Making cassava stronger in the Amazon

I had a chance to roam through the extensive exhibition of posters at SIRGEALC yesterday, and, although many of them were attractive and interesting, one in particular stood out. Actually, Dr Fabio de Oliveira Freitas of the Brasilian plant genetic resources programme (CENARGEN) had two posters up. That’s him in the photo below. One seems to be an update of his thesis work on DNA fingerprinting of archaeological maize remains, which you can read about online. That was interesting enough, but the second poster was even better.

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It told a great story from Dr Freitas’ work with a group of Amazonian indians. He’d been visiting a remote area right in the middle of the Amazon for about ten years when he noticed something he hadn’t seen before. In one village, one family had the habit of planting one stake of each of their cassava varieties all together on one mound. Later he found another family in another village doing the same thing. This is apparently an old custom that was more widespread in the past, and that for some reason is declining, although it is supposed to “make the cassava stronger.” Normally, people plant one or more stakes of a single variety in a given mound. But these two families built one somewhat larger, special mound in their field, and planted a specimen of each of their dozen or so varieties in it, so that they grew all together in close proximity, their spindly branches intertwining. That means more crossing among varieties, and more hybrid seedlings on the ground around the mound, for the people to select and nurture new varieties from.

It’s unclear why this agrobiodiversity-friendly ritual is disappearing, and what can be done to stop this happening. But my money is on Dr Freitas to find out and tell us about it soon.

Cows and ants interact in Argentina

A paper just out in the Journal of Applied Ecology is a really great illustration of the interactions among different components of agrobiodiversity that we’re always on about here. ((TADEY, MARIANA & FARJI-BRENER, ALEJANDRO G. Indirect effects of exotic grazers: livestock decreases the nutrient content of refuse dumps of leaf-cutting ants through vegetation impoverishment. Journal of Applied Ecology 44:1209-1218.)) The Argentinian researchers found that putting more cattle to graze on the steppe vegetation of the Monte Desert in Patagonia resulted in a progressive decrease in plant cover and species diversity. So what, right? Well, this affected the diet of leaf-cutting ants. And that meant that the ants’ refuse dumps were less rich in nutrients. Which meant lower soil nutrient avalability. And perhaps eventually less healthy and productive cows. As well as further changes in the vegetation. It just takes a slight reduction in stocking rate (the number of cows per hectare) to restore the ants’ diet and the fertility of the soil.

Seeds in the Antarctic

I have some more information on the seeds-in-the-Argentine-Antarctic story. A book was distributed yesterday at SIRGEALC entitled Avances de Investigación en Recursos Genéticos en el Cono Sur 2. It was put together by the regional plant genetic resources network for the Southern Cone (REGENSUR) and came out earlier this year. ((It should in due course appear on the publications page of the PROCISUR website, like its companion volume from 1999. PROCISUR is the regional agricultural research and development coordination mechanism for the Southern Cone.)) In it there’s a paper by BS Rosso and ME Ferrer, of one of Argentina’s agricultural research stations, describing a singular experiment.

It seems that, in 1983, batches of seed of maize and soyabean were dried, sealed into aluminium foil bags, placed in aluminium containers and left in ambient conditions at three research and military installations, two of then in the Argentine Antarctic ((The map will show you the location of Base Jubany, one of the sites.)) and one in southern mainland Argentina. Twenty years later, the seeds were tested for germinability. The samples left at the sites in the Antarctic, which enjoyed average temperatures of -18°C and -2°C, hardly degenerated at all in percentage germination. The seed batches left at 9.5°C did, substantially.

So I don’t think that germplasm is actually been safety duplicated under ambient conditions in the Argentine Antarctic. But it could be…

LATER: Well, maybe not. Marcelo Ferrer is here at SIRGEALC and I had a nice chat with him in front of his poster, which happened to be about maize characterization — he’s a maize breeder. I asked him whether, after his experiment, there were any plans to duplicate the Argentinian seed collections in the Antarctic. He said it would not be very practical. The only way to get to the bases is by sea, and then only for a short period each year. Some years, it’s not possible to get there at all because of the ice. Climate change may make access a bit easier, I guess, but you’d probably want your duplicate collection to be a little closer to hand.