PROBLEMS AND INVESTIGATIONS ON INDOOR AZALEAS RHODODENDRON SIMSII

J. HEURSEL
The story that started less than two centuries ago, when a few wild Rhododendrons imported from China and Japan were crossed, has now developed into a big industry which in Western Europe alone today produces not less than 100 million azaleas. Belgium's share is 52 and Germany's share is 38 million. The Netherlands produce some 7 million azaleas per year, and France, Denmark and Switzerland produce the rest. The oldest cultivars were purple, carmine red, red or white with stripes or flecks. The flowers were single and bloomed hardly a week; now they are double and bloom almost three weeks. The colour assortment itself has not fundamentally changed. The blooming period which originally was around Eastern has step by step moved up. One century ago, 'Madame Petrick' came on the market with a blooming time around Christmas. Since 1967, the blooming time has again changed, and it is now around August 15.

Growing too has considerably improved. One full-time labour unit today handles ten times as many azaleas as one century ago. The production speed has doubled so that in fact the multiplication factor is twenty. All this was possible because breeders developed cultivars with an ever accelerated growth vigor. In addition, scientific research contributed to optimal fertilisation. Accelerated growth was kept under control though by growth regulators, so that the shape of the plants could be preserved in accordance with consumer demands. Potted production helped to save enormous labour costs. Production is largely mechanised. Chemical pinching and chemical weed controls have also considerably cut the labour input.

Until 30 years ago, breeding was exclusively empirical. As scientific research managed to trace the inheritance of the flower colours, breeding for a specific colour is now much more productive. The same applies to the size of flowers and their form. This fundamental work in the first place provides the information breeders need for their future investigations.

We are convinced that progress will continue to be enormous in the next years. The door to progress will indeed be kept open by biotechnology, the various species within the Tsutsusi subgenus which have not yet been used, and new developments in the area of ecophysiology.

HEURSEL, J. (1994). PROBLEMS AND INVESTIGATIONS ON INDOOR AZALEAS RHODODENDRON SIMSII. Acta Hortic. 364, 111-118
DOI: 10.17660/ActaHortic.1994.364.13
https://doi.org/10.17660/ActaHortic.1994.364.13
flower colours and shape, breeding, Rhododendron noriakianum, growth regulators, mechanisation
English

Acta Horticulturae