Non-deep physiological dormancy, desiccation and low-temperature sensitivity in seeds of Garcinia gummi-gutta (Clusiaceae): A tropical evergreen recalcitrant species

This study aimed to determine seed dormancy, desiccation, low-temperature sensitivity and storage behavior of seeds of Garcinia gummi-gutta, a medicinally important tropical evergreen tree. These seed characteristics serve as important ecological traits to regulate the regeneration strategy of plants by synchronizing seed germination timing with the wet season. De-coated fresh seeds imbibed water and had > 90% germination within four weeks, but seeds with an intact seed coat required about 24 weeks of warm temperature to attain 90% germination. Desiccation of intact seeds with silica gel at 15, 25 and 35 degrees C revealed that the rate of desiccation varies with temperature. The critical moisture content (CMC), which is the moisture content below which there is a rapid fall in viability, for G. gummi-gutta seeds is similar to 34% and seeds completely lose viability at 24 and 17% moisture content (MC) at 25 and 35 degrees C, respectively. Based on these results, fresh seeds with MC of 43% and reduced MC of 34% were stored at six temperatures ranging from -10 to 35 degrees C for a period of 18 months. Rapid decline in germination was recorded at -10, 5 and 35 degrees C. However, at 15 degrees C, seeds with both 43% and 34% MC retained 90% viability for 18 months. The half viability period (P-50) indicated that an optimum condition for long-term seed storage is 15 degrees C with 34% MC. We conclude that seeds of G. gummi-gutta have non-deep physiological dormancy (PD) and are sensitive to desiccation and low temperature. Inspite of their recalcitrant nature, the seeds of G. gummi-gutta have PD, thus the species is classified as a tropical dormant recalcitrant.