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Spring 1993

Research Magazine > ARCHIVE > Spring 93 > Article

by Robert Rhoades

During his 1839 exploration and voyage aboard the H.M.S. Beagle, young Charles Darwin was fascinated by an amazing South American plant that was so adaptable it seemed to defy the very laws of nature. In his log, the great naturalist wrote:

It is remarkable that the same plant should be found on the sterile mountains of Central Chile, where a drop of rain does not fall for more than six months, and within the damp forests of the southern islands.

The remarkable plant Darwin observed was the potato, a gift of South American Indians to the rest of the world.

Today the potato is the world's fourth most important food crop and by far its most important vegetable. Cultures that may have very little else in common share the cultivation of potatoes. Varieties of spuds are grown by people in 130 countries around the world -- more than any other crop except maize -- and their production in developing countries is increasing faster than that of any other food crop.

Potatoes didn't mean much to me in 1979 when I became the first resident anthropologist at the International Potato Center (CIP), headquartered in Lima, Peru. A potato was still just a potato and nothing was more boring than a sack full of them. At the time I couldn't have realized that the search for facts about Darwin's remarkable vegetable would take me across four continents, through dense coastal jungles and into remote mountain villages. That 15-year journey continues today, and the mission remains deceptively simple: To document the dispersal of potatoes throughout the globe and how they have come to impact diverse environments and cultures.

I learned that however you slice it, few foods have a more legendary past, natural diversity, fascination to science or a greater potential to feed our hungry planet.

The potato's popularity flourishes because of precisely the same characteristic that Darwin scribbled in his notes during his 1839 Beagle expedition: Its adaptability allows it to prosper in more than a dozen distinct climates, from equatorial mountains slopes that soar 13,000 feet above sea level, to the ocean's edge in tropical Sri Lanka.

Yet more than a century and a half after Darwin wrote of its impressive adaptability, scientists and laypersons alike still share the misconception that potatoes are a cool-climate crop suited only to northern latitudes. The potato's diversity continues to elude us. Most Americans -- despite our voracious appetites for potatoes fried, mashed, baked or boiled -- actually are acquainted with only a handful of the thousands of varieties that thrive in fields and gardens around the world. We know surprisingly little about potatoes grown beyond our borders -- or even if we are growing the varieties best adapted to a given climate and soil.

Considering the global need for well-adapted, nutritious food crops, underestimating the power of the potato could be a fatal mistake. That's why scientists and farmers are working together to preserve the potato's genetic diversity, to explore its incredible tolerance of climatic differences and to determine which strains grow best in what regions.

With this in mind, I led a small cluster of researchers to track this quarry and map the myriad varieties that thrive from Maine to Manila. The knowledge gained from that effort is important to the future of the crop's cultivation. One result is the new and better matches between potato varieties and climates. Another is the rapid introduction, cultivation and migration of potatoes in developing countries, where inexpensive, wholesome foodstuffs are imperative.

Low-Budget, High-Quality Research

The major research thrust of the International Potato Center is to collect, preserve and develop the many varieties of the potato, Peru's national treasure. The fruits of that labor are distributed worldwide, especially to developing nations that can make quick use of the crop.

However, I soon realized the CIP potato breeding program was flawed. Germ plasm -- seeds, tubers and other parts that give rise to new plants -- was being shipped around the world in more or less a shotgun approach rather than according to concrete information on climatic zones or producers' needs. To fulfill its mandate, CIP needed a lot more information on potatoes -- their agro-ecological zones, diseases, pests, markets and types of producers.

Ideally, that information would be logged on a global, computer-aided reference work that research scientists, agricultural policy makers and farmers could use to make better-informed decisions.

They soon will have one. The World Geography of the Potato, scheduled to be published in 1995, includes data on everything from the history of its introduction in a particular country to how spuds fit into a nation's cuisine. In short, the book, which also will be available via a computerized, relational data file, contains almost anything you'd ever want to know about a potato plus things you'd never even think to ask.

But our potato geography research didn't start with such big aspirations. In fact, it was pretty "small potatoes" as research projects go. The project began as a small-scale, low-budget effort, quite literally with a single file drawer and a collection of notebooks.

Like most non-profit groups, the center was under the gun from donors and others to justify its allocations on research programs, so the project initially received no funding. I started slowly and simply, even though my long-term goal -- to develop maps of potato production throughout the world -- was ambitious.

The first step was to collect data on the precise conditions under which potatoes were being grown. Specifically, I needed to know when and where potatoes were planted and harvested, how they were cultivated, the kinds and severity of pests and diseases at each location, and post-harvest storage and distribution methods.

