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tohoku.ac.jp 酸性化多孔質ケイ酸カルシウム水和物の pH が 水稲苗（Oryza sativa L.）の生育に及ぼす影響 1 2 3 1 2 3 要旨@@@@@@@@@@@@@@@@@@@@@@@@@@APS : acidified porous hydrate calcium silicate pH pH APS @@@@@@@@@@@@@@@@@@@@@@@@@@@@ APS pH 5. 33. 93. 0 APS APS 5. 3APS 3. 9APS 3. 0 pH APS pH @@@@@@@@@@@@@@@@@@@@@@@@@ pH APS 3. 0 APS 5. 33. 9 @@@@@@@@@@@@@@@@@@APS 3. 0 APS APS 3. 0 APS 3. 0 @@@@@@@@@@@@@@@@@@ APS 2 APS 3. 0 APS 3. 0 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ APS 5. 33. 9 @@@@@@@@@@@@@@@@@@ APS pH 3. 9 5. 5 キーワード @@@@@@@@@@@@@@@@@@ pH @@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@ PSporous hydrate calcium silicate @@@@@@@@@@@@@@@@@@@@@@ APSacidified porous hydrate calcium silicate APS @@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@ 2003Heinai 2005 APS PS pH pH 5. 5 @@@@@@@@@@@@@@@@@@@@@@@@ 1973 1981 pH @@@@@@@@@@@@@@@@@ pH 1989 APS pH pH APS pH pH APS Jpn. Abstract : We have developed acidifi ed porous hydrate calcium silicates (APS) with the fi nal pH of 3.0, 3.9 or 5.3 by adding of sulfuric acid to porous hydrate calcium silicate material. In this study, the effects of APS at various pHs applied to nursery bed soil on the growth of rice seedlings were investigated to determine the optimal pH of APS as an ameliorant for raising healthy rice seedlings. APS at pH 3.0 decreased the plant length of the seedlings by 10 to 15% compared to that at other pHs. Treatment with the APS at pH 3.0 decreased both shoot dry weight, and the ratio of shoot dry weight to the plant length of the seedlings. The root dry weight was the lightest in the seedlings treated with APS at pH 3.0; these root tissues, especially exodermis, sclerenchyma and endodermis, were intensively stained with hematoxylin and evans blue, showing the symptom of Al toxicity. Key word : Acidifi ed porous hydrate calcium silicate, Al toxicity, Evans blue staining, Material pH, Hematoxylin staining, Rice seedling, Root.

(pp. 41–46) Silicon availability in 36 commercial nursery bed soils was evaluated by four methods the phosphate buffer (pH 6.2, 40 mmol L−1), incubation, supernatant and acetate buffer (pH 4.0, 1 mol L−1) Methods. The influence of silicon availability in the nursery bed soils on the silicon uptake of rice Oryza sativa L. cv. Hitomebore seedlings and the effect of silicon fertilizer application were examined in a glass house in 2002. The results revealed that the best correlation between silicon content in rice seedlings and available silicon in soils was obtained with the phosphate buffer‐solution method (r = 0.86). More precise evaluation of available silicon was achieved by grouping soils based on these phosphate absorption coefficients (PAC). The correlation coefficients between silicon content in rice seedlings and available silicon in soils were 0.92 and 0.72 for volcanic soils (PAC > 1500) and non volcanic soils (PAC < 1500), respectively. We concluded that the phosphate buffer method is the most easily adjusted method for estimation of silicon availability in nursery bed soils, and silicon fertilizers should be applied when silicon availability in non‐volcanic nursery bed soils goes below 200 mg kg−1, whereas the level is less than 350 mg kg−1 in volcanic soils.

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