Journal articles courtesy of:

BC Growers Association

Breeding Field Crops


Poehlman, John Milton. 1995. Breeding Field Crops. The Avi Publishing Company. Inc.



Chapt 18. Seed Production Practices

The primary purpose in plant breeding is to develop better varieties. To this end extensive breeding programs are carried out with all major field crops, the expense being borne by public or by private means, or by the joined efforts of both. The cost of this re- search can be justified if increased returns accrue to the growers who use the improved varieties. The growers receive the returns as a result of the in- creased production and superior quality of the crop grown from the new varieties. Before the potential benefits from an improved variety can be realized, the variety must he distributed widely, and sufficient seed must be produced so that the variety can be grown on the farms in the areas to which it is adapted. Otherwise much of the breeder's work would go for naught.

To facilitate the systematic increase and rapid dis- tribution of new improved varieties, fairly extensive and well-defined seed production practices are used (Fig. 18.1). In the development of these practices two assumptions have generally been made: (a) the development of the variety is the primary function of the breeder; (b) increase and distribution can be handled most expeditiously by farmers and seeds- men, who are experienced in the art of growing, cleaning, and marketing of pure seed. Much of the detail in variety distribution has centered around the steps by which the breeder turns over seed of a new variety to the seed grower, and the procedures by which pure seed of the new variety is increased, distributed, and certified.


Plant breeding in the United States and Canada is conducted both by public and by private resources. The public plant breeding projects in the United States are conducted by tax-supported agencies such as the United States Department of Agriculture, the state agricultural experiment stations, and the agri- cultural colleges. In Canada they are conducted by the Canada Department of Agriculture, the pro- vincial governments, and the agricultural colleges. Private plant-breeding research is conducted by pri- vate industries, such as hybrid seed corn companies, seed cotton firms, and the beet sugar industry. The extent to which plant breeding is done by public or by private agencies varies with the importance of the crop and the resources of the industry. In crops with large recurrent sales of seed, such as hybrid corn, hybrid sorghum, sugar beets, or cotton, private breeders participate to a much greater extent than for crops in which the recurrent seed sales are small.

Private industry in the United States and Canada participates very little in the breeding of self-polli- nated crops such as wheat, oats, soybeans, flax, and tobacco, in which seed sales are relatively small after the initial distribution of a new variety has been made. This is a logical development since seed com- panies can finance plant breeding programs only in relation to the returns from their seed sales. Some ex- ceptions are found in alfalfa and certain other forage crops where large recurrent seed sales are normal, yet there are no effective private breeding programs in forage crops. Breeding research for all major crops is conducted by various tax-supported agencies. Public support is also used in varying degrees to finance fundamental research which may lead to an advance- ment in knowledge or plant breeding procedures. At present the latter type of research is supported very little by private means and is therefore almost entirely dependent upon public support. In recent years cooperation between public and private breeders has been increasing. This is a trend that should he en- couraged, for it will lead to increased benefits to both groups.

Improved varieties developed by tax-supported in- stitutions, such as state agricultural ~ent sta- tions or colleges of agriculture, may he considered public property. Hence it is in the public interest that new varieties developed by these public agencies be increased as rapidly as possible and distributed in an orderly fashion so that seed will become available won to everyone who may wish to grow the new va- rieties. It is desirable also that no one he permitted to exploit a new variety developed hv a public institu- Lion by charging exorbitant prices for seed while the seed supply of the new variety is still scarce. Ale true benefits of an improved variety should come from the increased production received by the grower, not from excessive profits from the sale of seed that is still in short supply. For the purpose of expediting the orderly and efficient increase of new varieties and maintaining pure wed supplies of old varieties, seed iinproi,eznent organizations have been organized in nearly all the states, in Canada, and in many other countries. Through these organizations, procedures have been developed for the increase, distribution, and certification of new varieties originating at pub- lic institutions or, in some instances, bv private breed- ers. Procedures have been established also for main- tenance of pure seed and for certification of varieties after distribution. It is with these developments that we are concerned in this chapter.