Together with my Peruvian assistant, who was permitted to work part-time on the project, we established the International Potato Reference Files. With these files, we began to determine where potatoes were being farmed around the globe and correlate potato cultivation with climate. Later these files would form the basis of potato cultivation maps.

Despite the official-sounding name, the files were hardly auspicious. Folders were labeled with names of developing countries known to grow a significant amount of potatoes -- from Albania to Zimbabwe. These folders then were placed in the bottom drawer of the only filing cabinet in my office. Our approach was also low-key because biological scientists and CIP research managers alike typically regard reference file activity as "just another social scientist accumulating tons of information with no practical use."

The best way to tackle the problem was to adapt research methods used by anthropologist George Peter Murdock. In the 1940s Murdock classified and compared the world's human societies by systematically organizing available information on 330 groups of people into 700 subject categories -- technology, social patterns, economics, language, food production, etc. By the early '60s, he was using a computer to make cross-cultural comparisons and develop original maps for a variety of crops, including the banana, date palm and sweet potato.

Like Murdock I decided to glean and assimilate information from what is called "gray" literature -- unpublished or obscurely published materials, literature of sciences outside the field of agriculture, and knowledge that exists in the heads of scientists and extension agents who deal with potatoes but who are rarely asked to compile such information.

In our spare time, my assistant and I combed thousands of documents furnished by Lima libraries. We set up files on 95 developing countries, which grew to include 130 countries. I also interviewed potato scientists and other visitors to CIP and added their information to our expanding files.

As I reviewed official government maps of potato production from various countries and compared them with the gray literature, I realized I could learn much more than just national statistics on total crop production or average yields. In just one year our research was paying off: We had gathered a tremendous amount of information on potato production in developing countries that could be used internationally to make decisions about crop production.

By this time we had accumulated so much information that we had to augment our filing system with loose-leaf notebooks. Organized by continent and country, the notebooks contained categories on the history and trends of potato production; production zones and climate; production practices such as growing seasons, seed sources and varieties, and pests and diseases; and post-production information on storage and processing, distribution, and preparation and consumption.

A Picture of Potato Production

To get a precise understanding of the geography of each agro-ecological zone and the crops it would support, we translated information from our bulging reference files to zonal maps. Such maps are instrumental in calculating which varieties are most likely to flourish in a given region, based on climate, crop diseases, day length, soil temperatures and other factors. And they help CIP maximize its world-wide distribution of germ plasm.

We plotted our data by latitude and longitude on detailed maps that included provinces, cities and towns, rivers, mountains and other geographical features. We included information from the hand-drawn, and often crude, maps sketched for us by potato workers familiar with specific potato zone locations.

Then we double checked areas our maps predicted would be fertile possibilities for potato cultivation with an "eyeball" modeling approach. Our best guesses took into account many variables, including elevation, irrigation and latitude. Additionally, we sought opinions about those best guesses from scientists who were familiar with the countries in question. We even sent rough maps to farmers, scientists and extension agents in many countries and asked them to assess and correct our zonation. We also used descriptive data, such as provincial census information, to help define and refine the potential potato zones on our maps.

By 1987 we were using computers to generate digitized maps of 121 developing countries -- a further progression of the mapping process. Our maps confirmed that most climates in developing nations are potentially suitable for potato production.

The maps, which included latitude and longitude, ecological and climatic zones, topography, etc., helped us determine precise agro-ecological zones of potato production and plot sites for trial germ plasm distribution. We could predict the effects of climate, precipitation, temperature regimes, altitude and disease patterns on crop production at the continental or international level.

But all this file and map research did more than merely confirm the potato's amazing adaptability. It helped define it.

For example, we learned that, in developing countries, the potato is produced in at least 10 distinctly different climates, making it perhaps the most adaptive of the major food crops. Lowland tropical zones account for nearly half of the production in these countries. As long as night temperatures fall below 68°F -- a prerequisite for potato plants to produce edible tubers -- potatoes will grow in such hot, dry climates even when average daily mean temperatures climb to 86°F.

They can be grown in hot, humid tropical rain forests at mid-elevations of 2,500 to 3,300 feet. Even though it's difficult to grow them in climates with short dry seasons like those typical of tropical rain forests, CIP has grown them successfully at Yurimaguas, Peru, which falls into this category.

