Deep planting improved stem root growth, flower yield and quality of Lilium cultivars

ABSTRACT Lily species are considered one of the most important cut flowers worldwide. With annual production of 282 million flowers and total value of $200 million, lily is among the top five cut flower species auctioned in the international flower stock markets. The objective of this study was to assess the effect of different planting depths on morphology, physiology, root growth and flower quality of lilies. Three hybrid lilies [Lilium × elegans; Orienpet (‘Maytime’, white) and L.A. (‘Fangio’, pink and ‘Pavia’, yellow)] were used. Deep planting at 25 cm significantly improved total and stem root systems, stem diameter and leaf area. No significant differences were noticed between planting depths for plant height, chlorophyll content, and gas exchange (photosynthesis, stomatal conductance and transpiration). Flower quality variables, specifically, vase life from deep planting were higher in 25-cm compared to 5 and 15. The ‘Maytime’ cultivar had higher leaf area, total and stem roots, flower diameter, number of days to flowering, and brighter color (L*) while the ‘Fangio’ had higher leaf number per plant, more basal roots, flower number per plant, vase life, and red color coordinate (a*). Overall, our results revealed that lily growers can increase their lily flower quality by adopting the deep planting at 25 cm.摘要：百合属（Lilium）物种是全球最重要的切花品类之一。其年切花产量达2.82亿枝，总产值达2亿美元，是国际花卉拍卖市场交易量排名前五的切花物种。本研究旨在探究不同种植深度对百合形态、生理特性、根系生长及切花品质的影响。试验选用3个百合杂交品种：杂交百合（Lilium × elegans）、东方喇叭百合杂交系（Orienpet）品种‘Maytime’（花白色），以及L.A.杂交系品种‘Fangio’（花粉色）与‘Pavia’（花黄色）。25 cm深植处理可显著提升百合的总根系与茎生根量、茎秆直径及叶面积。不同种植深度对百合株高、叶绿素含量及气体交换参数（光合速率、气孔导度与蒸腾速率）无显著影响。在切花品质指标中，25 cm深植处理的瓶插寿命显著优于5 cm与15 cm处理组。‘Maytime’品种的叶面积、总根系与茎生根量、花径、开花天数及明度值（L*）均更高；而‘Fangio’品种的单株叶数、基生根量、单株花数、瓶插寿命及红色坐标值（a*）更优。综上，本研究结果表明，百合种植者采用25 cm的深植方式可有效提升百合切花品质。