More than 90 million desperately poor people depend on pearl millet for food and income. They generally live in the drier parts of Africa and Asia, places where most other crops just won’t grow, and local farm households literally have nowhere else to turn for food security. Fortunately, pearl millet is not just a resilient and dependable source of energy, but also a good source for other dietary needs, especially micronutrients.
Pearl millet covers an estimated 31 million hectares worldwide – an area about the size of Poland – and is grown in more than 30 countries located in the arid and semi-arid tropical and subtropical regions of Asia, Africa and Latin America.
The crop is well adapted to agricultural areas that are afflicted by severe drought, poor soil fertility, and high temperatures. It also grows well in soils with high salinity or low pH (highly acidic). Because of its tolerance to such challenging environmental conditions, it is often found in truly marginal areas where other cereal crops, such as maize or wheat, can’t survive. It is grown, for example, on the edge of the Sahel desert in Northeastern Mali, an area considered by many to be where the crop came from.
Origins of the crop
Pearl millet goes by several common names, including Bulrush millet, Babala, Ddukn (in the Sudan), and Bajra (in India). It appears to have emerged and first been domesticated in the Sahel zone of West Africa, which is known to be the crop’s main center of diversity. It has been grown in Africa and on the Indian subcontinent since prehistoric times.
Recent archaeological and botanical research has confirmed the presence of domesticated pearl millet in the Sahel of Northern Mali about 4,500 years ago. Cultivation subsequently spread to Northern India, where it took root just 5 centuries later, and over the next 5 centuries after being introduced, it spread throughout the country.
During this same period, cultivation also spread across Eastern and Southern Africa. Records show that farmers began growing pearl millet in the United States in the 1850s, and the crop found its way to Brazil as recently as the 1960s.
Where pearl millet is grown today
Pearl millet accounts for about 50% of the total global production of millets. India is the largest single producer of the crop, both in terms of area (9.3 million hectares) and production (8.3 million tons). The West and Central Africa (WCA) region has large areas under millets (15.7 million hectares), of which more than 90% is pearl millet. The crop is cultivated on more than 2 million hectares in the Eastern and Southern Africa region.
Pearl millet is largely grown as a rainy season crop under rainfed conditions in Asia and Africa. Under these conditions, and especially where open-pollinated varieties (local landraces or improved cultivars) are grown, it is often grown as a component of intercropped or mixed cropping systems with legumes, such as groundnut and cowpea, or with such cereals as sorghum and maize. Hybrids, on the other hand, are rarely grown in mixed or intercropped systems, except in the very dry areas of Northwest India.
In the Cerrado savannah region of Northeast Brazil, pearl millet is grown as a mulch crop in no-till soybean systems – taking advantage of its tolerance to the acidic subsoil to produce a dense mulch that limits weed growth, prevents soil erosion, and recycles soil nutrients recovered from depth. And in central Asia it is being tested as a rotational crop after wheat to increase cropping intensity and incomes, and to limit soil erosion.
Due to its superior adaptation (compared to all other tropical cereals) to drought, soil salinity, soil acidity, and high temperatures, not to mention its food, feed and fodder values, opportunities exist for pearl millet to make inroads in new niches in Central Asia, the Middle-East, Australia and the Americas where preliminary trials have yielded encouraging results, especially with respect to its forage value. It also has potential for wider use in conservation agriculture in humid areas of Africa and Asia outside the drier areas where it has traditionally been cultivated.
Main threats to production
The major constraints to pearl millet production include:
- Such bacterial diseases as bacterial spot (Pseudomonas syringae) and bacterial leaf streak (Xanthomonas campestris pv. pennamericanum);
- Various fungal and pseudo-fungal diseases, especially downy mildew (caused by Sclerospora graminicola and Plasmopara penniseti), blast (caused by Pyricularia grisea), smut (caused by Moesziomyces penicillariae) , ergot (caused by Claviceps fusiformis) and rust (caused by Puccinia substriata var. penicillariae);
- The parasitic weed, Striga hermonthica, which can significantly reduce productivity;
- Insect pests, including millet head miner and stem borers;
- Parasitic nematodes; and
- Abiotic stresses such as drought, soil acidity, soil salinity, and high temperatures during the time when seedlings are just starting to grow and when the plants are flowering.
Current and future research
- ICRISAT scientists have conducted extensive research on resistance to the major insect pests and diseases that limit pearl millet production, as well as on improving the crop’s natural tolerance to abiotic stresses, including drought, poor soils and high temperatures;
- Considerable effort has gone into the development of high yielding, early maturing pearl millet hybrids, especially for the sufficiently moist rainfed areas (600-800 mm of annual precipitation) and irrigated areas of the semi-arid tropics of the Indian Subcontinent;
- Future research will build on the growing interest in higher yielding hybrids for Sub-Saharan Africa, building on past successes in India and on the initial hybrid vigor classification of pearl millet landraces from West Africa;
- Research will focus on exploiting the high levels of mineral micronutrients (iron and zinc) found in pearl millet grain, the crop’s high optimum temperature for growth, and its increased use for alternative food products, feed, and fodder; and
- Work will also continue to develop new genetic and genomic tools for identifying and deploying favorable genes that can significantly improve grain and stover yield potential, biotic stress resistances and abiotic stress tolerances, as well as the nutritional value of pearl millet grain, green fodder and stover.