BIODIVERSITY AND SUSTAINABLE BANANA PRODUCTION

E.A. Frison and S.L. Sharrock, International Network for the Improvement of Banana and Plantain

Importance of bananas and plantains

Bananas and plantains are one of the world?s most important and yet poorly studied crops. They are a major staple food crop for many millions of people in the developing countries of the tropics and provide a valued source of income through local and international trade. They are grown over a harvested area of approximately 10 million hectares, with an annual production of around 86 million metric tons, of which around a third is produced in each of the African, Asia-Pacific and Latin America and Caribbean regions. They are the fourth most important global food crop after rice, wheat and maize in terms of gross value of production. The vast majority of producers are small-scale farmers growing the crop either for home consumption or for local markets. Bananas grown for export, which are almost exclusively of one variety (”Cavendish”) account for little more than 10% of global production. The remaining 87% or so of production is made up of a very wide range of varieties, each adapted to a specific eco-region and selected for specific eating or cooking qualities. These include the true plantains of West Africa and Central and South America, the highland bananas of East Africa, which are also used for beer-making, the cooking bananas of Southeast Asia and the Americas. and the Pacific Maia Moali/Popoulu type of banana. In addition, there are many other varieties of local importance in various countries around the world.

Bananas and plantains grow in a range of environments and will produce fruit year-round, thus providing a source of energy during the ”hungry-period” between crop harvests. They are particularly suited to intercropping systems and to mixed farming with livestock and they are also popular with urban populations. When grown in perennial production systems, they maintain soil cover throughout the year and if their biomass is used for mulch, soil fertility and organic matter remain stable. As well as being a cheap and easily produced source of energy, they are also rich in vitamins A, C and B6. Furthermore, with increasing urbanisation, bananas and plantains are becoming more and more important as cash crops, in some cases providing the sole source of income to rural populations, thus playing an important role in poverty alleviation.

Bananas and plantains are important in all tropical regions. In Africa, the crop provides more than 25% of food energy requirements for around 70 million people. East Africa alone produces around 15 million tons annually and it is in this region that bananas reach their greatest importance as a staple food crop. In countries such as Uganda, Burundi and Rwanda annual per capita consumption has been estimated at 220-440 kg, the highest in the world. Bananas and plantains are also a staple food crop in much of West and Central Africa. Around 10 million tonnes of the crop are produced in this region annually, 99% of which is consumed or traded locally.

In the Asia-Pacific region, bananas are the most widely produced fruit in the Philippines, Thailand, Indonesia and India, while they rank second in Malaysia. 95% of the region’s production, some 25 million tons annually, is consumed or marketed locally. In the Pacific, although the banana industry is small in absolute terms, in some countries its importance is great in relation to the national economy and the welfare of individual growers.

Bananas grown for export are almost exclusively produced in Latin America and Caribbean and the crop is of major socio-economic importance to the region. Even in this region however, export production constitutes only around 30% of total production, and much of this is still grown by small-scale farmers. In the Caribbean, three of the poorest countries, Cuba, Haiti and the Dominican Republic produce some 1.5 million tonnes of bananas and plantains annually, 64% of the sub-region’s total, less than 1% of which is exported. Even the largest exporting country, Ecuador, produces almost as many bananas for local consumption as it does for export and a country such as Colombia exports only a third of its production.

Major constraints

Pest and disease pressures have increased considerably in recent years, and a number of important pathogens are causing severe yield losses world-wide. Black Sigatoka leaf spot disease caused by the fungus Mycosphaerella fijiensis is considered to be the most serious constraint to plantain and banana production globally. This pathogen can cause severe leaf necrosis reducing yields by 30-50% and many important and widely grown cultivars are susceptible. The first appearance of black Sigatoka outside Asia was in Honduras in 1972, and this was followed by the development of a serious epidemic throughout central America. The disease subsequently spread to Colombia, Ecuador and Venezuela. Black Sigatoka has been present in Cuba since 1992, and has also been confirmed in Jamaica and the Dominican Republic. The disease continues to spread and its presence was recently reported in Bolivia and Peru. The disease is now threatening the important banana production areas of Brazil and is expected to reach the banana-dependant Windward Islands in the Caribbean in the near future.

