Sorghum

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Sorghum (Sorghum bicolor [L.] Moench) is the world’s fifth major cereal in terms of production and acreage. It is a staple food crop for millions of the poorest and most food-insecure people in the semi-arid tropics of Africa, Asia and Central America. The crop is genetically suited to hot and dry agro-ecologies where it is difficult to grow other food grains. These areas are frequently drought-prone and characterized by fragile environments.

In many of these areas, sorghum is a dual-purpose crop: both grain and stems are highly valued outputs. Sorghum is grown in two broad groups of countries. In the first group (primarily in Asia and Africa), production is traditional, subsistence and small-scale, and sorghum is mainly used for food. Yields are generally low and can vary considerably from year to year. Both yield and quality are affected by a wide array of biotic stresses (pests and diseases) and abiotic stresses such as drought and problematic soils. In the second group (industrialized countries and some developing countries), production is modern, mechanized, high-input and large-scale, sorghum is primarily used for animal feed, and yields are higher.

A Farmer's Sorghum Field in Moshi, Tanzania (Photo: ICRISAT HOPE/Christine Wangari)
A farmer's sorghum field in Moshi, Tanzania (Photo: ICRISAT HOPE/Christine Wangari)

Origin and use

Sorghum originated in north-eastern Africa, with domestication having taken place there around 5,000–8,000 years ago. The largest diversity of cultivated and wild sorghum is also found in this part of Africa. The secondary center of origin of sorghum is the Indian Subcontinent, with evidence for early cereal cultivation dating back about 4,500 years.

Traditional foods made from sorghum include unfermented and fermented breads, porridges, couscous and snacks, as well as alcoholic beverages. Sorghum blended with wheat flour has been used over the last two decades to produce baked products, including yeast-leavened pan, hearth and flatbreads, cakes, cookies, and flour tortillas. Malt drinks and malt cocoa-based weaning food and baby foods are popular in Nigeria. Hard endosperm sorghum is used extensively in south-east Asia for noodles.

Sorghum grain is one of the major ingredients in swine, poultry and cattle feed in the western hemisphere, China and Australia. Sorghum is also grown for forage; in northern India it is very common and fed to animals fresh or as silage or hay. Sweet sorghum is used to a limited extent in producing sorghum syrup and ‘jaggery’ (raw sugar) in India and has recently gained importance in ethanol production.

Production

In 2010, the USA was the world’s largest producer of sorghum (8.8 million metric tons annually), followed by India (7.0), Mexico (6.9), Nigeria (4.8) and Argentina (3.6).

Over the past 30 years, annual world production and the area planted to sorghum have both decreased marginally from 62.8 to 59.3 million metric tons and 44.5 to 41.9 million hectares. Yields in 1978–80 and 2008–2010 were virtually the same (1400 and 1412 kilograms per hectare). However, these global figures mask wide variations at the national level. In India, for example, between 1978 and 2010 the area planted to sorghum fell from 16. 1 to 7.7 million hectares and annual production fell from 11.4 to 7.0 million metric tons, but yields increased by 40% from 689 (in 1978–80) to 965 kilograms per hectare (in 2008–10).

Nutrition

Sorghum grain contains 11.3% protein, 3.3% fat and 56–73% starch. It is relatively rich in iron, zinc, phosphorus and B-complex vitamins. Tannins, found particularly in red-grained types, contain antioxidants that protect against cell damage, a major cause of diseases and aging.

The protein and starch in sorghum grain are more slowly digested than those from other cereals, and slower rates of digestibility are particularly beneficial for people with diabetes. Sorghum starch is gluten-free, making sorghum a good alternative to wheat flour for individuals suffering from celiac disease.

Impact of CGIAR Centers

The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), and national program partners in Asia and sub-Saharan Africa, assessed the ‘spillover’ potential of sorghum varieties and hybrids. This aimed to find out how successful these varieties were in areas outside those that they were originally bred for. It has often been argued that, in heterogeneous environments, returns on the investment in breeding new varieties will be low, because new cultivars will tend to perform well in only the locations that they were initially bred for. However, the study demonstrated that this was not the case. In fact, cultivars originating from collaborative national and international research can prove to be highly transferable across different environments.

The productivity gain from improved cultivars more than makes up for the cost of additional inputs like fertilizer used for their cultivation. The cost–benefit ratio of production of improved cultivars ranged from 1:1.25 (in West and Central Africa) to 1:1.4 (in India). The net present value of benefits from the cultivar S 35 was estimated at US$15 million in Chad and US$4.6 million in Cameroon. The internal rate of return was 95% in Chad and 75% in Cameroon. The adoption of improved cultivars in eight Southern African Development Community member states together contributes an additional US$19 million per year in income streams.

Improved varieties occupy approximately 36% of Tanzania’s sorghum area. They are widely popular, mainly for their early maturity (and thus drought tolerance) and high yield – 10–38% higher than local varieties. Adoption has been stimulated by interventions by ICRISAT and local partners to strengthen local seed systems and community-based seed production.

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