Carrots have favorable nutritional characteristics, containing antioxidant vitamins, carotenoids, and other bioactive micronutrients (Metzger and Barnes, 2009; Nicolle et al., 2004). Carrots are suitable basic material for the production of functional food products (Arscott and Tanumihardjo, 2010), mainly as a result of the high level of biologically active carotenoids. In orange carrots, β-carotene and α-carotene have been found dominant in different organic solvent extracts of such a crop (Baranski et al., 2012; Nicolle et al., 2004; Surles et al., 2004). In European countries, carrots contribute to 40% to 60% of β-carotene and from 80% to 90% of α-carotene intake from vegetables (O’Neill et al., 2001).
Beside the genetic factors, environment can substantially affect the carotenoid content in carrots. Warmer conditions usually result in a higher content of carotenes (Kaack et al., 2001; Tsukakoshi et al., 2009). Fikselová et al. (2010) found that irrigation and a larger amount of rainfall decreased β-carotene content of carrot.
Vegetables are not the main dietary sources of tocopherols; the richest sources are cereals and plant originated fats and oils (DellaPenna and Méne-Safranné, 2011). However, carotenoids and tocopherols share a common precursor [geranylgeranyl pyrophosphate (GGPP)] and because ofs being antioxidants, both have important roles within the human diet (DellaPenna and Méne-Safranné, 2011). Thus, from a nutritional point of view, the concentration and the composition of these two groups of phytonutrients are of specific importance. Genotypic effect on tocopherol content in carrot and on the relationship between carotenes and tocopherols has been investigated (Koch and Goldman, 2005; Nicolle et al., 2004) and parallel accumulation of these phytonutrients was found. We have hypothesized that water shortage, as a stress factor, may alter these correlations and the composition of carotenoids and tocopherols.
The objective of the present study was to investigate the effects of irrigation, compared with a rain-fed control, on the content and composition of carotenoids and tocopherols and on the relationship between them in an orange-colored carrot cultivar in 2 years with considerably different precipitation conditions.
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U.S. Dept. Agr. Agr. Res. Serv2011National nutrient database for standard reference. Release 26. 7 Dec. 2011. <ndb.nal.usda.gov> <ndb.nal.usda.gov/ndb/foods/show/2949?fg=&man=&lfacet=&count=&max=&sort=&qlookup=&offset=&format=Full&new=&measureby=>