| Pogostemon cablin is one of staple genuine medicinal materials in Guangdongprovince.It may exist continuously cropping obstacleits as lower production aftersuccessive years of cultivation. Tissure culture technology was used for the first time toresearch the allelopathic autotoxicity and the toxic substances of pogostemon cablin in thispaper. We researched in the allelopathic or autotoxicity of different organs of water extractsand root exudates to the tissue culture seedlings of pogostemon cablin、domesticationseedling of pogostemon cablin、 radish、 and desmodium styracifoliurn. We primaryidentified the allelochemicals of phenolic acids in pogostemon cablin by the method ofHPLC, added different concentrations of the four single phenolic acids and mixed phenolicacid to tissue culture medium, and then verified the allelopathic effects of various phenolicacids by bioassay experiments. The main results are presented as follows:1. Callus induction and differentiation of pogostemon cablin were studied to eastablish aplant regeneration system for tissue culture. The leaf segments from pogostemon cablinwere cultured in medium. We found out that the optimum medium for inducing the callus,buds, strong sprout, rooting was MS+6-BA(2.0mg·L-1),MS+6-BA (0.1mg·L-1),MS+6-BA(0.1mg· L-1)+NAA(0.05mg·L-1)and1/2MS+IBA(0.2mg·L-1), respectively.2. The growth of tissue culture seedling and domestication seedling of pogostemon cablinwere inhibited with different organs of water extracts of Pogostemon cablin and theinhibition to plant height, root length,plant fresh weight and root fresh weight ofreceptor enhanced with the increased concentrations of water extracts. The water extractof stems or leaves had effect on the antioxidant enzyme system such as POD, CAT, SOD,PAL activity, the MDA content and the H2O2content of the tissue culture seedling withdifferent concentration.Total flavonoids content and total volatile oil content were showeddecreasing change with higher treating solution concentration.3. the root exudates of pogostemon cablin tissue culture seedling inhibits the growth of theirown tissue culture seedling and desmodium styracifolium seedling. On the other hand low concentration of it promotes the growth of radish seedling and high concentration inhibitstheir growth. Plant height, root length, fresh weight and the number of root weresignificantly inhibited after were treated with0.4and1.0g·mL-1water extracts of rootexudates which came from pogostemon cablin continuous cropping soil and the higher theconcentration, the stronger inhibition of growth, with significant concentration effect. Tomention the increase of the concentration, the total flavonoids and total volatile oil contentof tissue culture seedling showed a downward trend.4. Four phenolic compounds content of pogostemon cablin root exudates identified byusing the HPLC method were hydroxybenzoic acid1.524×10-3mg·mL-1, vanillic acid1.783×10-3mg·mL-1,caffeic acid1.113×10-3mg·mL-1, ferulic acid5.772×10-3mg·mL-1respectively. The verification experiment showed that different concentrations of abovefour single phenolic acids and mixed acids had different allelopathic effects on the plantheight, root length, plant fresh weight, root fresh weight, the PAL activity andMDA content of tissue culture seedling. The allelopathic inhibitory effect on Pogostemoncablin tissue culture seedling of the mixed phenolic is stronger than that of foursingle phenolic acids with the same high or moderate treating concentrations, especiallyunder higher treating concentrations,the RI value was showed-1.6391. |
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