Influence of soil tillage and Phoma macdonaldii on sunflower (Helianthus annuus L.) yield and oil quality

Plant yield and oil content determine sunflower production. Those plant production determinants depend in turn on the plant environment interaction. In the South West of France, there have been recent advances in soil tillage. To date, 35% of the soil surface dedicated to sunflower is cropped under a reduced tillage system. Major constraints to sunflower cropping are water stress and cryptogamic diseases. The second most important sunflower disease in the South West of France is premature ripening caused by Phoma macdonaldii. Aims of this work were to: 1) understand how these factors influence sunflower yield, and 2) quantify the fatty acid quality variation under reduced tillage and Phoma macdonaldii infection. Results showed that 1) soil tillage influences sunflower oil fatty acid composition, 2) Phoma macdonaldii-induced premature ripening impacts plant nutrition through its effects on organs (leaves, stems, roots), yield and yield components, and 3) the disease influenced oil quality and the balance oleic-linoleic fatty acids.