Advances in floral dud differentiation and floral sex determination in litchi

Litchi（ Litchi chinensis Sonn.），a subtropical evergreen fruit tree，originates from China. Almost all litchi cultivars lie in the phenomenon of instable yield，which is affected by unreliable flowering. The study of floral differentiation and sex differentiation is always one of the focal points and hot problems of researchers and growers studying in the field of litchi. In this paper，the effects of environmental factors，the state of trees and shoot and plant growth regulators impacting differentiation of flower bud，and recent research of molecular mechanism of lower bud differentiation in litchi were reviewed. And research progresses of floral sex determination from aspects of morphology，physiology and molecular biology in litchi were summarized. Then some opinions on the further research of floral dud differentiation and floral sex determination in litchi were put forward.