Fruit maturation and in vitro germination of macaw palm embryos

Abstract

Acrocomia aculeata (macaw palm) is oil producing palm tree with significant agro-industrial potential. Seed dormancy in palm species may be due to embryo immaturity, which could result from delayed embryogenesis. We evaluated the correspondence between the visual characteristics of maturing fruits and their physiological aspects and the in vitro germination capacity of the embryos. 11 fruit bunches in different stages of maturity were collected and classified in terms of the degree of maturation of the endosperm, the color of the exocarp, and the occurrence of abscission. The water and oil contents of the mesocarp and seed were determined, and lipids and proteins were identified through histochemical analyses of the mesocarp, endosperm, and embryo. The embryos from each fruit bunch were cultivated in vitro in 75% Murashige and Skoog (1962) media with added organic compounds. The water contents of the seeds varied from 71.2 to 21.1% among the different stages of fruit ripening and were related to the visual markers of fruit maturation (exocarp color ranging from dark green to brown). Lipid accumulation in the mesocarp occurred later than in the endosperm, and only occurred in fruits from bunches showing signs of abscission. Embryos from bunches in different stages of maturation showed similar germinative capacities, as well as similar patterns of lipid and protein storage. Embryogenesis in A. aculeata is precocious, and the embryos of immature fruits can be utilized for in vitro cultivation.   Key words: Acrocomia aculeata, embryo culture, embryogenesis, water content, oil content.