1. Fruit mature in about 210 to 240 days.
2. Colour changes from green to pale green or pale yellow or orange.
3. Outer rind looks shiny and one can see oil glands on the fruit.
4. Mandarin 0.4% acidity and 12 to 14 % T.S.S. orange 0.3% acidity and 12% T.S.S.
5. Fruits become soft.
Harvesting of Mandarin and Sweet Orange:
1. In India the fruit picker collect the fruits manually by climbing on a ladder when the tree is tall, with a collecting bag on his shoulders. In U.S.A mechanical harvesting is done particularly for processing industry.
Original Article HEre