Hybridizers Staying One Step Ahead of The Bees

Nature has planned to use insects or the wind for breeding flowering plants. Food and drink in the form of pollen and nectar induce insects to do the work. Even though bees do not know what they are doing, the job is done.

bee nature pollenatePin

A new element now enters nature’s plan—intelligence on the part of the breeder or pollinating agent. This began at the die time of the Romans, or even earlier among the Chinese, when someone found that shaking the pollen of a flower upon the open face of another would produce seed-yielding- plants that bore flowers different from either parent.

Homo sapiens, with his intelligence, is nature’s new tool—one step ahead of the bee. A degree with a seven-league boot!

The Great Architect has a simple plan upon which the flower is built. The brush drawings on these pages aim to show this. Although nature plays the tune with many variations, the theme is the same. The stamen with its pollen-hearing anther (male) and the bottle-shaped pistil (female) holds the ovules or egg cells —the seed-that-is-to-be.

At the top of the pistil, the stigma has a sticky receiving surface where the pollen grains are deposited by wind, insects, or man and sprout awl grow into pollen threads or tubes. These tubes extend through the neck of the bottle, called the style, into the ovary.

The male reproductive cell is formed at the end of the pollen tube. One male cell fuses with an egg cell, and from this union, the seed, which contains the embryo, develops.

A Variety Of Blooms On The Same Plant

In the flower, the pistil may be single or compound. Stamens and pistils are usually found in the same flower on most plants, but they may be in different flowers on the same plant, as in corn, or on two other plants, as in holly, which has male and female plants.

Your job, as a breeder, is to select the parents and bring the pollen of one to the stigma of the other.

In the drawings below, the flowers are arranged in order from the simpler to the more complex — the lilies to the composites. The gladiolus is out of place; it belongs to the iris family. Like the iris, it has three stamens and three stigmas.

flowers are arranged in order from the simpler to the more complexPin
The flowers are arranged in order from the simple to the more complex

This arrangement is the same as that in which flowering plants appeared on the earth. This is indicated by the fact that, as yet, no fossil composites have been found — roses, yes, but no composites.

For example, the composites—dahlias and chrysanthemums, among garden flowers — are nature’s most recent achievement. Wild forms have conquered the world — note the dandelion. Each seed is separate and is provided with a means for wind dispersal.

The small size of the pistils stamens in the composites presents real difficulty to the breeder. Some resort to parents’ segregation allowing insects to do the work; others use a lens.

The thrilling adventure of producing something new and better is always the breeder. 

Where To Start The Adventure Of Breeding New Varieties

Gladiolus, iris, or daylilies are suggested as places to start. The stamens and pistils are prominent, the pollen is plentiful, the seedlings are quickly grown, and they bloom the second year. It isn’t brilliant to start with daffodils or orchids, which take five to seven years to bloom.

The unfurling of the flower petals is the invitation to the bee and the signal that the flower is ready for pollination. The bud may be bagged in the waxed paper just before opening to prevent insects’ chance of pollination.

When the petals are large, they may be cut off at the base as the flower begins to open, but care should be taken to avoid injuring the stamens and pistils. Little is left to attract insects when the petals have been removed and their foothold is gone.

The pollen parent may be cut open indoors. Cut the stalk just before the blooms start to open. In this way, contamination with offered foreign pollen is prevented, and there will be more pollen with which to work.

The stigma is receptive when a sticky secretion appears on its surface. This is the time to pollinate. ‘Since the pollen holds its life a long ‘time, it is good to pollinate as soon as the flower opens; the pollen will then be there when the stigma becomes receptive.

Dust the pollen gently to prevent injury. Repeated pollinations on successive days with pollen of the same cross helps to ensure success.

Removing The Stamens

Avoid self-pollination by “emasculating” the flower of the seed parent—this means removing the stamens. However, do this before the anthers open, for otherwise, the pollen may fall or blow upon the stigma as you handle the stamens.

Most flowers have plentiful pollen supplies, but sometimes it is not easy to find. Slitting the anthers in the iris sometimes reveals unsuspected pollen. The anthers of the African violet must be cut open with a razor blade to obtain the pollen. Highly bred varieties may have no pollen, and only the disk flowers in chrysanthemums and dahlias carry pollen.

When working with these, watch them bloom as it matures and collect the pollen as it appears. Pollen may be stored in the refrigerator between waxed paper at 40° to 50°.

The temperature and time of day are essential when pollinating, but this varies with the flower. For glads. It is said, before 9 A.M. and after 6 P.M. on a sunny day is best. With iris, the time is unimportant so long as the day is fair and still. With chrysanthemums, a warm, sunny day is needed. Camellias require 65° to 70° degrees Fahrenheit for the pollination to take.

What is a good cross? Experience alone answers this question. Some varieties will always make better parents than others: some will be found sterile, and some crosses will not take.

Camel hair brushes were once thought best for transferring pollen, but they must be dipped in alcohol between different crosses, and the alcohol is slow to evaporate from the inside of the brush. Fingers may be used but locking forceps work much better, preventing contamination from soiled fingers.

My favorite tool is a locking hemostat, a surgical instrument somewhat like scissors but without cutting edges and blunt tips. The handle can be locked when the stamen is seized between the ends.

Magnifying Lens For Tiny Flowers 

Magnifying lenses are excellent when working with tiny flowers. Mounted and worn like eyeglasses, they leave the hands free. 

Brightly colored small labels upon which to write the time, date, and name of seed and pollen parent are essential, as is a notebook to enter the crosses as they are made. Also helpful are glass vials in which to transport pollen with labels.

