Abstract
We have developed acidified porous hydrate calcium silicates (APS) with the final 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.
