Pre-anthesis CPPU low dosage application increases ‘Hayward’ kiwifruit weight without affecting the other qualitative and nutritional characteristics J.G. Cruz-Castillo a , A. Baldicchi b , T. Frioni b , F. Marocchi c , S. Moscatello d , S. Proietti d , A. Battistelli d,⇑ , F. Famiani b,⇑ a Centro Regional Universitario Oriente, Universidad Autónoma Chapingo, Huatusco, Veracruz, Mexico b Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy c APOFRUIT, Aprilia, LT, Italy d Istituto di Biologia Agroambientale e Forestale, CNR, Porano, TR, Italy article info Article history: Received 21 October 2013 Received in revised form 28 January 2014 Accepted 31 January 2014 Available online 12 February 2014 Keywords: Actinidia deliciosa Ascorbic acid Carbohydrates Cytofex Citric acid Forchlorfenuron Kiwifruit storability KT-30 Malic acid Oxalic acid Prestige abstract In 2008, in Central Italy, a low dosage of CPPU solution, 4 lLL À1 (6 hL/ha), was sprayed on the canopy of vines of ‘Hayward’ kiwifruit, at the ‘‘break of sepals’’, about one week before anthesis, to study its effects on fruit weight/size and on qualitative and nutritional characteristics. At harvest, CPPU, with respect to control, significantly increased the fresh weight by about 12% (+ 12.6 g fruit -1 ) and consequently the yield per vine, without affecting fruit shape, firmness, dry matter (%), total soluble solids, glucose, fructose, sucrose, starch, citrate, malate, vitamin C and soluble and insoluble oxalic acid. After 3 months of storage, CPPU-treated kiwifruits and the control fruit showed no difference in dry matter content, fruit firmness and total soluble solids. The results indicate that a low dosage of CPPU applied in pre-anthesis can improve fruit weight/size without any negative effect on fruit qualitative and nutritional characteristics. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction To reach the best quality by harvest time, ‘Hayward’ kiwifruit must attain a relatively large size, a good shape, high concentra- tions of carbohydrates and vitamins, a low content of oxalic acid and a good balance between soluble sugars and organic acids, which is responsible for its taste. These fruit parameters depend on suitable management of cultural practices, such as pollination, fruit thinning, irrigation and pruning (Costa, 1999; Cruz-Castillo, Woolley, & Famiani, 2010), and can also be affected by girdling and the application of bioregulators (Famiani, Proietti, Pilli, Battistelli, & Moscatello, 2007; Woolley & Cruz-Castillo, 2006). Among the others, fruit weight/size and dry matter content are the main parameters to grade kiwifruit (Famiani et al., 2012). Therefore, practices which allow to increase the weight of the berry without negative effects on its dry matter content are desirable in order to improve its commercial value. In the last twenty years, it has been demonstrated that with the use of the bioregulator CPPU, which is a synthetic cytokinin of the phenylurea group, it is possible to add 10–30 extra grams to each fruit at harvest in well managed kiwifruit orchards (Costa, 1999). Also other bioregulators, such as Benefit Ò (Woolley & Cruz-Castillo, 2006), Thidiazuron (Famiani, Battistelli, Moscatello, Boco, & Antognozzi, 1999; Famiani et al., 2002), 2,4-D (Famiani et al., 2007) and Maxim Ò (Bregoli, Fabbroni, Raimondi, Masia, & Costa, 2007) can increase the size of kiwifruit, but CPPU has been the most used and studied. This bioregulator is commercially known as forchlorfenuron, Prestige, Cytofex or KT-30, and when mixed with natural bioregulators, it is known as Agromil-Plus Ò . The com- mercial use of CPPU for kiwifruit production is legally allowed in Chile, Italy, Japan and the USA. The mechanism of CPPU for enhanc- ing kiwifruit size seems to be related to increase in the level of http://dx.doi.org/10.1016/j.foodchem.2014.01.131 0308-8146/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding authors. Tel.: +39 0755856254 (F. Famiani). E-mail addresses: alberto.battistelli@ibaf.cnr.it (A. Battistelli), franco.famiani@ unipg.it (F. Famiani). Food Chemistry 158 (2014) 224–228 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem