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NH_4—N可明显抑制田菁根瘤的形成和每株根瘤重量。在一定浓度下每株根瘤重的降低,主要是由于根瘤形成数量减少。30ppm NH_4—N已可使抑制达到严重程度。此外,NH_4—N对田菁根瘤的发育也有抑制作用,不过程度较轻。化合态氮的抑制作用与浓度密切相关。即使开始时浓度较高,在植物吸收后浓度降低,抑制作用也可随之消除。NH_4—N可明显抑制田菁根瘤的固氮酶活性。在本试验条件下,浓度越高抑制作用越强。至70ppm时,已检不出乙烯的生成。 化合态氮明显地增加田菁植株的生长量,在有一定量的磷、钾和其他营养存在的条件下,其施用量越多植株干重越重。但如果较稳定地维持在一定浓度,则NH_4—N10ppm即已满足要求,浓度继续增加,田菁植株的生长并不一定会明显增长。 磷、钾供应在达到一定水平之后,再增加其供应量,对田菁的生长、根瘤的形成和发育都没有明显的促进作用。在无氮情况下,K从2mM提高至20mM对田菁根瘤干重有抑制,在供氮情况下,则有促进作用,氮与钾有极显著的正交互作用。
NH_4-N can significantly inhibit the formation of Stem Nodules and nodule weight per plant. The reduction of root nodule weight per plant at a certain concentration was mainly due to the reduced nodule formation. 30ppm NH_4-N has been able to suppress the severity. In addition, NH4-N also inhibited the development of Stem Nodules, but to a lesser extent. The inhibitory effect of compound nitrogen is closely related to the concentration. Even if the concentration is high at the beginning, the concentration decreases after the plant is taken up and the inhibitory effect can be eliminated. NH_4-N can significantly inhibit nitrogenase activity of Sesbania nodules. Under the experimental conditions, the higher the concentration, the stronger the inhibition. At 70 ppm, no formation of ethylene was detected. Nitrate significantly increased the growth of Sesbania plants. The more dry matter of the Sesbania plants, the heavier the plants were, the more the amounts of P, K and other nutrients existed. However, if more stable to maintain a certain concentration, then NH_4-N10ppm that has met the requirement, the concentration continues to increase, the growth of Sesbania plants does not necessarily increase significantly. After the supply of phosphorus and potassium reaches a certain level, the increase of supply will not obviously promote the growth, nodule formation and development of Sesbania. Under the condition of no nitrogen, the increase of K from 2mM to 20mM inhibited the dry weight of Stem Nodules, and promoted the effect of nitrogen supply. There was a very significant orthogonal interaction between nitrogen and potassium.