Sunflower growing guide

Recommended types:

Starter Fertilization

Top dressing

1 Introduction

1.1.1 Global and National Importance

Worldwide Production: More than 50 million tons per year.
Main Productive Countries:
- Ukraine, Russia, Argentina, China, United States.
Greece:
- Approximately 1000 hectares are cultivated, with high concentration in Northern Greece.
- Greece is a major producer of biofuel feedstock in the European Union.

1.1.2 Uses of Sunflower

Transportation:

Use in the food industry (cooking oil, margarines).
Production of biodiesel as a renewable energy source.

Trace elements:

Use of the residue (sunflower pie) for protein-rich animal feed.

Trace elements:

Use of oil in cosmetic and dermatological products.

Trace elements:

Crop residues for energy production and soil conditioners.

1.2.1 Temperature Requirements

Minimum Growing Temperature: 6–8°C.
Optimal Growth Temperature: 20–26°C.
Maximum Strength: Up to 38–40°C, but with sufficient moisture in the soil.

1.2.2 Sunshine Requirements

Sunflower or sunflower requires 8–12 hours of sunshine daily for optimal growth.
High photosynthetic ability, especially in areas with intense sunshine.

1.2.3 Humidity Requirements

Resistant to drought due to deep-rooted system.
Sufficient moisture is needed during the critical flowering and filling stages of the seeds.
Sensitive to excessive moisture leading to fungal growth.

1.2.4 Cultivation Zones in Greece

Thrace (Evros, Rodopi): Ideal for biodiesel production due to large areas.
Macedonia (Serres, Kilkis): Suitable for high oil varieties.
Thessaly: Cultivation for animal feed and seed production.

1.3 Sunflower Cultivation Advantages

Transportation:

Yields up to 300–500 kg/acre of seeds.

Trace elements:

Suitable for areas with low rainfall.

Trace elements:

Secured production uptake through contracts with biodiesel companies.

Trace elements:

Use as a feedstock for biofuels and reduction of the environmental footprint.

Trace elements:

It improves soil structure and is incorporated into crop rotation with cereals or legumes.

2. Botanical Characteristics and Physiology

2.2 Radical System

Pallid and deep root system with main root reaching up to 2–3 meters deep, ensuring drought resistance.
lateral roots that increase nutrient and water absorption.

2.1.2 Shoot

Erect and strong, 1.5-3.5 meters high (depending on the variety).
Cylindrical and fluffy to protect against evaporative water losses.
It develops with directed growth towards light (heliotropism) in the early stages, while stopping this behavior during flowering.

2.1.3 Sheets

Large, cardioid (heart-shaped) with a rough texture and fluff that reduces moisture loss.
are placed alternately on the stem with long stems.
High chlorophyll content for effective photosynthesis.

2.1.4 Flower (Head)

The characteristic flower-head diameter of 15–30 cm consists of:
- Peripheral flowers (lingual): Sterile, to attract pollinator insects.
- Inner flowers (tubular): Fertile, produce pollen and seeds.
Heliotropism: The flower follows the course of the sun until flowering, improving production.

2.1.5 Fruit (Seed)

The seed is achene (dried fruit), contains:
- Outer pericarp (shell): Protects the sperm.
- Endosperm and germ: Rich in oils (35–50%).
Used for the production of oil, feed and food.

2.2.1 Growing Stage (0–10 days)

Root and cotyledon

growth.
Requires sufficient moisture and soil temperature of 8–10°C for rapid installation.

2.2.2 Leaf and Shoot Development Stage (10–40 days)

Rapid growth of shoots and leaves.
Creation of flower roots (heads).
Increased nitrogen (N) and phosphorus (P) needs for strong growth.

2.2.3 Flowering Stage (40–70 days)

Head

opening and flower fertilization.
Critical stage with maximum water and potassium (K) requirements for seed formation.
Sensitive to drought and nutrient deficiencies.

2.2.4 Seed Filling Stage (70–100 days)

The seeds grow and fill with oil.
Increased potassium (K) needs for transport of sugars and oils.
Nitrogen (N) confinement to avoid excessive vegetation.

2.2.5 Maturity and Drying Stage (100–120 days)

The shoot and leaves are dried.
The moisture of the seeds is reduced to 9–10% for harvesting.
Stage suitable for harvesting with sunflower harvesting machines.

2.3.1 Photosynthesis and Heliotropism

The heliotropic system during development improves photosynthetic performance.
During flowering, the stabilization of the flower optimizes pollen and fertilization.

2.3.2 Resistance to Drought and Water Adsorption

Deep root system for extracting water from greater depths.
Low water requirements during the early stages of development.

