Peach palm - World Agroforestry Centre

4 0 Peach palm. Bactris gasipaes Kunth
paper moistened with a 2.5% sucrose or 5% glucose solution, but this method is
more difficult in practice. The fibres of white filter paper are similar in appearance
to the pollen tubes, making it difficult to count germinated grains (C.R. Clement,
1997, pers. observ.). Fresh pollen germinates in about 75 minutes on these media
at room temperature (about 25°C).
Controlled pollination will be most effective if done when female flower
anthesis begins, i.e. late in the afternoon on the first day of the flowering cycle (see
Section 3.4). At this time, however, contamination by airborne and insect-dispersed
pollen from other inflorescences is very likely. For these reasons, controlled
pollination is recommended early the following morning when curculionids are
inactive and there is little airborne pollen. Using a simple hand-held blower, the
pollen is introduced through an opening in the protective bag enclosing the
inflorescence (bag put in place 1-2 days earlier), and the bag is then carefully
resealed. Bags can be removed the day following pollination.
Prior to controlled pollination, emasculation of male flowers is often
considered to prevent self-pollen contamination, but this has serious
disadvantages in peach palm. In theory, emasculation is not necessary, since male
anthesis occurs late on the second day of the flowering cycle (see Section 3.4) and
by that time fertilization should have occurred if the controlled pollination was
done properly; it is also possible to test the degree of self-sterility a year before,
although nothing is yet known about the effects of the environment on the genetic
self-sterility system. In practice, however, there is no guarantee of 100% crossing
success, so some self-pollen contamination is possible. Emasculation is difficult,
however, especially in tall trees. It is also time consuming (30-45 minutes for one
inflorescence), tends to block the pistil with trichomes which reduce pollination
efficiency, and may stress the inflorescence so much that even successfully
pollinated flowers may abscise. Selfing can be checked after germination by
analyzing the isozyme or DNA profiles of the seedling progeny, if their parents
have contrasting alleles at one or more loci; this is only justified, however, for very
important crosses and probably cannot serve as a general practice at this time.
8.2 Seed
Peach palm seed may be purchased from commercial dealers in Brazil, Colombia,
Costa Rica and Peru (contact researchers listed in Appendix I for appropriate seed
sources). Although commonly known as the seed, technically this is the endocarp
with enclosed seed. Most of this seed is collected from local farmers, and is of
unknown genetic quality. Improved seed for fruit production is practically
unavailable. There are small plantations in Brazil and Costa Rica that produce seed
from selected germplasm, primarily for heart-of-palm plantations. However, the
genetic base of some of these plantations may be very restricted and create a
phytosanitary risk in future (C.R. Clement, 1997, pers. comm.). For example, the
main plantation in Manaus, Brazil is derived from four accessions from Yurimaguas,
Peru and these accessions are probably related. Two subsequent selection cycles