Influence Of Arbuscular Mycorrhizal Fungus Inoculation On Plant Residue Degradation

As the basic carrier of nutrients in the ecosystem-Plant residues, is connected to the plant and soil nutrient cycle of "link", and is the main ways of ecological system of substance circulation and energy exchanges. Arbuscular mycorrhizal(AM) fungi are widespread in the soil. Study of the effect of AM fungi on plant residue’s degradation, expanded the role of the AM fungi in substance circulation of ecosystem. First, This study preliminary understanding the influence of AM fungi on plant residue degradation by the pot experiment, and then split-root device with two or four compartments was used to investigate the mechanism of plant root, mycorrhizal and hyphae on plant residue degradation of different C/N ratio which was quantitative compare. The main results as followed.(1) To investigate the influence of AM fungi inoculation on degradation of Zea mays(maize) straw, a pot experiment was carried out maize as host plants and two different AM fungi, Glomus intraradices and Glomus mosseae were inoculated. Harvested samples respectively in30,40,50,60days, maize straw was oven dry and measured the degradation mass, carbon release and nitrogen release, and calculated the degradation coefficient(k) of degradation mass, carbon and nitrogen release by the Olson’index model. The results showed that mycorrhiza inoculation caused more maize straw degradated and higher degradation rate compared with non-mycorrhizal treatment. Carbon release and carbon degradation index increased significantly. But nitrogen release and nitrogen degradation index were reversed alone with the sampling time. Carbon and nitrogen degradation coefficients directly reflected their degradation speed, mycorrhizal inoculation affected the C/N of corn straw, made the C/N be facilitated to degrade. Research results show that AM fungi has important significance in substance circulation of ecological system.(2) The split-root device with tow compartments was used to quantitatively compare the change of degradation process in mycorrhizosphere and rhizosphere. We choose maize straw as the representative of plant residues, two different AM fungi, Glomus mosseae and Glomus etunicatum were inoculated. The results showed that inoculation with two different AM fungi, the maize straw degradation mass and degradation coefficient in mycorrhizosphere compartment were higher than that in root compartment at all stages, Mycorrhizal inoculation enhanced C release but prejudiced the release of N, and then, the decrease of C/N ratio reduced so as to facilitate its further degradation. For the soil biological performance, we found that the catalase, protease, acid phosphatase, microbial biomass carbon and soil respiration have been enhanced in mycorrhizosphere which compared with rhizosphere, further formed the active microbial community. The increase of these indexes involved in the degradation process, and become the important reasons for mycorrhizal speed up the degradation. The different ability of AM fungi to improve maize straw degradation revealed the function diversity of AM fungi. More AM fungal species and soil types will be considered in our following studies.(3) To investigate the influence of AM fungi inoculation on degradation ofvicia faba residues, the split-root device with tow compartments was carried out maize as host plants and two different arbuscular mycorrhizal fungus, Glomus mosseae and Glomus etunicatum were inoculated. The results showed that inoculation with G. mosseae and G. etunicatum tent to increase the vicia faba residues degradation mass. Mycorrhizal inoculation enhanced C release and N release, then cause C/N ratio keep in a conducive its further degradation. Under the conditions of this experiment, the rhizosphere enhanced the activity of catalase, protease and acid phosphatase, formed the active microbial community. And that catalase, protease, acid phosphatase, microbial biomass carbon, nitrogen and respiratory quotient (9CO2) involved in the degradation process, and become the important reasons for mycorrhiza speed up the degradation.(4) Split root device with four compartments was used to quantitatively compare the change of degradation process in rhizosphere, mycorrhizosphere and hyoheasphere. We choose maize straw as the representative of plant residues, AM fungi, Glomus mosseae (G m) was inoculated. The results showed that inoculation with G. m, the maize straw degradation mass and degradation coefficient in mycorrhizosphere compartment were higher than that in root compartment at all stages, Mycorrhizal inoculation enhanced C release but prejudiced the release of N, and then reduced the C/N ratio, and so as to facilitate its further degradation. For the soil biological performance, we found that the catalase, protease, acid phosphatase, microbial biomass carbon and soil respiration have been enhanced in mycorrhizosphere compartment compared with root compartment, and the same as hyoheasphere compartment with non-rhizosphere compartment, formed the active microbial community further. The increase of these indexes involved in the degradation process, and become the important reasons for mycorrhizal speed up the degradation.(5) Split root device with four compartments was used to quantitatively compare the change of degradation process in rhizosphere, mycorrhizosphere and hyoheasphere. We choose vicia faba residues as the representative of plant residues, AM fungi, Glomus mosseae (G.m) was inoculated. The results showed that inoculation with G.m, the vicia faba residues degradation mass and degradation coefficient in mycorrhizosphere compartment were higher than that in root compartment at all stages, Mycorrhizal inoculation enhanced C release and N release, then cause C/N ratio keep in a conducive its further degradation. For the soil biological performance, we found that the catalase, protease, acid phosphatase, microbial biomass carbon and nitrogen, soil respiration and respiratory quotient (qCO2) have been enhanced in mycorrhizosphere compared with rhizosphere, and the same as hyoheasphere with non-rhizosphere, formed the active microbial community further. The increase of these indexes involved in the degradation process, and become the important reasons for mycorrhizal speed up the degradation.