Private seed companies which conduct breeding programs generally have established outlets for mar- keting the seed of their new varieties. Many of the larger companies, such as those that produce hybrid corn or seed cotton, have efficient advertising depart- ments and sales staffs already in the field. In the case of sugar beets, the beet sugar companies distribute seed of improved varieties directly to the growers who supply them with sugar beets. The increase and dis- tribution of seed of a neiv variety developed by a pri- vate breeder is generally controlled by the seed corn- pany financing the breeding program, with the ac- tual operations carried out through the company's production department. In some cas", privately bred varieties may be produced by other growers under a seed certification program. The public generally has little information or knowledge of the problems in- volved in the increase of privately developed and pri- vately distributed varieties, or how they are handled. However, the technical operations by which pure seed stocks are increased and maintained are similar, whether carried out by a seed improvement associa- tion or a cornmerdal seed company.

Before a variety is distributed from a state experi- ment station, it is generally tested thoroughly in the state, or states, where it originated and from which it is being distributed. Through regional cooperation the tests may he conducted over an area of several states. The results of these rests are available to make possible recommendations about the area of adaptaption of the new variety. Generally less information is available to guide the grower regarding the acceptance of a new variety developed by a private plant breeder. For this information the grower must rely almost completely upon the integrity of the company and its advertising. Generally, large seed companies conduct yield trials, comparing the performance of their new strains with those in production, or with standard varieties already grown. In many states corn hybrids and other crops developed by private com- panies may be included in tests conducted by the state agricultural experiment station. Usually a small fee is paid by the seed company for each strain in- cluded in the tests. Results of the tests are then pub- lished and made available to the public.

In general, education of the public, seed regulatory laws, and competition have forced reputable seeds- men to set a high standard in the sale of seed of new and established crop varieties. Unfortunately, some unethical seedsmen still foist inferior or unadapted varieties on the public with misleading publicity and pressure sales tactics. One common practice is to sell, at an exorbitant price, seed of an established variety in an area totally unsuited for good performance by that particular variety. This practice could be largely prevented if farmers would purchase seed only of va- rieties recommended for their area and from seeds- men whose reputation for excellent products and fair dealing has already been established in the communi- ty. Use of cerfified seed, whenever available, is one assurance of obtaining seed of high quality (Fig. 18.2). It is not an assurance of obtaining an adapted variety, unless the .,ariety has been tested and has been found to be suitable for production in the area where the buyer expects to plant the seed. For example, a variety of oats adapted and certified in Minnesota may he unadapted for production in Missouri or Kansas. Performance trials conducted by the state agricultural experiment stations are the best guides for determining whether a variety is adapted. Rec- ommendations by experiment stations may not extend to privately developed varieties, unless the experi- ment stations have had an opportunity to test the va- rieties developed by the private companies. Also, ex- periment stations may not recommend a privately de- veloped variety unless specific knowledge of the breeding behind the variety is made public, and there is assurance that seed sold by the seed company under the variety name will always he of the same genetic composition.


In the United States various public and private agencies are concerned with the testing, increase, re- lease, and distribution of new varieties of field crops and the maintenance of pure seed stocks of the varie- ty after the initial distribution has been completed. Although the details of organization may differ from one state to another, the ox,er-all pattern of thew or- ganizations is quite similar.

State Agricultural Experiment Stations and United States Department of Agriculture. The public-supported breeding and research organizations responsible for the development of new varieties in the United States include the various state agricultural experiment stations and agricultural colleges and the United States Department of Agriculture. The breeding work of the United States Department of Agriculture is closely coordinated with the breeding work of the state agricultural experiment stations, how- ever. With the former, emphasis is generally more toward development of varieties with broad regional rather than local adaptation. In many states both agencies cooperate on a single breeding project to such an extent that it is impossible to differentiate between the activities of the tivo groups. This provides a fortunate and desirable ivorking relationship. The United States Department of Agriculture, by sponsoring Uniform Regional Tests, is helpful in promoting interstate and regional testing of a new va- riety before its final release. The state agricultural experiment stations are responsible for the final release of a new variety within the boundaries of their state. The participation of the state agricultural experiment stations in the final increase and distribution of the new varieties varies somewhat from state to state according to the specific relationship of the experiment station with the seed certifying agency and other seed increase organizations operating within the state.

