Author: Luigi Guarino

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The long road to perennial cereals

ResearchBlogging.orgWhy are there no perennial grain crops? That’s the provocative question posed by a recent paper in Evolutionary Applications written by three scientists working at The Land Institute. 1 Whose institutional mission, of course, is to breed just this sort of crop, on the assumption that they “could reduce soil erosion while maintaining production of food staples.”

So what’s the answer, and what can be done about it? The authors start by pointing out that if you plot life form against net annual reproductive effort for angiosperms there’s a gap in the graph where herbaceous perennial crops with big, plentiful seeds and fruits should be. You have annual grain crops, of course, and fruit and berry cultivars, but nothing in between. Could it be that this particular “morphospace” is impossible on logical grounds? Or that there has not been enough time for the combination to develop?

After looking at a number of different possibilities, the authors come up with a very stark statement:

We suggest that the simplest explanation for the absence of perennial herbs with high reproductive effort is that, while biophysically possible, this lifeform could not have evolved by natural selection.

Let’s unpack that a bit. The authors point out that wild, out-crossing perennials are great at generating genetic diversity because

…somatic mutation generates heterozygosity in long-lived individuals … and allogamic recombination ‘destroys the associations built by, and favored by, selection’ … yet inefficiently purges deleterious recessive alleles.

This means that high genetic load results (the build-up of lethal recessive mutations), and therefore, the authors argue (with plenty of evidence to back them up), low seed set. Now, couple that with the fact that perennials tend to be ecologically dominant. What do you end up with?

You end up with a bunch of plants which are “poor candidates for rapid natural selection” in the new, open agricultural environments of the Neolithic: slow to colonize, still connected by geneflow to surrounding “wild” populations, and able to spread by vegetative propagation once established. This made “rapid domestication by sexual cycles unlikely.” Rapid domestication by vegetative propagation, yes, but that’s another story.

No wonder that

…domestication of annuals … under natural selection would have been faster than—and probably pre-empted—the domestication of perennials.

So, if you want perennial grain crops, you have to use artificial selection where natural selection has “failed.” The key is to minimize genetic load. You can do that by prioritizing for domestication perennials that are self-pollinating, which tends to be better at getting rid of deleterious mutations. Or by developing inbred lines by selfing and then re-combining the “purged” lines to restore heterozygosity, including in hybrid varieties. Or by selecting forcefully and strictly for high seed set (which has been working, say the authors). Crosses between annual grains and their perennial wild relatives can bring together “domestication traits and the perennial life history,” as has begun to be done for rice, wheat, rye, sorghum and sunflower.

Definitely worth a try. Because, as the authors conclude:

Adding herbaceous grain type crops to the inventory of existing, mostly tree-like, perennial food crops would give farmers additional options for balancing humanity’s demand for both nutritional and ecological services. We predict that artificial selection will open previously inaccessible regions of plant morphospace to agriculture and will reveal that some promising taxa were under-sampled. The grass family, for example, has given us our most valuable grain crops, but 70% of the 8000 grass species are rhizomatous perennials (Crepet and Niklas 2009) and were almost certainly overlooked in the early rounds of domestication which relied on natural selection.

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Rice, baby, rice!

Another contribution from Don Strong of UC Davis.

A fascinating video has appeared on Vimeo, “Filipino Rice Policy.” The topic of agricultural biodiversity is just below the surface of the narrative. The commentators are sophisticated economists and bureaucrats who tell an intriguing story of what amounts to a cult of rice in the Philippines. The crop and the commodity are sacrosanct politically, with secretive and lucrative importation monopolies. The commentary highlights the fact that even with a long history of premier educational and research institutions in tropical agriculture as well as high yields of rice, in few of the last 100 years has Philippine production been sufficient to meet domestic demand. The popular image of rice as the mainstay to the economy and the officially encouraged yearning for rice self-sufficiency are misleading, according to the narrative. First, the country simply lacks the physical land for rice self-sufficiency. It cannot compete in volume with the vast rice-growing areas in mainland Asia (many of which Philippine institutions fostered during the heady days of the early Green Revolution). Also, rice is just one among many crops and commodities in the diverse agricultural economy of the Philippines.

The main theme is that the government importation monopoly for rice is part and parcel of high level corruption that actually threatens food security. It is claimed that some 40% of monies dedicated to importation end up in the pockets of privileged insiders — “cronies” — rather than in the rice bowls of the poor; though the the poor are the prima facie rationale for the importation monopoly. The argument is made that were rice importation opened up, the diversity of agricultural production would increase as farmers made market-based decisions rather than monopoly-based ones; other crops and animals produce more income as well as a richer life for rural agriculturalists. This video is a professional product, well edited, and lively. The dialogue is nuanced and often waxes into advanced political economics. It would be a great supplement to graduate courses in agricultural economics, development, and environmental science. A highlight is disagreement with the theme by one commentator who fears that an end to the monopoly could bring collapse to the rice market, disaster to the country, and the downfall of the politicians who broke the monopoly. While breaking the monopoly would certainly be politically perilous, the Philippines is not among the largest global players in rice. It seems unlikely that their monopoly could be much of a factor in the global rice market.

An important sub theme of the video is how the pro-natalist policies of the Philippines have made food security an increasingly difficult goal. These populations are now much larger, still growing, and a much greater challenge to both poverty reduction and future food security than they were in 1960 when the Green Revolution widely lowered death rates and led to rapid population growth. Persistent poverty of a segment of the agricultural sector is a feature shared by many of the rice economies.

In larger perspective, the Philippines are not alone with such myths. The quixotic propaganda of rice self-sufficiency for the Philippines is analogous to that of oil self sufficiency for the US so prominent in slogans such as “Drill Baby Drill.”

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A plan to keep cacao alive in Ivory Coast, but for how long?

A long article in the Financial Times a few days ago described the woes of the Ivorian cacao industry. Fundamentally, it’s down to old, and therefore increasingly sick and unproductive, trees. And the quantity squeeze is forcing farmers to compromise on quality.

All this is important because Ivory Coast accounts for 39% of the world’s cacao production. A “chocolate crisis” is looming. And companies like Nestlé are worried. They employ a small army of agronomists, breeders and extensionists just to guarantee their supply of raw materials.

Hence their “Cocoa Plan” to replant 12 million trees (out of a total of 2 billion in the country) over the next decade at a cost of almost $100 million. A monumental task for a crop grown by hundreds of thousands of smallholders. The article does not go into detail on the varieties that are being used in the replanting, beyond saying that they are not GMOs and that the plantlets

…have already been nicknamed “Mercedes” for their supposedly upmarket quality. “They grow very, very quickly,” says Jebouet Kouassi, a 43-year-old who runs one of Nestlé’s nurseries in Ivory Coast.

Neither, alas, does the Cocoa Plan’s website. Elsewhere I found this:

The seedlings will be produced from high-yield and resistant varieties by somatic embryogenesis, which produce replicas of high performance cocoa trees, with high yield and high resistance to disease.

I hope that the narrowing of genetic diversity that this approach seems to imply will not store up problems for the future.