As mentioned above, there is evidence in the literature that fruit size increases when Fe fertilization is carried out, therefore producing fruits with higher quality and better price. This has been shown to occur mainly in peach (Perez-Sanz et al, 1997; 2002; Sanz et al, 1997).
Factors affecting fruit quality other than fruit size have been mainly studied in Citrus spp. The first trials with Fe-EDTA in Florida already indicated that Fe fertilization in Fe-deficient Citrus trees improved fruit quality, increasing soluble solids and volume of juice per fruit, slightly decreasing titratable acid in the juice and improving fruit color (Sites et al., 1953). Increases in yields of Fe-deficient Citrus aurantifolia after soil and foliar Fe fertilization were associated with increases not only in fruit weight (30%) but also in juice contents (10%), and also to decreases in total acidity (10%), total soluble solids (25%) and ascorbic acid concentrations (10%), probably because of the dilution effect caused by a larger amount of juice per fruit (El-Kassas, 1984). Foliar Fe treatments repeated 10 times during the year (from August to February) increased the quality of March-harvested fruits in Citrus sp. through increases in fruit size and juice content and decreases in citric acid concentration, whereas total soluble solids increased significantly in tangerine (Pestana et al., 2000), but not in orange (Pestana et al., 2001b; 2002). These fruit quality improvements caused by Fe fertilization would mean a very significant 35-85% increase in gross income by the farmer (Pestana et al., 2000; 2001b). Soil Fe-EDDHA treatments applied from April to September at different frequencies increased somewhat the fruit quality of November-harvested Citrus clementina (Banuls et al., 2003). Treatments tended to increase juice contents, total soluble solids, total acidity and color index, although differences were not statistically significant.
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