Studies on Introducing Nodulation and Symbiosis in Rice with Rhizobium

Rhizobium was introduced into rice root for nodulation and symbiosis by the addition of synthetic auxin 2,4-D (2,4-Dichlorophenoxyacetic acid) (final concentration was Ippm).A number of upland rice and some lowland rice varieties have been treated since 1988.The results showed that rhizobium can be introduced into rice root to nodulate and symbiosis with rice by this method.The repetition and reappearance of inducing nodulation were very well.The date of the first nodule appearance,nodulation rate and size of nodules vavied with different rice varieties.Upland rice varieties of Fan 289033,Futiannuo and Youhan showed higher nodulation rates with larger nodule size.The diameter of nodules was about 2 to 3 mm four weeks after inoculation.Fan 289033 with highest nodulation rate(reached to 85%)anong 10 varieties tested.Nodule sections of rice were observed under electron microscope.The results showed that there were numerous rhizobia inside the nodule,indicating that rhizobium can enter rice root and propagated in the nodule.The novel association between rhizobium and rice plant revealed here may be important to the research on nodulation and nitroge fixation of non-legume plants.