WATER STRESS MANAGEMENT FOR SUNFLOWER UNDER HEAVY SOIL CONDITIONS
An experiment was performed for two seasons to test the impact of water stress and drip irrigation lateral arrangements on yield and water productivity of the sunflower crop (seed and oil). Water stress treatments were Full crop evapotranspiration 100% ETc (FI100), 80% ETc (DI80), 60%ETc (DI60) and 100-60 % ETc (DI100-60). The DI100-60 treatment was applied as 100 % ETc up to seed formation then reduced to 60% ETc. The drip irrigation lateral arrangements were single planting row per one drip line with 2 L h-1 drippers (T1) and double planting rows per one drip line with 4 L h-1 drippers (T2). Results revealed that applying water stress by either DI80 or DI100-60 produced almost the same or more yield of sunflower seeds and oil than that obtained from full irrigation FI100, besides saving about 20% of irrigation water. These two water stress treatments maximized water productivity (WUE). The highest seed yields were 4.51 and 4.34 Mg ha-1 obtained from T1 and T2 under DI100-60 respectively. The oil yield values were taken the same trend as seed yield. Accordingly, it could be recommended that irrigating row crops such as sunflower under clay soil conditions could be done by using one lateral line of 4 L h-1 drippers per two planting rows and applying DI80 or DI100-60 water stress strategy, leading to increase seed and oil yield, maximizing water productivity, reducing the cost of drip lines by 50% and saving water by about 20%.