A seedling of [('Voluptuous' x 'Point Defiance') #1] x ('Gold Medal' x 'Bud's Yellow'), which is a Werner Brack hybrid, has been determined to be a diploid using flow cytometry by
Dr. João Loureiro, Dr. Silvia Castro, José Cerca, and Mariana Castro
Plant Ecology and Evolution Group,
Centre for Functional Ecology,
Department of Life Sciences,
Faculty of Science and Technology,
University of Coimbra, Portugal.
Three seedlings were ploidy tested from the Brack cross of 'Voluptuous' x 'Point Defiance'. 'Orange Leopard' and 'Stony Brook' tested as diploid. An unnamed seedling tested as triploid. This indicates that the offspring of a given cross can have different ploidy levels from one offspring to another.
The cross 'Voluptuous' x 'Point Defiance' and the cross [('Voluptuous' x 'Point Defiance') #1] x ('Gold Medal' x 'Bud's Yellow') producing diploid seedlings indicates that descendants of tetraploids can be diploids. 'Point Defiance' is a tetraploid.
When used as a seed parent, 'Horizon Monarch', which tested as a tetraploid using flow cytometry, has produced diploid as a well as tetraploid offspring.
Rhododendron 'Marinus Koster', which was determined to be a tetraploid, is the seed parent of the diploid 'Rendezvous'.
Summary of Ploidy Levels
Diploid 'Orange Leopard',
Diploid 'Rendezvous',
Diploid 'Stony Brook',
Diploid 'Voluptuous',
Diploid [('Voluptuous' x 'Point Defiance') #1] X ('Gold Medal' x 'Bud's Yellow'),
Diploid 3 Seedlings of 'Horizon Monarch' open pollinated,
Triploid Seedling of 'Voluptuous' x 'Point Defiance',
Tetraploid 'Horizon Monarch',
Tetraploid 'Marinus Koster',
Tetraploid 'Point Defiance',
Tetraploid 1 Seedlings of 'Horizon Monarch' open pollinated
Source: Werner Brack
John and Sally Perkins
