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What are breeders selecting for?

ResearchBlogging.org One of the arguments in the organic-can-feed-the-world oh-no-it-can’t ding dong is about the total yield of organic versus non-organic. 1 Organic yields are generally lower. One reason might be that, with a few exceptions, mainstream commercial and public-good breeders do not regard organic agriculture as a market worth serving. The increase in yield of, say, wheat over the past 70-80 years, which has been pretty profound, has seen changes in both agronomic practices — autumn sowing, simple fertilizers, weed control — and a steady stream of new varieties, each of which has to prove itself better to gain acceptance. Organic yields have not increased nearly as much. A new paper by H.E. Jones and colleagues compares cultivars of different ages under organic and non-organic systems, and concludes that modern varieties simply aren’t suited to organic systems. 2

The basics of the experiment are reasonably simple. Take a series of wheat varieties released at different dates, from 1934 to 2000. Plant them in trial plots on two organic and two non-organic farms for three successive seasons, measure the bejasus out of everything, and see what emerges. One of the more interesting measures is called the Cultivar superiority (CS), which assesses how good that variety is compared to the best variety over the various seasons. As the authors explain, “A low CS value indicates a cultivar that has high and stable performance”. The expectation is that a modern variety will have a lower CS than an older variety, and for non-organic sites, this is true. At organic sites, the correlation is much weaker.

You can see that in the figure left (click to enlarge). For the open circles (non-organic) more modern varieties have lower CS (higher, more stable yield), while for filled circles (organic) there is no relationship. Why should this be so. Because of those changes in agronomic practices mentioned above.

[M]odern cultivars are selected to benefit from later nitrogen (N) availability which includes the spring nitrogen applications tailored to coincide with peak crop demand. Under organic management, N release is largely based on the breakdown of fertility-building crops incorporated (ploughed-in) in the previous autumn. The release of nutrients from these residues is dependent on the soil conditions, which includes temperature and microbial populations, in addition to the potential leaching effect of high winter rainfall in the UK. In organic cereal crops, early resource capture is a major advantage for maximizing the utilization of nutrients from residue breakdown.

To perform well under organic conditions, varieties need to get a fast start, to outcompete weeds, and they need to be good at getting nitrogen from the soil early on in their growth. Organic farmers tend to use older varieties, in part because they possess those qualities. Concerted selection for the kinds of qualities that benefit plants under organic conditions, which tend to be much more variable from place to place and season to season, could improve the yileds from organic farms.

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San Francisco apes Svalbard global seed vault — locally

In our line of work it is common to hear people rave about the importance of informal seed systems for ensuring that farmers have access to the agricultural biodiversity they need and want — in developing countries. Not so common elsewhere. Now, from the Ethicurean, comes news of a project to build a Backyard Seed Vault, which sounds very like an informal seed system in San Francisco, California. The project’s instigator, who is co-executive director of a group called Agrariana (and check out their origins and mission statement), has this to say:

We’re looking for approximately 100 San Francisco Bay Area gardeners for the inaugural season who would like to work as a community to save heirloom vegetable seed. … Agrariana will lead hands-on workshops in participants’ gardens on properly saving seed. The Backyard Seed Vault is working in conjunction with the Bay Area Seed Interchange Library (BASIL), a project of the Ecology Center, for their immense knowledge on properly saving, labeling, cataloging, and storing seeds. Seeds not redistributed to participants will be donated to BASIL, providing an opportunity for any community member to “check out” seed to grow in their gardens. Gardeners of all skill levels are welcome to participate.

Sounds like a lot of fun. And there are actually lots of similar seed exchanges all over Europe, North America, Australia etc etc. Will they, I wonder, ever attract the attention of people who study the value of informal seed networks elsewhere?

