Impact of pedoclimatic and agricultural conditions on sunflower seeds characteristics in relation to the dehulling process

Dehulling sunflower seeds can increase meal protein content by up to 35-36%. However, high variability in seed quality constitutes an obstacle to optimizing the dehulling process. This study has sought to identify the parameters that influence the protein content of sunflower seeds and the ease with which they can be dehulled. Genetic, climatic and crop management effects were studied using seed samples taken from farmers' fields in south-west France. Soil and climatic effects were revealed to be important for protein content and ease of dehulling (hullability). Some cultivars were found to be significantly more difficult to dehull than others. No relationship was observed between oil content and protein content expressed as a proportion of DDM (defatted dry matter), but there was a significant negative linear relationship between hullability and oil content. Due to the wide range of locations and agricultural practices encountered in the farmers' fields, it was not possible to verify with confidence the influence of other interactions such as nitrogen fertilization and the potential fertility of the fields. This work nevertheless showed that locality and growing conditions affect the quality of sunflower seeds. This variability in quality could be measured by crushers in order to optimize the dehulling process and thereby produce a meal of consistent quality, with a guaranteed protein content.