The chemical control of black Sigatoka is not only expensive and beyond the means of the majority of small-scale producers, but is also extremely damaging to the environment. Moreover, the harmful effects of chemical use on the health of plantation workers is of great concern. In Costa Rica, over-use of chemicals for the production of export bananas has resulted in the development of fungicide-resistant populations of the pathogen. Furthermore small-scale plantain production has been reduced by 40% as a result of the disease as farmers are unable to afford the high cost of fungicides needed to control it.

In Africa the disease was first reported in Zambia in 1974. It had spread to Gabon by 1979, and to Burundi and Rwanda by 1986. It has now been recorded in 19 countries in tropical Africa. In Asia its distribution is uncertain but it has been reported in the Philippines, Java, Sumatra, Western Malaysia, Thailand and most recently in Australia.

Considerable losses are also caused by Panama disease (Fusarium wilt), caused by Fusarium oxysporum fsp. cubense, a soil-borne fungus which affects many important cultivars of banana and plantain. The pathogen is present in virtually every area where bananas are extensively grown and is considered to be the most important constraint to production in the Asia-Pacific region. In addition, a complex of plant parasitic nematodes (Radopholus similis, Pratylenchus spp. and Helicotylenchus multicinctus) cause serious crop losses in all regions. Nematode infestations interfere with nutrient uptake and transport, resulting in slow growth, reduced fruit filling and susceptibility to wind lodging.

Resistant varieties - the basis of sustainable production

It is clear that the basis for the development of sustainable banana and plantain production in the future is the use of resistant varieties. Such varieties can be grown without resorting to the use of chemicals to control pest and disease attack as the plant naturally defends itself against such enemies. The use of resistant varieties not only reduces production costs, but also benefits the environment as the polluting effects of pesticides are reduced and the workers themselves are not exposed to health-damaging chemicals.

The need to develop, through plant breeding, varieties which are resistant to the major pests and diseases affecting bananas and plantains has been recognised for some time. Resistant varieties are needed which are suitable not only for the export banana market, but will also meet the very varied needs of smallholder producers in many countries worldwide. However, as many of the important banana and plantain cultivars are highly sterile, these cannot be used in conventional breeding programmes. Other cultivars that are used are only partially fertile, requiring huge numbers of crosses to be made for the generation of very little seed. The cost and resources required for such breeding programmes are significant. Therefore, due to the intrinsic difficulties in breeding bananas and the lack of funding directed to research in this area, it is only very recently that the first bred improved varieties have been released for widespread testing and cultivation.

This means that, up to today, there has been virtually no replacement of local cultivars by improved material from breeding programmes. Throughout Africa and Asia a wide range of local varieties are still being cultivated by farmers. Many of these have not, as yet, been fully tested for natural resistance to the major pests and diseases. Useful germplasm may therefore be available, but not recognised, and greater efforts in varietal evaluation are required. This is especially the case as increasing moves towards commercialisation of production is putting many of these farmers’ varieties under threat as single cultivar plantations replace mixed farming systems. The risks of monocropping are well known, and single cultivar plantations are likely to result in enhanced pest and disease problems for producers.

Banana breeding

Banana breeding first started in the 1920’s at the Imperial College of Tropical Agriculture in Trinidad and soon after this, a parallel programme was developed in Jamaica. Initial efforts were directed towards breeding for resistance to Panama disease (Fusarium wilt), already present in the Caribbean and to which the principle export clone, Gros Michel was susceptible. The continuing spread of Panama disease and the ensuing destruction of Gros Michel plantations led to the initiation of a breeding programme by the United Fruit Company in Honduras in 1959. The United Fruit Company decided to withdraw from genetic improvement research in 1984 and donated its programme to the Honduran Government. Nevertheless, banana breeding continued and the programme, now maintained by the Fundación Hondureña de Investigación Agrícola (FHIA), continues to play a lead role in the production of hybrids for worldwide evaluation. In recent years several new breeding programmes have emerged and breeding efforts, which were initially focused on improving the principal export clone, have now changed to include the varieties which are important for subsistence and small-holder producers. Most of the main sub-groups of bananas are now being addressed by one or more of the breeding programmes.

