Effects of mycorrhizal inoculum on the dynamics of heavy metals in the rhizoshere.

以向日葵为试材，在根箱系统中研究了接种无菌和非无菌丛枝菌根菌后根际重金属的动态变化。当非无菌菌根接种物提供的根箱的中央室，营养成分的芽增加，而不减少植物的生长。根际土壤的分析表明，水溶性锌和铁的数量增加，除了磷，磷酸单酯酶活性。然而，既没有排泄的低分子量有机酸（LMOAs）的治疗，也没有增加的量LMOAs观察。这些结果表明，AM真菌和/或菌根根中的酶能溶解土壤中的难溶性磷，而被难溶性磷吸附的Zn和Fe则随磷一起释放，因此，适当施用菌根接种物能有效地利用土壤中积累的养分。在马来西亚SarawakState的ForestResearchStationNiah检测了外生菌根真菌从菌根树到非菌根幼苗的繁殖。研究了接种密度、距离菌根树的远近对苗木的侵染率、生长和养分含量的影响。本试验中，由于土壤养分状况较差，无法明确根际重金属的动态。但是，高感染率的根系的磷含量高于低感染率的根系，这表明即使在土壤有效养分有限的情况下，菌根树也能有效地为幼苗提供养分。需要进一步的实验，特别是在土壤条件下，外生菌根真菌不寄生对幼苗。

To investigate the dynamics of heavy metals in the rhizosphere under the application of steriled and non-sterile arbuscular mycorrhizal inoculum, sunflower, plants were grown in a rhizobox system. When the non-sterile mycorrhizal inoculum was supplied in the central compartment of the rhizobox, nutrient contents of the shoots increased without reducing the plant growth. The analysis of the rhizosphere soils showed the increase in the amounts of water soluble Zn and Fe in addition to the P, and in the activity of phosphomonoesterase activities. However, neither the excretion of low-molecular-weight organic acids (LMOAs) specific to the treatment nor the increase in the amounts of LMOAs was observed. These results indicated that the dissolution of insoluble phosphates was caused by the enzymes originated from arbuscular mycorrhiza and/or mycorrhizal roots and that the Zn and Fe sorbed by the insoluble P were released together with the P.It was supposed that appropriate application of mycorrhizal inoculum would be effective to utilize the nutrients accumulated in the soil.On the other hand, propagation of ectomycorrbizal fungi from the mycorrhizal tree to the non-mycorrhizal seedlings was examined at Forest Research Station Niah, Sarawak State, Malaysia. The effects of planting density and distance from the mycorrhizal tree on the infection rate, growth, and nutrient contents of the seedlings were evaluated. In this experiments, the dynamics of heavy metals in the rhizosphere could not be clarified due to the poor nutrient condition of the soil. However, the p content of the roots with high infection rates was higher than those with low infection rates, which suggested that the mycorrhizal tree was effective in supplying the nutrients to the seedlings even when the available nutrients in the soil are restricted. Further experiments will be needed, especially under the soil conditions which ectomycorrhizal fungi do not act parasitically towards the seedlings.