Every gardener dreams of producing a wonderful new plant.
A few get the job done. Luther Burbank, helped only by a discerning eye, created bigger, better, more fruitful, and more beautiful varieties of almost every plant he worked with.
Successful Hybridization
Take the work on lupines begun by James Kclway at the turn of the 20th century. He successfully crossed the North American Lupinus polyphyllus with the European tree lupine.
These creamy flowered hybrids were grown for several years, and in 1912, a rose color break appeared spontaneously. G. R. Downer and John Harkness, famous English plant breeders.
They went to work and produced a range of colors from amber, orange, copper, and salmon shades to reds and roses.
Finally, the now-famous but then-unknown George Russell began to select for massive, dense spikes and produced the magnificent Russell strain of garden lupines.
Imagine the consternation when this unknown gardener strolled into the Royal Horticultural Society offices in Vincent Square with lupine specimens of unbelievable beauty.
What Famous Plant Breeders Know
What did these famous plant breeders know that we don’t know? Were they the forerunners of the latter-day plant geneticists? Not exactly.
They were men with open eyes who could see minute differences in a crop of seedlings.
They were men with the patience to cross-pollinate their best specimens carefully and wait for a new crop to produce.
They were ruthless men, willing to destroy thousands of seedlings to keep only the best.
They were not scientists in the laboratory sense of the word— they were just skilled gardeners.
Basic Botany Of The Flower
Knowledge of basic botany is a great aid to the would-be plant breeder.
You must know the structure of the flower— where the pollen-bearing anthers are to be found and where the stigmatic surface that is to receive the pollen is located.
From your study of botany, you will remember that the pollen grain germinates after pollination.
The pollen tube grows down through the pistil wall, into the ovary and through the micropyle of an ovule.
The sperm cells from the pollen grain are then freed, and one fertilizes the egg cell of the ovule. Once you understand all of this, you can begin to experiment with pollination.
Rules Of Thumb Of A Plant Breeder
Several rules of thumb help the amateur plant breeder. First, be sure that you are the only pollinating agent for the particular flower you are working on.
The wind will be a factor if your flower has a light and fluffy pollen. However, insects can confuse your best efforts, whether the pollen is light or heavy.
You may wish to enclose the blossom on which you are working with a small paper or plastic bag.
Knowing The Presence Of Insect In a Flower
How do you know an insect hasn’t beaten you to the flower? You will probably decide to begin with an almost mature bud.
Open it gently, and with tweezers, remove the anthers without touching the stigma. Now, if you enclose your flower in a bag, it is safe.
When should you pollinate a blossom? First, spend some time observing various opening stages in the same species.
Usually, the stigma is receptive when it becomes slightly sticky, and the blossom’s petals are fully expanded. Early morning pollination is most successful, too.
Collecting Pollen
Pollen is easy to collect; just shake or brush it onto a piece of tissue paper, fold it up and label it.
To apply it to the stigma, use a clean, pollen-free paint brush —the smaller, the better.
If the pollen plant blooms earlier than the stigma plant you wish to pollinate, you may be able to store pollen from the early blooming species until the later one blooms.
Place the little tissue folders of pollen in a jar in the refrigerator. Often it will keep for months.
Keep complete records of what you have done. For example, use a log book, recording when and from what variety the pollen was collected, when and on what variety it was applied, and whether the pollination appeared successful.
Tagging Pollinated Blossom
Tag each pollinated blossom using a weatherproof pencil on a plastic label. Then, when you harvest your seeds, carry the information along with the seed packet.
A final point is most important to the well-being of our horticultural community. Discard everything that is not better, in all ways, than its predecessors.
A good ratio on the first culling is to discard a thousand seedlings for each one that goes into the trial garden. Grow these chosen few for a few years.
Undisciplined Breeding Program
If one of them comes up to quality, send it to a botanical garden for further testing. The African violet mess is a good example of what happens with an undisciplined breeding program.
Unless the new variety is wonderfully better than the original parents, discard the seedlings and start over.
Polyploids
Now, about the new strains of plants with more than two sets of chromosomes. They are called polyploids.
You can do interesting experiments by obtaining colchicine (prepared from the autumn crocus) from your garden shop. Follow the manufacturer’s instructions.
Special Kinds of Cell Division
Normally, when the sperm and egg cells are formed, special cell division results in a reduced chromosome number in the sperm and egg.
The sperm cell has one set of chromosomes, as does the egg cell. However, when they unite (fertilization), the new cell (the zygote) has two sets of chromosomes, as will all of the other progeny cells that make up the new individual’s body.
Colchicine-Treated Pollen
If colchicine is applied at the correct time, the reduction division is inhibited, and the sex cells have two sets of chromosomes.
If a colchicine-treated pollen grain is placed on the stigma of a colchicine-treated flower, the resulting seedling should have four sets of chromosomes.
If a treated pollen grain is placed on the stigma of an untreated flower, the resulting seedling will have three sets of chromosomes and will be sterile.
Other Methods In Producing Unusual Types Of Plants
Geneticists use other methods to produce unusual types of plants. Ultraviolet irradiation can disrupt the genes of a pollen grain and result in different offspring.
You can try exposing small amounts of pollen to your sunlamp for varying lengths of time, beginning with just a few seconds or less. You may come up with something unusual.
Better Plant Specimens
Watch for better plant specimens in your garden. Then, carefully interbreed them and keep only the finest seedlings.
Have definite goals for bloom size, quality, and duration; foliage quality and color; disease and weather resistance and other desirable characteristics.
Upgrading Native Flowers
Try upgrading some of your native flowers.
We ignore many roadside composites (sunflowers and asters, for instance), but Europeans love them and have improved them.
We need new strains for every climatic area in the country. Our best chance for fine new flowers lies with local gardeners.
44659 by Dr. John P. Baumgardt