Abstract: In order to improve the pertinence of meteorological service during the fruit enlargement of satsuma mandarin, orange and meteorological observation data of Yiling District Meteorological Bureau from 1995 to 2016 were used to analyze the laws of fruit enlargement and its relationship with meteorological conditions in Weizhang and Guijing satsuma mandarin. By using Logistic function simulation and first order derivation, the peak and occurrence time of fruit volume growth over the years were obtained. Meteorological factors were screened to establish fruit growth peak regression equations of Weizhang and Guijing satsuma mandarin. The correlation between the fruit size at harvest and the main meteorological factors before harvest was analyzed. The main meteorological disasters during the fruit enlargement period in typical years were sorted out. The results showed that, low temperature, cloudy and rainy weather before midsummer and high temperature and drought from midsummer to autumn were the main meteorological disasters during fruit enlargement of Yichang satsuma mandarin.

Key words: satsuma mandarin（Citrus reticulata ‘Unshiu’）, fruit enlargement, meteorological condition, Yichang City