JARS v42n1 - Propagation By Cuttings Of Evergreen Rhododendrons At Pruhonice

Propagation By Cuttings Of Evergreen Rhododendrons At Pruhonice
Karel Hieke
The Institute of Ornamental Gardening
Pruhonice, Czechoslovakia

Comparative trials of propagation by cuttings using 299 evergreen, large-flowered European rhododendron cultivars was carried out at the Research and Breeding Institute of Ornamental Gardening, Pruhonice, during the period from 1977 to 1983. Each cultivar was tested by taking 180 cuttings. Although the trials ran for six years, each cultivar was tested only for two years during that time. Cuttings were taken for rooting at the beginning of November and tested until the end of March each year.

Besides unstimulated control cuttings, additional cuttings of each cultivar were treated with 4% indolyl butyric acid + 1 % nicotinic acid/talc + orthocid/ and others were treated with a stronger combination of 8% indolyl butyric acid + 2% nicotinic acid/talc, both in dust form.

A long cut with a lateral incision was made on each cutting. Trimmed, treated and untreated cuttings were placed in propagation benches and rooting cases under polythene. The propagation substrate was a mixture of peat and sand (1:1). Substrate temperature was about 16 degrees C. The cuttings were lifted and planted out the end of March.

Out of the total of 299 cultivars (European assortment), 70-100% of cuttings rooted in 49 cultivars:

Pink flowers —
'Duchess of Teck'
'Kate Waterer'
'Lady Clementine Mitford'
'Madame Jules Porgès'
'Mrs. R. S. Holford'
'Rose Marie'
'Roseum Superbum'
'Sir Henry Havelock'
'Von Oheimb-Woislowitz'

White or whitish flowers —
'Catawbiense Album'
'Cunningham's White'
'George Cunningham'
'Gloire de Gandavensis'
'Gomer Waterer'
'Hermann Nitzschner'
'Madame Masson'
'Mrs. Anthony Waterer'
'Snow Queen'

Red to rosy red —
'Antonin Dvořák'
'China Boy'
'Don Juan'
'El Alamein'
'F. D. Godman'
'Frederick Waterer'
'Kluis Sensation'
'Marie Forte'

Lilac, blue to purple —
'Catawbiense Grandiflorum'
'Fastuosum Flore Pleno'
'Ponticum Imbricatum'
'Ponticum Variegatum'
'Violett Blau'

Rosy Lilac —
'Ponticum Roseum'
'Roseum Elegans'

Yellowish to creamy —
'Mrs. Betty Robertson'

Dark Violet —
'Lee's Dark Purple'

The best percentage of rooting took place with the cuttings that received the 8% indolyl butyric acid + 2% nicotinic acid treatment. We were able to conclude that certain rhododendrons rooted much more easily than others. We considered the ones that rooted at 70% or better to be very good. All the cultivars mentioned are growing at Pruhonice.

8% Indolyl Butyric Acid
+ 2% Nicotinic Acid
'Delta' — 8% Indolyl Butyric Acid + 2% Nicotinic Acid
Photo by H. Atanasova
4% Indolyl Butyric Acid
+ 2% Nicotinic Acid
'Delta' — 4% Indolyl Butyric Acid + 2% Nicotinic Acid
Photo by H. Atanasova
Unstimulated Control
'Delta' — Unstimulated Control
Photo by H. Atanasova

The Institute of Ornamental Gardening, Pruhonice, Czechoslovakia
Horticultural tradition in Pruhonice started 100 years ago when the founder of the local park, Earl A.E.S. Tarouca came to Pruhonice. The park with its grand conception of natural and landscape architecture and its quantity of woody plants of foreign origin became an important center of garden architecture and dendrology.

Czechoslovak state bought the property in Pruhonice in 1927 and the foundations of horticultural research were laid there. Up to 1951, research work in the field of fruit and vegetable growing and ornamental gardening was carried out here.

Since 1951, Pruhonice has become the seat of the Research Institute of Ornamental Gardening the aim of which has since the beginning been research work in the field of ornamental plants' problems as well as their application both in interiors and landscape architectonical forming of the environment.

The Institute administered the park in Pruhonice till 1962. Then the park was transferred to the administration of The Czechoslovak Academy of Sciences with the purpose to found a Botanical Garden there.

Since 1976, the basic research department for garden architecture and dendrology has been under construction. The aim and purpose of this department is the evaluation and testing of assortments of ornamental woody plants, concentrated in units of identical character.

The 1984 mean annual temperature at Pruhonice was 8° C - 2° C. Mean annual rainfall for 1984 was 513.2 mm.

Reprinted from the Index Seminum Et Plantarum 35, Institute of Ornamental Horticulture, Pruhonice, 1986.