Impact of boron, calcium and genetic factors on vitamin C, carotenoids, phenolic acids, anthocyanins and antioxidant capacity of carrots (Daucus carota).

Carrots (Daucus carota L.) were used to investigate the effects and interactions of cultivar and mineral supply on the nutritional quality (antioxidant potential, vitamin C, carotenoids and phenolic acids) of the resulting storage roots. The supplement of boron (B) and or calcium (Ca) in the feeding solutions, during plant growth, influenced the accumulation of other minerals, such as P, K, Mg, S and Na, in the storage roots (p<0.05). When no additional B or Ca was supplied (e.g. -B or -Ca treatment), we observed 33-50% increase in the accumulated levels of α- and β-carotenes, and 45-70% increase of vitamin C. Carrots grown with no supplement of B in the nutrient solutions (e.g. -B treatment and -ve control) had significantly higher (p<0.001) levels of total phenolic acids compared to the carrots with the supplement of B (e.g. -Ca treatment and +ve control). A strong positive correlation was observed between the total phenolic contents and ORAC values (r=0.932) in all the cultivars. The results suggest that both cultivar and mineral supply were major determinants of nutritional quality of the carrots. The nutritional value of carrot crops (with an acceptable physical quality) can be enhanced by manipulating mineral nutrient applications.