植物磷营养状况对丛枝菌根真菌生长及代谢活性的调控*

采用四室隔网培养装置,以玉米为宿主植物,通过在植物生长室设0、50、250和500 mgPkg-1 4个施磷水平,研究了植株体内的磷营养状况对AM真菌Glomus sinuosum和Glomus intraradices生长及活性的影响。研究发现在不施磷条件下,接种AM真菌G. intraradices显著促进了植物生长和磷的吸收;低磷条件(50 mgPkg-1)下,接种菌根真菌显著促进了植物对磷的吸收,但对植物生长没有明显的影响;而在高磷条件(250 mgPkg-1 和500 mgPkg-1)下,接种菌根真菌不但没有促进植物的生长和磷的吸收,反而对其有抑制作用。随着施磷水平的提高, AM真菌根内菌丝的碱性磷酸酶活性显著下降;与不施磷相比,低量(50 mgPkg-1)供磷增加了AM真菌土壤中根外菌丝的密度,高磷(250 mgPkg-1 和500 mgPkg-1)降低了土壤中根外菌丝的密度。上述结果说明:⑴ 给宿主植物施用磷肥引起的植物磷营养状况的改变,对AM真菌生长和代谢活性具有一定的调控作用;⑵ G. sinuosum和G. intraradices两种AM真菌的生长和代谢活性对施磷水平的响应程度无显著性差异;⑶ 高磷抑制AM真菌生长和代谢活性,使真菌吸磷量减少,可能是造成菌根效应降低的原因之一

REGULATION OF P STATUS IN HOST PLANT ON ALKALINE PHOSPHATASE (ALP) ACTIVITY IN INTRARADICAL HYPHAE AND DEVELOPMENT OF EXTRARADICAL HYPHAE OF AM FUNGI

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.