2.3.3 Nutrient Growth and Absorption Rate

Maximum phosphorus (P) absorption in the early stages for root development.
High potassium (K) requirements during seed maturation.

Nitrogen (N)

absorption throughout growth, but particularly until flowering.

3. Soil Preparation and Seeding

3.1.1 Suitable Soils for Sunflower

Light sandy loamy soils with good drainage.
Moderate soils that retain sufficient moisture without flooding.
Avoid heavy clay soils that prevent root penetration and drainage.

3.1.2 Ideal Soil pH

6.0-7.5 (neutral to slightly alkaline).
tolerance: Up to pH 5.5 using calcium (Ca) to improve the reaction.
Resistance to saline soils: Moderate tolerance to EC up to 3 dS/m.

3.2 Soil Preparation

Preparation

Steps:

Deep Tillage (Fall):

Depth 25–30 cm for breaking compressed mattresses and improving ventilation.

Trace elements:

Any plant residues are incorporated by ploughing , to increase the organic matter.

Treatment (Spring):

Creation of a thin and uniform seed-layer.

Application of Water Lubrication or Surface Lubrication:

Incorporation of phosphorus (P) and potassium (K) before sowing.

Leveling: (optional)

Ensure uniformity on the surface for better water distribution during irrigation.

3.3.1 Sowing season

Southern Greece: Late March – early April.
Northern Greece: Mid – late April.
Minimum Ground Temperature: 8–10°C for rapid vegetation.
Ideal Soil Temperature: 15–18°C.

3.3.2 Seeding Depth

3–5 cm in light soils.
2–3 cm in heavy soils or soils with high humidity.
Uniformity in seeding depth ensures simultaneous germination.

3.3.3 Planting Distances and Plant Density

Line Plant

Type of Cultivation	Spacing (cm)	Spacing (cm)	Plants/acre
Sunflower for Seed (Oil)	70–75	20–25	5,000-6,000
Sunflower for Animal Feed	60–70	15–20	7,000-8,000
Sunflower for Biofuels	70–75	20–25	5,000-6,000

3.4.1 High Yield Varieties

Oil Varieties:
- High oil content (40–50%).
Industrial Varieties:
- Resistance to mechanical harvesting and transportation.
Varieties:
- High biomass production for silage.

4. Lubrication and Nutrition

4.1.1 Importance of Balanced Lubrication

Proper lubrication management ensures:

Optimal root and shoot development.
Increased seed production and oil content.
Resistance to drought and disease.
Better use of soil in dry or poor areas.

4.1.2 Special Nutrition Characteristics of Sunflower

Transportation:

It takes advantage of the deeper layers of the soil, absorbing residual nutrients.
It withstands dry conditions but requires continuous nutrient adequacy.

Potassium (K):

Critical for the transport of sugars and seed growth.
Increases the percentage of oil in seeds.

Boron (B):

Necessary for fertilization and formation of heads.
Low concentrations of boron cause gaps in the seeds.

4.1.3 Lubrication Strategy by Development Stage

DevelopmentStem and Leaf Seed Oil Seed

Stage	Main Nutrition Needs	Essential Nutrients
Sprouting and Root Growth	Development of a strong root system and first leaves.	Phosphorus (P), Nitrogen (N)
Growth	Rapid biomass growth and head formation.	Nitrogen (N), Potassium (K)
Flowering and Fertilization	Flowering and fertilization for seed formation.	Boron (B), Potassium (K), Nitrogen (N)
Fill	storage and seed weight gain.	Potassium (K), Phosphorus (P)
Maturation	Stabilization of production and improvement of oil quality.	Potassium (K), Magnesium (Mg)

4.1.4 Nutrient Intake Rate

60-70% of nitrogen (N) is absorbed before flowering.
80% of phosphorus (P) is required in the first 40–50 days of growth.
70-80% of potassium (K) is absorbed during the seed filling stage.

4.1.5 Treatment of Nutrition Problems

Nitrogen (N):

Pigmented leaves, limited growth and small heads.
Solution: Basic and superficial application in doses.

Phosphorus (P):

Delayed root development and reduced flowering.
Solution: Integrate P into soil preparation.

Potassium (K):

Low oil quality and plant lying down.
Solution: Gradual application of K during cultivation.

Boron (B):

Formation of empty seeds on the heads.
Solution: Foliar application B before flowering.

4.2.1 Nitrogen (N)

Role of Nitrogen in Sunflower:

A key component of chlorophyll and proteins.
Enhances vegetative growth and photosynthesis.
Promotes the formation of heads and the growth of biomass.
Affects the oil content in seeds.

requirements:

Development Application Nitrogen Imbalance

Stage	Dose (kg/acre)	Objective
Basic Application (Before Seeding)	5–7	Enhancement of radical growth and germinal organs.
Surface (40–50 days)	4–5	Support flowering and head growth.
Final Application (70–80 days)	2–3	Supporting seed filling without excessive germination.

