Effect of soil water stress on water economy and oil composition in sunflower (<i>Helianthus annuus</i> L.)

Abstract

SUMMARY In a field experiment sunflower plants were subjected to soil water stress (SWS) at — 15 bar during stages of slow elongation, rapid elongation, flowering and ripening. Significant decreases in yield, 100-seed weight and oil content were found as a result of SWS. The treatment resulted too in less evapotranspiration and a better water economy for production of seeds and oil. The iodine value but not the acid or saponification values of the oil was affected by SWS. No qualitative differences in oil composition occurred at different treatments. However, percentage of oleic acid was higher than that of linoleic acid; SWS resulted in a clear tendency for an increase in the ratio of oleic/linoleic acids especially for plants subjected to SWS during elongation stage. Sunflower plants were more sensitive to SWS during the elongation and flowering stages than during ripening stage