Biomass production and essential oil of lemon balm cultivated under colored screens and nitrogen

ABSTRACT The aim of this study was to evaluate the effect of light quality and nitrogen availability on the biomass production, yield and composition of essential oil of lemon balm (Lippia alba). Five doses of N (0; 40; 80; 120 and 160 kg ha-1) were studied, using urea and three light quality conditions obtained with the use of colored shading nets (blue and red), 50% irradiance and under full sun. The experiment was arranged in a 5x3 factorial scheme, in split plots, with seven replicates. After 60 days of cultivation under the shading nets, a higher dry leaf biomass (4.83 g per plant) was observed in the plants under blue net cultivation at a dose of 102 kg ha-1 of N. The plants grown under full sun presented greater amount of neral and geranial, major components of the essential oil of the lemon balm, which give commercial value to the species. The use of colored shading nets does not influence the composition of the essential oil of lemon balm, but increases the concentration of the compounds found in it. Nitrogen does not affect the quality of the essential oil of lemon balm, but it provides higher oil yield (0.27 g per plant) at the dose of 65 kg ha-1 of N.

摘要 本研究旨在探究光质与供氮水平对柠檬香蜂草（Lippia alba）的生物量积累、产量及精油组分的影响。实验设置5个施氮水平（0、40、80、120、160 kg·hm⁻²），以尿素为氮源；同时设置3种光质处理：分别通过蓝色、红色遮光网实现的50%光照强度处理，以及全光照对照。本实验采用5×3裂区因子设计，设置7次生物学重复。遮光网覆盖栽培60天后，施氮量为102 kg·hm⁻²的蓝色遮光网处理组植株的单株干叶生物量最高，达4.83 g。全光照处理的植株精油中柠檬醛（neral）与香叶醛（geranial）的含量更高，这两种物质是该物种精油的主要活性成分，赋予其商业应用价值。有色遮光网的使用虽未改变柠檬香蜂草精油的组分构成，但可提升精油内化合物的总浓度。施氮水平不会影响柠檬香蜂草精油的品质，但当施氮量为65 kg·hm⁻²时，单株精油产量达到峰值，为0.27 g。