SOUTH DAKOTA SEED CERTIFICATION STANDARDS

Hybrid Corn

Seed Certification Standards
(In Addition to the General Standards Listed on the Standard's Home Page )

I. Definitions
A commercial hybrid is one to be planted for production for any use except seed. It may be any one of the following:
1. A double cross: The first generation of a cross between two Foundation single crosses.

2. A three-way cross: The first generation of a cross between a Foundation single cross as one parent and an inbred line or a Foundation backcross as the other parent.

3. A single cross: The first generation of a cross between two inbred lines, an inbred line and a Foundation back cross or of two Foundation back crosses.

4. A top cross: The first generation of a cross between an inbred line and an open-pollinated variety, or the first generation of a cross between a single cross and an open-pollinated variety.

II. Eligibility of Stock Seed
1. Only certified Foundation single-cross and Foundation back cross seed planted for the production of double-cross, single cross, three-way cross, or top-cross hybrids are eligible and they must have been officially certified by a recognized seed certifying agency.

2. Inbred line seed planted for the production of single cross or three-way cross hybrid corn seed to be used for grain or forage production or for export must meet requirements for the definition of an inbred line and be certified. Evidence of eligibility shall be a Certification tag taken from the seed planted.

3. Only the class "Certified" is recognized.

III. Field Inspections
At least three field inspections shall be made by a representative of the certification agency during the pollinating period. These inspections will be made without previous notification to the grower. When the previous crop was corn, at least one additional inspection ("Final inspection") shall be made to verify that the field is sufficiently free of volunteer plants from the previous crop.

IV. Field Standards
A. Isolation
1. A specific hybrid must be located so that the seed parent is not less than 660 feet from corn of a different grain color or texture except hybrid seed production fields of dent sterile popcorn need not be isolated from yellow dent field corn.

2. A specific hybrid must be located so that the seed parent is not less than 415 feet from other corn of the same grain color or texture. This distance may be modified by the planting of pollen parent border rows and the size of the crossing field according to the following table.

3. Different dates of planting will not divide a field for isolation purposes but may divide the field for detasseling inspection.

4. Adequate natural barriers are permitted for modifying isolation distance.

5. Differential maturity dates are permitted for modifying isolation distance provided less than 5% of the seed parent plants have receptive silks at the time pollen is being shed in the contaminating field.

6. The border rows and pollen parent rows must be planted with certified first generation seedstock, must be shedding pollen simultaneously with silk emergence of the seed parent and must not be separated from the seed parent by more than 33 feet.

7. A field planted with the same eligible pollen parent may be used as an isolation buffer, provided it is applied for certification, inspected and meets field requirements for certification.

8. Full credit will not be given where poor stands of border corn exist, where the border rows have been detasseled, or where, for any reason, the border rows are not shedding pollen as plentifully as the pollen parent rows. (Because of the difficulty of obtaining and maintaining a good stand of corn the planting of more than the minimum number of border rows is recommended.)

9. The maximum distance a seed parent row may be from a pollen parent row shall be 15 feet.

10. When the contaminating sweet corn is aggregating less than one-quarter acre on one exposure the isolation distance may be modified in accordance with the table under IV, A, 2.

11. Corrections for improper isolation must be made by one of the following methods:
a. By completely destroying or by detasseling the necessary contaminating corn before silks appear on the seed parent in the field to be certified, or

b. By completely destroying, before the final field inspection, the seed producing plants which are improperly isolated from contaminating corn.

B. Detasseling or pollen control
Five percent or more of the stalks of the seed parent must have apparently receptive silks for the following provisions to apply. (Apparently receptive silks are emerged silks which are not wilted or brown.)
1. A field (individual female by male combination) will not be accepted for certification if at one inspection, more than one percent of the stalks of the seed parent have shed pollen, or if the total number having shed pollen on any three days of inspection exceeds two percent.

2. When more than one seed parent is being grown with a common pollinator and one or more of the seed parents is shedding pollen in excess of 1.0 percent, all other seed parents having 5 percent or more apparently receptive silks at the time will be disqualified unless adequately isolated from the shedding seed parent.

3. Sucker tassels and portions of tassels will be counted as shedding pollen when two inches or more of the central stem, the side branches, or a combination of the two have the anthers extended from the glumes.

C. Male Sterile Seed Parent
A male sterile seed parent can be used to produce certified hybrid corn seed by either of two methods.
1. Seed of the normal fertile seed parent must be mixed with the seed of the male sterile seed parent of the same pedigree either by blending in the field at harvest or by size at conditioning time. The ratio of male sterile seed parent to normal seed parent seed should not exceed 2:1.

2. The male parent must involve a certified pollen restoring line or lines so that not less than one-third of the plants grown from the hybrid corn seed produce pollen which appears to be normal on quantity and viability.

D. Roguing
1. Definitely off-type plants in a parent line planted for the production of single cross or three- way cross hybrid corn seed to be used for grain or forage production must be completely destroyed so that suckers will not develop.  Plants showing definite hybrid vigor or a definitely different type from the parent being inspected shall be classified as definitely off-type.

2. A field (an individual female by male combination) in which more than one-tenth of one percent (1 per 1000) of definitely off-type plants in the parent or parents have shed pollen, at a time when more than five percent of the seed parent plants have apparently receptive silks, shall be disqualified for certification.

3. A field (an individual female by male combination) in which more than one-tenth of one percent (1 per 1000) of definitely off-type plants are present in the seed parent at the final inspection shall be disqualified for certification.

V. Seed Inspection
A. Seed Lots

The applicant may elect to divide a supply of cleaned seed of a given variety and class that has passed field inspection into two or more lots. It is recommended that large quantities of seed be divided into lots convenient for sampling and if sampled as bulk cleaned seed in more than one bin, each bin should be considered a separate lot.

VI. Seed Standards

A. Genetic

B. Quality**

* See definition Number 4. B. on Standard's Home Page.
** Quality standards listed here are recommendations only. Seed lots failing to meet the minimum quality standards will not be rejected for purposes of certification.

Web page last modified on March 06, 2000 by Kay Ruden.