Rice as a typical silicified plants needs the intemal absorption of silica, especially during the growing period. The leaves and culm of plant are erected up by uptake of silicic acid. Sun light could reach the bottom leaves in the plant communities. In addition, the nitrogen uptake would be physiologically controlled by the application of silica and the quality of rice could be improved by reducing the quantity of protein in grian. In the field experiment designed, the rice cultivar was DonhjinⅠho, Daeanbyeo and transplanting day was May 25, 2007. N levels per ha were 100 and 200kg, respectively and liquid silica(ai 11%, manufactureed by Dongbuhiteck Co.) was sprayed on flag leaves according to 500fold and 1000fold with distilled water and 3 times at an interval of 1week from 30 days before heading. The rice culms treated with each liquid silica levels were shortened and panicle length were increase as compare with the control in the level of each N. The lodging was reduced in the plot that treated with the higher liquid silica application of 100kg as compared with 200kg plot in the filed. The rice yields of the plots treated with silica application were more increased than in the control plot. All yield components, except of panicle number in DongjinⅠ, increased as compare with 200kg plot in the filed. Changes measured by 2-DE in display expression of flag leaves and seed in relation to nitrogen treatment level and silica trements were similar in fashion, yet still displayed distinguishable differences in display strength spots.

Recently with increase tendency of direct sowing cultivation, lodging problem which affect to the high quality rice plant is again raising its ahead. In order to reduce this lodging problem there is a chemical method which uses plant growth retardant. This experiment was conducted to evaluate the effect of lodging reduction as affected by plant growth retardant which is IBP-Metconazole (IPM) in direct-seeded rice on flooded paddy field. IPM treatment carried out 50, 40, 30 days before heading. Hexaconazole treatment carried out 30 days before heading. IPM treatment 30 days before heading resulted the shortest plant culm among the IPM treatments. 4 internode length was shorter by 3.75㎝ in IPM treatmenst than in control. breaking strength was not a difference from between IPM treatments but breaking strength was significantly increased by IPM treatments than control. IPM treatments increased yield 10~11% as compared with control. The protein contents of flag leaves by 2-DE were visually higher in the plot treated with the IPM application than in the plot control plot. The proteome approach to elucidate the mechanism which inhibited gibberellin synthase will be future performed in the on-going research.