Proposal of coexistent ecosystems with paddy and water-covered plant for promoting an efficient production of biomass resources

Research Project

Project/Area Number	14560279
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	生物資源科学
Research Institution	University of Tsukuba
Principal Investigator	SAKAI Naoki University of Tsukuba, Institute of Agriculture and Forestry, Professor, 農林学系, 教授 (00092213)
Co-Investigator(Kenkyū-buntansha)	HAYASHI Hisayoshi University of Tsukuba, Institute of Agriculture and Forestry, Lecturer, 農林学系, 講師 (70251022)
Project Period (FY)	2002 – 2003
Project Status	Completed (Fiscal Year 2003)
Budget Amount *help	¥2,900,000 (Direct Cost: ¥2,900,000) Fiscal Year 2003: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 2002: ¥2,100,000 (Direct Cost: ¥2,100,000)
Keywords	Coexistent ecosystems / Paddy field / Water hyacinth / Biomass production / Structure of community / Carbon fixation / Complication of systems / Water-covered plant / 複雑化 / 密度
Research Abstract	In an ordinary paddy field whose cultivated dominant crop is a paddy, we tried to propose a new cropping systems based on coexistence with the plural crops for expecting the mitigation of environmental impact and escape of monoculture systems. In this study, the effect of plant density in coexistent systems on growth rate, structure of community and yield of the two crops were investigated in the 2002-2003 experiments with three repetitions under the same condition of application rate of fertilizer. We used a water hyacinth as the water-covered model crop. Plant densities were 22.2 hills/m^2 for paddy, and 22.2, 16.7, 11.1, 5.6 and 0 hills/m^2 for water hyacinth, respectively. As a result, an introduction of water-covered crop contributed the increment of carbon fixation rate per unit area although some increased plant densities affected the competition of resources utilization and paddy yield negatively. Finally the optimum plant density of water hyacinth was estimated at the neighbor of 11.1 hills/m^2 from the viewpoint of carbon fixation.