STUDIES ON THE WHEAT WEEDS COMMUNITIES IN WHEAT FIELDS IN JINGQU BASIN OF ZHEJIANG PROVINCE

In the wheat fields of thirteen counties (or cities) of Jingqu basin in Zhejiang Province, 724 random sampling fields of 80 sites were surveyed in detail by vision of seven grades to obtain the weed damage index, these data were analysed by the maximal tree method of fuzzy graphy theory. Study shows: there are four main Triticum aestivum-weeds communities in wheat fields, Which are Triticum aestivum-Alopecurus aequalis-Stellaria alsine-Malachium aquaticum-Polygonum persicaria community in the rice-earth fields with the rotation of wheat and rice, Triticum aestivum-Avena fatua-Polygonum persicaria-Capsella burapastoris-Galium aparine var. tenerum community in damp-sandy-soil fields near the rivers with the rotation of wheat and soybean (or sweet potato or cotton or peanut), Triticum aestivum-Galium aparine var. tenerum-Avena fatua-Veronica persica community in lower-subdued red earth dryland fields with the rotation of wheat and soybean (or sweet potato or cotton or peanut), Triticum aestivum-Juncus alatus-Ranunculus sieboldii-Alopecurus aequalis-Polygonum persicaria community in sand bog fields. Investigations indicate that the types of soil, pH, cultivation regime and topography are the main factors influencing the distribution and structure of Triticum aestivum-weeds communities in wheat fields in Jingqu basin.