濃尾平野における農業用水路の水生雑草の分布と2,3の環境要因
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概要
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During the period from July to August 1981, studies were carried out to evaluate the relationship between some environmental conditions and the distribution of aquatic weeds growing in the irrigation canals of the paddy area located in the basin of the Ibi River over a distance of 56 km from the estuary to the upper reaches of the river, in the western part of the Nobi Plain. The area surveyed was divided into 51 units each covering a surface of 16km^2. The area was further subdivided into three groups including the upper reaches, the central part and the lower reaches of the river. Within each unit various species of aquatic weeds excluding Phragmites communis Trinius and Zizania latifolia Turcz. were sampled to analyse the frequency of their appearance in the basin of the river. On the basis of these studies, 5 groups of aquatic weeds were identified as follows: Group A: Weeds occurring throughout the basin of the river (11 species): Spirodela polyrhiza (L.) Schled., Lemna paucicostata Hegelm., Hydrilla verticillata (L.f.) Casp., Elodea nutalli (Planch.) St. John, etc. Group B: Weeds distributed from the lower reaches to the central part of the river (7 species) : Hydrocharis dubia (Bl.) Backer, Ceratophyllum demersum L., etc. Group C: Weeds distributed in the lower reaches of the river only (15 species): Paspalum distichum L., Potamogeton pectinatus L., Ruppia maritima L., etc. Group D : Weeds distributed from the central part to the upper reaches of the river (2 species) : Sparganium erectum L. and Potamogeton malaianus Miquel. Group E: Weeds distributed in the upper reaches of the river only (1 species) : Batrachum nipponicum (M.) Kitam. var. major (H.) Kitam. Studies on the environmental conditions of the waterways including the presence of current as well as the properties of the water such as pH, content in Cl^-, Ca, K, Na and Mg revealed significant differences among the three zones of the river basin. Based on the results obtained, it is suggested that the difference in the frequency of distribution of the aquatic weeds within the various zones of the river basin is related to environmental factors which control the growth of the weeds.
- 日本雑草学会の論文
- 1983-12-20