Accumulation dynamics of dry matter, oil and major fatty acids in sunflower seeds in relation to genotipe and water regime

Water availability is one of the agronomic factors that can influence the production and quality of sunflower oil. For this reason, a trial was done in southern Italy to study the effects of different water regimes (0, 33, 67 and 100% of ETm replacement) on dry matter and oil accumulation in the seed of a standard and an oleic sunflower hybrid. METHODS. The changes in dry matter, oil and major fatty acids in the seeds were defined by functional analysis and calculating their accumulation rates. RESULTS. Dry matter, oil and oleic acid contents were higher in the three irrigated treatments than the rainfed one. The irrigated treatments differed only at the intermediate ripening phase, with values increasing from the most stressed treatment to that better supplied. Differences in the accumulation rate of linoleic acid were less marked. The intermediate water regimes, independently of genotype, determined a more marked intensity of initial increase but also the sharpest decrease. In comparison, the initial seed growth levels of the two extreme treatments were more than halved and the most sustained accumulation rate was measured in the intermediate seed filling phase. The accumulation rate of oil and oleic acid was similar to that of the dry matter, while that of linoleic acid clearly differed. The variability in dry matter and oil accumulation caused by genotype was fairly insignificant in comparison to that of water regime. Variations on the oleic acid accumulation determined by the two studied factors were instead, similar, whereas genotype was the most important source of variation for linoleic acid. CONCLUSION. The trial provided useful results to add to the basic knowledge on the subject. The interaction effect between the two studied factors on the content of the two major fatty acids also gives the possibility of being able to programme, within determined limits, the quality of the raw material intended for industry.