IBA生根剂对卡罗来纳杜鹃插条生根的影响

The Influence of IBA Rooting Hormone on the Rooting of Rhododendron carolinianum Rehd.Stem Cuttings

卡罗来纳杜鹃是一种优美的常绿灌木,原产美国东部沿海并能耐-33℃的低温。由于该植物无性繁殖技术困难,限制了其及其栽培变种在园林中的应用。于10月份采集卡罗来纳杜鹃的木质化枝条,在美国缅因大学的植物繁殖温室中进行扦插繁殖。处理后的插穗被随机放在具有恒温（24℃）低温加热的苗床上。结果表明：IBA对卡罗来纳杜鹃木质化插条的生根有显著影响,IBA处理后的插条生根率为25.0%-84.4%,对照没有生根。IBA浓度对插条生根也有显著影响,处理Ⅳ即先快蘸液态KIBA（8 000 mg/L）再迅速蘸取粉状IBA（8 000 mg/L）的插条生根率最高为84.4%;当IBA浓度≤8 000 mg/L时,生根率≤43.8%;液态KIBA 16 000mg/L的浓度太高会使插穗出现烧死现象;当KIBA浓度为200 mg/L和400 mg/L时,浸泡插穗24 h后生根率分别为31.3%和37.5%。IBA的类型及处理浓度对根质量（根体积）有显著影响,混合处理Ⅳ的生根质量最好,体积为38.9 cm^3;KIBA浓度200 mg/L时浸泡24 h后处理的插穗生根体积最小,为12.1 cm^3。生根插穗移入低温储藏8周后,可移栽和培育出圃。

Rhododendron carolinianum Rehd.is a beautiful evergreen shrub.It is native to Eastern US coast and alle to survius at the temperature of-33 ℃.The plant and its cultivars are not common in the landscapes because of their vegetative propagation difficulty.Hardwood cuttings of Carolina rhododendron were collected in October 2006 and treated with IBA powder and potassium salt in the greenhouse of University of Maine.All cuttings were placed randomly under mist benches equipped with 24 ℃ bottom heat.IBA rooting hormones significantly affected rooting of Rhododendron carolinianum hardwood cuttings.Plants with hormone treatment were rooted from 25.0% to 84.4%.No root was observed from cuttings without IBA application.IBA concentration played an important role on the rooting of the cuttings.The highest rooting percentage（84.4%） was obtained from the double-dip treatment of 8 000 mg/L KIBA quick dip,and then of 8 000 mg/L IBA powder.IBA concentrations at 8 000 mg/L or lower resulted 43.8% or lower rooting rates.Liquid 16 000 mg/L KIBA alone was too strong for the plants and stem burn was noted from many dead cuttings.Cuttings soaked for 24 hours at 200 mg/L and 400 mg/L KIBA generated 31.3% and 37.5% of rooting respectively.Root quality,as indicated by root ball volume,was significantly affected by hormone concentrations and application methods.The biggest root ball,38.9 cm^3,was found under double dips of 16 000 mg/L IBA.The treatment with 24-hour soaking at 200 mg/L KIBA yielded the smallest root ball of 12.1 cm^3.Root cuttings were moved to the cooler for 6 weeks and vernalized for the flash growth.