Experienced breeders will be more apt to tell than to listen when it comes to such matters as technic but the beginner will want to profit from the experiences of others. 

Label each cross with a tag on the stem, placing the name of the seed parent first—Snow Flurry x Snow Carnival, meaning that the iris Snow Flurry is the seed parent and Snow Carnival, the pollen parent.

It is common sense to know the culture of the plant before starting to breed it. Control of diseases and pests ought to be understood. Otherwise, the time given to breeding is apt to be wasted. Virus diseases are significant.

Although the seeds, themselves, do not carry the virus, the seedlings may become infected. Daylilies seem to be the only group free from diseases and pests and owe much of their popularity to this factor.

Breeding for disease resistance is a profitable field, much more beneficial than breeding for form or color. However, the problem is mainly beyond the amateur, although he should be aware of its importance. Destroy all but healthy stock to reduce the prevalence of the disease.

Although most seed germinates a few weeks after planting, some need an after-ripening period. This is the time between the ripening of the source and the time it starts to sprout or germinate.

Seeds On November

For instance, in the holly, the seed is ripe in November but will not grow until two winters have passed over it. Other sources require an after-ripening period of from six months to a year.

In general, growing seed plants depends on keeping the seed free of fungi and insects and preventing the soil from infecting the seedlings. Captan is a good fungicide for treating seeds; sterilized soil may also be helpful.

What Plants To Cross Is Always A Question 

Crosses between families or genera are impossible, for they are too unlike. Crosses within the same species are apt to be successful, as are crosses between two species with the same chromosome number.

Inter-species crosses, those made between different forms or varieties of the same species, are likely to take. The beginner should confine himself to such crosses.

Plant breeders work in different ways. Some will cross every way with no planned results; they will be grateful if something good appears. Others plan crosses carefully. They will dream up an ideal variety and then plan the parentage to bring it to reality.

Inter-species crosses, those between different species, yield hybrids. Some hybrids may start a whole new line of plants if they prove fertile, i.e., able to reproduce themselves. This is a field for the experienced breeder.

The personality of the breeder often shows itself in the selection of varieties he crosses. However, good advice to the beginner is to breed from the best and breed close. For instance, to produce an excellent white mum, strike two of the best whites that are most nearly alike.

Discard Blooming Poor Seedlings

What varieties you choose to keep or discard depends on your dream and what you are working for. A tip to the wise—discard inferior seedlings while they are in bloom. Always recognize the value of the previous selection.

Scientific plant breeding has a brief history. Sex in plants was a debatable question 250 years ago. A little over 150 years ago, in 1866, Gregor Mendel discovered unit characters. 

Since then, chromosomes and genes, as the units of inheritance, have given rise to the science of genetics and have made possible significant advances in breeding.

Although much has been done without such knowledge, failures can be avoided and successfully predicted with it. Chromosomes are the bearers of inherited characters in all plants and animals’ sex and body cells. They are microscopic and constant in number in each compartment within a species.

They are constructed of smaller units, genes, which carry the unit characters. Once in every generation, the chromosomes are re-assorted, and new individuals are thereby produced.

In the iris, the “diploid” bearded iris has 24 chromosomes; Iris pumila has 32; some dwarf forms 40, and the tall bearded 44. The chrysanthemum also, is a “polyploid” genus with the primary number nine, though species with nine chromosomes are not known.

Diploids with 18 are numerous; the arctic daisy has 90; the garden chrysanthemums, Chromosomes sibiricum (Korean hybrids), and Chromosomes modfolium have 54. Species with the same number of chromosomes are more apt to cross successfully.

Species crosses where the counts are different are more complicated though, in many cases, possible.

As they are carried from generation to generation, some unit characters exert dominance. To get a good red in-curved pompon, the chrysanthemum Grenadier, a red reflex pompon. Was crossed with a buff incurved pompon. All the seedlings were predominantly red and also reflexed.

However, in a few days, all the blooms turned an unattractive brown, a character also inherited from Grenadier. This and the reflexes are examples of unwanted dominance.

Recessive Iris

The plicata character in the iris is recessive. Recessiveness is the opposite of dominance, the surface appearing to be lost although it is not. In breeding for this character, it should be present in both parents. If present in one, it may be brought out in crossing back on the plicata parent.

None of the first generations were duplicates in a cross with Blue Shimmer, a plicata, and Great Lakes. Backcrossing on Blue Shimmer gave an expectancy of one in nine. I got two duplicates from the total of 18 seedlings that I grew.

Breeding from the best varieties worked well for me. Crossing the two best white iris at the time, Snow Murry and Snow Carnival, gave me Two flurries of snow, a ruffled, flaring white with good substance.

Making pedigree charts, using color to show the inheritance of color, is good winter work. The iris checklist, for example, makes it possible to search into the parentage of wide varieties before an attempt is made to breed them.

Other than sexual reproduction, new varieties appear from time to time as sports or mutations. 

Many of these turn out to be sterile, so nature has no use for them, but they are helpful in the garden. The camellia Herme has given 17 sports, many of which have been introduced as new varieties. Our Herme has sported to Pink Herme, but the parent is a better camellia.

The chrysanthemum Valencia has given numerous sports, and Indianapolis has three popular ones. Everyone should look for a new form or color on an old variety. 

Since there is no control over the origin or nature of sports, cross-breeding alone offers the only method of power and, hence, a more practical and exciting way of getting new varieties.

44659 by Aleita H. Scott