Prediction Study of Weed Seedbank Dynamics for Weed Control without Herbicides Application

30多年来一直以来都在控制一种herbicides effective for annual weeds used to controlweeds in Japan. Recently，we can find the paddy rice fields where are few annual weeds and decrease the number of weed seedsin soil after application of effective herbicides. A potential use of seedbank information in weedmanagement is the use of models that incorporate seedbank dynamics and prediction of weed emergenceinto the decision making process.In 1998I tried to estimate the seed density in soil based on the number of seedlings emerging from paddysoil samples collected from 25 paddy fields. At firstwe make sure of the tendency toward the seedbank change of the rice field. When herbicides wereapplied consecutively,the seedbank decreased 12.7% per year at the rice field. Where the seed contained more than 30,000in plow layer soil. And the decreased rate was 12.7 ~ 2.3% per year in the rice field contained lessthan 30,000 seeds in plow layer soil.In 1999I conducted to clear the weed competion in rice cultivation and to define precisely the number ofweed seedbank in soil. And I proved that the loss of grain yield was under 10% in rice plow layersoil contained less than 34,000/m weed seeds. We will be be develop the计算决策-aid software to predict the economic weed management from these results

More than 30years have passed since a herbicides effective for annual weeds was used to control weeds in Japan. Recently, we can find the paddy rice fields where are few annual weeds and decrease the number of weed seeds in soil after application of effective herbicides. A potential use of seedbank information in weed management is the use of models that incorporate seedbank dynamics and prediction of weed emergence into the decision making process.In 1998, I tried to estimate the seed density in soil based on the number of seedlings emerging from paddy soil samples collected from 25 paddy fields. At first, we make sure of the tendency toward the seedbank change of the rice field. When herbicides were applied consecutively, the seedbank decreased 12.7% per year at the rice field. Where the seed contained more than 30,000 in plow layer soil. And the decreased rate was 12.7〜2.3% per year in the rice field contained less than 30,000 seeds in plow layer soil.In 1999, I conducted to clear the weed competion in rice cultivation and to define precisely the number of weed seedbank in soil. And I proved that the loss of grain yield was under 10% in rice plow layer soil contained less than 34,000/mィイD12ィエD1 of weed seeds. We will be able to develop the computerized decision -aid software to predict the economic weed management from these results