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

固氮菌与豆科植物一起固定大气中的氮，并且血管丛枝菌根（AM）帮助豆科植物以及许多其它植物从土壤中吸收磷和其它无机营养物。而非菌根化的大豆植株只能与菌根共生。明确两类微生物（慢生根瘤菌、维管-丛枝菌根）的互作效应;（2）找出大豆在互惠共生下生长的最佳土壤条件.双侵染大豆植株的生长发育、商品荚产量、根瘤形成和固氮活性均显著高于单侵染大豆植株.根际限制使结瘤大豆植株的生长、结瘤和固氮活性降低，但根瘤重和单位根重固氮活性反而增加.菌根侵染率与土壤有效磷含量呈负相关，并与耕作制度等栽培管理因素有关。万寿菊根系的菌根侵染率以甜玉米种植时最高.施用稻壳炭等土壤净化剂可促进万寿菊的菌根侵染和植株生长。施用壳炭后，虽然没有增加菌根侵染，但对双侵染大豆植株的生长、植株全氮和植株全磷均有促进作用。这些结果表明，施用壳炭对双感病大豆植株的影响主要取决于构件提供的固定氮。

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.