| Rheum tanguticum Maxim. is widely planted in Gansu Province but can hardly needmarket demand with its medicinal range continuously expanded and the wild resourcesgradually decreased. The sexual reproduction system, pollination characteristics, seed fillingcharacteristics and seed germination characteristics of the medical plant were studiedthoroughly in this paper in order to provide theory and technical bases for setting up the seedproduction standard in the GAP base construction. The main results are as follows:1. As indefinite raceme inflorescence, the flowering duration of R. tanguticum plantpopulation was from May to June. The blossom for a single flower generally continued6to8days but the whole inflorescence lasted35to40days. The maximum pollen activity reachedafter3days following blossom in the process of flower development and the maximumperoxidase activity representing stigma receptivity also achieved in the same day, revealingthat the duration of the pollen activity and the stigma receptivity was significant synchronicity,i.e. the best period of stigma receptivity was just the period when the pollen activity was thehighest.2. The flower of R. tanguticum is smaller, the diameter of flower was2.49-4.27mm,Pollen cracking period and stigma receptivity were significant synchronicity. Those9stamenscompletely dispersed on the third day after blossom, and also the anthers and stigma, inaddition, the flower of OCI was3, combining with the different bagging and emasculationpollination treatments, those results show that the breeding system of Rheum tanguticum canbe both self-compatible and also cross-pollination, the wind was the main pollinating medium,Sometimes need pollinators, so it have no apomixis phenomenon.3. The fresh weight of hundred seed of Rheum tanguticum was growing at first, and thendecline, at last study stable in filling stage; The change trend of the dry weight of hundredseed in an s-shaped curve in filling stage after flowering10-58days, and it conform to the Logistic curve equation, and the dry weight of hundred seed increased slowly to sustainedsignificantly after the blossom of hundred seeds dry weight, and reached maximum at49days.the change trend of the dehydration rate of seeds was gradually increased slowly withthe filling stage, but the content of seed moisture continued to decline. the dry weight ofhundred seed and the dehydration rate were very significant positive correlated to filling stage,but the content of seed moisture was very significant negative correlated to filling stage; thedehydration rate was very significant negative correlated to the content of seed moisture infilling stage.4. The seed germination quality has a significant effect on seed maturity of R. tanguticum.The seeds harvest before flowering19days do not have the ability of germination. The seedsharvest after flowering20days were start to germinate after implanting7days,and finishedgerminating on the17th day. The germination rate, the germination potential and germinationindex of harvest seeds were significantly increased with the filling stage, the germination rateof seeds harvest after flowering34days reached maximum, and then changed little around themaximum. The dynamic change trend of seed germination potential and germination indexwere roughly the same, compared with the germination rate, the maximum seed germinationpotential and germination index was appeared after flowering49days, and delayed6days tothe maximum of the germination rate, and then the germination rate, germination potentialand germination index all started to decline with the further growth in plant.In summary, the pollination characteristics of R. tanguticum is between cross pollinationand self-pollination, which was self-compatible. Acceleration of dry matter accumulation andstable seed dehydration rate were the important sign indicating seed maturity. The seedsgerminated the best when the seed moisture was10%, meanning the best harvest time of theplant seeds was55days after blossom. |
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