This research was conducted at the State University of Maringa, Umuarama Campus, Parana State, in the season 2008/2009, with the objective to evaluate the growth and irrigation use efficiency on yield of grain, oil and dry weight of sunflower under irrigation levels. In the irrigated treatments (L1, L2, L3 and L4) the crop coefficients (kc) used were equal (L2), below (L1) and above (L3 and L4) those proposed by FAO. The irrigation favored the crop growth and the highest yield was obtained from values of kc 100% above those proposed by FAO (L4). The highest irrigation use efficiencies were obtained from values of kc by FAO (L2). The grain yield without irrigation (L0) was equal to 4788 kg ha-1, while in L2 and L4 treatments, grain yields were equal to 6304 and 6963 kg ha-1, respectively. The irrigation did not increase the oil content and oil yield was proportional to grain yield.
crop coefficients; irrigation levels; Helianthus annuus L.
