantity were respectively surveyed after sowing 20 d and 55 d.The results showed that,soybean root rot severity in S-S-S was lower than W-C-S,and no significant differences between them,but significant differences were found between W-C-S and fallow.Plant height was the highest in fallow,which were significantly different to S-S…-S and W-C-S.After sowing 55 d,the plant height was the highest in fallow,has significant differences to S-S-S and W-C-S;the plant height of W-C-S was the second and in S-S-S was the lowest.Fresh weight was the highest in fallow,W-C-S…W-C-S was the second and S-S…-S was the lowest,but there were no significant differences among them.Two genus pathogens of Fusarium spp.and Pythium spp.were isolated in soybean root.Fusarium spp.had higher isolation frequency than Pythium spp.,but no difference between S-S…-S and W-C-S.The cysts quantity of W-C-S…W-C-S on soybean root was higher than S-S…-S,and significant differences were found between them,but no cyst was found in fallow.In short,soybean root rot of potted soybean plants were no significant differences between S-S…-S and W-C-S soil,but the growth and development of soybean in S-S…-S were slightly inferior to W-C-S…W-C-S.