A Preliminary Study on Longan Artificial Crossing and Several Traits of the Hybrid Populations

In this study, three longan cvs. 'Fengliduo', 'Dawuyuan' and 'Shixia' were used as crossing parents. In the springs of 2002 and 2004, artificial cross pollination was performed for 'Fengliduo' x 'Dawuyuan', 'Dawuyuan' ×'Fengliduo' and 'Dawuyuan'×'Shixia'. A Total of 455 hybrid seeds were obtained and 438 of them germinated and grew well. RAPD analysis was applied to 99 individuals (coded as FD01-FD99) of 'Fengliduo × Dawuyuan' and the result confirmed a 97% of true hybrid. From 2003 to 2008, the growth status, flower and fruit qualities were recorded among the populations. The record showed that the shortest juvenile phase of the hybrids was only 2.5 years, and the longest of them was only 3.5 years. For population of 'Fengliduo × Dawuyuan', the individuals with a juvenile period of 2.5 years accounts for 0.3% and those with 3.5 years juvenile phase for 1.2%. In the case of 'Dawuyuan × Fengliduo' population, only 0.03% of hybrid individuals had a juvenile phase of 2.5 years and about 25% with 3.5 years. For 'Dawuyuan x Shixia' population, no individuals with 2.5 years juvenile phase individual occurred, but those with a juvenile phase of 3.5 years took up as high as 81.8%. These results showed that the juvenile phase of longan is not very long. In addition, five outstanding individuals were selected according to the fruit quality from 143 fruiting hybrids in 2007. They were FD34, FD57, FD73, FD82 and FD97. Among them, FD97 was the best as it matures in mid-September with high-yield, even fruit shape, large fruit size (average weight is 12.7 g), yellowish and semi-transparent flesh, crisp and tender flesh texture, high SSC (23.2%) and flesh recovery (66.7%). The traits of fruit size, SSC and flesh recovery of FD97 were all better and matured 5-10 later than those of 'Caopuzhong', the famous high-quality and late season cultivar in Guangdong Province.