CPPU treatment and pollination: Their combined effect on kiwifruit growth and quality

The influence of N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) on 'Hayward' kiwifruits was evaluated in the field under different pollination conditions: (a) natural pollination, (b) assist pollination and (c) absence of pollinators. Residue dynamics of CPPU on kiwifruit revealed that half life values in all treatments did not exceed 6 days, although in absence of pollinators the dissipation rate was reduced. At harvest, CPPU treatment increased the weight and the size only of pollinated fruits compared to untreated pollinated ones. Absence of pollinators resulted to more soften fruits with lower seed number and Ca2+ content, while CPPU application resulted additionally to misshapen fruits. No differences were detected on fruit total soluble solids, titrable acidity and ascorbic acid. In contrast, phenolics were higher on kiwifruits grown in absence of pollinators irrespective of CPPU treatment and antioxidant capacity was significantly lower only on untreated with CPPU fruits under assist pollination. These results suggest that (i) under good pollination conditions, CPPU indeed contributes to superior product quality of kiwifruits, and (ii) a strong influence of seed number on Ca2+ accumulation and phenolic content probably exists as indicated in the case of fruits grown under limited pollination conditions. (C) 2015 Elsevier B.V. All rights reserved.