氮_磷_钾对异果山绿豆结瘤固氮特性的影响

本试验发现磷对异果山绿豆结瘤、固氮和生长都起到极其重要的作用.含磷者结瘤多、根瘤发育正常固氮活性高,植株生长良好;而缺磷者根瘤小而白、植株生长差.缺磷钾时,少量化合态氮0.61mM Ca(NO_3)_2或1.87mM NH_4Cl]对植物生长结瘤都引起有害的作用.在磷钾水平一致时,低水平化合态氮〔0.61mM Ca(NO_3)_2或1.87mM NH_4Cl〕对异果山绿豆结瘤固氮及生长都是有益的;而中水平氮〔3.05mM Ca(NO_3)_2或9.35mM NH_4Cl〕则不利;高水平氮〔6.1m MCa(NO_3)_2或18.7mM NH_4Cl〕有明显的抑制作用.植株含氮量随着化合态氮的水平提高而降低.

COMBINED NITROGEN, PHOSPHORUS AND POTASSIUM EFFECTS ON NODULATION AND NITROGEN-FIXATION OF DESMODIUM HETEROCARPUM

Phosphorus plays an important role in the nodulation, nitrogen-fixation and the growth of Desmodium heterocarpum. phosphorus being present in the culture medium, the number of the root nodules which develop normally is more, the nitrogen-fixation is high and the plants grow well. But when phosphorus is absent, the root nodules become small and white, thus the plants grow poorly;when both phosphorus and potassium are absent, the small quantity of combined nitrogen 0.61mM Ca (NO3)2 or 1.87mM NH4CL] becomes harmful to the nodulation and growth of desmodium heterocarpum. Under the condition of same level of phosphorus and potassium is benifical to the nodulation, nitrogen-fixation activity and the growth of D. heterocar-pum. On the contrary, the middle concentration C3.05mM Ca ( NO3) 2 or 9.35 mM NH4Cl] is poisonous, and the higher level C6.1mM Ca ( NO3)2 or 18.7mM NH4Cl] exerts apparently inhibition on them. The content of nitrogen in the plant bodies decreases with the increasing of combined nitrogen concentration used.