Tissue culture versus bits and suckers
Tissue-cultured (TC) plants are healthy and uniform and in the parent crop offer a yield advantage of up to 20% over conventional bits and suckers. Because of their uniformity, TC plants can also be used to manipulate cycling to coincide with high price market windows. But TC plants produce somaclonal mutants (off-types), cost more and need careful management during establishment.
TC technology has improved and off-types have been reduced to 3-5%. There is still a need to develop culling and establishment techniques suitable for Western Australia.
Tissue culturing is the only way to ensure that new banana plants to be planted are free from pest/disease, viruses and nematodes. Tissue cultured plants are also the only way to legally obtain banana planting material from outside quarantine restricted areas.
Tissue culture plant handling
Tissue-cultured plants are grown in a laboratory in sterile sealed containers. Because the plantlets are grown in this way, there is a need for them to be hardened off in a shadehouse prior to planting out in the field.
The plants need to remain in a high humidity shadehouse environment for a few weeks to develop new leaves outside the tissue culture environment that will be tougher and have a waxy cuticle which makes them less likely to be damaged by drying out and the sun.
Following this initial hardening off, over the next few months the plants need to be potted up in stages with the humidity reduced and exposure to sunlight increased gradually until the plants are fully sun-hardened and ready for field planting.
When planting out in the field, tissue culture plants need to be planted deeper than other plants. This is in order to prevent the developing rhizomes and suckers from emerging above soil level. It is also important that plants are not allowed to become water stressed. Tissue culture plants do not have the starch reserves that bits and suckers have and are therefore less able to withstand environmental stresses when first planted.
Tissue cultured plants are also more susceptible to pests such as nematodes and banana weevil borer (in the ORIA but not present in Gascoyne) during early establishment so effective control needs to be maintained during this time. Good fertiliser and weed strategies need to be in place to provide tissue culture plants with a good start.
Other planting material
Alternative types of planting material are:
- Suckers: A good sucker is free from insects and leaf mottling and has narrow tapering leaves. Suckers should only be removed from non-fruiting plants.
- Pieces or bits: Portions of the corm with a mature bud or eye. Separate according to maturity to ensure even emergence. Do not plants pieces or bits of less than 1kg for good establishment. Roots should be pruned to minimise nematode infection.
The identification of Panama disease (race 1) in Carnarvon in 1992 resulted in the recommendation that growers use their own planting material or tissue culture material.
Planting material with the typical internal brown/black discolouration of Panama disease should not be used and should be shown to the local DPIRD officers.
Varieties
The giant Cavendish type, Williams, is the primary variety grown commercially in WA. With good management Williams will produce higher yields per hectare than other varieties.
It is a tall plant typically 2.5m in the parent crop and 3.4-3.5m in ratoon crops.