Sunflower Farming in South Africa: Strategies to Combat Drought and Heat Stress

Article published on Farmers Magazine on 4 December 2025

Sunflower farmers in South Africa face increasing challenges from drought, heat, and other environmental stresses that threaten yield and oil quality. Pannar agronomists support farmers by combining research, field trials, and expert advice to optimise hybrid selection and planting strategies, helping them maintain productivity under variable climate conditions.

Corné van der Westhuizen, a product agronomist with Pannar Seed’s Western production region, brings 20 years of experience to the field. He explains that modern farming demands more than good seeds. Farmers must make informed decisions about hybrids and planting times to manage abiotic stresses effectively. “These decisions are crucial to maintain yield and oil content,” he notes, emphasizing the growing impact of climate variability on sunflower production.

Abiotic Stress and Its Impact on Sunflowers

Van der Westhuizen defines abiotic stress as non-living environmental factors such as drought, heat, and low humidity. These stresses affect sunflower morphology and physiology by reducing cell division, leaf area index, and photosynthesis, ultimately lowering grain yield and oil content.

“Sunflower (Helianthus annuus L.) is a versatile crop in South Africa, valued for its high oil and protein content. Its deep-rooted growth habit allows moderate drought tolerance, providing farmers with reliable yield and quality under challenging conditions,” he explains.

The primary abiotic stresses impacting sunflowers occur during sensitive stages such as flowering and grain-filling. Drought, heat, and low humidity disrupt nutrient uptake, photosynthesis, and overall plant development. “Prolonged or severe stress can significantly reduce productivity and oil quality, even though sunflowers are moderately drought-tolerant,” says Van der Westhuizen.

Managing Heat Stress and Drought

Drought and heat lower the plant’s relative water content, triggering stomata closure. This reduces CO₂ uptake and transpiration, leading to chlorophyll degradation, pale leaves, and decreased photosynthetic efficiency. Reduced leaf area index further limits the plant’s capacity to produce energy, resulting in lower grain yield, grain weight, and fewer seeds per head.

Effective management focuses on hybrid selection and planting date. Choosing locally adapted hybrids and planting to avoid peak stress periods can improve yield stability and oil quality. These strategies address the Genotype x Environment x Management (GxExM) interaction, reducing crop exposure to stress during critical growth stages.

By combining expert guidance, field-tested hybrids, and carefully timed planting, South African sunflower farmers can mitigate the effects of drought and heat stress. These practices help safeguard productivity, ensure high-quality oil, and maintain the crop’s economic value despite increasingly challenging environmental conditions.