Experiments were conducted to investigate the factors affecting fruit set in 'Yu Her Pau' litchi (Litchi chinensis Sonn.) in Taiwan. We were particularly interested in the effect of cool weather during flower development on setting, and the competition among individual flowers on an inflorescence. In the first experiment, the relationship between setting and temperature during flower development was assessed by recording set in inflorescence flowering at different times. In the second experiment, the effect of pruning the inflorescence on set was recorded with pruned and non-pruned inflorescence evaluated. The size of the inflorescence increased as flowers was delayed, while the rate of fruit set decreased possibly because of cool weather during flower development. Pruning part of inflorescence increase set compared with the set in unpruned inflorescence. The optimum size of the inflorescence in this cultivar in length of fruit set was about 20 cm, independent of flowering time or pruning. It can be concluded that cool weather during flower development and competition among the flowers influence fruit set in 'Yu Her Pau'. (C) 2013 Elsevier B.V. All rights reserved.
