Studies On Colonization Dynamics Of Mesorhizobium Huakuii JS5A16L And AM Fungi Glomus Mosseae In Rhizosphere Of Rice (Oryza Sativa L) And Astragalus Sinicus And Their Effects On Plant Growth During Rotation

To investigate the viability and colonization dynamics of JS5A16L marked with bioluminescence genes luxAB under the Astragalus smicus-rice rotation condition in rice field, JS5A16L inoculum was introduced into a rice field that had a long history of rotation. Results showed that JS5A16L colonization was stable at 104, 105 cfu/g during the period of A.sinicus growth. After A.sinicus was turning over, flooding and during the growth of rice, however, its colonization density sharply declined to 10 cfu/g. JS5A16L was detected in rice endorhizosphere after approximately 60 days of rice planting. Compared with inoculated and non-inoculated treatments, there was no significant difference between the growth of rice. Besides, A.sinicus showed promoting effects on the rhizosphere colonization of JS5A16L,Bacillus Actinomycetes, Fungi, Aerobacteria and Pseduomonas; whereas rice showed negative effects on Actinomycetes, Fungi, Aerobacteria and positive effects on Pseduomonas ,and insignificant effects on Bacillus.Four treatments were set up with pot experiment: singly inoculated with JS5A16L, singly inoculated with Gl.mosseae, doubly inoculated and Control for investigating interactions of JS5A16L and Gl.mosseae as well as their plant-growth-promoting effects on rice. Our results showed that. double inoculated treatment could significantly promote nodulation of JS5A16L and the infectivity of Gl.mosseae on A.sinicus, increase colonization of both on rhizosphere, ectorhizoshphere and endorhizoshpere of rice. Compared with two single inoculated treatments and Control, double inoculation showed promoting effects on plants' height, fresh weight at different significance levels but not very significant effects were shown on the tiller numbers and output of rice.Gl.mosseae spores were inoculated around rice roots in pot experiment under dry and flooding conditions for investigating the infection potential and viability of Gl. mosseae as well as its possible growth-promoting effects onrice. Results showed that: after 20 days, the infectivity in dry-inoculated treatment increased to 30%; arbuscular structure was formed and several vesicular structures were observed. After 40 days, the mycorrhizal infectivity reached the climax at 50% and kept stable at 45% later. In flooding treatment, the spores couldn't infect the rice roots. During 20 to 40 days, the rice growth was best in dry-inoculated treatment but after 40 days, the rice plants in the treatment of flooding control grew best.