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Carnival Time: Science for the People No. 27

Yes indeedy, the latest edition of Scientia Pro Publica — science for the people — the blog that celebrates good science blogging is up at Melliferax. As usual, there’s a load of interesting stuff there, though not much of it is specifically agricultural. We should note, however, that Melliferax is herself a bee-keeper, and where would we be without bees? That said, two pieces caught my eye. In Always eat fruits before a meal?? the science behind false claims, Akshat Rati dissects the ludicrosity of an email that is apparently doing the rounds but that has so far had the good sense to leave me alone. And in Evolution: watching speciation occur Christie Wilcox gives not one but two examples of evolution in action, one from a neglected and absolutely delicious and beautiful crop, salsify, and one from a crop pest, the apple maggot fly.

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Early farmers got high on chickpeas?

ResearchBlogging.orgA somewhat cryptic comment a few days ago on a year-old post on domestication eventually led us to an intriguing 2007 article in The Times which we unaccountably seem to have missed the first time around. The article quotes liberally from a Journal of Archaeological Science paper which puts forward something of an unorthodox take on chickpea domestication. 3

The authors, from various Israeli institutions, start by saying that chickpea is an unusual member of the “founder package” of Middle Eastern crops, which also includes diploid einkorn wheat, tetraploid emmer wheat, barley, pea, lentil and bitter vetch. That’s because its wild precursor (Cicer reticulatum), unlike those of the other first crops, has a relatively narrow distribution and an indehiscent pod (that is, the pods don’t split open when the seeds are ripe), and the crop itself is grown in the summer rather than the winter, basically to escape the fungal disease Ascochyta blight. A rare precursor and a problematic agronomy: why bother with the damn thing? There must have been something special — or at least different — driving the domestication of chickpea. That something, according to the authors, is the amino acid tryptophan.

Free tryptophan levels are an average of three times higher in seeds of cultivated chickpeas compared to their wild precursor, but with a lot of variation among cultivars. The usual sorts of processing have no effect. The levels are such that the authors are able to suggest that “consuming domesticated chickpea will elevate the levels of tryptophan available for processes other than growth and maintenance.” What processes might these be?

Tryptophan is a precursor of the neurotransmitter serotonin in the brain. More tryptophan in the diet means more tryptophan in the blood which means more serotonin in the brain, which has a whole suite of interesting effects. Apart from a feeling of satiety, these include higher ovulation rates in women, improved performance under stress, lowering of aggression and greater receptivity.

So the authors are suggesting that early farming communities consuming wild chickpeas would have been more fertile, less hungry, less depressed, more accepting of social complexity, more innovative and more self-confident. Sounds like I should be eating more chickpeas. Anyway, recognizing the effect that eating these wonder grains had on their mood — and farm animals are apparently able to recognize high tryptophan feeds — early farmers would have selected for ever higher levels, leading to the domestication of the species: “it seems that the inclusion of chickpea in the founder crop package is best understood in light of its high nutritional seed properties.”

Well, it’s a great story, and I really hope it turns out to be true, although I’m not entirely sure how one might further test the hypothesis. Shades of the tale of the domestication of coffee. But I think it might be worth revisiting that initial assumption. Is chickpea really all that different from the other members of the founder package? The distribution of its precursor is certainly limited compared to some of the cereals (the map is courtesy of GBIF).

But wild lentils are not exactly common, and much more inconspicuous. And anyway we don’t really know what the distribution of C. reticulatum was like in the Neolithic. Its pollen doesn’t turn up in cores, according to one expert I asked, so it’s going to be difficult to reconstruct its ancient distribution and frequency. And why should seed indehiscence make chickpea a poor candidate for domestication? Wouldn’t it have been just the opposite? What about tryptophan levels in the other early legumes? And finally, as suggested by a former legume breeder I consulted, was Ascochyta blight a problem in the Neolithic? And is C. reticulatum susceptible to it anyway?

It does seem that perhaps the authors may have erected a bit of a straw man, which they then attacked with a very ingenious, utterly plausible, but ultimately unnecessary argument. But that’s not going to stop me eating my pasta e ceci a bit more often than before I read this paper.