Problems:

Deficiency (N): Old leaf
- chlorosis and reduced head growth.
- Smaller seeds and low oil yield.
Excess (N):
- Excessive leaf growth to the detriment of the seeds.
- Delay in maturation and increased risk of disease.

4.2.2 Phosphorus (P)

Role of Phosphorus in Sunflower:

It enhances the growth of the root system and the plant’s establishment.
Important for Energy Transfer (ATP).
Promotes fertilization and fruit setting.
Enhances disease resistance and color quality.

Requirements:

Development Application Root Phosphorus Imbalance

Stage	Dose (kg/acre)	Objective
Basic Lubrication (Before Seeding)	3–5	development and early shoot support.
Surface (20–30 days)	2–3	Support growth and flowering.

Problems:

Deficiency (P):
- Delayed root growth and small plants.
- Poor fertilization and reduced seed percentage.
Excess (P):
- Reduction of the absorption of zinc (Zn) and other trace elements.

4.2.3 Potassium (K)

Role of Potassium in Sunflower:

Enhances seed quality and size.
Improves sugar transport and oil content.
Increases drought resistance and disease resistance.
Regulates water management in the plant.

requirements:

Development Application Seed filling Potassium Imbalance

Stage	Dose (kg/acre)	Objective
Basic Lubrication (Before Seeding)	6–8	Steady growth and formation of heads.
Surface (50–70 days)	4–5	support and oil augmentation.

Problems:

Deficiency (K):
- Reduced quality and quantity of seeds.
- Poor drought resistance and disease susceptibility.
Excess (K):
- Limited absorption of calcium (Ca) and magnesium (Mg).

4.2.4 Secondary Nutrients (Mg, S)

1. Magnesium (Mg):

- Role: Chlorophyll synthesis and photosynthesis.
- Dose: 1–2 kg/acre with chelations.

- Deficiency: chlorosis of old leaves.

Calcium (Ca):

Role: Protein synthesis and resistance enhancement.
Dose: 1–2 kg/acre with chelations.
Deficiency: Yellowing of young leaves and reduction of production.

4.3.1 Basic Lubrication (Before Seeding)

Target:

Support the initial growth of roots and shoots.
Provide nutrients that do not move easily in the soil (P, K).

Nutrient	Dose (kg/acre)	Method of Application
Nitrogen (N)	5–7	Integration by ploughing or in the seeding line.
Phosphorus (P₂O)	4–6	Incorporating 5–7 cm below the seeding line.
Potassium (K₂O)	6–8	Application to soil with integration for even distribution.
Boron (B)	0.2-0.3	Addition in granular form or foliar application.

Note:

In poor soils or areas with low organic matter, it is recommended to add organic fertilizers or compost to improve soil structure.
In acidic soils, the application of lime (CaCO ①) can adjust the pH to the desired range.

4.3.2 Surface Lubrication (During Growth)

Target:

Support vegetative growth and flowering.
Maintaining high levels of potassium and nitrogen for photosynthesis and nutrient transport in seeds.

Stage	Nitrogen (N)	Potassium (K₂O)	Special Applications
20–30 days (germination)	3–4 kg	2–3 kg	Foliar application of Zn (150–200 g/acre).
40–50 days (Flowering)	4–5 kg	4–5 kg	Addition B (100–150 g/acre) for fertilization aid.
60–70 days (Seed Formation)	3–4 kg	4–5 kg	Application S (100–150 g/acre) for oil quality.

Special Recommendations:

Nitrogen (N) is applied in 2–3 doses to reduce losses.
Potassium (K) is maintained at high levels, especially during flowering and seed filling.

Foliar applications of microelements (Zn, B)

proposed.

4.3.3 Fertilization Program for Seed Maturation

Target:

Supporting the ripening of seeds and improving the quality and quantity of oil.
Enhancing resilience to environmental stress and disease.

Stage	Nitrogen (N)	Potassium (K₂O)	Special Applications
80–90 days (Seed Filling)	2–3 kg	3–4 kg	Enhancement with Mg (200–300 g/acre) for photosynthesis.
100–110 days (Maturation)	1–2 kg	2–3 kg	Addition S (100–150 g/acre) for oil stabilization.

4.3.4 Foliar Nutrition and Corrective Applications

Boron (B):

Dose: 100–150 g/acre before flowering.
Objective: To enhance fertilization and avoid gaps in seeds.

