The behaviour of macaw palm (Acrocomia aculeata) seeds during storage

A hard endocarp and physiological dormancy make studies of the propagation and ex situ conservation of macaw palm seeds difficult and necessitate adaptations to existing protocols for classification of seed behaviour during storage. In vitro culture was used to evaluate the viability of embryos from seeds dehydrated to water content levels of 10 and 5% (fresh weight basis; seeds dried over silica gel at 20 degrees C and in a drying oven at 35 degrees C) and from seeds dried to 5% water content and stored for 90 days at -196, -20, 10 and 35 degrees C, and at room temperature (average 22 degrees C). Fruits were also kept in the open for one year under natural conditions, or were buried, left in the shade or stored in a cold-chamber (10 degrees C). Embryo viability and seed water content were determined before storage, after 15 days, and subsequently on a monthly basis over 12 months. The embryos maintained their viability when the seeds were subjected to dehydration by the two methods (silica and oven) and low temperatures (-196, -20, 10 degrees C). Storing the fruits at 10 degrees C maintained 85% embryo viability, has the advantage of not requiring prior processing and can thus be used for ex situ conservation. Burial and storage under shade conditions maintained 67% seed viability, while 34% of the seeds stored in the open remained viable. Macaw palm seeds are orthodox and can potentially form soil seed banks.