| Distilled water and methanol extracts from Houttuynia cordata roots of six differentlocations by different treatments(drying method, methanol concentration, pH, ultrasonic time,and extraction temperature) were used in this research to stimulate O.aegyptiaca seeds andO.cumana seeds germination, and we also researched a preliminary approach to separate thegermination stimulant from H. cordata.By the influence of these factors we knows the qualityof the germination stimulant, then we can offer some theoretical basis and separate method toidentify and separate the new germination stimulant from H. cordata.No matter what kinds of drying methods、stimulate what kinds of Orobanche seed togerminate、undiluted or diluted, H. cordata from Guangxi has a higher germination rate tostimulate two kinds of Orobanche seeds, but Sichuan、Anhui and Hunan has a lowergermination. This indicated that germination stimulant content between different germplasmresources of H. cordata was also different. But no matter stove、freeze-drying or dry in theshade，the leach liquor of same location of H. cordata stimulate Orobanche seeds togerminate, the germination rate has no rule can be followed. This indicated that dryingmethod has a litter impact to germination stimulant content in H. cordata.Extraction result is good when the concentration of methanol is high, concentration ofone hundred percent methanol has the highest germination rate to stimulate two kinds ofOrobanche seeds to germinate. Germination stimulant of O. aegyptiaca in H. cordata is moresensitive to temperature treatment, high temperature can restrain its function, the germinationrate of O. aegyptiaca seeds raised with temperature but O.cumana seeds was not sensitive totemperature treatment.The germination rate of O.cumana seeds was reduced when the pH of leach liquor wasraised, the O.cumana seeds was not budding when the pH of leach liquor exceed7.0. The O.aegyptiaca seeds can germinate only when the pH of environment was4.0. The germinationinhibition was disappeared when the leach liquor was diluted, this indicated that germinationstimulant of O.cumana can play a role in faintly acid and neutral condition but germinationstimulant of O. aegyptiaca can play a role in pH of4.0. The germination rate of Orobancheseeds was reducing with ultrasonic time. This might because too long ultrasonic time canextract some germination inhibitor from H. cordata.No matter what kinds organs of H. cordata, the higher or lower elevation offer a higher germination rate of two kinds of Orobanche seeds. The influence of elevation may greaterthan its own organs.The dry sample extracts of H. cordata to stimulate O. cumana seeds and O. aegyptiacaseeds to germinate, the germination rate of two kinds of Orobanche seeds show differenttrend in the experiment of column chromatography. The O. aegyptiaca seeds have only onepeak. The O. aegyptiaca seeds were not germinate when the eluent of methanol concentrationexceed70%but the O. cumana seeds have two peaks. Separating with different developersolvent in the experiment of Thin layer chromatography, when the developer solvent of ethylacetate and trichloromethane was in the proportion of nine to one, the separating effect ofgermination stimulant of O. cumana was better than the others; when the developer solvent ofethyl acetate and normal hexane was in the proportion of nine to one, the separating effectgermination stimulant of O. aegyptiaca was better than the other.Through these experiments above we can find out that there could not be only one orone kind of germination stimulant of Orobanche seeds in H. cordata. Differ from strigol isunstable and easy to resolve, we hopefully separate some new kinds of germination stimulantof Orobanche seeds from H. cordata, then we can compound some bioherbicide which ispersistent in the soil, prevent and kill off the Orobanche seeds with “suicide of germination”and exterminate the Orobanche seed bank in the soil to solve the most hardly problem ofworst weed Orobanche. |
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