REGULATION OF P STATUS IN HOST PLANT ON ALKALINE PHOSPHATASE (ALP) ACTIVITY IN INTRARADICAL HYPHAE AND DEVELOPMENT OF EXTRARADICAL HYPHAE OF AM FUNGI
植物磷营养状况对丛枝菌根真菌生长及代谢活性的调控*

In order to investigate the influence of phosphorus (P) status of host plant on development and metabolic activity of AM fungi, a four-compartment cultivation system was used. Maize was grown in soil supplied with different P fertilizer levels, in association with the arbuscular mycorrhizal (AM) fungi Glomus sinuosum, Glomus intraradices or left un-inoculated. The result showed that P uptake and plant dry matter were enhanced by inoculation with Glomus intraradices when no P (P0) was supplied into soil. There was significantly increase of P uptake by mycorrhizal maize plant, but no significant influence on plant dry matter under 50 mgkg-1 P level. Under 250 or 500 mgkg-1 P level, there is no increase of plant dry matter and P uptake by mycorrhizal maize plant. ALP activity in intraradical hyphae decreased significantly with the increasing of supplied P level. In compared with non-P supplying treatment, extraradical hyphal density in soil was increased at 50 mgkg-1 P level and decreased at 250 and 500 mgkg-1 P levels. It is concluded that ALP activity in intraradical hyphae and development of extraradical hyphae of AM fungi can be regulated by P status of host plant by appending P into soil. There were no significant differences of ALP activity and development of AM fungi responded to P supplied levels between Glomus sinuosum and Glomus intraradices. Due to the development and metabolic activity of AM fungi inhibited by higher P level, P uptake by AM fungi was decreased. It may be one of the reasons resulting in the decrease of mycorrhizal efficiency.