Magnolia Cultivation, Propagation, Breeding and the Gardens Growing Them In Europe

摘要

For more than 300 years, magnolias have been cultivated in the United Kingdom with Magnolia virginiana being the first in 1687. North American, then Asian species (from 1789) have been grown extensively primarily from the subgenus Yulania however in recent times greater interest and awareness of Asiatic evergreen species from the genus formerly known as Michelia have been introduced into gardens predominantly in the south-west of England. Magnolias have been cultivated in mainland Europe and Ireland for a similar period of time however this is shorter in Sweden. The author will discuss the collections, climatic conditions and soils found in the following gardens as well as their landscape value and potential: The Royal Horticultural Society's Garden, Wisley (in south-east England), Caerhays Castle, Cornwall (south-west England) Mount Congreve, Waterford (southern Ireland), Herkenrode and Arboretum Wespelaar (Belgium), the gardens of the southern alpine lakes (Lake Maggiore, Italy and Switzerland) and the gardens of southern Sweden. With the exception of Magnolia x soulangeana, comparatively little breeding work has taken place in more recent times, instead relying on chance seedlings to be used in gardens along side those introductions predominantly from North America and New Zealand. However many of these seedlings have been widely planted. Magnolia campbellii, Magnolia campbellii subsp. mollicomata, Magnolia sargentiana var. robusta and Magnolia sprengeri 'Diva' in particular have produced hybrids of note however Magnolia x loebneri 'Leonard Messel' has proved to be one of the most successful introductions world wide. In addition,the Indian geneticist Dr. E. K. Janaki Ammal, while working at Wisley in the 1950's, carried out breeding work using colchicine on Magnolia kobus seedlings. Commercial Nurseries in the UK and Europe are raising magnolias using a number of techniques. Seed has been germinated in small quantities for garden use however Magnolia kobus, Magnolia campbellii subsp. mollicomata and Magnolia sprengeri have been used for the production of rootstocks. Bench grafting and budding techniques are used as are cuttings (both softwood/greenwood and semi-ripe ) under glass being the most used procedures.