We have investigated some factors influencing on the color of tomato fruits by means of the colorimetrical method. The results were as follows ;
1. The relationship between the color of fruit-juice and the lycopene content showed high and positively correlated.
2. In Fukuzyu No. 2 of pink colored variety, the value b of Hunter's coordinate of fruit color was nearly equal to that of fruit-juice color. In H 1370 and Chico of red colored variety, Hunter's coordinate b of fruit color showed 14.3 and 15.1 respectively, and on the other hand those of fruit-juice color showed 10.7 and 9.6 respectively, i. e. the fruit-juice color showed more reddish than the fruit color in red colored varieties.
3. The classification of coloring degree by observation with naked eyes made good agreement with the measuring by the colorimeter.
4.. There were remarkable differences in the temperature of fruit skin between ones grown in sunlight and ones in shade. For instance, the former showed 34.5℃ and the latter 21.5℃ under 33.5℃ of air temperature. The value a/b of Hunter's coordinate was 1.67 and 2.05 in the former and the latter respectively.
5. Comparing tomatoes grown in plain with ones grown in mountainous district, the latter revealed more reddish and superior color than the former.