Similarities:
Dissimilarities:
Root and tuber crops share some common similarities, based on their biology and agricultural production and used. However, they also have a number of dissimilarities that are not immediately evident to those not directly involved in research or the development of relevant technologies.
The similarities of the root and tuber crops are:
· Perishability of the harvested product.
· Vegetative propagation, and some related consequences.
· The need to conserve genetic resources, and some related complications.
· Labor demands for production and marketing.
· Marketing, from a farm perspective.
· Research program needs, from a national level.
· Biotechnology.
· Technologies yet-to-be-developed.
Harvested Product Perishability: The perishability of the harvested products of root and tuber crops (i.e., high water content) is a fundamental consideration that leads to a rationale for greater investments in post-harvest technology research. The suitability of the root and tuber crops to the CGIAR mission hinges on the need for technologies that will allow either extended storage or the processing of the harvested products to avoid otherwise enormous losses that can occur with these commodities. The distinct advantage of grain crops is their "storageability" and their "transportability". Root and tuber crops, in much of the developing world, need to be consumed at or near the point of production. This raises key policy issues regarding the definition of who are the intended claimants of the benefits of CGIAR research investments (e.g., rural vs. urban consumers).
Cassava and sweet potato can be "field stored" in the ground for a few months with minimal loss of quality if conditions are right. All of the root and tuber crops have the distinct disadvantage, following harvest, of limited storability, and are fairly perishable if the conditions are not suitable. This characteristic of root and tuber crops predetermines the need for post-harvest treatment of these crops to preclude very large post-harvest losses.
If the CGIAR System's research agenda of the future is to focus on rural community development exclusively, then certain crop and technology choices become evident. However, if the CGIAR's future research agenda is to include humankind's poverty needs, broadly defined it will, in turn, become necessary for the CGIAR to address the food needs of both urban and rural populations in the next decades and beyond. A post-harvest technology research strategy for the CGIAR on root and tuber crops could extend the consumption of roots and tubers beyond proximal rural settings, through enhanced processing, transportation and marketing technologies.
The TAC Secretariat desk study of root and tuber crops production and consumption trends does not (indeed cannot) accurately project what some foresee as the enormous potential impact for new post-harvest technologies for root and tuber crops that would permit better storage, transportation, and processing of these otherwise perishable commodities. How this perspective can be incorporated into a valid, quantitative assessment for TAC priority setting and resource allocations is a key issue.
Consequences of Vegetative Propagation: Another similarity of root and tuber crops is the common practice of vegetative propagation. Relative to grain crops, root and tuber crops require sophisticated technologies for their propagation. Moreover, vegetative propagation of crops increases the likelihood of transmitting many different plant pathogens. In most developed countries, this type of need is dealt with through institutional outreach programs (a.k.a. Cooperative Extension in the U.S.A.). But this solution is very costly. The expense of this type of a technology transfer system seems beyond the financial reach of many developing nations. The policies (implied or otherwise) on the IARCs' restricting allocations for "technical assistance" to NARS precludes the Centres from openly dealing with this key issue. With regard to the CGIAR mandated commodities, the problems attendant to vegetative propagation, and thus the implications for technology transfer, are unique to the root and tuber crops, and the Musa spp. crops.
Complications for Genetic Resource Conservation: Another similarity of root and tuber crops relates to specific requirements for the conservation of genetic resources. The requirement to propagate vegetatively, and the perishability of the vegetative organs means that root and tuber crops require substantially more resources to assure adequate reserves are 'banked' for future generations. For some of the root and tuber crops true seed can be substituted for vegetative materials, but this approach usually compromises the genetic integrity of the collections.
For each of the individual root and tuber crops a complementary approach to their genetic conservation will need to involve a mix of different methods (primarily ex situ), as appropriate. This would include field gene banks, in vitro conservation, and seed and pollen storage, along with the storage of vegetative materials.
In situ conservation, (e.g., on farm gene banks) has some limited applications for root and tuber crops. Field gene-bank conservation is costly and carries the risk of loss of the collection, when in some situations, proper safeguards cannot be provided. Moreover, the requirements, particularly for the latter approach and with in vitro conservation, vary significantly from crop to crop. These issues are sometimes not accommodated during the allocation of resources for this important area of science enablement.
Labor for Production and Marketing: The production, harvest and marketing of root and tuber crops are generally labor intensive. The sheer bulk of root and tuber crops, compared to cereals, is an even bigger problem than is their underground harvest. Root and tuber crops can be harvested by means other than simply digging up individual plants (e.g., ploughs, spinners, mechanical harvesters) but the volume to be dealt with (stored or transported) remains a significant labor problem. The processing of traditional consumable products from these crops may also require high labor inputs.
In many countries, women are heavily involved in each of these tasks, and thus the role of women is worthy of special attention.
Marketing, From a Farm Perspective: Root and tuber crops share some similarities from a market perspective at the farm level. For instance, much of root and tuber crop production is consumed on-the-farm, or at distances that are relatively close to production. In these situations the similarities of the various root and tuber crops could be considered as one category, for research purposed. It seems reasonable to project that inter-Centre collaborations on these research topics could be organized. But the similarities of marketing characteristics for root and tuber crops become quite dissimilar when considered from an off-the-farm marketing perspective (see later section for off-farm market dissimilarities).
National Program Research Needs: Root and tuber crops share similarities at the national program level, wherein for most NARS the capacity for research on these commodities is small, relative to other commodities. Commonly, one researcher has responsibility for more than one crop (e.g., cassava and sweet potato). This situation places increased demand on IARCs to work on root and tuber crops in ways to assist national programs through partnerships that are oftentimes unbalanced.