In Canada, similar relationships exist between the Canada Department of Agriculture and the provin- cial governments and agricultural colleges.

Seed-Certifying Agencies. Seed certification programs are carried on in 44 states, Alaska, and Canada. The Canadian Seed Crowers' Association, organized in 1900, and the Canadian Department of Agricul- ture certify seed on a national basis in Canada, but in the United States seed cerfification is a responsibility of the individual states. The purpose of seed certification as defined by the International Crop Improvement Association is as follows:

"The purpose of seed certification is to maintain and make available to the public sources of high quality seeds and propagating materials of superior varieties so grown and distributed as to insure genetic identity. Only those varieties that contain superior germ plasm are eligible for certification. Cert!Ged seed is high in varietal purity and of good seeding value.

"Varieties eligible for certification have resulted either from natural selection or through systematic plant breeding. In either case without a planned method for maintaining genetic purity, there is dan- ger of losing varietal identity.

"Varietal purity is the first consideration in seed certification but other factors, such as weeds, diseases, viability, mechanical purity and grading are also im- portant. One of the most effective methods of pre- venting the wider distribution of weeds is to plant weed-free seed. Adverse effects of plant diseases can be reduced by planting clean seed from disease-free fields. Properly cleaned and graded seed is easier to plant and gives more uniform stands.

"Seed certification is designed, therefore, to maintain not only the genetic purity of superior crop varieties, but also reasonable standards of seed condition and quality.

The plans by which the various state seed-cerdfr ing agencies are organized differ, but the general pattern of organization is as follows:

1. The membership comprises seed growers and other parties interested in the production of good seed.

2. The management is vested in a board of directors elected by the members.

3. The agency, through its officers, sets up procedures and standards for inspecting, testing, and certifying seeds in the state in which it is organized.

4. The agency is closely affiliated with the state agricultural experiment station, the state agricultural extension service, and/or the state department of ag- riculture through membership of staff members on the board of directors of the seed-certifying agency, by stalt members serving as officers of the agency, through advisory committees, or by other means.

5. In most states the seed-certifying agency has legal status as the official seed certification organiza- tion within the state. Legal status may be from direct legislative action, or legal status may he vested in the state agricultural experiment station or the state department of agriculture, who in turn designates the seed-cerfifying agency as the official seed certification organization.

International Crop Improvement Association. The International Crop Improvement Association was organized in 1919. Its membership includes the seed- certifying agencies in the various states, Alaska, and Canada. Its major effort has been directed toward coordination of the cerfification programs of the mem- ber seed-certifying agencies. This has been accom- plished by the establishment of minimum certifica- tion standards for the guidance of member agencies. Procedures have also been established for interagency certification of seed samples. For example, a potential certified lot of grass seed grown in one state may be shipped to a seed-processing plant in another state for final cleaning, processing, bagging, tagging, and scal- ing. By mutual agreement the seed-certifying agen- cies of the two states may combine efforts, each mak- ing the field and processing plant ~tions neces- sary in their respective state to complete final certification on the seed.

Agricultural Extension Service. The Agricultural Extension Service, through its extension agronomists and county agents, offers useful service by encourag- ing the general use of pure seed of the best varieties throughout the state. It is also its function to assist in the education of the seed growers and the seed trade regarding certification procedures and to disseminate information regarding new and adapted varieties and those eligible for certification in the state concerned. In some states extension agronomists serve on the board of directors or on advisory boards of the state seed-certifying agency.


Four classes of seed are recognized by seed certification agencies:

1. Breeder seed. Breeder seed is seed or vegetative propagating material directly produced or controlled by the originating plant breeder or institution. Breeder seed provides the source for the increase of foundation seed.

