Endosperm and endocarp effects on the Ilex paraguariensis A. St.-Hil. (Aquifoliaceae) seed germination

To develop a procedure for regenerating plants directly from pyrenes, as an alternative to in vitro embryo culture, germination studies were done on maté tree, Ilex paraguariensis, seeds using aseptic conditions. The effect of the endosperm, the woody endocarp and cold treatment on embryo development and germination were examined by culturing isolated embryos, intact, acid-scarified and bisected pyrenes from mature fruits. The results show that maté tree plantlets may be obtained by in vitro culture of bisected pyrenes on solidified (0.65% agar) quarter-strength Murashige and Skoog medium containing 3% sucrose. It is recommended to pre-culture the pyrenes at 4 ± 2°C to obtain a higher germination rate and more vigorous seedlings. This is the first report of the in vitro culture of Ilex pyrenes. Compared to the culture of isolated embryos this procedure shortens the duration of the embryo culture technique and minimizes damage to the young embryos.