Developmental studies on weed control method by mulching recycled paper.

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The objectives of this study were (1) to promote seedling emergence and establishment on the direct sowing in flooded paddy field, (2) to make clear the characteristics of photosynthesis on main weeds and (3) to pursue the possibility of realization on the direct sowing with mulching recycled paper.(1) We investigated germination and seedling emergence on seeds coated with calcium peroxide (CaO2) adding several chemicals under the conditions of 2 cm sowing depth and 3 cm flooding.When boric acid (H3BO3) and/or magnesium nitrate hexahydrate (Mg (NO3 ) 2) were added 1% to CaO2, percentage of seedling emergence was higher than only CaO2. This efficacy of both chemicals was seemed that H3BO3 sterilized soil around a seeds and Mg (NO3) 2 supplied oxygen and nutriment for seeds.(2) We prepared the light and photosynthesis curves in water of main weeds and examined the illuminance at the respiration rate and amount of photosynthesis became the same (illuminance at the compensation point) . The results was considered that no weed would be able to grow if about 90% of the light was shaded.(3) The most important point in using the paper mulch direct sowing was make sure that the paper and soil stick firmly to each other.For this purpose, it should do soil puddling and leveling work carefully to make soil surface as flat as possible. And the irrigation water should be 1 cm deep or less. This is because pieces of paper will rise to the surface after sowing and shade seedling if the water is too deep. Thus, this will affect their growth adversely.