Symbiotic dinitrogen fixation and accumulation of assimilants by the leguminous plants.

花生根际供应硝态氮增加了干物质积累，降低了种子产量和根瘤固氮量。吸收的结合态氮主要以天冬酰胺的形式输送到地上部。雌蕊侵入土壤后，果实带中的硝态氮直接被豆荚吸收并用于种子形成。钙的存在促进了大豆对硝酸盐的直接吸收，大豆植株对硝酸盐的吸收速率在10-25ppm的中氮浓度下达到饱和。与氨态氮相比，硝酸盐来源的氮素在根瘤中的分配相对较困难，而天冬酰胺和酰脲则通过根供应在根瘤中积累。结瘤大豆植株体内的环孢素醇含量高于非结瘤大豆植株，根际供应肌醇可增加单株根瘤重和ARA，延缓结荚后根瘤的降解和ARA的下降。与菜豆相比，大豆对氮素的固定相对不敏感，根瘤平均大小的减小没有菜豆那么明显，尽管两种豆类对氮素的吸收在植物器官中的分布模式几乎相同。Hup阳性根瘤菌只属于一个按胞外多糖类型分类的类群。具有丝氨醇结构的根瘤菌毒素对HUP阳性菌株摄氢酶的诱导有强烈的抑制作用。

Supply of nitrate nitrogen via roots to peanut plants increased dry matter accumulation and decreased seed yield and nitrogen fixed by nodules. Absorbed combined nitrogen was transported to the shoots mainly as asparagine. After intrusion of gynophore into soil, nitrate in fructification zone was directly absorbed by pods and utilized for seed formation. The direct absorption was enhanced by calcium coexistence.The rate of nitrate uptake by soybean plants was saturated at 10-25 ppm of medium nitrogen concentration. The nitrogen originated from nitrate was relatively hard to distribute in nodules as compared with nitrogen derived from ammonium, although asparagine and ureides were accumulated in nodules by the nitrate supply via roots. Higher content of cyclitol was obserbed in nodulated soybean plants than in unnodulated one, and, by the supply of myoinocitol via roots, nodule weight and ARA per plant were increased and nodule degradation and ARA decline after pod filling stage were delayed. Dinitrogen fixation by soybean was relatively insensitie to the combined nitrogen supply comparing to that by kidney bean, and reduction of mean nodule size was not so conspicuous as kidney bean, although distribution pattern of uptaken nitrogen among plant organs was almost same between two kinds of bean.Hup positive strains of rhizobium japonicum were belonged to only a group classified according to the type of extracellular polysaccharides. Rhizobiotoxin, which has serinol structure in it, strongly inhibited induction of uptake hydrogenase in the Hup positive strain.