Carotenoid Accumulation by Carrot Storage Roots in Relation to Nitrogen Fertilization Level

Abstract

The accumulation of carotenoid compounds in carrot (Daucus carota L.) roots of five cultivars, in relation to different nitrogen fertilization levels was investigated. The experiment was carried out at the Warsaw University of Life Sciences. Carrot cultivars ‘Karotan’ F1, ‘Trafford’ F1, ‘Krakow’ F1, ‘Komarno’ F1 and ‘HY 7842’ were used in the study. Nitrogen fertilization was applied as urea form, in doses ranging from 0 to 120 kg N ha–1, and on two terms: pre-sowing and in the middle of the growing season. The carrot seeds were sown at the beginning of May and the roots were harvested in mid-October at maturity. Total carotenoids and β-carotene contents in the carrot roots were determined after the harvest by means of the standard spectrophotometric method. CIE L*a*b* colour parameters of the roots and the juice, as well as dry matter in the roots were determined. Results of the experiment showed that carotenoid accumulation in the roots was significantly affected by carrot genotype. ‘HY7842’ carrot showed the highest accumulation of total carotenoids and β-carotene. Nitrogen in the rates applied, did not significantly influence carotenoid content in the roots. Moderate correlation between carotenoid content and colour a* parameter (redness intensity) of the roots and the juice was found.