Abstract: The characteristics of fruit development and flower and fruit drops of Xanthoceras sorbifolia in Dingxi district of Gansu were studied. The results showed that: (1) X.sorbifolia fruit need about 2.5 months from developing to ripening, and its main development and growth stage was in the 40 days after flowering. Its fruit development feature was as follows: fruit growth was the fastest in 10 days after blossom period and its growth increment rate reached 193%, in the next month the fruit still keep faster growth and had a growth increment rate of 120%, but it grew slowly in the last month and the increment rate was only 7%, and during the whole growth process, the width of fruit grew always faster than the length of fruit; (2)X.sorbifolia flower and fruit drops occurred in the early stage of its fruit developing and growing process, and it had a higher drop rate of flower and fruit of 94.65% (flower drop rate 5.74%, fruit drop rate 88.91%), but a very low fruit-bearing rate of 5.35%. Its feature of flower and fruit drops was as follows: the fruit drop was an ongoing process and there was always fruit drop from fruit expanding to ripening after blossom stage. However, there were some peak days in fruit dropping, namely in the 10 days after blossom stage the fruit drop was very serious and the fruit drop rate nearly reached 40%. According to this study, it was regarded that, for the consideration of preserving flowers and fruits, the late flowering stage was the key period for X.sorbifolia to enhance the water and fertilizer management. However, considering the facts that X.sorbifolia profuse flowers and the concentration of fertile flower could lead to heavy drops of flower and fruit because of its high consumption nutrients of tree and top inflorescence, it should thin flower and fruit or let it drop naturally in late flowering stage and young fruit stage, but strengthening water and fertilizer management is needed in the middle and late periods of fruit development to promote its fruit-bearing rate.

Key words: Xanthoceras sorbifolia, drops of flower and fruit, feature of fruit development, fruit-bearing rate