BANANA AND PLANTAIN - Tropical Fruits - page 200

leaf sheaths are pulled down to the bottom of the pseudostem, in order to
expose the axillary buds, and then soil is mounded around the base. All these
practices prevent fl owering, and induce axillary bud growth that develops into
numerous suckers.
For high-density plantain plantings developed in the last decade in Central
America for the 'Curraré Enano' (AAB) plantain variety, the corms are graded
by size into three or four grades then planted in dif erent areas to ensure fi eld
uniformity. Larger corms, 500-2000 g, are planted directly into furrows in the
fi eld in either a horizontal or vertical orientation. Smaller corms of 200-500
g are planted into plastic bags and kept for 6-8 weeks before grading by size,
with the larger corms planted into the fi eld. The advantage of planting bagged
plants is that no fi eld irrigation and weeding are necessary before planting out
and the growth in plastic bags means that a more uniform stand and no empty
spaces are obtained, as only sprouted suckers from the corm are planted. The
corms are pared and if possible disinfected before planting in the fi eld or bags,
as for dessert bananas.
Tissue culture ( in vitro plantlets) allows for rapid multiplication of
uniform, disease-free materials (Loyola Santos et al. , 1986). Other advantages
of tissue culture include very high fi eld establishment rates, uniformity of
harvest timing, precocity and high production, at least in the fi rst crop cycle.
These advantages have to be balanced against higher cost, extra care at
multiplication and the transmission of viruses that have not been eliminated.
Somatic variation is the major problem and care in multiplication is necessary
to reduce the incidence to an acceptable level (<3%) (Smith, 1988).
Field preparation
The fi eld should be ripped, ploughed and disced before planting. This
may involve cross-ripping to 1 m to break up any soil compaction. Lime,
phosphorus (P) and potassium (K), as determined by soil analysis, should be
added at this time. Sloping land should be prepared so as to avoid erosion.
Drainage is vital to avoid waterlogging, which can reduce yields. The water
table should be kept below 1.2 m in depth. Extra drainage can be installed
during fi eld preparation via trenches and drains. Drainage preparation can be
a fairly expensive task in the export banana production fi elds, as the fi elds are
expected to remain in production for many years. In Chapter 3, there is a brief
description of these drainage systems.
Transplanting and spacing
A planting hole slightly larger than the material is dug or a furrow made. The
corms are usually covered with 10-15 cm of soil. Planting is scheduled in