水田多年生雑草オモダカの水稲に対する雑草害

概要

論文の詳細を見る
The damage caused by the Sagittaria trifolia L. used to rice cultivated under ordinary conditions was analysed at various densities of the weeds planted immediately after rice transplanting . The results obtained were as follows ; 1) The plant length of the weeds grew toller at lower planting densities , and shorter at higher densities (Figs . 2 and 3) . However , in both cases , the weeds grew enough to cover the area between rice rows and hills after midseason drainage . 2) The larger the top dry weight of the weeds in mid-September , the smaller the whole top-weight of the rice community and the lower the yield of rice (Fig. 4) . 3) The decrease of rice yield which was mainly caused by nutrient competition with the weeds resulted firstly in the decrease of the number of ears , secondly in the decrease of the number of grains per ear when the weeds grew at higher densities , and thirdly in the decrease of the percentage of ripened grains when the weeds grew at lower densities (Table 1) . 4) The ratio of rice yield loss to top dry weight of the weeds was higer for arrowhead than for other main paddy weeds (cf . Echinochloa oryzicola . Cyperus serotinus , Eleocharis kuroguwai) . Presumably due to the high content of nitrogen in arrowhead plants. 5) A negative high correlation between the top dry weight of the weeds in mid-September and the number of rice ears was obtained in rice cultivated under ordinaly conditions from 1980 to 1984 . It was considered that 100 g /m^2 of top dry weight of the weeds was equivalent to a loss of rice yields amounting to 12-15% (Fig. 6) .
1988-05-26

水田多年生雑草オモダカの水稲に対する雑草害

スポンサーリンク

概要

著者

関連論文

スポンサーリンク