TISSUE CULTURE BANANAS
To establish new fields, banana in smallholder farmer systems is traditionally propagated by means of suckers. The problem is that these suckers are full of soilborne pests, such as nematodes and banana weevils. In other words, by using these suckers, the farmers unknowingly distributes and perpetuates the pest problems.
Tissue culture plants, because they are produced axenically in the laboratory, are by definition a pest and disease free planting material.
There is one exception to this, viruses, and I will get back to this later. There are many added benefits of using tissue culture, besides being pest- and disease free. 1) Plants are more rigorous, allowing for faster and bigger yields; 2) plants are more uniform, allowing for better marketing; and 3) plants can be produced in huge quantities in short periods of time and in small spaces, allowing for faster and better distribution, for example of new cultivars.
This technology can help farmers make the transition from subsistence to income generation.
Tissue culture production chain
Tissue culture plants are made in specialized laboratories. Tissue culture consists of a few basic steps: 1) apical meristem is isolated from mother plants and induced to form shoots, 2) shoots are multiplied, 3) whenever plants are needed, the multiplied shoots are put on a root-inducing medium, 4) the young plants are transferred to a screenhouse for hardening, something we call "weaning", and 5) finally plants are ready to be planted in farmer fields. Tissue culture banana is the norm in the rest of the world, but is only now beginning to see the light in sub-Saharan Africa, mainly carried by the commercial sector.
Tissue culture production chain
In East Africa, there are now at least 10 private laboratories, producing over a million plants per year, Most of them take the entire production chain in their hands, from sourcing the motherplants to weaning.
Barriers to tissue culture adoption in Africa
Tissue culture plantlets are very fragile, and they need high management and maintenance for them to fully unleash their potential. Often, in East Africa where majority of farmers are small-scale farmers, these delicate tissue culture material are planted in fields burdened with biotic pest pressures and abiotic constraints. In Latin America, banana fields are often harvested and plants destroyed, fields sterilized and freshly replanted after one cycle.
This is where endophytes come in. ‘Endophytes' is a general term for naturally occurring microorganisms, mostly bacteria and fungi, inside the plant that protect the plant from pests and diseases and that enhances plant growth. Every single individual of all plant species, including banana contains them.
Endophyte enhanced tissue culture banana
By producing banana plants aseptically in the laboratory, through tissue culture, the plants do not only loose the bad guys, read pests and diseases, but they also loose the good guys, read endophytes. By reintroducing the endophytes into the banana tissue culture plants one restores the natural equilibrium. In other words, incorporation of endophytes extends the benefits of clean planting material.
Endophyte-enhanced tissue culture technology enables farmers in East Africa to overcome the barrier to adopt tissue culture, because it allows tissue culture plants to fully exploit their potential and grow under high biotic and abiotic constraint pressure, and under minimal management conditions.
Getting the endophytes back into the plant is simple, and occurs after the plants come out of the test tubes and before they are moved to the screenhouse.
The endophyte turns on pathways that induce biochemical and structural changes in the plant, in effect giving a susceptible cultivar the same phenology as a resistant cultivar. You are immunizing the plant with endophytes acting as vaccines.
Endophytes in the field: effect on nematode populations
The effect of endophyte enhanced plants on nematode populations. Depending on the type of endophyte, nematode populations are reduced by 20 to 50%, Interesting in this on-station trial is that we also included a positive control, namely a nematicide that is routinely being used in commercial plantations in Latin America against Radopholus similis. The endophytes can outperform the nematicide.
Advantages of endophytes
Our work with endophytes made us realize that they circumvent many of the bottlenecks traditionally associated with application of conventional biopesticides. First, costs and quantities involved for mass production are problematic for conventional biopesticides. For endophytes in tissue culture plants, however, very low quantities needed and the technique is easily integrated in a commercial lab. Second, the use of conventional biopesticides is often logistically and economically not feasible for farmers. However, for endophytes, farmers do not need to apply the product themselves; the plants already come ready-armed. Third, abiotic factors greatly reduce field performance of conventional biopesticides because they are exposed. For an endophyte, the product is protected inside the plant.
In most countries, to use a biopesticide you must seek approval from the Government, something which is called registration. Registration is a very long and complicated process, and in Kenya it is the Pesticide Control Product Board (PCBP) that ultimately gives the approval for commercial use of a particular formation on a particular crop. The registration dossier consists of two parts: The first part is an "eco-toxicological" dossier which contains very detailed information on the applicant, which is JKUAT, which needs to be a body that is approved by the BCBP, the physical and chemical properties if the active ingredient, the formulation, toxicology, which is includes the effect on bees and rats etc, and a residue analysis. The second part is a highly controlled large field experiment. So we spent a lot of time on this, and our eco-toxicological dossier has been approved now by the BCBP. In Kenya, we are now conducted the registration field trial.It is pretty amazing we got this far in Kenya, because in 2007 we still needed special permission even to move our endophyte in Petri dishes, and needed to quarantine them.
In Uganda and in Burundi the situation is less clear terms of government regulations.
Transfer to the private sector
We need to have the private sector pick up on this technology. Here,we use two different approaches. In Kenya, we have transferred the technology, which includes the Fusarium oxysproum strain, the know-how and equipment, to RealIPM, a bio-pesticide company. RealIPM is the same company that is already the registration holder of the commercially approved Beauveria bassiana IMI1 and Trichoderma asperellum, and these are the strains that we have been using as of recent as artificial endophytes. In other words, if these strains prove to be excellent artifical endophytes, no need for us to start worrying about registration and licensing.
In Kenya, the idea is that RealIPM then sells the bio-control product to tissue culture producers. There are two problems we are facing. Problem one is licensing. Basically, we are talking about a strain, Fusarium oxysporum V5w2, that belongs to the Ugandan Government and that is registered in a different country by a different registration holder. So there has to be an agreement between the Ugandan Government, JKUAT and RealIPM in terms of profit sharing and exclusivity. Another problem is profit. The quantities of endophytes needed per banana plant are tiny. This is a good thing for the tissue culture labs and the farmer, but a bad thing for the bio-pesticide company. In Ugandawe have embedded the technology directly with a tissue culture company, namely AGT. The idea is that AGT produces its own endophyte-enhanced plants, at a cost of 5 cent extra per plant.
Training: the full package
We are also conducting training to farmers and nurdry operators to overcome barriers mentioned in the adoption of tissue culture material.
We have a total of 9 training modules, 4 for nursery operators and 5 for farmers. The modules are agronomy, marketing, business, financing and, for farmers, group formation and group dynamics.
For nursery operators, we establish demonstration gardens which serve a very important dual role: they are marketing tools for the nursery operators, and sites for agronomy training for the farmers. For farmers, we are using the established farmer groups to enter in dedicated market linkages.
For both groups, we are conducting cost-benefit analyses. For nursery operators this is straightforward. For farmers, we are following about a 100 farmers in the three countries and we split them in three groups: those that grow tissue culture and were trained, those that grow tissue culture and were not trained, and those that grow conventional sucker material. For each of these groups, we are measuring the cost benefit on individual banana plants, hoping to give us some quantification on the impact o the training.
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