Productive, metabolic and anatomical parameters of menthol mint are influenced by light intensity

Abstract The cultivation of aromatic species to obtain essential oils has great economic importance, presenting an increasing demand from different industrial sectors, especially to menthol mint (Mentha arvensis L.) essential oil, rich in menthol (70-80%). Consortium cultivation has been an important practice in agricultural systems whose land use is necessary, consequently promoting strong competition for light in reduced space. Thus, this study aimed verifying if different light intensities might promote chemical, metabolical and anatomical alterations in menthol mint. Plants were grown in greenhouse at different average of light intensities (137, 254, 406 and 543 µmol photons m2 s1). Samples were collected 43 days after germination and submitted to following analyses: Gravimetric test, photosynthetic pigments, soluble fractions, enzymatic activity, N-total, trichome density and histochemistry and chemometric test based on essential oil chemical profile. Fresh mass gain, trichome density, essential oil content and soluble sugars were positively influenced by light intensity increase. On the other hand, total-N, NO3−-N and pigments content have decreased influenced by light intensity increase. In the secretion from the trichomes, phenolic substances were reported, as well as lipophilic ones in the peltate ones. The increase of oxygenated monoterpenes was favored by light intensity decrease.

摘要 种植芳香植物以提取精油具备重要经济价值，不同工业部门的需求持续增长，其中以薄荷醇含量达70%~80%的野薄荷（Mentha arvensis L.）精油需求尤为突出。复合种植是土地资源受限背景下农业生产的重要模式，会在有限空间内引发激烈的光照竞争。据此，本研究旨在验证不同光照强度是否会对野薄荷产生化学、代谢及解剖结构层面的影响。本试验于温室中开展，设置4组平均光照强度梯度（137、254、406及543 μmol光子·m⁻²·s⁻¹）培育植株，播种43天后采集样品并开展如下分析：重量检测、光合色素测定、可溶性组分分析、酶活性检测、全氮含量测定、腺毛（trichome）密度及组织化学分析，以及基于精油化学特征的化学计量学分析。结果表明，鲜重累积量、腺毛密度、精油含量及可溶性糖含量均随光照强度提升呈正向响应；与之相反，全氮、硝态氮（NO₃⁻-N）及光合色素的含量则随光照强度升高而降低。组织化学分析显示，腺毛分泌物中含有酚类物质，盾状腺毛（peltate trichome）中还存在脂溶性成分；光照强度降低可显著促进含氧单萜（oxygenated monoterpenes）类物质的合成与累积。