engleski

The influence of mineral fertilizing on the yield components, polyphenols and antioxidant activity of sweet potatoes (Ipomoea batatas L.)

Sweet potato ia a perennial tropical plant which has recently been introduced into commercial production in Croatia. The aim of the research was to determine the influence of different mineral fertilization on the yield components, the concentration of polyphenols and the antioxidation activity of sweet potato. The fertilizing test in the field was conducted in 2008 and 2009 in Croatia and included two cultivars Boniato and Bat1, and mineral fertilization with three nitrogen-potassium ratios (1:1, 1:2.5 and 1:5). The yield components were determined on the basis of the root and leaf mass, as well as the share of larger root fraction. The analyses of the total quantity of polyphenols were conducted by means of UV/Vis spectrometric method, and the antioxidation activity by ORAC method. It was found out that the root mass of Boniato and Bat1 had increased by 18 % and 12 % at nitrogen-potassium ratio of 1:2.5 and 39 % and 41 % at the 1:5 ratio when compared to the control nitrogen-potassium ratio 1:1. More intesive fertilization resulted in a bigger portion of larger root fraction (the mass above 400 g) with both cultiuvars. Regardless of fertilization Boniato produced significantly larger mass of leaves (43 % to 120 %) then Bat1. Boniato root contained the total of polyphenols between 5.05-14.38 mg/g dry weight and the antioxidant activity ranging from 20.34 to 51.00 μmol Trolox equivalent/g dw, whereas the total polyphenols concentration in the root of Bat1 ranged from 2.30 to 16.08 mg/g dw, and the antioxidant activity from 9.26 to 73.03 μmol Trolox equivalent/g dw.

cultivar; nitrogen-potassium ratio; leaves; root

nije evidentirano