Impact of new varieties

Although the number of banana breeding programmes in existence today remains small considering the scale of the problems to be addressed, progress is being made. New hybrids are being made available for testing by several breeding programmes and following the release of improved hybrids from FHIA in Honduras and IITA in Nigeria, the common assertion that ?all cultivated bananas and plantains come from natural germplasm? is no longer valid. Improved hybrids have been distributed to more than 50 countries worldwide for evaluation, and although none of these new hybrids have sufficiently good post-harvest characteristics to be able to replace Cavendish in the export market, there are some which may be suitable for particular niche markets. It will, in fact not be easy to replace Cavendish as an export banana. Northern consumers, having never been exposed to varieties other than Cavendish, are completely accustomed to its particular taste and appearance and will not readily accept alternatives. However any industry which is completely dependant on a single variety is extremely vulnerable. Alternatives must be developed.

FHIA-01 is the first new banana variety from a breeding programme to be adopted for commercial production. It has been released in Australia as ”Goldfinger” where it is showing good potential for production in sub-tropical areas. This variety is resistant to Sigatoka and Fusarium diseases as well as to nematodes. It is cold tolerant and can therefore be grown in the sub-tropics with the minimal application of pesticides. It produces good yields of fruit with a sweet-acid flavour but the texture of the fruit at maturity is rather softer than Cavendish. Similarly, in Costa Rica a local company has been established to export FHIA hybrids as organic bananas and plantains. The first shipments to the USA and Holland were well received by consumers.
The potential impact that new Musa hybrids may have on banana and plantain production in the future is already evident in Cuba. By the end of 1997 it was predicted that at least 8,000 hectares would have been planted with a number of different FHIA hybrids (FHIA-01, FHIA-02, FHIA-03, FHIA-18 and SH-3460). This represents some 7.6% of the total banana production area. These resistant cultivars are increasingly replacing susceptible banana and plantain clones on the island.
In another initiative, within the framework of a Belgium - Tanzania bilateral project, FHIA-01, FHIA-02 and FHIA-03 hybrids, together with other varieties, are being introduced into the Kagera region of Tanzania. The first plants arrived in 1994 and they are proving to be well appreciated by local farmers. These three varieties have already been renamed in Swahili - FHIA-01: Goldi (gold), FHIA-02: Mbonwa (good to be seen) and FHIA-03: Bahati (fortune). Multiplication in the field and distribution in the Kagera region is carried out by various different players, including 8 NGO's and the Ministry of Agriculture.

The role of INIBAP

The International Network for the Improvement of Banana and Plantain (INIBAP) was created in 1985 in response to the rapid spread of black Sigatoka disease and the recognized need to increase Musa breeding efforts. INIBAP was thus established as an independent research institute with a Board of Trustees and a Support Group to provide programme oversight. Rather than creating a conventional International Agricultural Research Centre with its own research facilities, it was decided to follow an innovative approach to addressing the problem, and INIBAP was therefore established as a network. In 1994, INIBAP was merged with the International Plant Genetic Resources Institute (IPGRI) and now operates as a programme of IPGRI.
INIBAP’s mission is to increase the productivity and yield stability of banana and plantain grown on smallholdings for domestic consumption and for local and export markets. It operates as a research and information service with networking as its main modus operandi. INIBAP’s key partners include the national programmes which collaborate in the framework of regional networks, and the advanced research laboratories which carry out INIBAP-supported research. INIBAP coordinates and catalyses research carried out by its many partners in both developing countries and industrialised countries worldwide and it also assumes a special service role in conserving and distributing germplasm and in compiling and distributing Musa research methodology and information throughout the network.

A supply of germplasm is a key component in many Musa research activities. However germplasm movement in a vegetatively propagated crop such as Musa can result in the inadvertent spread of pests and diseases, particularly virus diseases. In recognition of this, INIBAP has put in place a system for the safe movement of Musa germplasm based on a series of virus indexing centres. INIBAP has also assembled the world?s largest in vitro collection of Musa germplasm consisting of some 1,114 accessions. This material is maintained at the INIBAP Transit Centre (ITC) and is freely available to bona fide users worldwide. More than 6,000 samples of germplasm have so far been distributed to over 70 countries.

