Effect of light spectra on stem cutting rooting and lavender growth

ABSTRACT. French lavender (Lavandula dentata L.) is of great ornamental, medicinal, and aromatic interest. It is generally propagated vegetatively using stem cuttings. When using artificial lighting, a specific light composition can modify the entire plant phenology and is a factor that can be managed in controlled conditions. This study evaluated the rooting of stem cuttings and growth of lavender under four spectral LED lights. The LED lights used were: T0 (white LED, Roblan®), T1 (AP67 Milky, Valoya®), T2 (NS1, Valoya®), and T3 (AP673L Milky, Valoya®). The first phase evaluated the rooting of stem cuttings and initial development. The plants were then transferred to plastic pots to evaluate plant growth. In both rooting and growing phases, the plant morphological characteristics and water and light efficiencies were evaluated. Nutrient-uptake efficiencies were also evaluated after the growing phase. It was observed that cuttings rooted under the influence of T1 showed greater height. After the growing phase, plants under T3 showed better results in electricity use efficiency, water use efficiency, and nutrient-uptake efficiency and less nitrate leaching. They also presented more uniform growth with a compact canopy. Thus, T1 was better for the stem cuttings rooting phase, while T3 was better for growth and energy efficiency.

摘要：齿叶薰衣草（Lavandula dentata L.）具备极高的观赏、药用与芳香价值，通常采用茎插方式进行无性繁殖。在人工光照条件下，特定的光谱组成可调控植株物候，且该参数可在可控环境中进行优化管理。本研究针对四种光谱LED光源下齿叶薰衣草的茎插生根与植株生长情况展开评估，所用LED光源分别为：T0（白色LED，Roblan®品牌）、T1（AP67 Milky，Valoya®品牌）、T2（NS1，Valoya®品牌）以及T3（AP673L Milky，Valoya®品牌）。
实验分为两个阶段：第一阶段评估茎插生根效果与植株初期生长状况；随后将植株移栽至塑料盆中，开展生长阶段的相关评估。在生根与生长两个阶段中，均对植株形态学指标、水分与光能利用效率进行了测定；生长阶段结束后，额外测定了植株的养分吸收效率。
实验结果表明，经T1处理的插穗生根后株高更高。生长阶段结束后，T3处理组的植株在电能利用效率、水分利用效率与养分吸收效率上均表现更优，且硝酸盐淋失量更低，同时植株生长更均匀，冠层更为紧凑。综上，T1光源更适用于齿叶薰衣草的茎插生根阶段，而T3光源则更利于植株生长与能源利用效率提升。