2. Foundation seed. Foundation seed, including elite in Canada, is the direct increase from breeder seed. The genetic identity and purity of the variety is maintained in foundation seed. Production is carefully supervised or approved by representatives of an agricultural experiment station. Foundation seed is the source of all certified seed classes, either directly, or through registered

3. Registered seed. Registered seed is the progeny of foundation or registered seed. Registered seed maintains satisfactory genetic identity and purity of the variety for the production of certified seed. Registered seed is used as the source of certified seed in some states, or with some crops. In other states, or with certain crops, registered seed is not grown.

4. Certified seed. Certified seed is the progeny of foundation, registered, or certified seed. Certified seed must he handled so as to maintain sufficient genetic identity and purity of the variety that it will be approved and certified by the certifying agency.

Foundation, registered, and certified seed is identified by a distinctive tag on each bag of seed (Fig. 18.2). A white tag is used for breeder and foundation seed, a purple tag for registered seed, and a blue tag for certified seed. Or the regular blue certification tag, if stamped with the word, Foundation, or Registered, may be used to identify these two classes.

In certain states, or with certain crops, the registered class is omitted, the progeny d foundation seed being classed as certified. In some states, a limited generation plan for the production of certified seed has been adopted. With this plan cerfified seed can be produced only from registered (or foundation) seed, and in some cases a limited number of generations, usually one, of certified seed. In other states the progeny of certified seed can be recertified as long as the genetic identity and purity of the variety is maintained.

Each state seed-certifying agency sets up the pro- cedure by which each class of seed may he produced and the standards of purity for each class of each crop within their state. However, the standards should not fall below the minimum standards approved by the International Crop Improvement Assmiation. Each state seed-certifying agency publishes the standards applicable in its state and assumes responsibility for inspection, sampling, testing, and certifying seed that meets certification standards.


Before a variety of a field crop can be certified by a seed-certifying agency in a particular state, it must first he approved by the certification committee for that state. Normally, only varieties recommended by the agricultural experiment station in the state are certified. However, additional varieties may be certified if there is a demand for the seed in other states which recommend the variety but which cannot produce the seed satisfactorily. For example, seed of a forage crop variety adapted to an eastern state may he grown and certified in California. The seed is then shipped back to the eastern state for sale.

Exact certification procedures vary from state to state and with different crops. In general, certification involves the following steps:

1. The grower must plant foundation, registered, or certified seed of an approi.ed variety. In some states only progeny of foundation or registered seed, or, in some cases, first generation increases from certi- fied seed can be certified. Generally, certification must he completed on the total acreage of each varie- ty grown by or belonging to a grower.

2. The seed must he planted on clean ground. The field should not have been planted in the year previ- ous to a-iother variety of the same crop, or to other crops which might volunteer and affect the purity of the crop being certified, such as rye preceding wheat. The ground should he free of noxious weds that might affect the purity of the crop.

3. In cross-pollinatid crops, isolation of the seed- producing field is required, either by planting a specified distance from all other fields of the same crop or by planting a specified number of pollinator rows around the border of the field to reduce the opportunity for cross-pollination with other varieties planted in neighboring fields.

4. Off-type plants are rogued out by the grower before harvest or before flowering, in the case of a cross- pollinated crop. Noxious weeds are removed before harvest, and borders or fence rows are clipped where necessary to maintain seed purity.

5. Field inspections are made by official representatives of the seed-certifying agency to cheek on the purity of the variety, freedom from other crop plants, freedom from noxious weeds, amount of disease that might altect cer6fication, and general conformity by the grower to the seed certification rules. Inspections are made at the time that purity and other observations can he seen best. In the case of hybrid corn several visits are usually made to cheek on thoroughness of detasseling or on freedom from pollen shedding in male-sterile lines in the event cytoplasmic male steril- ity is being used to eliminate the detasseling procedure.

6. Seed inspections are made by official representatives of the seed improvement association as necessary to observe and supervise the harvesting, cleaning, grading, bagging, and other processing operations. Representative samples are drawn by the inspector from the various lots of seed after they have been prepared for sale. The seed samples are tested for bushel weight, moisture, impurities, germination, or other factors allecting seed quality according to the particular crop. Only seed meeting minimum stand- ards of the association in all respects is accepted for certification. An exception to this is that the stand- ards are sometimes temporarily relaxed when it is necessary to maintain an adequate supply of germ Plasm of the variety.

