Abstract: The results of the study on the absorption of N nutrition in the plants of Dendrobium cultured from tissues show that(NH)₂C₄H₄O₆ as N source is the best for promoting the growth(height,diameter of stem and biomass) of the plants which have mycorrhizae.Also,(NH)₂C₄H₄O₆ can promote growth of mycelium of F9903 which is a strain of mycorrhiza of Dendrobium.So,(NH)₂C₄H₄O₆ is a best N source for the propagations of both the plants and the mycorrhiza myceliaum.There is a strong interaction between the plants and their mycorrhizae.Different concentrations of(NH)₂C₄H₄O₆ can effect the growth of Dendrobium plants and absorptions of the mycorrhizae to N,P and C.Through a variance analysis,it has shown that the 2.72 mol·L^-1 of(NH)₂C₄H₄O₆ is the most suitable concentration for culturing plants of Dendrobium.

Key words: Dendrobium, mycorrhized, nitrogen nutrition