7.1 Present Constraints in Taro Production
7.2 Research Priorities
7.3 Future Perspectives
From the foregoing presentation, it is clear that there are several constraints that limit the scope of present-day taro cultivation and production. The major ones, especially as they apply to the Asia/Pacific region are as follows:
i) The Taro Leaf Blight Disease: This disease automatically precludes the development of a taro export trade in many countries, and in some cases threatens the internal food supply. Research must continue in order to develop resistant cultivars, or to identify effective control measures.
ii) The Taro Beetle: At present, this is the most serious pest of taro in the region. There is no effective control measure at present, and it may yet take several years before the biological control measures being developed can be tested and disseminated to farmers.
iii) Laboriousness of the Production System: Taro production at present is very labour intensive. Even in high-technology production systems, such as in Hawaii, there is still a great deal of manual labour required, especially for harvesting. In the rest of the region, the labour required is even greater, coupled with even lower yields.
iv) Scarcity of Planting Material: Like most of the other tropical root crops, the planting material for taro is bulky, making it expensive to transport over long distances. It is also perishable, and cannot be stored over a long time. The net effect of these two factors is that the availability of planting material is frequently a limiting factor in taro production. This is particularly so in countries like Tonga where droughts every few years have the effect of reducing the available planting material for several years afterwards. With planting material being so scarce, it is not surprising that some farmers use whatever planting material they can get. All the preaching by extension agents about discriminating against disease-carrying or low-yielding cultivars is only partially heeded.
v) Post Harvest Handling and Marketing: At present, the bulk of taro produced is handled and marketed as the fresh corm. The corm itself has a high water content, and cannot be stored for more than a few days at ambient temperatures. Post harvest losses are therefore heavy, and transportation costs are high. The development and use of processed forms is a partial solution. Frozen taro, Poi, and taro chips are examples. However, for a commodity that has so much cultural and sentimental baggage attached to it, there is likely to be rejection of forms that do not retain the traditional patterns of culinary preparation, presentation and consumption. Marketing channels also need to be improved, as an incentive for farmers to produce taro for cash.
vi) Limited Taro Research and Extension: The amount of research currently being done on taro is very little especially in countries where it performs mainly a subsistence function. A similar neglect of the crop is found in the extension services, so that the technical knowledge base of the producers is very low. Given the smallness of the national economies particularly in Oceania, there is a challenge for cross-national bodies to spear-head and sustain research into the problems of taro. They can also take steps to strengthen the extension services.
Most of the above constraints in the taro production system can be effectively tackled and possibly solved through research. The major research priorities at present are:
i) Control of the Taro Leaf Blight
It is amazing how very little research is being done on this problem at present. The most promising effort so far is the breeding and selection work going on at Bubia, Papua New Guinea. Yet even this work is very seriously hampered by lack of equipment and personnel (especially since the senior breeder left in 1996). The technological breakthrough which gives promise for this work is that taro flowering can now be induced reliably by use of gibberellin, as already discussed in the section on taro botany. With this method, thousands of new genotypes have been produced, and there is hope that through recurrent selection, good quality resistant cultivars can be identified, tested, and distributed.
ii) Taro Beetle Control
The most active research on this problem is taking place in the Solomon Islands and Papua New Guinea. The project is supported by the European Union under the Pacific Regional Agricultural Programme. The search for chemical and cultural control methods having proved unsatisfactory, attention has now turned to biological control. Good progress has been made since the mid-1990s. However, the future of the project is now (1998) uncertain, since the external funding support may be withdrawn. This would be quite unfortunate because the taro beetle remains a very serious problem in the region and there is yet no satisfactory control measure. Again the breeding programme is on the lookout for lines that may show tolerance to the taro beetle, although given the versatility of the beetle in terms of host range, the prospects might be less bright than expected.
iii) Taro Germplasm Conservation.
Within the region, there is a very large pool of taro germplasm (on farmers fields, in research stations, and in the wild). Many of these genotypes are being lost daily for various reasons. There is a need to conserve and characterise the taro in the region. Such a collection would not only insure against further genetic erosion of the germplasm, but would serve as a source of desired genotypes for various countries in the region. The foundations for such germplasm conservation have been laid at the Papua New Guinea University of Technology and other locations where protocols for taro tissue culture have been developed. Hopefully, this will permit in vitro maintenance of the germplasm to complement accessions that are maintained in the field.