In an effort to enhance the flow of germplasm from breeding programmes to national programmes, INIBAP established the International Musa Testing Programme in 1991. This programme allows national programmes early access to improved germplasm while at the same time providing breeding programmes with worldwide screening sites with a wide range of environmental and disease pressures. Presently, improved varieties from 4 breeding programmes are being evaluated in 37 sites worldwide within the framework of IMTP. An increasing number of breeding programmes are already contributing new and promising pest/disease-resistant germplasm for evaluation in future IMTP trials.

INIBAP, in accordance with it own networking modus operandi, has been instrumental in establishing 4 regional banana research networks which bring together some 46 countries from the major banana and plantain producing regions of the world. Such networks have proved to be efficient mechanisms for setting regional research priorities and enhancing regional research activities. In relation to the use of Musa diversity, the regional networks have an important role to play. They provide a forum for the exchange of information on Musa germplasm available within the region and outside. In addition, collaborative projects and scientific exchange visits between network members allow national scientists to become familiar with varieties, techniques and cultural practices being followed in other countries in the region. Collaboration and partnerships between Musa researchers at the global level have also been stimulated by INIBAP, culminating in the creation of a global programme for Musa Improvement (PROMUSA) which brings together all the major players in Musa improvement. INIBAP provides the Secretariat for PROMUSA

As well as supporting strategic research undertaken by its partners in areas related to germplasm conservation, the safe movement of germplasm and germplasm improvement, INIBAP has also recently completed the software for the Musa Germplasm Information System (MGIS). This software is being made available to all curators of Musa germplasm collections and will allow data on accessions in genebanks to be compiled using a common format. MGIS operates as a decentralised system, with collection curators maintaining control of their own data. INIBAP provides technical back-up and facilitates the exchange of data between MGIS participants. The ready availability of information on varieties in collections will encourage the use of such material.

Future prospects

The use of Musa diversity is still at an early stage in banana and plantain production. There has been relatively little movement of germplasm from country to country or region to region and few varieties have had any impact outside their traditional areas of production. It is only in recent years that a system has been put in place for the safe movement of Musa germplasm and the necessary virus indexing capabilities established. In the past, the international movement of Musa germplasm was severely restricted by the high risks involved.

Nevertheless, diversity has a major role to play in the development of sustainable production systems for the future. Many countries are increasing their efforts to characterise and evaluate varieties already existing in national genebanks in an attempt to identify the most useful material. Furthermore, an increasing number of interesting new varieties are being produced by Musa breeding programmes. There is therefore a an ever increasing flow of germplasm to national evaluation programmes. Resistant varieties will play an important role in banana and plantain production in the future, particularly at the smallholder level, where for many, they will provide the only alternative to chemical control for certain pests and diseases.

It is not only small-scale subsistence farmers who need new varieties. The export industry also needs them. Pest and disease resistant varieties are environment-friendly and will be an essential component in any serious attempt to develop organic production. The reduced chemical applications associated with the production of new varieties will also be of major benefit to banana workers. Furthermore, a range of different varieties will allow the development of niche markets and alternative marketing strategies. Finally new varieties may be the saviour of the entire export industry in the event of a major disease outbreak of the type which wiped out Gros Michel as the main export variety in the first half of the century.

INIBAP has a contribution to make in this regard. Through direct support to Musa improvement programmes, and through encouraging increased collaboration and partnerships, greater numbers of improved varieties will be produced by the breeding programmes. Through the International Musa Testing Programme, and the activities of the INIBAP Transit Centre, this improved material will be made available to producing countries. Research into improved virus indexing techniques will speed up the whole germplasm distribution process, while the ready availability of information on Musa accessions will encourage their use by national programmes.

However, research needs remain many, and there is an urgent need for increased support for work on this crop. It is essential to raise the awareness amongst scientists, policy makers and indeed the general public, of the importance of bananas and plantains as a staple food crop. Increased support for research is essential, and the donor community in particular, needs to be made aware that the potential for impact by research on this crop is great. In recent years many of the barriers to hybridization in Musa have been overcome and the first improved varieties ever produced by breeding programmes have been released for widespread testing. However, there is still a long way to go, and particularly in this time of scarcity of resources, it is important that a crop with the global significance of bananas and plantains does not continue to be neglected by researchers and donors alike.