Aurélio Rubio Neto

Effects of drying temperature on viability of macaw palm (Acrocomia aculeata) zygotic embryos.

In response to a growing interest in improving seedling production of oilseed species (like macaw palm), a fruit drying protocol for facilitating seed extraction was proposed. This enabled the production of macaw palm seedlings, but the temperature most suitable for seed extraction without losing its physiological quality is unknown. The goal of this study was to evaluate the effects of different drying temperatures on the physiological quality of macaw palm zygotic embryos to improve previously published drying methods. Fruits were dried in a forced-air drying oven at 57 or 37°C at different time periods (zero, two, four, six and eight days). Following each drying period, the fruits were removed from the drying oven, and the water content of the fruits and seeds were measured in addition to embryo viability and in vitro germination. Seed water content could be estimated based on fruit water content at both drying temperatures, eliminating the need to remove the seeds from the fruit. Drying at 57°C decreased the drying time by 50% compared to drying at 37°C; however, it was detrimental to embryo viability and germination. Therefore, drying of fruit at 37°C is recommended. Embryos dried at this temperature were still able to germinate after 16-day drying period, which corresponded to a decrease of 24.8% in the initial fruit water content. Key words: Arecaceae, biodiesel, dehydration, physiological quality, propagation

Alternative tube caps on in vitro growth of Orbignya oleifera Burret.: An Arecaceae native cerrado domain

The babassu ( Orbignya oleifera Burret) is a palm that contains oilseeds whose biomass can be used for biofuel production. Due to difficulties in germinating the species, in vitro cultivation techniques are sought as a viable alternative to expand studies on germination. The objective of this study was to evaluate different types of tube caps for in vitro growth of babassu seedlings. Thus, zygotic embryos were inoculated in tubes containing MS medium with a 50% salt concentration, which were sealed with diferent caps, a cotton plug, plastic cap, PVC film and plastic cap with PVC film. During the in vitro culture, the mean length of seedlings, the formation of the cotyledon petiole and root, as well as oxidation of the explants were evaluated. The cotton plug exhibited a positive effect on the initial steps of in vitro cultivation, which promoted more vigorous plants with greater mean lengths; however, its effect decreased as the cultivation time increased. The cotton plug is an alternative and eight-fold less expensive than a conventional plug, which favors early in vitro growth of O. oleifera Burret. Key words : Babassu, Goias Cerrado, tissue culture.

In vitro germination and growth of babassu (orbygnia phalerata Mart.) embryos subjected to different drying temperatures

The aim of this study was to evaluate the physiological quality of babassu ( Orbygnia phalerata Mart.) embryos in relation to drying rate. The fruits were kept in a dry chamber with forced air circulation at 57 ± 2°C and 37 ± 2°C for 0, 6 and 11 days. An interaction between the drying time and temperature on water loss was not observed. Fruits dried at 37 ± 2°C failed to achieve the same water content values as those dried at 57 ± 2°C. Embryos dehydrated at 37 ± 2°C remained viable even after 11 days of drying, while embryos dehydrated at 57 ± 2°C were dead after 6 days of drying. Germination percentages above 67% were obtained for all times at drying 37°C, even for seeds with 9% water content, which highlights a possible orthodox behavior. Under the experimental conditions of the present study, drying embryos at 57 ± 2°C decreased the percentage and speed of germination as well as the initial growth of seedlings. Keywords: Arecaceae, desiccation tolerance, orthodox seeds