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Horticulture Digest

Date Last Edited:  08/24/2001

Hawaii Cooperative Extension Service

Horticulture Digest #108

Dendrobium Manoa Beauty 'K404-2', a Dendrobium phalaenopsis-type tetraploid hybrid with attractive red-purple flowers, has proved to be an excellent breeding plant. It was crossed to amphidiploid D. Jaquelyn Thomas 'K333-22-4N' to produce uniform offspring (K1121) with red-purple flowers on relatively short pseudobulbs, and to amphidiploid D. Mini Gem 'K780-21 ' to produce floriferous short-statured offspring (K1419). The former hybrid was registered with the Royal Horticultural Society as D. Miyoko Azuma and the latter as D. Sharon Sewake. Both are being released for commercial cropping as seed-propagated potted plant cultivars.

The cross between tetraploid D. Manoa Beauty 'K404-2' and amphidiploid D. Jaquelyn Thomas 'K333-22-4N' was first made on December 15,1985 bearing the cross number K1121. Because of the excellent performance of this hybrid, the cross was repeated on November 9, 1991 and given a new number, K1465, germinated in March 1992, compotted in November, 1992, moved into 2-inch pots in March 1993, repotted into 6-inch shallow plastic pots with No. 3 crushed rock in June 1994, and grown under 45% saran shade. Offspring began to flower in June 1994. Monthly flower data were accumulated until the termination of evaluation on January 31, 1996.

The characteristics of D. Miyoko Azuma are:

Flower color (RHSCC)                             Red-purple (71A)
Flower length (in.)                               2.2 +/- 0.2
Flower width (in.)                                2.6 +/- 0.2
Scape length (in.)                                6.1 +/- 1.3
Spray length (in.)                               16.3 +/- 3.7
No. flowers per spray                            11.3 +/- 5.6
Leaf length (in.)                                 5.3 +/- 0.5
Leaf width (in.)                                  1.9 +/- 0.2
Pseudobulb height at first flower (in.)           9.4 +/- 2.6
Pseudobulb height at end of evaluation (in.)     18.2 +/- 4.7
Percent bud drop                                  5.5
Half-life of sprays on plant (days)              66.3 +/- 16.5

The attributes of D. Miyoko Azuma are:

  • attractive, velvety, dark red-purple flowers inherited primarily from D. Manoa Beauty
  • favorable seasonality, peaking from October to March
  • exceptional long half-life of flowers on plants of about 66 days, and
  • relatively short stature for a PPPC-type hybrid.
The half-life of sprays is the number of days it takes for half of the flowers on the spray to wilt or drop.

As mentioned earlier, D. Manoa Beauty is a D. phalaenopsis-type tetraploid hybrid with essentially four sets of the Phalaenanthe or P genome. D. discolor from the Ceratobium (Spatulata) section has entered the pedigree several generations earlier, and therefore the C genome has been greatly diluted and its influence hardly recognizable in D. Manoa Beauty. The amphidiploid D. Jaquelyn Thomas, on the other hand, represents a primary hybrid that was selected for its short stature and subsequently doubled in chromosome number with colchicine in tissue culture to give a PPCC genome constitution. The amphidiploid transmitted the relatively short stature to D. Miyoko Azuma.

D. Miyoko Azuma has been released through dendrobium growers' associations as UH1121.

H. Kamemoto, haruyuki@hawaii.edu
A. R. Kuehnle, heidi@hawaii.edu
T. D. Amore, and N. C. Sugii

Department of Horticulture, CTAHR
University of Hawaii at Manoa

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