STUDY ON ECOLOGICAL DISTRIBUTION OF SOIL MICROORGANISMSAND COLONY DYNAMICS OF CYST-FORMING NEMATODES IN CONTINUOUSAND ROTATION CROPPING SYSTEMS OF SOYBEAN
Liu Zengzhu Zhou Yuzhi Han Jingshu (Institute of Applied Ecological, Academia Sinica, Shenyang)
The artical reported ecologcal distribution of soil microorganisms on different growing period of soybean in continuous and rotation cropping systems. Population dynamis of Heterodera glycines were also studied. The result showe that in the continuous and rotation cropping system bacteria daminante over other kinds of microorganisms whether for the total amount of soil microorganisms or for root surface microorganisms. The second dominant race was actinomycete. The amount of fungi was ths least. The total amount of root surface microorganisms was about 100 times over that of the soil microorganisms. The largest total amount of soil microorganism and root sursace microorganism was on the flowering stage. The highest density of root nodules and Heteroera glycines cyst was in the pod-setting stage, flowering stage the next, the least densities of root nodules and neinatode cyst was on the branching stage. The total amount of microorganisms and the densities of the root nodules ia the continuous cropping system was higher than those in the rotation cropping system. And toe densities of cyst-forming netnatodes in the continuous cropping field was higher than those in the rotation cropping system. The extra attention was deserved that the dynamic change of the amount of fungi and the change of cyst density was the same. The frend of the change was branching stageflowering stagepod-setting stage. The sameness may have some internal connection. The problem will be studied further.