Pedological and Plant Nutritional Aspects of Acid Sulfate Soil, and Physiological Responses and Tolerant Screening of Tree Species to Strong Soil Acidity

在本研究中，我们明确了日本第四纪和第三纪沉积岩中酸性硫酸盐土壤的分布。在印度尼西亚东加里曼丹和泰国那拉提瓦也发现了含黄铁矿（FeS_2）的第三纪岩石，黄铁矿可以氧化生成硫酸。热带国家的土地开发将使含黄铁矿的岩石形成硫酸酸性土壤，而目前只指出第四纪沉积物形成硫酸酸性土壤的问题。日本茨城县高速公路建设中出现了酸性硫酸盐土壤中锰的流失和种植树木锰中毒的现象。为了在酸性硫酸盐土壤上种植树木，树木必须具有对过量锰和低ph的耐受能力。在适应酸性土壤的桦树中，过量的锰破坏了光合机制。结果表明，热带豆科乔木马相思和金合欢能适应高锰和低pH条件。这表明金合欢树是强酸性退化土地复林的候选材料。建立了相思和金合欢的组织培养体系，进行了耐药育种。利用锰刺槐细胞培养系统，研究了细胞对低pH和过量锰的反应。通过在低pH和高锰条件下的连续培养，获得了耐药细胞系。我们的目的是阐明树木对这些胁迫的耐受机制，并为退化土地的再造林增加树木的耐受能力。

In this study, we have clarified the distribution of acid sulfate soils generated not only from Quaternary sediments but also from sedimentary rocks of the Tertiary in Japan. We also found Tertiary rocks containing pyrite (FeS_2), which generates sulfuric acid by oxidation, in East Kalimantan, Indonesia and Narathiwat, Thailand. Acid sulfate soil will be generated from the the pyrite-containing rocks by land development in tropic countries where now only the problem of acid sulfate soils generated from Quaternary sediments is pointed out. Elution of manganese from acid sulfate soils and disorder of planted trees by manganese toxicity were appeared by construction of high way in Ibaraki Prefecture, Japan. In order to plant trees on such acid sulfate soils, the trees is necessary to have tolerant ability to excessive manganese as well as to low pH.In the case of birch tree, which adapts on acidic soils, photosynthetic machinery was damaged by excess manganese. We showed that the tropical leguminous trees, Acacia mangium and Acacia auriculiformis, are adaptable to high manganese and low pH conditions. It suggests that the acacia trees are candidates for reforestation materials of degraded land with strong acidity. We have established the tissue culture system of Acacia mangium and Acacia auriculiformis for tolerant breeding. Using cell culture system of Acacia mangium, we clarified the response of the cells to low pH and excess manganese. Tolerant cell lines have been obtained by continuous culture under low pH and high manganese conditions. We are aiming to clarify the mechanism of tolerance to those stresses and to add tolerant ability to trees for reforestation of degraded land.