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Effect of growth regulators on kiwifruit (Actinidia spp.) quality in northern Italy

Granelli, G., Lo Scalzo, R., Eccher, T.
Acta horticulturae 2012 no.932 pp. 499-505
Actinidia, antioxidant activity, ascorbic acid, cold storage, color, cultivars, firmness, fruits, gels, growth regulators, kiwifruit, seedlings, soluble solids, sugar content, titratable acidity, Italy
Studies on the qualitative characteristics of kiwifruit, either following or not growth regulator treatments, has been carried out over four years: 2006, 2007, 2008 and 2009. The experiments used the most cultivated green-fleshed cultivar, 'Hayward' and two seedlings with yellow flesh, named P1 and P2. The growth regulators tested were: Pruning gel (α-naphtalenacetic acid), Maxim (3,5,6-trichloro-2-pyridyloxyacetic acid) and Spraydunger (α-naphtalenacetic acid and GA3). In all the years, at harvest, representative samples of 20 fruit for each treatment, including non-treated controls, were analyzed for the main quality parameters, such as weight, firmness, soluble solids content, titratable acidity and flesh colour. In 2006, 2007 and 2009 the same analyses were carried out also after cold storage. The main results were a significant increase of fruit weight in treated fruits, together with a concomitant decrease in sugar content and a decrease in quality after cold storage. Ascorbic acid, the main antioxidant present in kiwifruit, and the antioxidant capacity, measured by a DPPH assay, were measured on fruit from years 2006, 2007 and 2009. Generally, the amount of ascorbic acid and the index of antioxidant capacity, decreased in treated fruits with respect to untreated ones.