EFFECT OF WATER STRESS AND POTASSIUM ON YIELD, YIELD COMPONENTS AND WATER USE EFFICIENCY IN SUNFLOWER

A field study was conducted at the experimental farm of Field Crop Department of College of Agriculture, University of Baghdad during two spring seasons 2011 and 2012. That was to study the effect of different irrigation and potassium levels in yield and yield components and water use efficiency of sunflower (Helianthus annuus L.) cv. Euroflore. A RCBD was used in the arrangement of a split-plot with three replications. Irrigation treatments: control treatment (a depletion of 50% of available water) and 75%, 50%, 25% of the water amount of the control treatment were assigned in the main plots while potassium levels (0, 60, 120, 180) kg K.ha(-1) were assigned in the sup-plots. Results showed that, the possibility of saving 25% from fall irrigation that was about 950 m(3).ha(-1) without significant reduction in seed yield when irrigation with 75% watering amount of the control treatment which gave 3.25 and 3.43 ton.ha(-1) in the first and second season respectively. However watering with 50% and 25% amount of water of the control treatment caused a reduction in seed yield reach an average (33.07 degrees A 36.95%) and (55.28 degrees A 51.74%) for two season respectively, and significant increase in water use efficiency by 1.08 and 0.90 , 1.16 and 1.03 kg seed/m 1 water in the first and second season respectively. The application of potassium significant increased all studied triats. Fertilization with 180 kg K ha -1 gave the height capitulum diameter(16.26 and 15.83), seed number per captiulum (823 and 922) seed, seed yield (2.92 and 3.14) ton.ha(-1), water use efficiency (0.92 and 1.08) kg seed/m(3) water for two season respectively. The results show that under water stress treatment specially I-4 the application of potassium significant increase from more traits ex. seeds yield, harvest index, water use efficiency more than in control treatment. That show too in all most studied traits was less in the second season than in the first season. It was concluded that application of potassium with 180 kg K.ha(-1) might mitigate the deleterious effect of water deficiency on sunflower productivity.