Light intensities alter growth and essential oil of patchouli under shade nets

ABSTRACT: Pogostemon cablin (Blanco) Benth. is an aromatic species popularly known as patchouli. The essential oil rich in patchoulol extracted from leaves is used by the pharmaceutical industries. The objective was to investigate the effects of shade nets and shading intensities on P. cablin growth, anatomy, chemical composition and essential oil content. The experiment was conducted with two types of shade nets (black and Aluminet), three light intensities (30, 50, and 70% shading) and full sun. The different light intensities influenced the growth and the essential oil yield, and chemical composition. Patchouli plants grown in an environment with shading showed higher values for the leaf, stem, root ant total dry weights compared to full sun. At 50% of shading, Aluminet provided gain in stem and total dry weights. Aluminet and black net at 50 and 70% of shading enhance essential oil yield. Patchoulol and pogostol contents were higher under full sun, and, black net and Aluminet at 50% shading. The environment for patchouli cultivation can be improved by use shade nets, especially with Aluminet at 50% of shading.摘要：广藿香（Pogostemon cablin (Blanco) Benth.）是一种芳香植物，俗称patchouli。从其叶片中提取的富含广藿香醇（patchoulol）的精油可应用于制药工业。本研究旨在探究遮阳网与遮光强度对广藿香生长、解剖结构、化学成分及精油含量的影响。试验设置两种遮阳网类型（黑色遮阳网与铝箔遮阳网（Aluminet））、三种遮光强度（30%、50%、70%遮光）及全光照对照。结果显示，不同光照强度对广藿香的生长、精油产量及化学成分均存在显著影响。相较于全光照处理，遮光环境下栽培的广藿香叶片、茎秆、根系及总干重均更高。在50%遮光条件下，铝箔遮阳网可提升广藿香的茎干干重与总干重。50%与70%遮光条件下，铝箔遮阳网与黑色遮阳网均能提高精油产量。全光照、50%遮光的黑色遮阳网及铝箔遮阳网处理下，广藿香醇与广藿香二醇（pogostol）的含量更高。综上，使用遮阳网可优化广藿香的栽培环境，其中以50%遮光的铝箔遮阳网效果最优。