The growth, photosynthetic pigments and essential oil composition of monocropped and intercropped lemon balm with yarrow

ABSTRACT. The purpose of this study was to assess the influence of lemon balm intercropping with yarrow on the vegetative growth, photosynthetic pigments and essential oil contents as well as the chemical composition of essential oils. Accordingly, the lemon balm and yarrow monocroppings were compared to the intercropping of both species. The plants were cultivated for 120 days under field conditions. The experimental design followed randomized blocks with seven repetitions. Growth was assessed through the accumulation of shoot dry matter and through the leaf area. The photosynthetic pigment content was set based on the fully expanded leaves from five plants in each treatment. The essential oil was extracted through the hydrodistillation of the lemon balm leaves and yarrow leaflets dehydrated in a forced ventilation oven at 40°C. The chemical analyses of the essential oils were performed using GC-FID and GC-MS. Intercropping showed a reduction of vegetative growth. However, intercropping increased the lemon balm essential oil content. On the other hand, these parameters did not change in yarrow. There were variations in the level of chemical constituents in lemon balm and yarrow essential oils, which were more evident in the major constituents.摘要 本研究旨在评估柠檬香蜂草（lemon balm）与蓍草（yarrow）间作对二者营养生长、光合色素及精油含量，以及精油化学组成的影响。据此，本研究将柠檬香蜂草、蓍草的单作体系与二者的间作体系进行对比。供试植株于大田条件下栽培120天。试验采用随机区组设计，设置7次重复。通过地上部干物质积累量与叶面积两项指标评估植株生长状况。光合色素含量的测定以各处理中5株植株的完全展开叶片为材料。采用水蒸馏法对经40℃鼓风干燥箱脱水后的柠檬香蜂草叶片与蓍草小叶进行精油提取。精油的化学组成分析采用GC-FID与GC-MS完成。结果表明，间作会抑制植株的营养生长，但可提升柠檬香蜂草的精油含量；而就蓍草而言，上述参数未发生显著变化。柠檬香蜂草与蓍草精油的化学成分含量存在差异，且该差异在主要化学成分中更为显著。