In order to investigate the effect of shading on fruit maturation and coloration of fruit skin, Kaki fruits, variety Fuyu, were covered separately with bags made of polyethylene, black cheese cloth, and alminium foil at different stages of fruit development and maturation. These shading materials provided mean light intensities of 82.7%, 36. 1% and 0% of full sunlight, respectively. Time of shade application was as follows ; polyethylene bags--from Aug. 1 to Nov. 4 (harvest), cheese cloth hags--from each of Aug. 1, Sept. 1 and Oct. 1 to Nov. 4, alminium foil bags--from each of Aug. 14, Sept. 1 and Oct. 1 to Nov. 4. Therefore, the longer the duration of shading was, the less was the total light intensities which a fruit received in three months before harvest.
Mean fruit temperature was almost the same as the air temperature in the bags. It was the highest at fruits covered with polyethylene bags, and the lowest at fruits covered with alminium foil bags, that of fruits exposed to full sunlight and fruits covered with cheese cloth bags being intermediate.
Carotene and lycopene contents in the fruit skin were most abundant in fruits exposed to full sunlight, followed by fruits covered with polyethylene bags, cheese cloth bags and alminium foil bags in the order. They were also significantly positively correlated to the total light intensities received in three months before harvest, their respective correlation coefficients being + 0.647 and +0.818. Carotene content in the skin increased with increasing mean fruit temperature (in three months before harvest) in the range of 27℃ to 31℃, while lycopene content did not increase. Within mean fruit temperature range of 25℃ to 26℃, carotene and lycopene contents increase with increased total light intensities. They also increased concomitantly with the increase of soluble solids content in the fruit in the range of 10℃ to 16%. Soluble solids content was the highest in fruits exposed to full sunlight, follwed by fruits covered with cheese cloth, polyethylene and alminium foil bags in the order. There was no consistent trend in chlorophyll content and fruit weight between shade treatments.