The Role of Endomycorrhizas in Mineral Nutrient Uptake by Crop Plants.

在总磷含量高、速效磷含量低的辐照过的Aso土（andosol）上接种泡状-丛枝菌根真菌、mosseae和G. etunicatus孢子混合接种后，大豆的干物质产量、种子产量和磷积累量在不施磷肥的情况下均显著增加。在未灭菌的土壤中，添加磷酸盐对生长也有促进作用。菌根和非菌根大豆芽对<^(32)P>标记土壤磷素积累的磷具有相似的比放射性。菌根大豆对Fe <^(32)P> <O_4>或Al <^(32)P> <O_4>的吸收与非菌根大豆几乎相同。接种G. mosseae后Aso土中Al-phosphate含量的变化并不能完全解释菌根大豆芽中磷积累的增加。这些结果表明，由于菌根菌丝网络在根毛区以外的延伸，具有较大的固定磷酸盐能力，因此内生菌根在很大程度上促进了作物对土壤中磷酸盐的吸收。竹炭粉的添加有效地提高了在施肥良好的Aso和Sadohara土壤（andosol）中mosseae和etunicatus侵染率和密度。然而，囊状丛枝菌根对土壤中流动性较弱的养分、锌和铜的吸收没有刺激作用。接种较好的内生菌根真菌可以增加作物对土壤中磷酸盐的吸收，从而节省磷肥的施用。

The dry matter production, seed yield and phosphorus accumulation of soybean greatly increased irrespective of phosphate fertilization when a mixture of spores of vesicular-arbuscular mycorrhizal fungi, Glomus mosseae and G. etunicatus was inoculated in irradiated Aso soil (andosol) which had high total phosphate content but low available phosphate content. The growth stimulation also occurred in the unsterilized soil with added phosphate.Mycorrhizal and nonmycorrhizal soybean shoot had a similar specific radioactivity of phosphorus accumulated from <^(32)P> -labelled soil phosphate. Absorption of <^(32)P> by mycorrhizal soybean from Fe <^(32)P> <O_4> or Al <^(32)P> <O_4> added in water-culture solution was almost identical with that by nonmycorrhizal soybean. Changes in Al-phosphate content of Aso soil inoculated with G. mosseae did not always explain the increased accumulation of phosphorus in mycorrhizal soybean shoot. These results show that endomycorrhizas largely contribute the phosphate absorption of crop plants in andosol having large phosphate fixing capacity due to the extension of a network of mycorrhizal hyphae beyond the root-hair zone.The addition of powdered bamboo charcoal efficiently increased the rate and density of infection with G. mosseae and G. etunicatus in well-fertilized Aso and Sadohara soil (andosol). However, vesicular-arbuscular mycorrhizas did not stimulate the absorption of less mobile nutrients, zinc and copper from the soils.Inoculation with better endomycorrhizal fungi will increase phosphate absorption by crop plants from soil and may in turn save phosphate fertilizer to be applied.