INTERGENERIC HYBRIDIZATION BETWEEN LITCHI (LITCHI-CHINENSIS SONN) ANDLONGAN (DIMOCARPUS-LONGAN LOUR)

The breeding barriers between commercial litchi (Litchi chinensis Sonn .) and longan (Dimocarpus longan Lour.) cultivars were investigated by conducting reciprocal pollinations. This work has shown that it is po ssible to generate intergeneric hybrids using litchi as the female par ent. Investigation of comparative in vivo pollen tube growth demonstra ted that there is discrimination against cross- compared to self-polle n at all sites in the pistil. Pollen tubes were frequently observed in the ovary after cross-pollination in litchi but rarely in longan. Fru it production was reduced after crossing in both longan and litchi. Is ozyme analysis using phosphoglucose isomerase revealed that hybrid pro geny only developed when litchi was the maternal parent. Morphological ly the hybrid plants were similar to the maternal parent but leaves we re smaller. Three types of seeds developed in litchi following pollina tion with longan pollen. These were (1) normal seeds with a developed testa and embryo, (2) seeds with aborted embryos but normal testa deve lopment, and (3) seedless fruit where the ovule remained the same size as at anthesis without further development of embryo or testa. The po tential germplasm available to improve these crops within the Sapindac eae is discussed.