Seed handling of specific forest tree species : Recalcitrant and intermediate seed

Abstract Indonesia is a tropical country with an area of rain forests around 128 million ha. Forests have economic, social and environmental functions, therefore those functions must be sustained. Seeds are a very important part for maintaining the sustainability of forest functions, by providing good quality of seeds and seedlings. Nearly 70% of the seeds of forest plants in Indonesia are recalcitrant and intermediate, dominated by species of Dipterocarpaceae, Myrtaceae, Araucariaceae, and Verbenaceae. In general, the characteristics of the seeds can be divided into 3 groups based on their sensitivity of drying and storability, namely orthodox, recalcitrant and intermediates. The viability of orthodox seeds can be maintained for long storage periods in low temperatures, whereas recalcitrant seeds are difficult to store for long periods and loseitsviability in a short time. Intermediate seeds are in between of the two characters, that the viability can be kept for a longer time (generally less than 1 year) than recalcitrant seeds. The main problems for recalcitrant and intermediate seeds are their short life time and for some species, the flowering and fruiting periods do not occur every year, especially for the species of Dipterocarpacae. These problems makedifficult to get large quantities of high-quality seeds. Therefore, seed handling techniques of recalcitrant and intermediates seeds are urgently needed. A proper seed handling is the key to maintain the physical, physiological and genetic quality of seeds which should be carried out by involving several activities including techniques of seed production, seed testing, seed storage, and nursery technique.