African Rice

African rice was grown across West Africa for millennia before Asian rice arrived, and it was domesticated from a different wild species in a different place. Calling both simply "rice" hides the fact that they are separate species with separate histories and separate strengths.

The practical consequence is that agronomy, disease ratings and variety recommendations written for Oryza sativa are not automatically applicable, and neither are its weaknesses. Where the two are grown side by side, farmers frequently keep glaberrima for specific fields and specific years rather than as a general crop.

Glaberrima carries tolerance of drought, of soil acidity, and of iron and aluminium toxicity — the constraints that define much of the upland and inland-valley rice land of West Africa. Those are exactly the conditions under which an improved Asian variety underperforms its trial data.

It is also strongly weed-competitive: rapid early vigour and a droopy lower canopy shade the ground before weeds establish. In systems where weeding is the limiting labour input rather than fertiliser, that is worth more than yield potential.

The tolerances come with real costs. Yield potential is lower, the straw is weak and lodges when the crop is well fed, and the panicle shatters readily, so grain is lost between maturity and threshing.

That combination is why area under glaberrima declined as Asian varieties spread: under improved conditions it is comprehensively outyielded, and its advantages only appear where conditions are poor.

From 1992 the Africa Rice Center pursued crosses between Oryza sativa and Oryza glaberrima to combine glaberrima’s stress tolerance and weed competitiveness with sativa’s yield. The species are separated by strong reproductive barriers and the early progeny were largely sterile; viable lines were obtained by the mid-1990s and released as NERICA — New Rice for Africa.

The glaberrima accession CG14 is among the parents behind those cultivars. NERICA is therefore not a replacement for African rice so much as a way of keeping part of it in production under a different name.

Cultivation is concentrated in West Africa, in upland fields, inland valleys and the floodplains of the Niger and its tributaries. Floating and deepwater types exist among glaberrima landraces, adapted to rising floodwater rather than to controlled irrigation.

Much of the crop is grown for household consumption and local markets, so it is systematically under-represented in production statistics and is often not separated from Asian rice in them at all.

Glaberrima grain frequently has a red pericarp and mills to a lower head-rice yield than sativa, being more prone to breakage. In parts of its range that red grain carries a price premium for specific dishes and ceremonial use, which sustains production independently of yield.

A crop retained for cultural and culinary reasons at a yield disadvantage is a real agricultural fact and not a curiosity, and it is a substantial part of why glaberrima landraces still exist to breed from.

Glaberrima’s value to rice breeding is disproportionate to its planted area, so its diversity is maintained in germplasm collections as well as in fields. Traits under active investigation include the stress tolerances above and resistance to constraints such as rice yellow mottle virus and African rice gall midge.

That makes conservation of the landraces an input to the sativa crop as well as an end in itself — the argument for keeping it does not rest on the area it currently occupies.

Where glaberrima is grown deliberately it is generally managed at low input, because its advantages are advantages under stress and its weaknesses — lodging and shattering — are brought out by generous nitrogen and good conditions.

Harvest timing is tighter than for Asian rice for the same reason: shattering losses rise quickly once the panicle is ripe, so the crop is cut earlier relative to full maturity than a sativa crop would be.