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 mumol.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.