My views on the important question of whether and how agricultural crops will adapt and prosper in the future are based on two assumptions:
- Climate change poses one of the greatest single challenges to agricultural productivity and food security in all of history. It is giving us higher average temperatures, higher extremes, longer periods of extreme heat, and high temperatures during vulnerable periods in the plant life cycle such as anthesis. Pests and diseases are extending their natural ranges resulting in new and novel assemblages of species existing together in fields and gardens. Water, land, energy, nutrient and other issues will pose additional and complicated challenges that will interact with climate to affect crop production.
- Our crops do not come pre-adapted to constellations of conditions never before experienced.
Adaptation, as Darwin taught us, depends on diversity, inheritance, natural selection and time. In the case of our agricultural crops, we largely control diversity and, through plant breeding, natural selection. Without diversity—the “right” diversity providing the critically needed traits—there is no effective, sustainable adaptation. While individual farmers and gardeners in developing countries might, in a given year, have crop populations that are more diverse than the relatively uniform modern varieties of their counterparts in the U.S., for instance, there is no evidence that would suggest that this diversity will be appropriate or adequate to allow adaption to future developing country climates and conditions for which there are no analogues in the history of agriculture.
Modern seed systems have the virtue of being able to place new diversity—new combinations of genes—in the field from one year to the next. Furthermore, they draw on the immense genetic diversity found in gene banks. Consider that modern private or public sector plant breeders have access to perhaps 200,000 distinct samples or populations of wheat, yet even a so-called diversity-rich developing country farmer and his/her farming community will be growing only one or a handful at most. That will not change much from one year to the next.
“We cannot depend on chance mutation to facilitate adaption. With the rapidity and scale of climate change, most farmers will go out of business before chance mutation and selection produces crops adapted to the scale of change forecast by climate models. Introduction of new and appropriate diversity is the only practical way of ensuring adaptation “in time.’”
We cannot depend on chance mutation to facilitate adaption. With the rapidity and scale of climate change, most farmers will go out of business before chance mutation and selection produces crops adapted to the scale of change forecast by climate models. Introduction of new and appropriate diversity is the only practical way of ensuring adaptation “in time.”
To the extent that investments in plant breeding for climate change are being made or anticipated, these apply almost exclusively to the major cereal grains. Even so, seed systems in many countries are incapable of supplying these materials to many subsistence farmers. Moreover, many of these improved varieties would not be appropriate or even adapted to the specific conditions of subsistence farmers anyway.
There is simply no plan, globally or nationally (in any nation) for promoting adaptation of food crops other than the main cereals. Individually, many of these crops are very important to food security locally, nationally or regionally. Collectively, they are essential globally. A Stanford University study noted that 27 of these orphan crops collectively occupy 250 million hectares of farmland, an area greater than that occupied by rice. Clearly their contribution to food security is more than trivial. Moreover, even crops that are extremely important to millions (e.g., yams, bananas) have fewer than 10 Mendelian-trained plant breeders working on them today. Perhaps half the domesticated crops that have entered world trade have never had a single such breeder, ever.
“If farmers do not have access to broad diversity, including diversity from other countries and continents, and if there are few if any plant breeders, how can we expect crops to adapt? By magic? Adaptation and development without diversity? Unlikely.”
If farmers do not have access to broad diversity, including diversity from other countries and continents (that may be necessary for providing traits necessary for emerging novel conditions) and if there are few if any plant breeders, how can we expect crops to adapt? By magic? Adaptation and development without diversity? Unlikely.
The U.S., in the 1800s, engaged in a massive seed diversity distribution program supplying millions of packages of seed to farmers for experimentation purposes. At its zenith, the program was distributing 10 million packages annually. It was this program that resulted, for example, in the eventual adaptation of wheat from Florida to Washington State. Farmers were empowered to experiment and adapt. The best farmer-selectors ended up supplying their neighbours and becoming seed companies. It is not possible to explain the spread and success of agriculture in the U.S. without reference to the distribution of genetic diversity and the use of it in countless adaptation experiments by farmers.
We have more institutional and informational capacity now than centuries ago. We have increasingly detailed climate models. We have better and better gene bank records with accession-level data. One could construct models that would allow for “best-bet” packages of diversity to be assembled and provided to farmers on a massive scale to promote adaptation. Packages would not contain enough seed to cause harm if the seed failed. It would simply provide enough for experimentation and selection. These packages could consist of mixtures of landraces and modern varieties—the point being to constitute them with diversity appropriate to the environmental and climatic conditions we anticipate. Packages could contain seed diversity of multiple crops, even “new” crops.
There are several challenges to repeating the dramatically successful American experiment elsewhere. First and foremost, we have forgotten our history. Pursuing this approach may strike many as radical, strange, impractical, etc., even if it has been done before, successfully, in the 1800s, and even if they cannot conceive of or think about an alternative to promoting large-scale adaption of less-than-major crops.
Finding the appropriate institutional home is the second most important challenge. This institution—or institutions—would have to have credibility, scientific expertise, and would obviously need to have the ability to convene and enlist the participation of a wide range of partners. Without this, such a proposal could never succeed on any scale.
The third challenge could be resistance to allowing science to guide the content of the seed packages. Political pressures as well as restrictions on access to diversity in some national gene banks could decrease effectiveness by decreasing the range of traits provided.
Finally, of course, there would be the normal issues of securing country support and solving logistical issues with distribution. I believe these could be overcome with commitment and creativity.
Obviously, this approach is an ambitious one. A project or community-by-community approach is not likely to make a major impact quickly enough, nor is it likely to attract the attention and commitment of key scientific partners. Thinking big is the alternative I suggest, rooted in our own history and in the knowledge of how evolution works. Whether or not this approach is adopted or rejected, it is clear that global food security depends on having a very broad range of crops—not just a few—adapt successfully to the new conditions they are facing now and will face in the future.