Identification And Analysis Of Chemical Compositions Of Root Exudates From Flue-cured Tobacco

In order to study the chemical compositions of root exudates from flue-cured tobacco, theirallelopathy and their dispel rate in tobacco-planting soils, three varieties of tobacco (Zhongyan100,NC89,K326) were used to identify the root exudates in different extracting conditions. The mainmethods of the research are sandy culture, silane treating and GC-MS identification. Through analysingthe content, structure of root exudates from flue-cured tobacco and related articles, benzoic acid、cinnamic acid、fumaric acid、succinic acid and nicotine were used to study their allelopathy on tobaccoseed and tobacco seedlings. After confirming the main allelochemicals’, decomposition speed of essentialcomponent of root exudates（fumaric acid、succinic acid、benzoic acid and cinnamic acid）in plantingtobacco soil was researched by house culture in different temperature、humidness and concentrationsituations.(1) Root exudates in different extracting conditions of the three varieties mainly involve phenols,organic acids and ketones. Under neutral condition, the components of root exudates included2-hydroxyl propionic acid, Tetradecanoic acid, Neophytadiene, Scopoletin and Octanoic acid. Underacid condition, the components of root exudates included3-hydroxy butyrate, Neophytadiene, Succinicacid, Hexadecanoic acid and Cinnamic acid. Under alkaline condition, the components of root exudatesincluded Neophytadiene, Hexadecanoic acid and Stearic acid.2-hydroxyl propionic acid, Benzoic acid,Succinic acid, Nicotine, Neophytadiene, Tetradecanoic acid, Hexadecanoic acid and Fumaric acid wereidentified in the root exudates of all the three varieties of tobacco. The grade of influence by rootexudates of Zhongyan100in different extracting conditions on tobacco seed are (from high to low):neutral condition, alkaline condition and acid condition. Fumaric acid, Succinic acid and Nicotine hascertain inhibition on the germination rate of the tobacco seeds.(2) After a period of time, found that along with the increase of the concentration of the rootexudates（benzoic acid、cinnamic acid、fumaric acid、succinic acid and nicotine）, the tobacco seedlings,seed germination and tobacco plant characters all appear reduce gradually. And the tobacco seedlings,seed germination and tobacco plant characters were had the same inhibitory action among differentconcentrations of root exudates. The result showed that, the root exudates could inhibit the growth oftobacco seedlings, seed germination and tobacco plant characters. Different concentrations of benzoicacid、cinnamic acid、fumaric acid、succinic acid and nicotine could inhibit the growth of tobaccoseedlings, seed germination and tobacco plant characters, and the higher the concentration the bettereffect of the inhibition. But there were great differences in the extent of inhibition between the5rootexudates, benzoic acid>cinnamic acid>succinic acid>fumaric acid>nicotine.(3) Decomposition speed of fumaric acid、succinic acid、benzoic acid and cinnamic acid wasquickly，which could be disappear completely in7days. Temperature had little influence on thedecomposition speed,4kinds of organic acids at20℃decomposed faster than30℃. When the soilmoisture was60%of the maximum moisture capacity, the decomposition speed of4kinds of organicacids faster than40%and80%. Concentration had more influence on the decomposition speed, withincreasing of organic acids in the soil, the decomposition speed of them decreases quickly.