刈割对五节芒化感作用及次生代谢物质的影响

本文研究了刈割后五节芒(Miscanthus floridulus)叶、茎、根和根际土浸提液对生菜(Lactuca sativa)化感作用的影响,并运用气相色谱-质谱(GC-MS)联用技术鉴定刈割与未刈割之间五节芒叶片中次生代谢物质的差异。结果表明,不同浓度浸提液对生菜种子萌发、胚根长、子叶长、子叶宽、鲜重影响差异较大,其中五节芒叶片浸提液显著抑制生菜胚根的生长,刈割后五节芒化感效应指数比未刈割增加2~8倍;次生代谢物质组分分离后,发现抑制生菜生长的次生代谢物质主要是有机酸类物质;GC-MS总离子流图显示刈割组波峰数量明显增多,并且各峰峰度最大值高于对照1.35~5.15倍,说明刈割后五节芒叶片中次生代谢物质种类及其含量明显增加。刈割后五节芒叶片新出现3种次生代谢物质,多种次生代谢物质的相对含量明显增加,其中植物竞争类次生代谢物质(棕榈酸、亚油酸、豆甾醇)和抑制天敌次生代谢物质(反-乌头酸)相对含量增幅较大,这些次生代谢物质可能是五节芒应对刈割胁迫的化学防御物质。

Effects of Mowing on Miscanthus Floridulus Allelopathy and Secondary Metabolites

Allelopathy effects of aqueous extracted from leaves, stems, roots and rhizosphere soil of mowed Miscanthus floridulus on Lactuca sativa was investigated, secondary metabolites in mowed leaves were isolated and identified by gas chromatography mass spectrometry (GC-MS). The results showed that different aqueous extracts had different effects on the seed germination, radicle length, leaf length, leaf breadth and fresh biomass of Lactuca sativa. The aqueous extracts from leaves significantly decreased the radicle length of L. sativa. Allelopathic effect index of mowed M. floridulus increased 2~8 times than non-mowed ones. Main allelochemicals which inhibited the growth of L. sativa were organic acids. The GC-MS spectrum displayed that mowed group significantly increased the number of peaks, the maximum value of each peak was 1.35~5.15 times higher than the control. The relative contents of some secondary metabolism substances increased significantly in M. Floridulus leaves after mowed. Three new secondary metabolism substances appeared in the leaves of mowed M. floridulus. The allelochemicals relative contents of inhibiting other plants (palmitic acid, linoleic acid, stigmasterol) and natural enemies (trans-aconitic acid) had higher increase than other allelochemicals, so these secondary metabolism substances in M. Floridulus leaves may play a key role on inhibiting the growth of the L. sativa.