A factor related to taro germplasm conservation is the need to broaden the genetic base of the taro industry in various countries. The destabilising effects of a narrow genetic base have already been mentioned with respect to taro cultivation in Samoa. With effective conservation and characterisation of the regions germplasm, countries seeking to broaden their taro genetic base will have a source for desirable new genotypes.
Quite recently (1998), a project called the Taro Network for South-east Asia and Oceania (TANSAO) has been launched. It is supported by the European Union, and aims to assemble and characterize the taro gene-pool in the region, as well as determine the genetic diversity of Phytophthora colocasiae which causes the taro leaf blight. However, only six countries are directly involved (Thailand, Philippines, Vietnam, Papua New Guinea, Malaysia and Indonesia); and the work is strictly concerned with plant genetic resources. It is hoped that the more taro-dependent countries of Oceania may derive some down-stream benefits from the project. One of such benefits might be the ultimate broadening of the genetic base of the taro crop in each country, using the core sample of cultivars generated by the project as a starting point. Broadening of the taro genetic base is particularly needed in Oceania.
iv) Improved Production Practices
There is still a lot of taro production that relies on age-old, traditional production methods. Research into various agronomic practices is needed in order to improve productivity. In particular, simple methods for rapid generation and multiplication of planting material need to be explored. More effective low-technology methods of multiplying planting material need to be devised. At the other end of the technological spectrum, it may be possible, for example, for tissue culture to be explored as a method for routine commercial production of planting materials. Also, as new cultivars are produced and released, there is need to establish, through research, the best agronomic practices with respect to spacing, water requirements, weed control, fertilizer, maturity, etc.
v) Post-harvest Handling and Utilization
The aim here should be to find ways to minimise post-harvest losses. New culinary forms of preparing and presenting taro should be explored, as well as development of storable processed forms.
All the above research priorities need to be addressed in order to sustain the taro industry in the Asia/Pacific region. Research is expensive and money is scarce; most of the countries are not likely to support taro research without much inducement. One type of inducement is for the authorities to understand the importance of taro both in food security and in the cash economy. This will lead them to establish the appropriate policy framework within which taro production and promotion can occur. Also, the more taro can be placed on a cash crop footing, the easier it will be to acquire the resources to support research into the crop.
Taro is an ecologically unique crop. It is able to grow in ecological conditions which other crops may find difficult or adverse. There are at least three such situations:
a) Waterlogged and hydromorphic soils.Because the above ecological conditions are difficult for other crops, there is less likely to be competition with taro in exploiting them. So, the place of taro in these ecological conditions is reasonably assured. This is in addition to its cultivation in normal field situations.
b) Saline Soils: Some taro cultivars can tolerate salinity, and can grow in 25-50% sea water. Such saline conditions would prove lethal to most other crops.
c) Shady conditions: Taro has long been known to be shade tolerant. Onwueme and Johnston (1998) have recently shown that part of the physiological basis for shade tolerance in taro is the ability to maintain a reasonably high stomatal density even under shade. Shade tolerance in taro enables it to grow well as an intercrop between tree crops (e.g. coconuts), because it can profitably exploit the diffuse light reaching the plantation floor.
In the root crop cultures of Oceania, there is a great sentimental attachment to taro. This attachment will continue to propel and fuel taro cultivation far into the future. It will also continue to ensure a vibrant internal and external market for taro.
Even the rice cultures of south-east Asia have well appreciated that the field production system for taro is very similar to that of rice. Land that has been prepared for flooded rice is equally suitable for flooded taro. Thus, taro fits well as an alternative crop in the rice-based cropping systems.
The problems that beset taro production in the Asia/Pacific region are numerous, and have been discussed above. However, given adequate research effort and the appropriate policy framework, most of the problems can be easily surmounted. Taro can then continue to perform its age-old functions of providing food security, boosting the economy through internal and external cash earnings, and playing a critical role in the socio-cultural life of the people.