Seed characteristics and germination properties of four Garcinia (Clusiaceae) fruit species

Introduction. Seeds from Garcinia species are recalcitrant, which do not survive dessication and cold temperature. This poses a significant challenge for their long-term preservation, and hence more research is needed to understand the biology of such seeds. Materials and methods. Seeds from three under-investigated Garcinia species, namely G. atroviridis, G. hombroniana and G. prainiana, as well as the economically important mangosteen (G. mangostana), were studied using histochemical tests and microscopy techniques as well as moisture content and germination tests. Results and discussion. The seeds of these species varied in shape and size. G. hombroniana seeds were the largest, while those of G. prainiana were the smallest. Furthermore, during a period of desiccation, larger seeds (G. hambroniana and G. mangostana) retained their moisture content longer than the smaller seeds (G. atroviridis and G. prainiana). Consequently, species with larger seeds seemed to maintain a higher germination percentage compared with the species with smaller seeds. Moreover, G. prainiana seeds had the thickest testa, which perhaps underlay their significantly delayed germination time. Large amounts of lipid and calcium oxalate were also observed in all four Garcinia species, which may have a role in food storage and herbivore protection, respectively. During germination, all species had radicles and shoots emerged from two opposite ends, conforming to the Garcinia-type germination. The procambial tissues also increased in length during germination towards the ends where the radicle and plumule emerged. Conclusion. This study successfully characterised the seeds from four different Garcinia species, some of which are not yet reported elsewhere.