UV Irradiance Increases Development of Red Skin Color and Anthocyanins in `Hakuho' Peach

The contribution of the UV light component on the skin coloration was determined in `Hakuho' peach. Detached fruit partially covered with a UV-proof polyvinylchloride (PVC) film and a polyethylene film were exposed to sunlight for 4 days. Red coloration of the fruit and anthocyanin content in the skin were considerably reduced with the UV-proof PVC film. Irradiation with a UV fluorescent lamp at 3.58 W·m -2 markedly enhanced the red color development, while white fluorescent light at 120 μmol·m -2 ·s -1 did not affect the coloration. UV irradiation also increased the anthocyanin content in the cultured skin discs with increasing irradiance up to above 7.3 W·m -2 . These results suggest that the UV component contributes significantly to the enhancement of the fruit coloration by sunlight exposure.