Additionally, potatoes are easily cultivated in the highlands and temperate zones, especially northern China and Turkey. New pockets of potato production are emerging in several warm lowland climates, such as West Africa and the Caribbean. Although climates of some areas are modified by elevation, farmers in most areas are using techniques, such as selection of appropriate seasons, to enhance potato cultivation.

Our research is helping potatoes gain a foothold in many countries where they are helping feed large populations. The rapid expansion of potato cultivation in Asia, for example, is the result both of better adapted potato varieties and of the ability to capitalize on cultivation compatibility between potatoes and other important crops, especially rice and wheat. Potatoes are easily rotated with both these crops, since all three grow under similar ecological and climatic conditions. The Asian potato-cereal food system stretches from the Punjab of India throughout Southeast Asia into China. The potato now covers more land and feeds more people in this area than in any other potato production zone in developing countries.

Researchers and farmers continue to implement production systems and introduce varieties that flourish in subtropical areas such as the Indo-Gangetic plain, which has quickly become one of the world's leading potato-producing zones.

Tools of the Trade

Like the humble potato itself, the reference file method will continue to be an important weapon against hunger. It is easily used to map the cultivation and spread of any crop or livestock research program, and therefore, ideally suited to target appropriate technologies to the farmers' and consumers' needs. In fact, CIP has started a similar reference file on the sweet potato, and several institutions in the Philippines have started a root crops reference file. Although the process of gathering and organizing information for a reference file is slow, the files are easy to update. And they provide a structure to organize information in a permanent relational database and capitalize on available information and research.

This research method also can shed light on many other anthropological questions, such as technological changes, adoption patterns and many more. For example, the World Geographic Project recently used it to generate precise information on the migration of the potato around the world from its Andean homeland.

More importantly, the information becomes grist for our technology mills. Despite an ever-increasing dependency on technology to divine optimal crop strategies, satellite imagery, remote sensing devices and other sophisticated data systems just don't work without the data that reference files can provide. Our files not only were important in developing zonal maps but also they formed the foundation for the recently completed Geographic Information System for the potato.

Without a doubt though, the most important aspect of this research is its impact on future farming. By documenting the potato's remarkable versatility, we can help developing nations set priorities and make agricultural policies that will help put food on tables now and for generations to come.

And once The World Geography of the Potato is published, anyone will be able to find out when potatoes first arrived in China or how they are prepared in Singapore. Though the tome may not be nominated for Book of the Month, it's not a bad biography for the world's most misunderstood vegetable.

Robert E. Rhoades is head of the anthropology and linguistics department. In addition to numerous research papers for academic journals, he has written widely on science topics for the popular press, including National Geographic. In 1991, he received the Science-in-Society Journalism Award
from the National Association of Science Writers.

Debunking Potato Mythology
by Robert E. Rhoades

At one time or another, it seems, the potato has been blamed for just about everything -- wars, lust, TB and obesity, to name a few.

For example, when first introduced into Europe, the potato was cursed as the food of witches and officially banned. Beliefs developed that potatoes caused syphilis and rickets, and had aphrodisiac qualities. It's even been said the word spud is derived from the "Society for the Prevention of an Unwholesome Diet," a 19th-century activist group dedicated to keeping potatoes out of England.

The potato's popularity may have been hampered, in part, because of its family tree. A member of the deadly nightshade family, it has many plant cousins that are poisonous.

Resistance to eating potatoes was so strong in some parts of Europe that rulers who wished to overcome anti-potato sentiments literally had to force potatoes down their subjects' throats. In 1651, Frederick Will of Prussia issued an edict threatening to cut off the nose and ears of anyone who refused to plant potatoes. This didn't work, so his successor, Frederick the Great, allegedly held an open-air banquet and served potatoes to prove they weren't poisonous.

Although most myths disappeared long ago, one still persists that is potentially damaging: The potato is a cool climate crop unsuited for cultivation in many developing countries.

Actually, just the opposite is true. This myth, which may seem innocuous, has hampered the spread of the potato as a basic food crop for the world's undernourished, especially in developing nations.

In fact, potatoes are well suited for a variety of climates and countries. In northern regions potatoes take a minimum of 150 days to attain a maximum yield, but in tropical areas farmers may begin to harvest in one-third the time -- a mere 50 days after planting. And farmers in the tropics also may obtain yields that rival their northern neighbors -- 50 to 60 tons per acre -- in less than 90 days.

And there's no myth in the potato's supreme value as the world's most important vegetable crop. Once maligned by the masses, the potato, now grown from Alaska to the Azores, has invaded the cuisine of more than 130 countries and become a mainstay in the world's diet.

Research Communications, Office of the VP for Research, UGA
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