During the growing season, sunflower seed growers focus their efforts on ensuring that their crops reach their full potential and provide the highest possible yield and wholesale.
Yields around the world have risen over the past half century, record after record. 1 to 1.6 tons of seed per hectare (1,427 to 892 pounds per hectare) in 1970, today high-yielding countries such as France and China report average yields of 2 to 2.2 tons per hectare (1,784 to 1,963 pounds per cubic meter). . (One).
This increase in yield is mainly due to the development of new high-yielding self-fertilizing hybrids and improved agricultural practices and machinery. Interestingly, the wild or ancient species of sunflower were incompatible with themselves. This means that plants depended on pollinators for fertilization and seed production.
Modern breeders have overcome this problem and increased yields even without proper pollination. However, even modern sunflower hybrids can be very favorable for pollination.
Scientific reports show that yield can increase up to 48.8% and oil percentage can increase up to 6.4% in bee-exposed hybrids (2). If farmers want to exploit these insects, they should use poisons that are safe for bees, spray them at night, and inform the beekeeper of these actions.
Typically, average sunflower seed yield for an experienced farmer on fertile soil ranges from 2.3-2.5 tons/ha (2,050-2,230 lb/ha). These figures decrease to 0.7-2.0 t/ha (624-1784 lb/m/L) when the crop is grown under dry, unirrigated conditions with low rainfall.
With adequate irrigation or rainfall conditions and soil moisture, an experienced farmer can achieve a yield of 4 tons/ha (3,569 lb/m/L).
In oilseed sunflower, in most cases, oil yields can range from 1 to 3 t/ha (892 to 22,677 lb/ha) in the absence of limiting factors. Record yields of up to 5.7 tons/ha (5000 lb m/ha) have been recorded in some areas (Toensmeier, 2016).
Most sunflower species complete their life cycle between 90 and 120 days after planting. Of course, this time can be significantly different depending on various factors (living and non-living stress, variety, etc.).
For this reason, the farmer must have another signal indicating the physiological maturity of the plants, which can be used as a harvest signal. The color change of the back from green to yellow and the bracts to brown usually indicates the physiological maturity of the sunflower.
This stage is called R-9 and occurs 30-45 days after flowering, in mid-autumn. The seed humidity at this stage is still high and is 35% (20-50%). From this point onwards, harvesting can begin, as no further increase in yield is expected.
On the contrary, the period between ripening and harvesting should be as short as possible, because there is a risk of crop reduction due to disease, bird damage or wet weather.
After maturity, the plants should be dried and the humidity of the seeds should be reduced. For this, some flower growers can use the first autumn frosts or use a dryer.
These products should not be used before the physiological maturity of the crop, as they may reduce yield and oil content. It is important to mention here that even with the use of a desiccant, the drying of the seed will be much slower than the drying of the whole plant.
In general, mechanized harvesting (combination) can begin when the moisture content is 18-20%. However, some farmers delay harvesting until seed moisture drops to 9.5% to allow for safe and quick storage. However, such low moisture carries the risk of cracking the grain (2).
Farmers should also consider the quality requirements of the commercial sunflower seeds they grow. For example, sweet sunflowers typically require 10% moisture, less than 1% sclerotia and dark roast, and a test weight of 155 g/0.5 L (approximately 25 lb/unit) in contract (4).
How to harvest sunflowers and minimize losses
Sunflowers can be harvested by hand or machine. Of course, the second option is the most common option, especially for commercial products. To do this, farmers can use combination headers designed specifically for sunflowers, or conventional full headers for threshing smaller grains such as wheat and soybeans (5).
There are a variety of cutting attachments available, many of which are designed like thugs that simply cut off the heads and remove as much of the stems as possible. A flat cutter mounted on a traditional straight blade can be used.
In order to minimize crop loss during mechanical harvesting, farmers must be aware of the factors that cause it and make adjustments accordingly.
Header loss when the product enters the device and
Loss of threshing and detachment. Below are some common combine settings that can help farmers reduce the risk of losses during harvest. Harvesting speed is around 3-5 mph and sunflower seed moisture, plant number, is adjusted accordingly.
For example, if the seed moisture is low, the controller must reduce its speed to prevent the stubble from falling. Sunflower seeds are lighter than other crops, so the wind speed must be reduced to prevent the seeds from flying out of the combine.
The bore should be wide open and the cylinder should be rotating normally between 250-400 rpm. Finally, 1/2″ to 5/8″ top plates and 3/8″ bottom plates are available.
Farmers should also keep in mind that sunflower seeds are lighter in weight and larger in size compared to smaller seeds, which affects transportation costs. For reference, the typical test weight for sunflower oilseeds is 28-32 pounds per unit, and US quality standards are even lower.
