地黄根系分泌物化感效应与酚酸类物质的关系研究

Correlation of Allelopathy of Rehmannia glutinosa Root Exudates and Their Phenolic Acids Contents

目的：通过研究不同生育时期地黄根系分泌物化感潜力和酚酸类物质含量动态变化,揭示酚酸类物质与地黄化感效应之间的关系。方法：利用新型根系分泌物收集装置,收集地黄不同生育时期根系分泌物,采用HPLC分析5种酚酸（香豆酸、对羟基苯甲酸、香草酸、丁香酸、阿魏酸）含量变化并通过生物测试（萝卜种子发芽试验）评价其化感潜力,分析根系分泌物化感效应与5种酚酸含量的相关性。结果：地黄不同生育时期根系分泌物浸种后萝卜种子发芽率为97.89%、92.38%、89.52%、85.71%、85.71%、84.76%和83.81%,随生育期推进呈逐渐降低趋势,其中从块根膨大前期开始与对照表现出显著差异;芽长为5.68、5.76、5.91、5.65、5.41、5.28和5.11 cm,呈先升高后降低的趋势,同样从块根膨大前期开始与对照相比差异达到显著水平。HPLC检测地黄不同生育时期根系分泌物均发现了5种酚酸,但其含量未呈现与根系分泌物化感作用相似的变化规律,对两者相关性分析发现,除丁香酸与发芽长度呈显著负相关外（r=-0.833,P〈0.05）,其他酚酸含量均未与萝卜种子发芽率和芽长表现出显著相关性（r=-0.666-0.590）。结论：地黄于块根膨大前期开始表现出显著化感作用,且化感作用随生育期的推进逐渐增强。丁香酸可能是引起地黄化感效应的主导物质。

Objective： To study the allelopathic potential of Rehmannia glutinosa root exudates in different growth stages and dynamic change of phenolic acids contents,in order to reveal the correlation between phenolic acids and allelopathy effect of Rehmannia glutinosa. Methods： Root exudates of Rehmannia glutinosa in different growth stages were obtained by a new instrument which was used to collect the root exudates of xerophytes. After that,bioassay was applied to estimate allelopathy effect of the root exudates. HPLC was used to determine the contents of five phenolic acids（ coumaric acid,4-hydroxybenzoic acid,vanillic acid,syringic acid and ferulic acid） which were reported to relate to allelopathy effect. Correlation of bioassay data and HPLC data were also analyzed. Results： The germination rate of radish after soaking by root exudates of different growth stages of Rehmannia glutinosa was 97. 89%,92. 38%,89. 52%,85. 71%,85. 71%,84. 76% and 83. 81%,respectively,which indicated a decline trend. And significant differences were shown from previous enlargement stage compared with the contrast. The bud length after soaking by root exudates was 5. 68,5. 76,5. 91,5. 65,5. 41,5. 28 and 5. 11 cm,separately,which increased slightly before decreasing gradually. Previous enlargement stage was also the initial period when significant differences were shown. Five phenolic acids were detected in root exudates by HPLC,while the change of their contents and the allelopathy effect of root exudates did not perform a similar trend. Correlation analysis indicated the five phenolic acids did not have significant relevance（ r =- 0. 666 ~ 0. 590） with germination rate and bud length of radish except the negative correlation（ r =- 0. 833,P〈0. 05） of syringic acid and bud length. Conclusion： Significant allelopathy effect of Rehmannia glutinosa is performed from previous enlargement stage and enhanced with its growth. Syringic acid is a probable dominant allelochemical of Rehmannia glutinosa.