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| Research was conducted on Rehmannia glutinosa Libosch., a Chinese traditional medicinal plant, to investigate the effects of UV-irradiation and shade on the concentration of catalpol in seedlings and rhizosphere. The plants were grown under three irradiances: full light, partial shade (50% full light), and UV-irradiation. The R. glutinosa seedlings were harvested and the hydroponic culture solution in the containers was collected on day 3, 6, 9, 12, 15 after treatment respectively for determination of catalpol. The results showed that UV-irradiation increased the concentration of catalpol in leaves rapidly at the early stage, and then, instead of increasing, the concentration of catalpol decreased a little. In contrast, the catalpol content in R. glutinosa leaves was reduced under partial shade. Similar trends were observed in roots and stems of R. glutinosa under UV-irradiation and shade. The concentration of catapol in medium in which full-light, shade and UV-irradiated seedlings were grown all increased with time. But the concentration of catapol in medium of UV-irradiated seedlings was greater than that of full-light seedlings, and the concentration of catapol in medium of shade seedlings is lower. Therefore, UV-irradiation increased both production of catalpol in R. glutinosa seedlings, and secretion of catalpol into R. glutinosa rhizosphere. On the contrary shading decreased not only production of catalpol in R. glutinosa seedlings, but also secretion of catalpol into R. glutinosa rhizosphere. It was also found that UV-irradiation decreased the root vigor and partial shading increased the root vigor of R. glutinosa seedlings. |
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| Keywords:Rehmannia glutinosa; Catalpol; Rhizosphere; Shade; UV-irradiation; Root vigor |
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