Isolation And Identification Of Potential Allelochemicals From Aerial Parts Of Avena Fatua Land Their Allelopthic Effect On Wheat

Wild oats (Avena fatua L.), belonging to the Gramineae oats genus, is one of the18kinds of worstweeds. China is the country with the highest yield and widest area of the wheat planted, however, thewheat field weed, wild oats, is one of major grass weeds which can cause harm to China’s wheatproduction. According to the survey, wild oat threatens the crops with both competition and allelopathy.In order to study the mechanism of wild oats, to provide reasonable theoretical basis for the ecologicalcontrol of weeds in wheat fields of, wild oats was chosen as study object and tried to isolate and identifythe allelopathic potential substances, and determine their chemical basis and ecology meanings. Theresearch results were as follows:1. The potential allelopathy of the aerial parts of wild oats was investigated by studying thegermination and growth of the crops. The results revealed that when the concentration of water extractsfrom the aerial parts of wild oats at four-leaf stage reached to50mg/mL,50%germination wasinhabited on the third day after sowing. More over, the growth of the crop was affected by plant rottenand the higher of the concentration causing the higher of the inhibit rate. The growth of DuokangNo.1and Zhongmai12were inhibited by water extracts of the wild oats at head stage at high concentration.2. Second, allelopthic effect with different extract solvent such as petroleum ether, acetone,ethanol and methanol was investigated through the germination and seedling growth of the wheat. Theresults showed that ethanol extracts of the aerial parts of wild oats inhibited the germination andseedling growth of the wheat most. Ethanol was selected as the exract solvent to extract theallelochemicals. Meanwhile, DuokangNo.1was found that displayed more sensitive than Zhongmai12.So, in the following experiment DuokangNo.1was chosen as the studied object.3. After extracted by ethanol and concentrated, three solvents petroleum ether, chloroform andethyl acetate with different polar were used for the frist separation. Through series of TLC, silica geland sephadex column separation, five compounds were identified with the help of MS and NMR. Thefive compounds were as follows: Diosmetin, Acacetin, Syringic acid, Eleutheroside B and tricin.4. Finally, the activity of the five compounds was tested by bioassay. All the compoundsdecreased the germination speed index of the wheat. The tricin inhibited the most while diosmetinexhibited the least. With the increase of the concentration, the inhibit extent to the root length wasstronger and stronger. At the concentration of100mg/kg, the inhibit rate to the root length attained tomore than50%. As to the length of shoot, the inhibit rate was distinctly stronger with the increase of theconcentration of diosmetin and acacetin. Especially, tricin exhibited a little promotion to the shootgrowth at the concentration of10mg/kg. The fresh weight of the wheat was decieased unconspicuouslyat the lowest concentration by diosmetin, syringic acid and tricin. But when the concentration reach to100mg/kg, the inhibit extent was strong. The inhibit rates to the fresh weight of the five compounds at this concentration were61.4%,77.4%,65.8%,75.1%and48.8%respectively. Compared with thecorresponding crude extracts, the potential allelopthic compounds exhibited stronger inhibiting effectsand the needed concentration was lower.