NMPRO Magazine
April 2003 Issue, page 14-15, 71-72
Author: Dr. Michael A. Dirr
NMPRO Article
April 2003 Issue, page 14-15, 71-72
Permission to reprint granted by NMPRO and Dr. Michael A. Dirr
Plant Specialist Section
Evaluation program yields dynamite hydrangea, nandinas
Many of my nursery friends think Im retired and, indeed, there were rumblings about such a move several year past. E-mails and letters often greet me with, I hope yourre enjoying retirement.
Actually, the only real shift has been from teaching/research to a 100-percent research appointment. My energies are largely focused on the plant-improvement programs. About 3,000 plants are in stages of evaluation at the Center for Applied Nursery Research at McCorkle Nurseries in Athens, Ga., and at various other Georgia nurseries.
At the center, about 10,000 seedlings were under evaluation in 2001 and 2002, largely hydrangeas and crape myrtles. Fortunately, a system was devised for evaluation that simplified the process. Each selection is assigned an accession number, which is used to track the plant through the evaluation process. (Out past mistakes with hydrangeas, using textual descriptions, did not do justice.) A single sheet with digital images of flower and leaf characteristics is produced. Data are collected on flower, foliage, habit, diseases (particularly mildew) and other nuances. This allows tracking a seedling selection, such as Preziosa-01-02, that, although spectacular in flower, was ravaged by mildew in October and November 2002. One of the hydrangea breeding goals is mildew resistance, and no matter how great the flower, pronounced mildew susceptibility eliminated the plant from the process.
Sixty-nine seedling selections, largely of Hydrangea macrophylla Veitchii made in 2000 and 2001, were reduced to 10 in summer 2002. A Nov. 11, 2002, evaluation reduced the number to three. This photographic plus textual evaluation process is now applied to all plants in the breeding program.
Batter Up
As few as two seedlings of H. macrophylla Penny Mac and as many as 3,000 of two pink-flowered clones of H. arborescens were on the grounds at the center at one time. The program is prediucated on flexibility and the ability to turn on a dime. Nothing is too far-fetched.
Abundant fruit set in 2000 and 2001 on Nandina domestica Harbour Dwarf and Gulf Stream on the University of Georgia campus plantings prompted us to ask, What if? What were the chances of developing cultivars with qualities surpassing those of either Harbour Dwarf or Gulf Stream? By August 2002, several compact and/or colorful foliage seedlings (one from Harbour Dwarf and six from Gulf Stream) were targeted for systematic evaluation.
Visions of potential introductions dance through my head every time I see a fruit-laden specimen of this species which, in all honesty, could use some improvement. Our work is paying dividends and will continue to do so for the nursery industry.
The pipeline is full to the point of exploding, with the greenhouses chocker-block burgeoning with seedlings from controlled and open-pollinated crosses.
Here come Hydrangeas
Two of the promising future introductions include Lady in Red ( a seedling of H. macrophylla Otaksa) and Mini-Penny, also known as Half-a-Penny is a true remntant, reflowering taxon.
Lady in Red appeared on the radar screen because of its beautiful reddish-purple fall color. Further, it was one of the only two Otaksa seedlings (out of 265) that has no mildew.
The original 3-year-old Lady in Red, now in a 10-gallon container, remains quite compact, measuring 23 inches high and 43 inches wide. Propagules have grown faster and a 2-year-old plant in a 3-gallon container is 24 inches tall by 40 inches wide.
The sum of the parts is greater than the whole because no single characteristic elevates this selection above the rest. The 4.9-inch-long, 2.6-inch-wide, dark-green leaves turn a beautiful reddish purple in fall. The high degree of mildew resistance is consistent across plants growing at four locations.
The pinkish-white lacecap flowers turn burgundy rose with maturity. Although unspectacular compaed to the large mopheads, the flowers are colorful from late May to September/October. The most unique aesthetic quality is the colorful polished reddish-purple stems, petiols and veins (lower leaf surface0. From leaf emergence in April to October/November, the colors are rickly preserved. Faculty colleague Hazel Wetzstein, who is using the tissue culture to increase numbers of the potential introductions, said Lady in Red was gorgeous when she first saw it.
More microphyllas
Another H. macrophylla selection, which we call Penny Mac-01-02, shows great garden promise because of its compact habit, excellent foliage and remontant flowering. Our previous work showed that with H. macrophylla, the maternal parent exerts pronounced influence on the offspring. In essence, the seedlings carry many of the traits common to the mother seed parent.
Previous work with open-pollinated Endless Summer to produce remontant seedling populations met with failure. Although seeds germinated, seedlings were weak and died.
In 2001, two seedlings of Penny Mac germinated and flowered in 2002. Both produced pink mophead flowers, one with 49 inflorescences (Penny Mac-02-02), the other with 33 inflorescences (Penny Mac-01-02). The most obvious differences were in growth habit and foliage, with Penny Mac-01-02 clearly superior.
The true test of the plants net worth was in their ability to reflower, like the maternal parent. All inflorescences were removed on June 25, 2002, with no visible flower buds or fully expressed inflorescences or Penny Mac-02-02 on Nov. 4,2002.
However, Penny Mac-01-02 had 35 developed flower buds and inflorescences. The parent plant, now 2 years old, is 16 inches high and 36 inches wide. Each lustrous, dark green laef is 5.5 inches long and 3 inches wide and mildew resistant. Forty flower buds were present on the lower stems, nestled in the crown of the plant on Nov. 14, 2002.
Im anxious to learn if these buds will develop into full-blown inflorescences if the plant is injured by cold in its upper reaches. The plant almost looks too good to be true.
One of the great benefits of CANR is the open house, where nurserymen are able to provide their insights relative to the plant breeding and introduction activities. Also, many visitors come to the center throughout the year.
The greatest feedback I receive has nothing to do with statistically generated data. When the word wow is applied to a seedling selection, then theres some commercial worth there.
Lady in Red and Penny Mac-01-02 are definitely wow plants!
Caption: Genera being evaluated for improvement
Abelia
Buddleia
Camellia
Ceanothus
Cephalotaxus
Chamaecyparis
Clethra
Cleyera
Fothergilla
Hibiscus
Hydrangea
Hypericum
Koelreuteria
Lagerstroemia
Magnolia
Nandina
Nerium
Photinia
Rhaphiolepis
Sarcococca
Spiraea
Viburnum
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