Studies on the coloration of tomato fruits. (3)

Effect of light on the pigment contents in fruits

Abstract

The experiment has been carried out to ascertain the effect of light on coloring of tomato fruit using the variety “Kurihara” in 1958. A half of the flow-er clusters tested were shaded by leaves (shaded fruit) and the other half were exposed to the sun-light (exposed fruit). These fruits were analyzed for pigments and sugar contents from 25 days to 63 days after flowering. The results are as follows.
1. Chlorophyll, carotene and xanthophyll con-tents in exposed fruits were much higher than in shaded ones. The lycopene contents from 40 days to 55 days after flowering were slightly higher in exposed fruit than in shaded, but those on 60 days after flowering were much higher in shaded fruit than in exposed fruit.
2. Reducing and total sugar contents in exposed fruit were higher than in shaded fruit until mature green stage, but at mature stage (60 days after flowering) they increased more in shaded fruit than in exposed one. The difference of contents of non-reducing sugar between exposed and shaded fruit was not significant.
3. On the 25th and the 60th day after flowering, the exposed fruits were cut into the upper and low-er halves, and analyzed for pigments and sugar contents respectively. Chlorophyll, carotene, xantho-phyll and sugar contents in young fruits, and carotene, xanthophyll contents in mature fruits are much higher in lower half than in upper half, but in mature fruit, lycopene and sugar contents of upper half were more increased than in lower half.
4. On the 25th and the 60th day after flowering, the exposed fruits were divided into the exposed and shaded sides, and analyzed for carotenoid contents. Chlorophyll, carotene and xanthophyll contents in immature fruit, and carotene, xanthophyll contents in mature fruit were much higher in exposed side than in shaded side, but lycopene content in mature fruit was higher in shaded side than in exposed side.
5. It is considered that chlorophyll, carotene, xanthophyll and sugar contents in tomato fruits are increased by exposing to the sunlight, and that increase of lycopene content is affected by other factors, especially temperature as well as the ex-posure.