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对环境施磷增加田菁[Sesbania cannabina(Retz.)pers.]结瘤固氮的作用是有限度的,受环境供磷水平的制约。 在广州石牌地区花岗岩发育赤红壤中,田菁以磷增氮的土壤有效磷临界水平(ppm P)为25.6(0.1 N HCL法)。 在无氮培养液中,秋植和春植田菁以磷增氮的供磷临界水平(毫摩尔P)分别为0.78和0.48,植株体内含磷量的临界水平(P％)分别为0.213和0.157。该临界供磷水平与含磷量有受季节性影响的倾向。介质的高磷水平还会引起田菁固氮量的下降。 在低磷的介质中,增磷对田菁根瘤的形成,发育和固氮酶活性有明显的促进作用。在磷供应达到一定水平后,继续增磷的促进作用不显著。未发现高磷供应对田菁的根瘤数有不良影响,但对其根瘤干重、特别是固氮酶活性有抑制作用。
Increasing phosphorus application to the environment Sesbania cannabina (Retz.) Pers.] The role of nodulation and nitrogen fixation is limited by the level of environmental phosphorus supply. In the red soils with granite developed in Shipai area of Guangzhou, the threshold level of soil available phosphorus (P) of Pseudomonas aeruginosa growing by phosphorus was 25.6 (0.1 N HCL method). In the nitrogen-free culture medium, the critical levels of phosphorus supply (0.68 and 0.48 mmol / L) for nitrogen and phosphorus in autumn and spring were respectively 0.78 and 0.48. The critical levels (P%) of phosphorus in plants were 0.213 and 0.157 . The critical phosphorus supply and phosphorus content have a seasonal effect. Medium high phosphorus levels can also cause the decline of Nitrogen nitrogen sequestration. In the medium of low phosphorus, increasing phosphorus could significantly promote the formation, development and nitrogenase activity of Sesbania. After the supply of phosphorus reaches a certain level, the promotion effect of continuing phosphorus increase is not significant. No high phosphorus supply was found to have adverse effects on the nodulation of Sesbania, but its root nodule dry weight, especially nitrogenase activity was inhibited.