| Summary: | 碩士 === 國立屏東科技大學 === 熱帶農業暨國際合作系 === 103 === Rice (Oryza sativa L.) is the second most widely grown crop in the world, and the major staple food for more than half the world’s population. It is grown in over a hundred countries producing 715 million tons of paddy rice annually. Rice is a typical silicon accumulating plant, and silicon can make up to 10% of the shoot dry weight and these high levels are attributed to the superior ability of the roots to take up the element. Silica slag has beneficial effects on the growth of rice and soil fertility by alleviating both biotic and abiotic stresses. To investigate the effect of silica slag on the yield of rice, a randomized complete block design experiment, with four treatments (0, 2, 4, and 6 ton/ha silica slag) and the same number of replicates, was set up in a net house. Organic fertilizer was applied at 250 kg/ha N and was split into 3 applications. 125 kg/ha N fertilizer was applied 3 days before transplanting and the remaining half split into two, and 62.5 kg/ha N applied 15 days after transplanting and another 62.5 kg/ha N applied at panicle initiation. Rice (variety TN71) was planted in pots of 10 kg soil, with three seedlings per pot. Data for yield parameters and soil chemical properties were recorded and analyzed using S.A.S. 9.4 statistical package with significant differences determined using Duncan’s Multiple Range Test (p˂0.05). Data recorded for yield and yield parameters were grain yield, unshelled grain, filled grain, unfilled grain, rice husk, 100-grain weight, number of tillers, number of panicles and plant height. Soil chemical properties that were observed were the availability of silicon, calcium, magnesium, phosphorus, and soil pH value with cation exchange capacity. Results obtained showed that the application of silica slag had no significant effect on the number of tillers, number of panicles per hill, and plant height, neither was there a significant increase in grain yield (g/hill). All the other yield parameters showed significant differences among treatments. In soil chemical properties, available silicon, calcium, magnesium, pH, and C.E.C. increased with an increase in the application rate of silica slag, phosphorus decreased and potassium did not show any significant differences. Nutrient concentration in rice plant tissue was also observed where phosphorus and manganese showed significant differences, and their concentration decreased with increase in silica slag application rate. Calcium and magnesium displayed no significant differences among treatments yet an increase in their concentration was observed. To determine the concentration of silicon, the plant was divided into three parts, i.e., husks, leaves and stems. Silicon was found to be highly concentrated in the husks followed by the leaves and the least concentration was found in the stems. It is therefore recommended that silica slag be used to improve soil chemical properties and this could be done after determining the nutrient availability, especially phosphorus, and pH status of the soil. The high concentration of silicon in the rice husks makes it possible for resource poor farmers to recycle crop residue and use the husk to add silicon in the soil.
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