Sunflower Production Field Guide - Your "Home Page"

22
Sunfl ower plants will compensate for differences in
plant population by adjusting seed and head size. As
plant population decreases, seed and head size will
increase. Oilseed hybrids generally are planted at
higher populations than confection varieties, as the
size of harvested seed is less important. Plant populations
for oilseed sunfl ower should be between 15,000
and 25,000 plants per acre, with adjustments made
for soil type, rainfall potential and yield goal. Lower
populations are recommended for soils with lower
water-holding capacity and if normal rainfall is inconsistent
or inadequate. Confection sunfl ower should
be planted at populations between 14,000 and 20,000
plants per acre. Preharvest dry down is more rapid in
higher plant populations because of the smaller head
size. However, higher plant populations may result in
increased lodging and stalk breakage. Producers who
solid seeded sunfl ower use seeding rates of 18,000 to
23,000 plants per acre.
Proper planting equipment adjustment and operation
is one of the most important management tasks in
sunfl ower production. Plateless and cyclo air planters
have been used effectively to get good seed distribution.
Double-seed drops should be avoided and planter
adjustments should be made. Conventional plate
planters will provide good seed distribution by using
correct planter plates, properly sized seed and proper
seed knockers. Commercial seed companies have plate
recommendations for all seed sizes. Grain drills and
air seeders may be used for seeding, although uniform
depth of planting and seed spacing may be a problem
unless proper adjustments and modifi cations are made.
Postharvest Tillage
After harvest, tillage of sunfl ower stalks is not
recommended because snow-trapping potential is
diminished, thereby reducing soil water conservation
potential during the winter for the following crop.
Also, because of the nature of sunfl ower residues, a
late harvest followed by late fall tillage leaves the soil
extremely susceptible to wind and water erosion.
Table 8. Seed spacing required for various populations, assuming
90 percent germination and 10 percent stand loss.
Plants
Row Spacing
per acre 7.5 12 18 22 28 30 36
- - - - - - - inches between seeds in the row - - - - - - -
12,000 56.5 35.3 23.5 19.2 15.1 14.1 11.8
14,000 48.4 30.2 20.2 16.5 13.0 12.1 10.1
16,000 42.3 26.5 17.6 14.4 11.3 10.6 8.8
17,000 39.8 24.9 16.6 13.6 10.7 10.0 8.3
18,000 37.6 23.5 15.7 12.8 10.1 9.4 7.8
19,000 35.7 22.3 14.9 12.2 9.6 8.9 7.4
20,000 33.9 21.2 14.1 11.5 9.1 8.5 7.1
21,000 32.3 20.2 13.4 11.0 8.6 8.1 6.7
22,000 30.8 19.2 12.8 10.5 8.2 7.7 6.4
23,000 29.5 18.4 12.3 10.0 7.9 7.4 6.1
24,000 28.2 17.6 11.8 9.6 7.6 7.1 5.9
25,000
Feet per
27.1 16.9 11.3 9.2 7.3 6.8 5.6
1/1,000 acre 69.7 43.6 29 23.8 18.7 17.4 14.5
Highlighted seed spacings provide nearly equal-distant spacing between plants for a given row
spacing and plant population.