Official tags of the seed-certifying agency are sealed on the bags of seed accepted for certification. The tag is labeled to show that the seed meets the specific standards for the crop (Fig. 18.2).

The production, processing, and marketing of certified seed is exclusively the responsibility of the grower. The responsibility of the seed improvement association is limited to observing whether the grower follows the regulations outlined by the association and to determining whether the seed meets the prescribed standards for certification of that particular crop.

The exact regulations and rules for certification of specific crops may he obtained by writing to the seed improvement association of a particular state or to the Canadian Seed Growers Association in Canada.


A desirable procedure by which a new variety of a field crop developed by a state agricultural experi- rnent station reaches the farmer (Fig. 18.3) may be described as follows:

1. A variety is ready for release and distribution when it has been proved to he distinctly superior to existing commercial varieties in at least one or more characteristics, and at least satisfactory in all other important respects. The superiority should have been proved in tests carefully planned and conducted, in comparison with standard commercial varieties in the originating state, and in regional tests which will provide reliable information on the range of the variety adaptation.

2. The decision for release is made by the breeder in consultation with appointed boards of review. The boards of review are set up by appropriate authority within the state agricultural experimental station, to review proposals for release of a new variety. The Plant breeder makes a limited increase of the new variety, the amount varying from a few pounds to a few bushels. The breeder seed is then generally turned over to some agency responsible for making the foundation seed increase.

3. Foundation wed is increased from breeder wed. The organization making the increase varies in different states. In some states a foundation seed program has been developed within the agricultural experiment station. In other states foundation seed is produced by a private Foundation seed stocks organization closely associated with the agricultural experi- ment station. Increase may be speeded up in many summer-growing crops by growing a seed crop during the winter in one of the southern states.

4. At least one year before distribution by the originating station, each state experiment station in the region of adaptation of the new variety is normally informed of plans to release the variety, and seed is supplied to them in quantities to permit field plot testing at one or more locations.

5. The variety is named at the originating station, in consultation with representatives of other state agricultural experiment stations within the region, and the United States Department of Agriculture in the case of cooperative state-federal breeding programs.

6. Prior to distribution, either breeder seed or foundation seed is shared within the region with other state agricultural experiment stations who may wish to make a simultaneous increase and distribution of the new variety. In the case of grass or legume seeds, a limited generation increase may he made in states outside the region of adaptation under the supervision of the Nationad Foundation Seed Project, as will be described later. Normally a few hundred to several thousand bushels of seed may he available by the time the variety is ready for release. The amount will depend upon the crop, the facilities for increasing the seed, and the anticipated demand for the new variety. An adequate quantity of foundation seed should be built up to supply immediate needs for the production of registered or certified seed be- fore any release or distribution is made.

7. First distribution of foundation seed is usually made to selected growers who by past experience have proved their ability to produce registered and certified seed with a high standard of quality. Selec- tion of qualified registered and certified seed growers is necessary to insure a rapid increase of the new variety without loss of purity. This distribution, plus a public announcement, constitutes a formal release by the originating station. Seed increased from the foundation seed may be classed as registered seed, or certified seed, according to the crop and the policy of the state concerned. Control over distribution and price of the first increase is sometimes retained by the distributing agency.

8. Distribution of registered seed (or certified seed if certified seed has been produced directly from foundation seed) is made to certified growers throughout the state. The certified seed harvested from this increase then usually becomes available without restriction to any grower within the state insofar as the seed supplies are available.

Exact procedures vary in different states and with different crops. In some states advance release is made of superior inbred lines of corn, without regard to a particular hybrid combination in which they may be used. This makes inbreds with superior characteristics available to private breeders or others who might have a use for them. In some states delayed release of inbred lines of corn is practiced. With delayed release, the agricultural experiment station keeps control of the inbred, and produces and distributes the single crosses in which the inbred is a parent, until the single and double crosses have proved successful. Then the inbred is released. In other states inbreds are never released only the single crosses in which they are used. Many state seed-certifying agencies certify vegetable and horticultural crops as well as field crops.



Return to BCG main page