Silicon (Si) plays a significant role in the resistance of plants to multiple stresses including biotic and abiotic stresses. Silicon is also the only element that does not damage plants when accumulated in excess. However, the contribution of Si to plant growth has been largely ignored due to its universal existence in the earth's crust. From numerous intensive studies on Si, initiated in Japan about 80 years ago, Japanese scientists realized that Si was important for the healthy growth of rice and for stability of rice production. In a worldwide first, silicon was recognized as a valuable fertilizer in Japan. The beneficial effects of Si on rice growth in particular, are largely attributable to the characteristics of a silica gel that is accumulated on the epidermal tissues in rice. These effects are expressed most clearly under high-density cultivation systems with heavy applications of nitrogen. Si is therefore recognized now as an ''agronomically essential element'' in Japan.
Recently, Si has become globally important because it generates resistance in many plants to diseases and pests, and may contribute to reduced rates of application of pesticides and fungicides. Silicon is also now considered as an environment-friendly element. The achievements of Si research in Japan are introduced in this book, in relation to soils, fertilizers and plant nutrition.
1. Brief history of silicon research in Japan. 2. Silicon sources for agriculture. Silicon supply for paddy rice from natural sources. Irrigation water. Soils. Silicon supply from organic and inorganic fertilizers. Compost. Application rate in the past and the present. Short-term availability of Si in rice straw for rice plants. Long-term availability of Si in compost for rice plants. Rice husk. Silicate fertilizers. Calcium silicate slags. Fused magnesium phosphate. Potassium silicate fertilizer. Porous hydrate calcium silicates. Silica gel. Estimation of available silicon in silicate fertilizers. 3. Silicon in soil. Behavior of silicon in paddy soil. Estimating the silicon-supplying capacity of paddy soils. Measuring acetate-buffer soluble silicon (Acetate buffer method). Measuring silicon dissolved under submerged condition (Incubation method). Measuring silicon in supernatant (Supernatant method). Measuring easily soluble silicon (Easily soluble Si method). Measuring silicon dissolved in surface water (Surface water dissolution method). Measuring Si dissolved in phosphate buffer (Phosphate buffer method). Environmental factors controlling the availability of silicon for rice plants in paddy soils. Balance sheet of silicon in paddy soil-past and present. 4. Effect of silicate fertilizer application on paddy rice. Criteria for predicating silicate fertilizer requirement for paddy rice. Field experiments on the effects of silicate fertilizer application. Slag-calcium silicate. Porous hydrate calcium silicate. Silica gel and potassium silicate. Effect of calcium in slags on silicon uptake by rice. 5. Silicon-accumulating plants in the plant kingdom. Criteria for discriminating Si-accumulating plants from non-accumulating plants. Characteristics of silicon accumulators and their distribution in plant kingdom. Variety difference in silicon content in the Si-accumulating and intermediate-type species.
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- © Elsevier Science 2002
- 9th August 2002
- Elsevier Science
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Faculty of Agriculture, Kagawa University, Ikenobe 2393 Miki-cho, Kita-gun, Kagawa 761-0795, Japan
Kyoto University, Nakaadachi-cho 23-8, Yoshida Sakyo-ku, Kyoto 606-8306, Japan