Posts

Posted on

What is maize good for?

Two pieces of work on maize I recently came across are unconnected as to aim and place, but nevertheless make for an interesting combined story. One asks how far maize yield can actually be pushed by the environment; the other, how far we should define its success by yield anyway.

The first study is a systematic analysis of more than 14,000 yield observations across sub-Saharan Africa. It finds that maize generally produces more grain than pearl millet, even in relatively dry environments. That complicates the familiar story that the traditional, hardy millet simply “beats” the relative newcomer, more pernickety maize in marginal conditions. And you know how much we love complicating a conventional story here.

But, heaping complication upon complication, there is a catch: maize’s performance is much less consistent. Its high yields are associated in part with hybrids and the input packages that accompany them, whereas pearl millet produces yields that are lower, sure, but also more stable. And grain weight leaves quite a lot out anyway: millet brings higher levels of iron, zinc and protein. The authors therefore argue that comparing cereal crops by yield alone can obscure their actual advantage to farmers, under their own conditions. That’s been a recurrent theme with us here, actually, come to think of it.

The Philippine experience described in the second study makes a similar point from the farmer’s side of the equation. In Laguna, farmers evaluating maize varieties did not rank them simply by how many tonnes they produced. They cared about taste, culinary uses, familiarity, nutritional value, market prospects and climate resilience as well as yield. The authors recommend involving farmers in local testing and breeding efforts, rather than treating them as merely the final recipients of fancy new varieties.

Put together, the two stories suggest a useful way of thinking about the potential, and the limits, of maize — and indeed any other crop for that matter. Maize is remarkably productive and adaptable, and the evidence does not support writing it off completely in dry conditions. But its apparent superiority depends strongly on what we measure, where we grow it, and what we put into the system.

A tonne of maize produced with expensive hybrid seed and inputs is not necessarily a better outcome than a more modest but more dependable harvest of millet; nor is a variety that comes out on top in a yield trial necessarily the variety a farmer most wants to eat, sell or grow next year.

Maize can do a great deal, but its real potential emerges only when yield is considered alongside stability, inputs, nutrition, markets and, ultimately, what the people growing and consuming it really want.

Sometimes, in some places, even maize can be an opportunity crop. Other times, not so much. And that goes for millet too.

Posted on

Terere, in more ways than one



 		Terere (amaranth) is mainly a traditional leafy green vegetable in Kenya of course…
…and readily available these days in supermarkets.



But it’s interesting to see the grain also used…
…in lots of interesting products.

Quite the veggie revolution in the last 10 years1, but have we now reached peak terere?

I mean, how much more land is there?

Posted on

Cassava on a roll?



 		Is it me, or are there more cassava products…
…in Kenyan supermarkets these days?

Production has been up and down, though on a generally rising trend, mainly due to expansion of the area of cultivation, apparently.

Climate change could be one driver. But so, presumably, are disease-resistant varieties, promotion pushes, and a growing appetite for cheap calories. Including in the form of crisps.

Posted on

The plants that statistics forgot

FAO has just put out new guidance on capturing wild foods and neglected and underutilized species (NUS) in dietary surveys. It’s very much worth a look, even if your interest runs more to grain landraces on the farm than to greens gathered from the forest. The methodology is built to overcome a very real problem: standard dietary assessment tools are generally designed with the main staples in mind, so anything outside that narrow frame (think foraged, seasonal, localized, thinly documented) tends to fall straight through the cracks.

FAO’s fix is a set of very sensible, practical steps: engage local knowledge holders to compile inventories under their own names for things, survey markets to see what’s actually being sold and eaten, map harvest calendars against agroecological zones and seasons, and build simple identification tools (photobooks, reference databases) that let enumerators and communities work from a shared understanding of what they’re counting.

None of that machinery is specific to wild foods though. The same toolkit could easily be adapted to survey the diversity hiding in plain sight on farms: crops and landraces known only by a few, grown in a handful of villages, marginalized, on their way to be forgotten. And invisible to national crop statistics that only track the main crops and the most common named improved varieties, if that. A market survey designed to catch wild greens sold at the roadside works just as well for catching a local bean landrace in the same market. A harvest calendar built to track when forest foods peak works just as well for tracking when fonio gets planted or harvested, and why farmers still bother with it. Great for quantifying the opportunity presented by “opportunity crops.”

And there’s a useful downstream application: surveys built this way could help flag where crop diversity is thinning out on the ground, or where it’s abundant but under-represented in genebank holdings. In other words, the kind of gap analysis that ought to be steering germplasm collecting missions.

FAO’s framing kind of gestures at this already: wild, managed and cultivated aren’t three separate boxes but points on a continuum. A methodology built to navigate that blurriness for wild foods is also a methodology that ought to work for navigating the blurriness at the cultivated end. It would be a shame if this toolkit stayed confined to the wild-food side of the spectrum when the conceptual heavy lifting behind it applies just as well to neglected cultivated diversity.

Posted on

Crops made, and remade

Two new studies of very different crops – banana and chrysanthemum, of all things – end up telling surprisingly similar, deliciously complicated stories. For these crops, domestication was not once and done, so to speak. They were both repeatedly remade as people moved them through landscapes containing new wild diversity.

In the banana study, the authors suggest that a partly domesticated Musa acuminata lineage from New Guinea was carried westwards through Southeast Asia, encountering and hybridizing again and again with different local wild bananas along the way. Each encounter added new genetic material to an already changing crop, helping produce the genomic mosaics found in mainland Southeast Asian bananas today.

The chrysanthemum study reveals a strikingly parallel history: cultivated plants originating in China were introduced to Japan, where they encountered local wild populations and acquired new genetic diversity, before later movements to Europe and further breeding reshaped the crop again.

The papers also show that an essentially similar process played out somewhat differently in the two crops. In banana, repeated hybridization appears to have been important in the building of the crop itself, as domesticated or partly domesticated plants became the starting material for successive encounters with wild Musa. In chrysanthemum, genomic analysis reveals a more complex network of relationships among multiple wild and cultivated groups, with C. indicum among the important ancestral contributors. In this genetic cauldron, hybridization and introgression repeatedly diversified an established cultivated genepool, contributing to traits such as flower form, colour and plant architecture.

Taken together, these papers challenge the familiar “funnel,” or bottleneck, image of domestication: a one-way downward slide from diverse wild relative to genetically narrow crop. Instead, they point to a more stop-start, two-way, non-linear, geographically contingent process, in which (semi-)cultivated plants continue to encounter, absorb and be reshaped by wild diversity.

In both banana and chrysanthemum — and probably many other cases — wild relatives have been more active, continuous participants in creating the diversity of the crops we know today than we sometimes give them credit for. Or I have given them credit for at any rate.

That argues for treating the wild genepool not simply as a reservoir from which to fish out useful genes one at a time. The historical evidence suggests that crops have benefited in the past from repeatedly absorbing larger chunks of wild genetic diversity, allowing selection to reconstruct useful combinations. Might it be worth trying to make that happen again? Is anyone out there doing pre-breeding explicitly with an eye to the past?