| Guiyang city locates in the southeast of southwest of china. Its climate is typical moist monsoon in middle Asia and the warm and humid tropics is not only good for the development of tobacco but also advantage to weeds propagation. Through identifying more than 400 tobacco weeds specimens in three towns and one city from Guiyang city, we find that there are 105 species of 81 genera belonging to 31 families of tobacco weeds, include monocotyledons weeds 22 species of 19 genera belonging to four families, dicotyledonous weeds 83 species of 62 genera belonging to 27 families.The most number of species in families in tobacco field are Asteraceae(including 23 species of 19 genera) and Gramineae(including 16 species of 14 genera), followed by Polygonaceae(including 10 species of 5 genera) and Lamiaceae(including 5 species of 4 genera).The dominant weeds species are Digitaria sanguinalis, Stellaria media, Veronica polita and Cynodon dactylon.Galinsoga parviflora Cav. has the biggest advantage of important value in tobacco field weeds, recently G. Parviflora become an invasive weed in China, and caused serious damage to agricultural production and ecosystems in several provinces of China. Research biological and ecological characteristics of Galinsoga parviflora Cav. systematically could reveal the principle of its invasion. Using paraffin section method and scanning electron microscopy technology observed the anatomical structure of G. Parviflora vegetative organs and The morphology of seed, determine the reproductive characteristic of the seeds by drying and seed germination test, as well as investigated the niche characteristics and seed yield per plant in the field.. The resaults showed that, the climate of Guizhou looks similar to South America, that lead G. Parviflora invaded successfully and rapidly. G. Parviflora has large biomass, owns the biggest niche breadth and the overlap value, it's easy for emerging the single dominant community. The seed yield per plant is high, and its light weight and small size make the seed easy to spread in the wind. The seed germination rate is high, and it has a certain ability of resistance to acid and alkali stress, salt stress as well as drought stress. The structure of G. Parviflora also reflects the adaptability to different environment.Biology and ecology characteristics of dominant weeds such as G. Parviflora in tobacco field was studied, which provides a theoretical basis for weed control in the field. Six kinds of herbicide(Butralin clomazone EC, Quizalofop-p-ethyl clomazone EC, Rimsulfuron WP, Acetochlor EC, Napropamide WDG and Metolachlor EC) and mulching film were used for weed control test. The result showed that the six kinds of herbicide both have effect on the number and fresh weight of weed in tobacco field. The effect of herbicide is that Butralin clomazone EC > Acetochlor EC > Rimsulfuron WP > Napropamide WDG > Quizalofop-p-ethyl clomazone EC > Metolachlor EC, especially Butralin clomazone EC has the most significant effect among the six kinds of herbicide, as well as Acetochlor EC. Quizalofop-p-ethyl clomazone EC has the best effect on dicotyledonous weed and Rimsulfuron both have effect on dicotyledonous weed or endogen weed, however the last four herbicide have significant effect on endogen weed. In the Physical and chemical comprehensive prevention and control test, black mulching film have effect on the number and fresh weight of weed, the test with black mulching film and Butralin clomazone EC has the best significant effect on weed control.weeds in the Gap between tobacco field still needs to be be controlled by Butralin clomazone EC. |
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