Production and quality of carrot in function of split application of nitrogen doses in top dressing

ABSTRACT Fertilizers supply in the appropriate period and dose is important to obtain satisfactory production. In this research we studied the effect of different split applications and doses of nitrogen in top dressing on the production of the carrot and the physicochemical characteristics of the roots. Nine treatments, resulting from a factorial of 4x2+1 (control without nitrogen fertilization), were evaluated in the randomized blocks experimental design, with four replications. The first factor were four nitrogen (N) doses in top dressing (60, 90, 120 and 150 kg ha-1) and the second were two forms of splitting [three equal applications (1/3+1/3+1/3 of the dose) and one with increasing proportions (1/6+2/6+3/6 of the dose) applied 15, 30 and 50 days after emergence]. We evaluated shoot height, fresh and dry shoot weight, fresh and dry root weight, root diameter and length, yield and some physicochemical characteristics of roots (soluble solids, titratable acidity, maturation index, pH, carotenoid content and reducing sugars). For most of the studied characteristics were observed quadratic effects for N dose, with an estimated maximum yield of 117.7 t ha-1 for the dose of 138 kg N ha-1. The splitting 1/6+2/6+3/6 resulted in higher values for fresh weight of shoot and root, root diameter, yield and carotenoid content, compared to the splitting 1/3+1/3+1/3.