Review of Sunflower Water Management Research.

Reports in the literature indicate that sunflower’s taproot grows to as much as 10 ft. deep below ground, which gives it the ability to extract water from a large volume of soil and hence withstand extended periods of drought. Greater soil water depletion was observed with standard height sunflower cultivars than with dwarf cultivars in western Canada. In NW Kansas, sunflower required 2.3 in. less irrigation than corn to meet crop ET. In NE Colorado, a 60% water saving was achieved when irrigation was applied at the R-4 (immature ray flowers visible) to R-5 (beginning of flowering) growth stages, compared to full irrigation. Seed and oil yields were equal or higher than those obtained with full irrigation in 2 out of the 4-yr of the study. In SW Colorado, full-season irrigation (FSI) produced the highest seed yield (2,715 lb/ac), oil content (43.8%), and plant height (44.8 in.) in 2012.  Irrigation from the beginning of the reproductive stage through flowering (R1-6) produced 2,397 lb/ac with 46% less irrigation water than FSI.  In 2010 and 2011, applying water mostly during flowering produced similar yields as with R1-6.  These and other studies demonstrate that substantial water conservation and use efficiency can be achieved with limited but targeted irrigation of sunflower.