Phosphorus (P):

Dose: 150–200 g/acre in the leaf growth phase.
Objective: Development of roots and shoots.

Μαγνήσιο (Mg):

Dose: 200–300 g/acre during ripening.
Objective: Support photosynthesis and carry sugars.

Calcium (Ca):

Dose: 100–150 g/acre at critical stages (flowering, ripening).
Objective: Stabilize oil production.

4.4.1 Role and Functions of Microelements

1. Boron (B):

- Function:
  - Promotes fertilization and seed formation.
  - It contributes to the transport of sugars and the growth of cell walls.

Deficiency

Symptoms:
- Gaps in the head seeds (infertilization).
- Deformed leaves and delayed growth.
Dose and Application:
- Foliar: 100–150 g/acre before flowering.
- Basically: 0.2-0.3 kg/acre in soils poor in boron.

2. Zinc (Zn):

- - - Involved in the synthesis of enzymes and the production of auxins for the growth of shoots.
    - Function:
  - - Regulates photosynthesis and protein production.

Symptoms of Deficiency:
Bleaching on young leaves and limited shoot growth.
Poor fertilization and smaller heads.
Dose and Application:
- Foliar: 150–200 g/acre during germination.
- Fertilization: Add 0.5-1 kg/acre.

2. Magnesium (Mg)

Function:
- Main element of chlorophyll for photosynthesis.
- Supports sugar transport and oil composition in seeds.
Deficiency symptoms:
- Yellowing between nerves in older leaves.
- Poor oil quality and reduced head growth.
Dosage and Application:
- Foliar: 200–300 g/acre as magnesium sulfate.
- Dose: 1–2 kg/acre with chelations.

2. Sulphur (S)

- Role:
  - Enhances rooting and flowering.
  - Improves drought resistance and seed quality.

Deficiency

Symptoms:
- Yellowing of younger leaves.
- Degradation of seed quality and reduction of oil content.
Dose and Application:
- Foliar: 100–150 g/acre in flowering stages.
- Dose: 1–2 kg/acre with chelations.

4.4.2 Foliar Nutrition – Implementation Schedule

Foliar nutrition offers immediate deficiency correction and supports critical growth stages such as flowering and seed filling.

Development Root and leaf Fertilization

Stage	Trace Elements and Dosages	Target
20–30 days (germination)	Zn: 150–200 g/acre, Mg: 200–300 g/acre	growth.
40–50 days (Flowering)	B: 100–150 g/acre, S: 100–150 g/acre	enhancement and stress resistance.
60–70 days (Seed Filling)	K: 3–4 kg/acre, Mg: 200–300 g/acre, S: 100–150 g/acre	Increase in weight and oil content.

4.4.3 Benefits of Foliar Nutrition

Immediate absorption: Nutrients enter the cells directly.
Correction of Deficiencies: Improves growth during critical phases.
Combination with Plant Protection: Reduces costs, as it is applied together with pesticide sprays.
Improvement: Increases oil percentage and seed uniformity.

5. Irrigation and Water Management

5.1 Water Requirements and Drought Sensitivity

Total Water Consumption: 400–600 mm/growing season.
Critical Irrigation Stages: Stem
- Growth (20–40 days): Support of vegetative growth.
- Flowering (40–60 days): Maximum requirements for fertilization.
- Filling (60–90 days): Increase weight and oil content.
Resistance:
- Good resistance due to deep root system (up to 2–3 m).
- Sensitive to drought during flowering, affecting fertilization and yield.

7. Harvesting and Storage

7.1 Harvest Time

Determination of Harvest Time:

is ready for harvest when:
- The leaves are dried and detached.
- The heads are facing downwards (characteristic “ripening slope”).
- The seeds have hardened and their moisture has been reduced to 9–12%.

Environmental Benefits:

Addition of compost or manure.
Increase of moisture in seeds and growth of fungi (e.g. Alternaria).
Reduction of oil quality due to oxidation.

7.3 Seed Preparation and Drying

Transportation:

Ideal harvest humidity: 9–12%.
At higher humidity, drying is required to prevent fungal growth.

Environmental Benefits:

temperature: 40–45°C to maintain oil quality.
Avoiding overheating that can reduce the oil content.

7.4 Seed Storage

Transportation:

Moisture: <9% for long-term storage.
Temperature: <20°C to prevent the growth of insects and fungi.
Ventilation: Maintain low humidity and avoid condensation.

Environmental Benefits:

Use of insecticides or natural methods of disinfection.
Regular check for the presence of insects (e.g. moths).

Ποιοτικός Έλεγχος:

Measurement of oil content (>40%).
Check the acidity of the oil to avoid degradation.