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ProCrop |
Sunflower Yield Estimation
To estimate crop yield identify the following characteristics:
- Plant population
- Head diameter
- Seed Size category
- Good seed set
- Center seed set
Plant Population -- Step off a 10 ft. section at least 50 ft. from end rows.
| Plants per 10 ft of Row | ||||
| Population | 28" | 30" | 36" | Multiplier |
| 14,000 | 7.50 | 8.00 | 9.50 | 0.70 |
| 15,000 | 8.00 | 8.50 | 10.25 | 0.75 |
| 16,000 | 8.50 | 9.25 | 11.00 | 0.80 |
| 17,000 | 9.00 | 9.72 | 11.75 | 0.85 |
| 18,000 | 9.50 | 10.00 | 12.50 | 0.90 |
| 19,000 | 10.00 | 11.00 | 13.00 | 0.95 |
| 20,000 | 10.75 | 11.50 | 13.75 | 1.00 |
| 21,000 | 11.25 | 12.00 | 14.50 | 1.05 |
| 22,000 | 11.75 | 12.50 | 15.25 | 1.10 |
| 23,000 | 12.25 | 13.25 | 15.75 | 1.15 |
| 24,000 | 13.00 | 12.75 | 16.50 | 1.20 |
Head Diameter - Measure the diameter of an average* head.
| Head Diameter (Inches) | Multiplier | Head Diameter (Inches) | Multiplier |
| 4.5 | 0.37 | 7.5 | 0.91 |
| 5.0 | 0.46 | 8.0 | 1.00 |
| 5.5 | 0.55 | 8.5 | 1.09 |
| 6.0 | 0.64 | 9.0 | 1.18 |
| 6.5 | 0.73 | 9.5 | 1.27 |
| 7.0 | 0.82 | 10.00 | 1.36 |
Note:
* Need a good sampling of Head's to determine average size! Suggest 50 heads.
Seed Size - Remove a seed 2 inches from edge of the head and compare to the seed outlines below.
| Multipliers | ||
| Light (L) |  |
.8 |
| Medium Light (ML) |  |
.9 |
| Medium (M) |  |
1.0 |
| Medium Heavy (MH) |  |
1.1 |
| Heavy (H) |  |
1.2 |
Percentage of Good Seed set - Count one diagonal (arc) row of seed, the multiplier is the percentage of good seeds in the arc.
Center Seed Set - If no seed in the center 2 inches of the head, multiply by .95; if there is a hole in the center of the head, multiply by .90.
Seed Weevil Damage - This is difficult to estimate and any feelings of the effect on potential yield should be calculated in the percentage of good seed. For your information red weevil will consume about 30 percent of each kernel damaged; gray weevil will result in raised seeds on the head and will consume 100 percent of the kernel.
Yield is calculated by multiplying 2450 by the multipliers from the charts above. Fore example: A plot with a stand of 19,000 a head size of 7.5 inches, a seed size of light medium, good seed count of 85 percent, and no seed in the center 2 inches. Yield calculations for this plot would be:
2450 X .95 X .9l X .85 X .95 = 1539.3 lbs/acre
Multipliers used:
2450 X plant population X head size X seed size X seed count X center seed set = lbs/A
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