Rediscovering climate-tolerant crops

As East Africa battles its most severe drought in recent decades, there is growing awareness of the importance of crops that are resistant to drought and pests as a means to overcome famine.

Chee Yoke Heong

FOOD crops such as cassava, sorghum, maize, peanut, wheat, sugar cane and banana all have 'climate' properties including stress tolerance, biomass accumulation and drought tolerance. If these crops are given due attention and systematically improved and adopted as a means to confront climatic challenges, the food situation in countries across Africa will likely improve and scenes of hunger and death which we are witnessing in East Africa now can be a thing of the past.

Among these crops, the humble cassava is perhaps the most important, as around the world, cassava is a vital staple for about 800 million people, with some reports putting the figure at one billion. Because of its high productivity, even in harsh conditions, cassava constitutes a source of food and income for poor farmers in Africa, Asia and Latin America. In Africa, about 70% of cassava production is used as food for about 300 million people.

Long seen as the food for poor people in poor countries, the drought-resistant cassava has come to be regarded as an important source of food in drought-prone areas across Africa.

Besides its ability to withstand harsh environments, cassava, which is variously known as tapioca, manioc or yucca, produces more food energy per unit of land than any other staple crop. Its leaves, commonly eaten as a vegetable in parts of Asia and Africa, provide vitamins and protein. Nutritionally, the cassava is comparable to potatoes, except that it has twice the fibre content and a higher level of potassium. Cassava leaves and roots, if properly processed, can therefore provide a balanced diet protecting millions of African children against malnutrition.

Indeed, cassava is said to contribute more to the world's calorie budget than any other food except rice and wheat, which makes it a virtually irreplaceable resource against hunger.

Talking about cassava's adaptability to the tropical African environment, a cassava breeder at the International Institute of Tropical Agriculture reportedly said: 'Cassava is to the African peasant farmers what rice is to the Asian farmers, or what wheat and potato are to the European farmers.'

One problem with cassava is the poisonous cyanides, which need to be destroyed before the cassava is consumed. The cyanide content differs with each variety of cassava and it can be destroyed through heat and various processing methods such as grating, sun drying, and fermenting.

But because of the stigma attached to cassava, cultivation of the crop is limited. But its value is gaining traction among villagers and farmers looking for food security in times of prolonged drought. Some are able to grow enough to sell and generate income for the family.

Some countries which have taken the decision to aggressively adopt the growing of cassava varieties are already seeing promising results. In Nigeria, for example, both the government and farmers have adopted new technologies on cassava production and utilisation. Since 1990, FAO (UN Food and Agriculture Organisation) figures have consistently shown Nigeria as the world's largest cassava producer - moving from its fourth rank to relegate Brazil, Thailand and the Democratic Republic of Congo to the second, third and fourth positions. The achievement, according to FAO, is largely due to the availability of improved varieties developed by researchers and scientists.

A favourable factor is the creation of a conducive atmosphere by the Nigerian government for cassava expansion and spread. It adopted campaigns to popularise the improved cassava varieties, urging all relevant national institutions to embark on the multiplication and distribution of cassava planting materials in the rural areas.

Following the bitter experience suffered by Zimbabwe as a result of the 1992/93 drought that seriously affected that country's maize production, the country turned to cassava as an alternative to maize to safeguard the interest of peasant farmers and prevent any calamity in future.

Other successes were reported in the Democratic Republic of Congo, Tanzania, Mozambique, Zambia, Angola and Malawi.

Strains of disease-resistant cassava have also proved instrumental in saving lives and improving food security in Uganda, where a highly virulent form of the cassava mosaic virus began devastating crops in the late 1980s. The virus wiped out about 80% of the country's 500,000 hectares of land planted with cassava. In the ensuing years, the sweeping epidemic caused severe food shortages and economic hardship in parts of the country while several thousand people died of starvation. But a bold breeding programme which developed and disseminated new high-yielding varieties that were resistant to the Ugandan strain of the mosaic virus managed to bring the situation in check. The programme improved food security, restored economic balance to agricultural communities, and slowed the spread of the new mosaic strain to other cassava-producing countries in the region.

However, the risk of diseases remains a constant threat to cassava growing and production. A new study by scientists at the International Centre for Tropical Agriculture (CIAT) published in the journal Food Security has identified hotspots around the cassava-producing world where conditions are ripe for outbreaks of some of the crop's most formidable enemies, namely, whitefly, green mite, cassava mosaic disease and cassava brown streak disease.

Combined outbreaks of all four pests and diseases are seen as a risk in Africa's Rift Valley region, South-East Asia, southern India, Mato Grosso state in Brazil, and northern South America.

The method  of cultivating cassava - planting of stems cut from older plants and the transport of these stakes across large distances, at times across borders -  facilitates the spread of pests  and diseases.

'In an age of global travel, local risks to cassava production are now global risks - all it takes is one contaminated stake and a pest or disease could jump to an entire continent and establish itself very quickly,' one of the article's authors and also a CIAT entomologist and leading cassava expert, Dr Tony Bellotti, was quoted as saying. 

In light of climatic challenges coupled with the constant threat of diseases, the ability to cultivate food crops that are climate-tolerant and pest-resistant is ever vital for the food security and livelihoods of millions of people worldwide. While cassava is one crop that seems to have received such attention, other crops which come with 'climate' properties need to be given due importance as their survival could potentially mean the survival of many more people.

Chee Yoke Heong is a researcher with the Third World Network.

*Third World Resurgence No. 251/252, July/August 2011, pp 35-36