Study On Weeds Community Structure And Its Control Technique In Tobacco Field

A general investigation of weed in tobacco field was conducted in Zhangping county of Fujian province in 2004-2005. The variety and community structure of weed and its damage degree were studies by five-point sampling and five-level eyeballing methods from five-leave stage to mature seedling stage as well as from tuanke stage to ripe stage. The results showed that the weeds during tobacco seedling stage in Zhangping county belonged to 19 families and about 47 species, in which the main species belonged to Composite and Gramineae, such as Alopecurus aequalis sobol., Stellaria alsine Grimn, Cardamine hirsuta L., Soliva anthemifolia R.Br., Polygonum plebeium R.Br., and Polygoum caespitosum Bl., etc.. Five genera, 16 families and 43 species of weeds were found during the field period, while mostly were Gramineae, Composite and Cyperaceae, e.g. Echinochloa crusgalli (L.) Beauv., Digitaria sanguinalis (L.) Scop., P. plebeium, P. caespitosum, Cyperus difformis L. and Cyperus iria L., etc..When single herbicide was used in the field for two years, the dominant species took place corresponding alternation. The community structure that originally mostly consisted of dicotyledonous weeds, such as Alopecurus aequalis sobol., etc., evolved into a mixed structure composed mainly of D. snguinalis., Echinochloa crusgalli (L.), Beauv., Polygomum hydropiper L. and Ageratum Conyzoides L.. The results suggested that the application of herbicide would lead to a variation of weed community, therefore, more attention should be paid on the rotation of herbicide in practical application.In order to improve ecological economic benefit of weed control, the present paper preliminarily discussed the relation between weed and tobacco. Moreover, the herbicide Napropamide with high efficiency and low poison as well as a film-match color film method with best control efficacy were obtained from screen experiments. For the purpose to organic combine film and chemical control methods, a new idea of covering farmland with match color film + spraying Napropamide in the ditch wereput forward to get the best effect.