Biotechnology: Biotechnology represents an area of similarity for root and tuber crops. Biotechnology can provide new research tools for the identification and elimination of viruses, the propagation and conservation of plant materials, and genetic enhancement that have application across commodities. Biotechnology illustrates the opportunities that the Centres have for organizing certain types of research collaborations among root and tuber crops.
Technologies Yet-to-be-Developed: Finally, one of the greatest similarities among root and tuber crops is unrealized yield potential that could be attained through yet-to-be-developed technologies. The standing panel chose not to use the term "yield gap" for this concept, as "yield gap" has been used to describe crop production levels that could be increased using known technology. In the case of root and tuber crops, the potential for yield is considerably higher than the actual yield, in most settings. All too frequently, this is because the needed technology is not available to deal with yield-limiting factors (water, nutrients) and yield-reducing factors (disease, pests). As a consequence, increases in farmer yields is expected to be much greater than from attempts to increase the physiological yield potential of crops already trapped on a yield plateau.
There are, however, in addition to the similarities noted above, some dissimilarities that distinguish the individual root and tuber crops. These dissimilarities are:
· Genetic Systems of the Individual Crops
· Strategies for Genetic Improvement
· Farming Systems Perspectives
· Pest and Pathogen Systems
· Off-Farm Markets
· Starch Properties
· Policy Environment
· Available Scientific Knowledge
Genetic Systems: To scientists familiar with the biology of the root and tuber crops, the genetics of these crops are enormously dissimilar, as are the pests and pathogens that attack them and reduce yields. From a superficial inspection, it is true that the breeding of root and tuber crops is primarily done sexually, and that there are viruses, bacteria, fungi, insects, and mites that attack these crops to varying degrees. The reality is that each of the pollinating systems and different ploidy levels brings with it breeding complications, along with specific opportunities for genetic development.
Strategies for Genetic Improvement: Strategies for the genetic improvement of root and tuber crops differ significantly, since they must to take into account the various production systems and end-uses. Some crops (e.g., sweet potato, potato) may benefit from breeding cultivars adapted to shorter growing seasons, while other crops (e.g., cassava) may need to fit into different and contrasting growing cycles. Other considerations (e.g., crop and soil management practices, crop rotation schemes, rainfall patterns) mandate that decision making be done in the individual breeding programs. The needs for improvement are usually unique to the crop, rather than to the group of crops classified as root and tuber.
Farming Systems Perspectives: There are significant differences in the farming systems perspectives of root and tuber crops, ranging from contrasting systems of production for some crops, to complex systems of intercropping involving two or more root and tuber crops. All of these aspects are important considerations, inasmuch as the transfer of know-how from one crop's farming system to another is difficult, if not impossible. This means that most farming systems research must be done for each root and tuber crop, thereby giving the appearance, falsely, of duplication of effort.
Pest and Pathogen Systems: The pest and pathogen complexes of root and tuber crops are remarkably dissimilar, in that none of the viruses of one root or tuber crop can attack another. Knowledge of one pest or pathogen may be generally applicable to other situations in other root and tuber crops, but the specific information cannot be directly applied. This is an important consideration, in that the transfer of developed technology is just as difficult from cassava to potato as it is from sweet potato to wheat.
Off-Farm Marketing: Root and tuber crops produced for off-farm markets can have considerable dissimilarities in transportation, storage, processing, consumption, economics, consumer demand, and other factors. These differences need to be taken into account when inter-Centre opportunities are assessed for improving root and tuber crops, and for distinguishing among strategies for their improvement vis-a-vis the mission of the CG System. In fact, some individual root and tuber crops are presently experiencing a segmentation of markets that will undoubtedly require substantially different types of cultivars to meet divergent market needs. Some examples of this phenomenon are the emerging uses of cassava as an industrial raw material, as compared with its traditional uses as a food. Similar differentiation is occurring with potato and sweet potato.
Starch Properties: Another dissimilarity of root and tuber crops is the properties of the starches that are produced in the harvested roots and tubers. There has been a limited amount of work on the characterization of root and tuber crop starches (mostly for potato, and to a lesser extent for cassava and sweet potato), but work to date has shown considerable variability within and between the crops evaluated. However, the methods required to evaluate the quality characteristic and assess the product potential are similar for any starch source. In addition, the required primary processing technologies (flour/starch) are also similar for all root and tuber crops. This information gap represents a whole new area of research that needs to be addressed if post-harvest technology of root and tuber crops is to become a reality. How much of this research should be done by the public sector and/or the CG System is addressed elsewhere in this report.
Policy Environment: The policy environment for many food crops often differs by commodity. Some crops are often disadvantaged as a consequence of historical choices, political realities, and a host of other considerations that are driven by market demands, alternative foods, or substitute uses. Many of these policy factors are poorly understood for root and tuber crops. It is presumed that, for this group of commodities, the relationships are not universal, and that some unique and dissimilar factors are responsible for certain observed outcomes, for specific root or tuber crops.
Available Research Knowledge: The quantity and quality of available research generated from sources other than the IARCs is another dissimilarity between root and tuber crops. For instance, potato research at developed country institutions is quite advanced, and currently there are activities in a number of areas that are being tapped by CIP. This is not the situation for cassava and yam research. And, to a degree, there is little Advanced Research Organization (ARO) technology available for sweet potato. There is virtually no research activity of potential benefit for the aroids or for the lesser-known Andean root and tuber crops, (beyond the CG system), that Centres could adopt from alternative research suppliers.
