施用沼液和接种丛枝菌根真菌对甘草生长及重金属累积的影响

甘草(Glycyrrhiza uralensis Fisch)是一种重要的补益中草药。由于野生甘草面临过度采撷和资源耗竭,人工种植甘草规模日益扩大,发展低耗高效的甘草种植技术成为迫切需要。通过盆栽试验考查了不同沼液添加水平(沼液/去离子水体积比:10/0、9/1、5/5、1/9及0/10)下,接种丛枝菌根(arbuscular mycorrhiza,AM)真菌Rhizophagus intraradices对甘草生长及重金属累积的影响。试验结果表明,AM真菌能够对甘草根系形成良好侵染,菌根侵染率在25.0%~48.4%之间。AM真菌对甘草表现出显著促生作用,接种处理使植株生物量、磷浓度及叶片叶绿素含量分别提高了171%~271%、64%~143%和98%~127%。施用沼液显著提高了植株磷浓度和叶片叶绿素含量,在提高土壤有机质含量和土壤全磷的同时,也增加了植物及土壤铬、铜和铅浓度。在沼液稀释比为10/0和9/1水平下,植物铬、铜和铅浓度超标,而接种AM真菌显著降低了植株重金属浓度至安全阈值以内。施用沼液同时接种AM真菌可在促进甘草生长的同时保障甘草品质,因而在甘草人工种植中具有潜在应用价值。

Effects of biogas slurry and AM fungi on growth and heavy metal accumulation of licorice plants

Licorice(Glycyrrhiza uralensis Fisch) is a widely used Chinese medicinal herb. Due to irrational exploration of wild plants, intensive cultivation of licorice plants becomes a popular practice, and technological development for promoting plant growth and ensuring product safety becomes an urgent need. In the present study, a pot experiment was conducted to investigate the growth promoting effects of biogas slurry and arbuscular mycorrhizal(AM) fungi on licorice plants. Biogas slurry was applied at different dilution rates(biogas slurry/deionized water, v/v=10/0, 9/1, 5/5, 1/9, 0/10), while licorice plants were inoculated with/without AM fungus Rhizophagus intraradices at each biogas slurry application rate. The experimental results indicated that licorice roots could be well colonized by R. intraradices with mycorrhizal colonization percentages ranging from 25.0% to 48.4% which decreased with increasing biogas slurry concentrations. Mycorrhizal inoculation significantly increased plant biomass(by 171%~271%), P concentration(by 64%~143%) and leaf chlorophyll content(by 98%~127%). On the other hand, application of biogas slurry also noticeably increased root P concentration, leaf chlorophyll content, soil organic matter and P contents; but increased plant and soil heavy metal concentrations. Under biogas slurry dilution rate of 10/0 and 9/1, Cr, Cu and Pb concentrations in plants exceeded safety limit, while mycorrhizal inoculation significantly decreased plant Cr, Cu and Pb concentrations to meet the quality standard of herbal medicine. The study provided solid evidence for the growth promoting effect of biogas slurry in combination with AM fungi on licorice plants, and supported their potential use in intensive cultivation of this medicinal plants.