Strapping and a synthetic cytokinin promote cell enlargement in ‘Hiratanenashi’ Japanese persimmon

Abstract

The effects of N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) with and without strapping on fruit growth of ‘Hiratanenashi’ Japanese persimmon were evaluated by measuring parenchyma cell size and the number of cell layers in mesocarp throughout fruit development. Three-year-old branches were strapped with a wire 2 weeks before full bloom, and 10 mg l−1 of CPPU was applied to the fruitlet at 10 days after full bloom. CPPU alone prolonged the growth period, resulting in a larger fruit diameter at harvest than the control. Strapping promoted the fruit coloration and increased final fruit diameter. CPPU plus strapping shortened the growth period compared to CPPU alone, and the mature fruit diameter was similar to CPPU alone. The increases in fruit diameter caused by CPPU and strapping were involved with the increases in length of parenchyma cell. The number of cell layers was almost similar among the treatments. These results showed that strapping promotes the rate of parenchyma cell expansion, and CPPU with and without strapping prolong the duration of cell enlargement and promote the rate of the cell expansion.