Mutuallstic symbiosis between nodulating plants and two district categories of microorganisms.

固氮细菌与豆科植物一起固定大气中的氮和维管丛枝菌根（AM），帮助豆科植物以及许多其他植物从土壤中吸收磷和其他无机营养物质。结瘤型大豆植株可受慢生根瘤菌和菌根感染，而非结瘤型大豆植株只能受菌根感染。本研究的目的是：(1)明确两类微生物（慢生根瘤菌、维管-树胶菌根）的相互作用效应；(2)寻找互惠共生下大豆植株生长的最佳土壤条件。双侵染的大豆植株在生长、销售荚果产量、结瘤形成和固氮活性方面均比单侵染的大豆植株有显著提高。根际限制使结瘤大豆植株的生长、结瘤和固氮活性降低，但单位重根瘤重和根系固氮活性反而增加。结瘤大豆植株的菌根侵染率与土壤速效磷含量呈负相关，并取决于其他耕作管理，如种植制度。以金盏花根部菌根侵染率最高的栽培品种为甜玉米。作为指示植物的万寿菊在土壤中掺入秸秆炭等土壤改良剂后，菌根侵染率和植株生长均有所提高。秸秆炭对双侵染大豆植株的生长、植株总氮和总磷均有促进作用，但对菌根侵染没有促进作用。这些结果表明，秸秆炭对双病大豆根瘤植株的影响主要依赖于模块提供的固定氮。

Nitrogen fixing bacteria in concert with legumes fix atomospheric nitrogen and vescular-arbuscular mycorrhiza (AM) assist legumes, as well as many other plants in the absorption of phosphorus and other inorganic nutrients from soil.Nodulating soybean plants cam be infected by bradyrhizobium and mycorrhisa, while non-nodulating soybeam plants can be only associated with mycorrhiza.The purpose of this study ii (1) to clear the interaction effect of two categories of microorganisms (bradyrhizobium, vascular-arbuacular mycorrhiza) and (2) to find out the optimum soil conditions for soybean plants grown under mutualistic symbiosis.1. Dually-infected nodulating soybean plants showed the remarkable increase in plants growth marketable pod yield, nodule formation and nitrogen fixing activity over the single infected non-nodulating soybean plants.2. The growth, nodulation and nitrogen fixing activity of nodulating soybean plants decreased by the restriction of rhizosphere although nodule weight and nitrogen fixing activity per unit weight of root adversely increased.3. Mycorrhizal infection percentages on the nodulating soybean plants was adversely correlated with available phosphorus content in soiland also depended on the other cultivation managements such as cropping systems. The mycorrhizal infection on marigold roots was the highest at the cultivation of sweetcorn as the preceding plants.4. Mycorrhizal infection and plant growth of marigold grown as indicator plant were enhanced by the application of some soil amendants such as husk-charcoal. Howver, the growth, plant total nitrogen and plant totalphosphorus of dually infected nodulating soybean plants increased by the application of husk-charcoal although mycorrhizal infection did not increase. These results implies that the effect of husk-charcoal application on dually infected nodulating soybean plants mainly depend on the supply of fixed nitrogen from modules.