Oil Yield Components and Oil Quality of High Stearic-High Oleic Sunflower Genotypes As Affected by Intercepted Solar Radiation During Grain Filling.

Intercepted solar radiation per plant during grain filling affects yield and oil fatty acid composition of traditional sunflower genotypes. It is unknown if this response is similar in high stearic high oleic sunflower genotypes. This information is necessary for the crop management and the prediction of the behavior of these new genotypes in different environments. The aim of this work was to assess the effect of intercepted solar radiation per plant during grain filling on yield components and oil fatty acid composition of high stearic high oleic sunflower genotypes. Three field assays were carried out in Balcarce (37°S, 58°O), Argentine, with three high stearic high oleic sunflower genotypes. During grain filling, plants were subjected to 80% shading treatment, 50% thinning and a control. Weight per grain, grain number per plant, oil percentage (NMR) and oil fatty acid composition (GLC) were determined. The oil yield components were directly related with intercepted radiation per plant during grain filling. Reductions in intercepted solar radiation per plant reduced the palmitic, stearic and oleic acid percentages and increased the linoleic acid percentage. The total amounts of palmitic, stearic and oleic synthesized per grain (mg grain-1) were reduced by shaded treatments. However, the amount of linoleic acid per grain was not affected by radiation treatments. Probably, a minimum amount of linoleic acid per grain is needed for the seed to be viable and germinate. These results show that agronomic practices or environmental conditions that modify the interception of radiation per plant during grain filling could affect the oil yield and the oil fatty acid composition of high stearic high oleic sunflower genotypes. If we maximize the radiation intercepted per plant during grain filling we will ensure that the oil fatty acid composition of this genotypes can fall into the established marketing standards for such quality.