Oranges are a rich source of bioactive compounds with recognized benefits for human health. To guarantee high quality and production levels, citrus farms usually employ the combination of selected cultivars with well adapted rootstocks. This study analyzes the impact of four different citrus rootstocks (Forner-Alcaide no.5, ‘Cleopatra mandarin’, Citrus volkameriana and Carrizo citrange) on the bioactive compounds and antioxidant activity of two orange cultivars (‘Salustiana’ and ‘Sanguinelli’) widely used in the orange juice industry. For the hydrophilic fraction, the phenolic compound, anthocyanin, and organic acid profiles were determined by HPLC-DAD-HRMS, and the antioxidant activity by ABTS, DPPH, and ORAC assays. Besides, the total carotenoids and ABTS concentrations were calculated for the hydrophobic fraction. A set of three flavanones, one flavone, and eight anthocyanins were tentatively identified and quantified in the orange cultivars tested. The predominant phenolic compounds obtained in both orange cultivars were hesperidin and narirutin, while cyanidin-3-O-(6″-malonyl) glucoside followed by cyanidin-3-O-rutinoside and cyanidin-3-O-glucoside were the main anthocyanins found in the ‘Sanguinelli’ cultivar. Citric acid, followed by malic, oxalic, and ascorbic acids were the main organic acids. The higher amount of antioxidant compounds was found in fruit from the Forner-Alcaide no.5 rootstock. These results indicate that Forner-Alcaide n.5 affects positively the phenolic and organic acid composition and the antioxidant capacity of ‘Sanguinelli’ and ‘Salustiana’ cultivars, and is therefore a good option for the sector based on the healthy promoting properties.

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The Mediterranean Basin is the second highest citrus growing region in the world behind China. Citrus trees are known to produce several flush shoots per year, particularly during the spring–summer season. Farmers endeavor to reduce the growth of summer shoots by means of hand pruning, especially those located at the top of the tree, as most of these shoots become vigorous, nutrient consuming, non-productive, and attractive to several pests. Furthermore, hand pruning substantially increases the costs of citrus orchards production. This research was therefore intended to study new different treatments to control spring–summer flush shoots and thus reduce growers’ investments in citrus production. Six different treatments were applied in two experimental and high density orange orchards over two consecutive years: (1) control; (2) topping (mechanical pruning); (3) dichlorprop-p; (4) triclopyr; (5) topping + dichlorprop-p; and (6) topping + triclopyr. The treatment of dichlorprop-p alone reduced the number of summer young shoots in both years. Moreover, these applications did not negatively affect yield or fruit quality. These mechanical methodologies help citrus growers manage the density of flush shoots and reduce hand labor costs in citrus orchards.

The genus Citrus amounts to one of the most relevant fruit crops in the world. This work assays overall fruit quality information in order to ascertain the optimal harvest timing of three late-season orange cultivars (‘Barberina’, ‘Valencia Midknight’ and ‘Valencia Delta Seedless’) during two consecutive growing seasons. Thus, morphological and physicochemical parameters, organic acids, polyphenolic content and antioxidant activity (ABTS and DPPH) were analyzed. ‘Barberina’ yielded the highest morphological (large and heavy fruits, albeit with lower fruit color index) and physicochemical (high juice content and intermediate but optimal acidity) fruit quality, with April providing the optimal harvest timing. By contrast, ‘Valencia Delta Seedless’ offered the smallest fruits, while ‘Valencia Midknight’ reported the lowest physicochemical juice quality (low juice content and earlier sensory depreciation). Nevertheless, both ‘Valencia Delta Seedless’ and ‘Valencia Midknight’ had higher functional quality than ‘Barberina’, which could be interesting for the industry in terms of obtaining higher added value products. Thus, ‘Valencia Midknight’ fruits recorded the highest organic acids concentration, especially in citric acid, while ‘Valencia Delta Seedless’ fruits showed the highest antioxidant activity and ascorbic acid concentration. In addition, while March-April emerged as the optimal harvest timing in terms of the highest organic acids concentration and antioxidant activity, it was February the optimal harvest timing for polyphenols content. Finally, the 2017/2018 growing season proposed better response of color index, density, polyphenols and antioxidants, but lower results of total organic acids.

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