Category: Breeding

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Cassava in Africa

Cassava has a big problem in Africa, and it is called brown streak virus. A virulent strain is spreading rapidly across eastern and southern Africa from a beachhead in Zanzibar, devastating the tubers but leaving the leaves looking healthy, which means farmers don’t realize anything is wrong until it is too late. Scientists from the International Institute for Tropical Agriculture (IITA) have been studying the virus and have developed resistant varieties, by conventional breeding, and these are finding their way to farmers.

There’s a short SciDev piece about brown streak virus which points to a longer, very readable New Scientist article. I know we’re talking about a very serious problem and a very nice solution based on the exploitation of agricultural biodiversity, but normally I wouldn’t blog about this sort of thing, simply because there are so many similar examples out there. But I was inspired to do so on this occasion because I also spotted an article in a Ugandan newspaper (via the wonderful allAfrica.com) which talks about the resistant varieties and efforts to get sufficient planting material of these cultivars into the hands of farmers in a particular district. It’s always nice to see “big” stories from international news sources reflected in the local media.

Cassava is an important constituent of Kinshasa’s urban gardens, whose role in providing nutrition, especially to children, is so well described in a Christian Science Monitor article today. Let’s hope brown streak virus doesn’t reach Kinshasa, but if it does the resistant varieties would find a ready means of dissemination through a project which “organized a team of local volunteers called “Mama Bongisa” (‘mom improver’) to teach mothers in some … impoverished neighborhoods about nutrition and farming.”

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Undoing millennia of barley selection

Generations of beer-loving farmers have bred seed dormancy almost entirely out of barley, so that the grains will readily germinate in the malthouse. Unfortunately, that means that malting varieties are sometimes prone to jumping the gun and sprouting before harvest, while the crop is still standing in the field. That means that the grain cannot be used to make beer. Not a good thing.

Fortunately, a PhD student in Australia, a land well known for its love of the amber nectar, has compared the barley genome with that of Arabidopsis and identified some bits which may contain previously unknown dormancy genes. Should a negative effect on pre-harvest sprouting be confirmed in the field – and trials are under way – breeders could use markers for these genes to help them select genotypes which will only sprout where it would do the most good: in the maltings.

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Durum wheat erosion

If there’s a dominant meta-narrative in agricultural biodiversity circles it is that modern breeding programmes relentlessly decrease the genetic diversity of crops, increasing yields and quality but also, as new varieties displace landraces and older varieties in farmers’ fields, depleting the very resource on which they are dependent for continued success. But actually there’s not really that much in the way of hard figures on this process. So a recent paper on what breeding has done to diversity in Italian durum wheat is very much to be welcomed.

The researchers used molecular and biochemical markers to compare genetic diversity among five different groups of durum varieties, ranging from landraces from before 1915, to pure lines derived from landraces in the 30s, to genotypes selected from crosses between local material and CIMMYT lines in the 70s. In general, there was indeed a narrowing of the genetic diversity within these groups over time. In fact, the degree of narrowing was probably underestimated, because only a relatively few of the pre-1915 landraces were still available for analysis. Conserving what is left is all the more important.

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Making grains relevant

The low-carb craze of a few years back has spoiled the nutritional reputation of cereal grains, and it is up to the industry to get people eating them again. So said Francesco Pantò of the pasta giant Barilla yesterday at the first European congress of the American Association of Cereal Chemists International (AACCI), in Montpellier. He suggested five ways to do that:

  1. develop new durum wheat varieties and special products that can differentiate them, as for grapes and wine
  2. market grains as mainstream and everyday products
  3. use innovative technology to incorporate new grains into familiar products
  4. aim for convenience, and promote the goodness of cereals and fiber
  5. add extra components to cereal products in order to make them into a more complete meal

The first of these will of course be particularly welcome by those of us interested in agricultural biodiversity, and I wonder whether pseudocereals like buckwheat and quinoa might also find a place under the third point.

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Organic agriculture

FAO has a paper out on organic agriculture, as part of the International Conference on Organic Agriculture and Food Security, going on in Rome as I type. Here’s a quote:

The strongest feature of organic agriculture is its reliance on fossil-fuel independent and locally-available production assets; working with natural processes increases cost-effectiveness and resilience of agro-ecosystems to climatic stress. By managing biodiversity in time (rotations) and space (mixed cropping), organic farmers use their labour and environmental services to intensify production in a sustainable way.

Those are some of the strengths, and very significant they are too. An often-quoted weakness of organic agriculture, however, is that yields are often lower than what you’d expect from “conventional” agriculture. But why? Well, according to a recent study using wheat as a model, part of the reason is that the varieties used are poorly adapted to the particular conditions of organic agriculture: “increasing yield in organic systems through breeding will require direct selection within organic systems rather than indirect selection in conventional systems… With crop cultivars bred in and adapted to the unique conditions inherent in organic systems, organic agriculture will be better able to realize its full potential as a high-yielding alternative to conventional agriculture.”