EFFECT OF WATER STRESS AND POTASSIUM FERTILIZATION ON SOME GROWTH TREATS OF SUNFLOWER

Abstract

A field study was conducted at the experimental farm of Field Crop Department, College of Agriculture, University of Baghdad during two spring seasons of 2011 and 2012, in order to study the effect of different irrigation and potassium levels on some growth traits, of sunflower (Helianthus annuus. L) variety Eurofloer by using Randomized Complete Block Design (R.C.B.D.) in the arrangement of a split-plot with three replications. Irrigation treatments: control treatment (depletion of 50% of available water), 75%, 50% and 25% of the water amount of the control treatment were assigned in the main plots while potassium levels (0, 60, 120 and 180) kg K.ha-1 were assigned in the sup-plots. Result showed that there was no significant difference between I1 (control treatment) and I2 irrigation treatment (75% of the watering amount of the control) in stem diameter , number leaf area , biological yield which means a 950 m3 amount of water per hectare could be saved in both seasons. Also the plants of these treatments gave the maximum amount of chlorophyll and relative water content. However I4 treatment watering (Irrigation of 25% amount of water of the control) gave the maximum amount of proline. The applications of potassium significant increase all growth traits. Fertilization with 180 kg K.ha-1 gave the highest high plant (139.05and 137.57) cm, Leaf area (3214 and 2743) cm2, chlorophyll content (42.58 and 36.09) mg.g-1 fresh weight, relative water content (78.82% and 78.01%), stem diameter (2.88 and 2.73) cm, biological yield (10.98 and 10.79) ton.ha-1 in both seasons. We therefore, recommend in the case of the limited possibility of irrigation water by 75% of the irrigation needs (50% depletion of available water) amount 345mm and possibility of applying K fertilizer 180 kg K.ha-1 to decrease negative effect of water deficiency.