Sunflower (Helianthus annuus L) is currently the fourth largest oilseed crop in the world with a production of more than 50 million tons in 2024 (www.mordorintelligence.com/industry-reports/global-sunflower-market, 2024).

Sunflower seeds are processed for both industrial and food production, and therefore both the oil content and the seed yield are crucial. Thus, the economic total must be calculated thoroughly and is it necessary to find a good balance between a lower oil content with a higher yield, and a lower yield with a higher oil content. Oil content has nothing to do with the colour of the seed coat.

For successful edible oil production, it is important to use sunflower hybrids that produce high grain output per hectare. The aim is to produce as much oil per unit area as possible, and the oil yield per area is therefore the ultimate target in the cultivation of sunflower genotypes.

To effectively manage sunflower for oil production and oil quality, we need to understand the plant traits, agronomic and farming practices that affect oil yield. Sunflower seed oil is of high quality, but the oil’s composition can change when the crop is grown in different climates, more so than the sunflower genotype used.

There are several factors that affect the oil content in sunflowers and they determine the quantity and quality of the oil produced:

Genetic factors:

Different sunflower varieties have different abilities to produce oil. Some are specifically bred for a high oil content (such as oilseed sunflowers), while others are used for food or ornamental purposes. The genetic composition plays a large role in the percentage of oil that the seed contains.

Plant date:

The oil yield is greatly influenced by the year of planting, as well as the planting date. According to De la Vega and Hall (2000), the most important factor affecting the oil yield is the planting date. Earlier plantings appear to be favourable for better oil yields. In most cases, however, sunflower is planted as a replacement crop, for example after hail has destroyed another crop, or when other crops are not planted due to the lack of timely rainfall. This therefore causes sunflowers to be planted too late, which can lower the oil yield.

Environmental factors:

Temperature: Optimal temperatures during the development of sunflower seeds play an important role in the balance between oleic acid (monounsaturated fatty acid) and linoleic acid (polyunsaturated fatty acid) in the oil. Higher temperatures (above 25 °C) during the seed development phase promote an increase in oleic acid concentration, which contributes to the oil’s stability and health benefits. Linoleic acid, on the other hand, usually decreases at higher temperatures. Lower temperatures (below 25 °C) lead to a higher concentration of linoleic acid, but temperatures that are too low can negatively affect the total oil yield. Ideally, warm, but not too hot, temperatures (around 25 to 30 °C) during seed development promote a healthy balance between these two fatty acids, which is beneficial for both oil quality and oil yield.

Soil type and fertility: Nutrient-rich, well-drained soil with sufficient organic matter helps to get better oil yields. Nitrogen, potassium, and phosphorus are crucial for optimal growth and oil production.

Water availability: Adequate water, but not too much, is important. A shortage of water, especially during seed development, can reduce the oil content, while too much water can also harm the yield and quality of the oil.

Plant population:

Sunflowers that are planted in well-spaced rows at optimal quantities generally produce more oil. If sunflowers are planted too densely, they can compete for light, water, and nutrients, reducing oil production.

Exposure to sunlight:

Sunflowers require full sunlight for photosynthesis and energy, which supports seed development and oil accumulation. Lack of enough sunlight reduces the oil content due to insufficient energy supply.

Growth stage and harvest time:

The timing of the harvest plays a critical role. Seeds harvested too early may not have reached their full oil potential, while late harvest may lead to a decrease in oil quality because overripe seeds may break down.

Pests and diseases:

Parasite infestation can impair the health of sunflower plants, negatively affecting seed development and oil content. Healthy plants tend to produce more oil.

These factors work together, and good management of these factors is essential to maximise oil content in sunflower production.

For more information, contact Pioneer at info.rsa@pioneer.com or visit www.pioneer.com/za.