Variation of Coloration and Influence Factors of Early Maturing Citrus Fruit in Yunnan Province

【Objective】The object of this study was to discuss the bad cause of fruit coloration and its influence on Satsuma mandarin.【Method】S. mandarin was used as material. The influence of the state of nature,tree shading and urea treatment on fruit quality and coloration of S. mandarin were analyzed. 【Result】From June to July,the L value and the b value of the peel rose continuously,and reached the maximum value in September. The value in the peel was almost unchanged from July to June,and which was negative and had a downward trend.【Conclusion】The peel value( red green color difference index) was low in June and July,which was the main reason for poor coloring of early maturing citrus in Yunnan province. After shading treatment in July,green fell,and red and the total color depth were higher than that of the control. The L value and b value were almost the same in September after shading treatment,but the value was significantly lower than that in the control. The L and b values could be improved in July( treatment 45 days) and the value of the peel was lower than that of the control,and the quality was decreased after treatment with urea. In July,the value of the peel was related to the peel weight and soluble solids content. The values of the peel were correlated to L,b and a/b values of that with different degrees.