CPPU application on size and quality of hardy kiwifruit

For the purpose of determining the appropriate conditions of application to increase the size of a hardy kiwifruit, Actinidia arguta ‘Mitsuko’, N₁-(2-chloro-4-pyridyl)-N₃-phenylurea (CPPU) was applied at three different growth stages of the crop: at petal fall, 10 and 25 days after petal fall (DAPF), and three different concentrations: 1, 5 and 10 mg l⁻¹. A significant increase in fruit size was obtained by treatment at the concentrations of 5–10 mg l⁻¹ and at 10 DAPF. The fruit weight doubled. Although a significant reduction in the concentrations of total soluble solids (TSS), titratable acids (TA) and ascorbic acid (AsA) in the CPPU-treated fruits was recorded, the TSS/TA ratio and AsA content per fruit increased by the treatment. CPPU application at petal fall induced abnormally protruding fruit tip.