Sowing, tips for good development
- Sowing: the sowing depth must be adapted to the water status of the soil:
- fresh seedbed: 2-3 cm
- dry soil on the surface: 3-4 cm (4-5 cm for non-sloping soils).
- Weather conditions: early sowing generally avoids early water stress at the flowerbud stage. Vegetation zero is around 6°C. The minimum soil temperature for germination is 4°C (the optimum temperature being 8°C at 5 cm depth). Germination must take place quickly after sowing and within 10 days later to avoid attacks by pests (wireworms, slugs, tanymecus,... ).
The cold resistance of sunflower varies according to the stage of development:
- Cotyledon stage: down to -5°C.
- From one leaf: down to 0°C with necrosis on the leaf but without causing the death of the plant.
- Soil: the taproot can reach a depth of 3m deep. This root particularity gives the plant great capacity to exploit water, nitrogen and mineral elements even in extreme situations. This is why the sunflower crop is very demanding in terms of structuring of the ground: a deep compaction could be an issue for a good implantation. These accidents can lead to a drop in the leaf area index, increased sensitivity to water stress and grain filling defects (low thousandkernel weight)...
Seedbed quality is also essential to achieve homogeneous emergence.
To prepare the seedbed:
- Give preference to favour non-powered tine tools.
- Work the soil in optimal drying conditions and limit the use of tools.
- Weed control: the false sowing technique can be an option but at least 1 month before the real sowing. It is recommended to apply herbicide at post-sowing or pre-emergence stage.
To know deeper, download our sunflower brochure: click here