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Seeds of Nates carrot cultivar were sown on plots and furrows, then plants were sprayed twice after thinning and once more at the commencement of root swollen after 3 months by naphthalene acetic acid (NAA) at rates of either 0, 20, 30 or 40 mg. l-1, to improve growth, yield and yield quality of carrots irrigated whenever 25% of soil available water capacity (AWC) is depleted to a depth of 25 cm. Results revealed that carrots under both cultivation required 175.5 mm supplementary irrigation in addition to 254.3 mm rainfalls. 30mg. l-1 appeared to be the most potent NAA applied rate as it gave the highest root marketable yield (13.6 kg. m-2) in relation to other rates. Marketable yield responses to varying NAA rates are governed by the following cubic equation:(yield kg. m-2= 9.8125–0.909406 (NAA rate)+ 0.066172 (NAA rate)** 2–0.0010498 (NAA rate)** 3). The highest marketable yield (15.8 kg. m-2) was found in plot cultivated carrot plants sprayed with NAA rate of 30mg. l-1.