Investigations of So-Called “Yellowish Fruit” among Satsuma Mandarins

Abstract

These investigations were carried out from 1973 to 1977 in order to clarify the conditions of occurrence and the quality of “yellowish fruit” in crops of satsumamandarins, because of the problems raised by their occurrence in recent years in Nagasaki.
1. The “L” and “b” values for the rind surfaces of yellowish fruit as measured on Color-Difference Meter were higher than for those of “reddish”, but the “a” values were lower. The ranges of “L”, “a” and “b” values were 60-63, 17-20 and 34-38, respectively for yellowish fruit, and for reddish fruit, 56-60, 22-27 and 32-37, respectively.
2. The juice of the yellowish fruits was lower in sugar content and higher in acid content than that of the reddish ones, and the proportion of small yellowish fruit below “S” size was greater than that of small reddish fruit. The rind surface of the yellowish fruit was smooth, less susceptible to injury, and showed a lower occurrence of puffing and wilting during storage.
3. The ratio of yellowish fruit in the packing house ranged from 10% to 30%, varying according to the year and the regions.
4. The occurrence of yellowish fruit in the lower part of the bearing area of the tree crown was greatest, especially that on the hill side of the tree. A relationship was found to exist between the occurrence of yellowish fruit and light intensity.
5. There was a quantity of yellowish fruit in light-deficient orchards facing north-east.
6. It was concluded that yellowish fruit was less colored, smaller fruit produced in the inner or lower parts of the tree crown, and that its occurrence depends largely on light conditions in the bearing part of the tree crown.