Laying the Foundation
Tuesday, February 1, 2000
filed under: Planting Systems
Two out of every six rows of sunflower that Euvene Gilbert and his grandson, Warren, produce are never harvested. Furthermore, their
remaining rows - all of which are irrigated - probably will not, even in
a good year, average much more than 500 pounds of seed per acre.
A Great Plains commercial sunflower producer would shudder at the
thought of losing one-third of his acreage and ending up with that sort
of yield level. For Gilbert, however, it's just business as usual; the
same outcome occurs every year.
The Gilberts, who farm near Chico, Calif., are foundation seed
producers, serving as the crucial "intermediary" step between seed
company breeding nurseries and the hybrid seed production fields. It's
their job to increase the volume of female seed available for planting
in hybrid seed fields the following year.
The Gilberts' 1999 30-acre confection foundation seed field was
planted in a "4:2" pattern: four rows of females for every two rows of
males. That's a common configuration in California foundation sunflower
fields - and different from hybrid seed production fields, where
configurations such as 14:4, 10:2, 8:2 or 6:2 are more likely to be
Why is the ratio of male-to-female rows higher in foundation seed
fields? There are several reasons, according to Bill Vaccaro of Vaccaro
First, the foundation male line often is a single-headed plant, whereas
the males in hybrid seed production fields are multi-headed. So these
males do not produce as much pollen on a per-plant basis.
Second, when producing the female inbreds, "it's very important to
have as high a genetic purity as possible," Vaccaro says. Increasing
the percentage of male plants helps bees "flood" the females with pollen
to maintain the necessary genetic purity.
Finally, a 4:2 pattern ensures a closer proximity of each male row
to the female rows. "Often, the amount of pollen isn't as critical as
the distance away from the female," Vaccaro explains. "Because these
females are all pollinated by bees, we need to keep the male close to
the female. So pollination efficiency becomes a matter of how many
times the bee crosses over from the male to the female."
Euvene Gilbert, who has been growing sunflower for more than 20
years, used to be a hybrid seed producer. Now, however, he and Warren
raise foundation seed exclusively. The per-acre sunflower income
doesn't match that from their almond orchards, he says - but it compares
quite favorably with other crops in their rotation.
Because it is sourced directly from breeders' nurseries, the volume
of planting seed for foundation seed fields is limited. Field sizes
("blocks") are usually quite small. Today, block sizes of 10 to 15
acres are fairly common; years ago, sizes of two, three or four acres
were routine. At 30 acres, the Gilberts' 1999 field was abnormally
large, making life easier for both the grower and the seed contractor.
Like hybrid seed producers, the Gilberts try to do as much ground
preparation as possible in the fall. In March, following a preplant
burndown with Roundup, they make a pass with their Lilliston cultivator,
simultaneously applying and incorporating starter fertilizer into the
Their herbicide (Treflan) goes on during the planting pass and is
immediately incorporated. "We run a knife ahead of our row gangs to cut
off the tops of our beds; then we throw moist soil from the side of the
bed up on top," Gilbert says. "We plant through that to place the seed
into moist, firm soil with the loose mulch on top."
The Gilberts' six-row sunflower planter carries female seeds in its
four center units and male seed in the outer two, so each pass leaves a
1:4:1 pattern. (Some growers use a separate two-row planter for the
males. Also, it's not uncommon for half the males to be planted several
days ahead of the other half to ensure the availability of sufficient
male pollen in the field across the entire female bloom period.)
Every row is irrigated in the Gilbert foundation seed fields.
Soils within their fields range from a light loam to heavy clay,
providing a real irrigation efficiency challenge. They'll typically
irrigate four times a season. Since the ground is still fairly loose at
the time of the initial watering and readily soaks up moisture, "we put
on a tremendous amount of water - sometimes more than an acre-foot,"
Euvene reports. Later applications are not as heavy, but he estimates
they'll still use a total of 3.0 to 3.5 feet per acre of water per
season, "plus our [normal] 20 inches of winter rain."
Because they don't have a drainage network on their ranch, the
Gilberts must manage their irrigation very proficiently to avoid having
standing water at field ends. Not only is that wasteful; but
temperatures often are around 100 degrees during irrigation periods, so
sunflower plants surrounded by standing water would essentially be
The man who sets irrigation tubes for Gilbert has been with him for
12 years and understands how each field handles water. That's a huge
benefit, Euvene affirms. During the initial irrigation, for example,
pushing that acre-foot of water through the field's first 70 rows might
take 17 to 18 hours; but because of differing soil types within the
field, "the next 70 rows might take only nine hours." The volume of
water is managed via the number and diameter of siphon tubes feeding
each row from the main ditch at the head of the field.
Vaccaro pays foundation seed growers like the Gilberts an attractive
flat rate per acre for their services. Yields are lower than those of
most hybrid seed fields. That's partly due to the higher percentage of
male rows in foundation fields; also, because foundation seed often
tends to be more difficult, culturally, to produce.
Seed is provided at no cost to the grower. The contractor also is
responsible for in-season roguing and for the harvesting of the
foundation fields. (In hybrid production fields, the grower typically
carries out the harvest under supervision of a company fieldman.) The
foundation seed grower is responsible for weed control, fertilization,
irrigation, bees, removing male rows, defoliation and any insecticide
applications. The company monitors each foundation field very closely
and, under terms of the contract, has the right to require such
"Because the foundation fields are so important for our hybrid seed
production the next year, we ask these growers to do a lot of things,"
Vaccaro relates. "Fields have to be perfect. If hand weeding needs to
be done, we expect them to do it. If we ask them to bring in extra
bees, they'll do so."
Assurance of genetic purity actually begins with field location.
The California Crop Improvement Association (CCIA) mandates that
foundation seed sunflower fields cannot be within 2.5 miles of each
other. CCIA personnel inspect each foundation field at least twice per
season, normally at the onset of bloom and again at full bloom. To
ensure genetic purity, very restrictive requirements govern the number
of allowable "off-types," and such plants must be promptly removed if
the number exceeds the limit. - Don Lilleboe