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Crops for security, crops for health - page 2 of 3

In the late 1980s and 1990s CIMMYT breeders, Magni Bjarnason and Kevin Pixley built on Villegas and Vasal’s work to help develop high-yielding QPM varieties, while Hugo Cordova has spearheaded recent work to test and promote high yielding QPM. In general, QPM has been developed by conventional plant breeding, but the programme is aided by various advanced techniques including the use of molecular markers. In October 2000, Drs Vasal and Villegas received the prestigious World Food Prize. This was established in 1986 by Norman Borlaug, who received a Nobel Prize for his work in the Green Revolution of the 1960s and ‘70s. Evangelina Villegas is the first woman recipient.

QPM is now catching on worldwide. Tests have taken place in more than 40 countries. Varieties derived from QPM are now grown on more than a million hectares in more than a dozen developing countries; but dozens more are expected to follow suit in the next few years and the total sown area could rise to 3.5 m ha by 2003. Several countries have launched major production programmes. In general, the new varieties are providing almost twice as much nutritionally useful protein as conventional varieties, and increasing yields by about 10 per cent. This is a bonus, since high-protein crops must divert more of their total energy to protein, so that their overall yield is often reduced. The new varieties also match local varieties for tolerance to drought and resistance to pests and disease. All in all, says Dr Masa Iwanaga, Director General of CIMMYT, “We believe we are witnessing a revolution unfolding”.

Of huge significance is that QPM is not simply a single variety. Rather, the QPM qualities are being combined with those of traditional varieties that are adapted to local conditions, and are resistant to local pests and diseases. As Dr Iwanaga says, “We are not promoting one variety of maize with one genetic background, but dozens of varieties of maize that have the QPM trait.” He adds: “Maize is typically grown in complex cropping systems, and this reduces its vulnerability to pests and diseases as well.” CIMMYT is also helping countries to produce their own seed, which is necessary since when crops such as maize are grown in hybrid form the seed must be re-created each year.

Many particular successes are being recorded. Thus in 1999 QPM was growing in Guizhou, China’s poorest province. Before QPM the people were reported to be “scratching round” for roots and tubers. With QPM they were able not only to feed themselves but also to keep a sow or two, raising the nutritional plane yet again, and improving the gastronomy. Pigs and poultry have been reported to grow far more quickly when fed on QPM maize. Sasakawa Global 2000 has helped to promote QPM in Ghana, where it has produced healthier children in villages beset by severe malnutrition, and has led to economic gains. Malnourished children in Columbia and Peru, too, have been restored to health on controlled diets with QPM. Studies by Johns Hopkins scientists from the United States have also shown nutritional gains. The environment gains as well, since high-yielding, highly-nutritious crops produce more food on smaller areas. There is less need to spread into the marginal, more fragile lands that are less rewarding and liable to erode.

All in all, says Evangelina Villegas, “It is easier and less expensive to convert to more nutritious varieties of maize than to change or supplement the diet. I know our enhanced protein maize will not solve all of the world’s nutrition problems, but it is a major improvement”. And in the words of Ian Johnson, Chair of CGIAR, “The development of quality protein maize is people-centred science at its very best, providing better nutrition while fostering economic growth for the world’s poor.”

In the 1970s and 80s, CIMMYT’s work on QPM was supported by a $17 million grant from the United Nations Development Programme, and in the 1990s also by the Nippon Foundation.

In the world at large, lack of Vitamin A is one of the most damaging of the specific nutritional deficiencies. UNICEF estimates that the diets of 124 million children worldwide are too low in A. Deficiencies lead to damage to the conjunctive and cornea, mainly in children, which leads to blindness. An estimated five million children in SE Asia develop xerophthalmia and, relative to the population, the condition may be equally severe in parts of Africa, Latin America and the Caribbean. It is also thought seriously to exacerbate corneal damage caused by the measles virus, which is the most common cause of blindness among children in Africa. Worldwide, around 500 000 children per year become irreversibly blind through lack of Vitamin A. The number blinded in sub-Saharan Africa alone has been put at around three million. Many die, not least through increased susceptibility to infection: indeed it is estimated that improved Vitamin A nutrition could prevent between one and two million deaths per year in children aged one to four, and another 250 000 to 500 000 in later childhood. WHO reports that women deficient in Vitamin A have a significantly higher death rate in pregnancy. All in all, Vitamin A deficiency is known to be a serious public health problem in at least 26 countries.

Thus, to eliminate Vitamin A related disease is a specific goal of the UN. Chemically, Vitamin A is Retinol; but it is typically consumed in the form of precursors, chief of which is Beta-carotene (or “Provitamin A”). This is the yellow pigment that colours many fruits and roots, from papaya to carrot, and enriches the colours of dark green leaves. Each molecule of Beta-carotene provides two molecules of Retinol.

Nutritionists commonly stress that the ideal solution to Vitamin A deficiency is through a diet rich in fruit, vegetables, and various animal products including liver and dairy. Yet this is not always the easy option. WHO has programmes both to fortify food and to distribute capsules (involving 12 million children, in 1997). These programmes have been extremely effective. They are claimed to have reduced blindness from Vitamin A by two thirds over the past 20 years, while the World Bank estimates that every dollar spent on supplements is re-couped 100 fold in increased productivity and reduced health costs. Yet even these programmes may fail. In Africa in particular, many women and children are beyond their reach (not least for lack of all-weather roads). Thus many agree with Juergen Erhardt of the University of Hohenheim, who has been working with scientists from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), a Future Harvest Centre, that in many cases “To have a staple food with a high natural content of Beta-carotene would be the easiest way to alleviateVvitamin A deficiency”.

The ICRISAT scientists have been aiming to provide pearl millet with endosperms coloured yellow with Beta-carotene: that is, Golden Millet. This, says ICRISAT’s Director General, Dr William D Dar, “would reduce but not eliminate the need for vegetables and other sources of Pro-vitamin A”. Pearl millet is a most important staple in the semi-arid tropics. Golden millet has Beta-carotene levels comparable with golden rice and would be an important substitute in regions where rice cannot be grown.

The new golden millet genotypes have been developed by conventional and low-cost breeding techniques, and there is still a little way to go. University of Hohenheim scientists are now completing studies to show the range of genetic variation available in cultivated pearl millet germplasm; and Dr C T Hash, millet breeder at ICRISAT, says that more time is needed to optimize extraction procedures and analyze isomers. He adds that the new strains will be acceptable to farmers if and when “this higher nutritional value can be delivered in locally-adapted, pest and disease resistant cultivars that have reasonable yield potential”. But already, says Dr Dar, “Golden millet is the ideal show-case to demonstrate what global research, development and extension teams can do by effectively linking conventional plant breeding, participatory research methods, and the tools of molecular biology to address a major health issue of the world’s poorest people using naturally occurring crop genetic variation”.

Another project, again aimed at a staple that is vital for large numbers of people in difficult areas, is the orange-fleshed, high carotene sweet potato, subject of more than 10 years research led by the International Potato Center (CIP), a Future Harvest Centre based in Peru, and intended in particular for people in remote parts of Africa.

Sweet potato is in many ways an excellent crop: easy to grow, it is native to South America but a staple in many African countries. Many species are orange-fleshed, rich in Beta-carotene, and a recent survey shows that orange-fleshed sweet potatoes are an inexpensive year-round source of Vitamin A. But in much of sub-Saharan Africa the white-fleshed varieties are preferred; these contain little or no Beta-carotene. Indeed, for many years, development workers have claimed that the orange-fleshed types were too moist and sweet for African tastes. This is of less consequence in west Africa where red palm oil is used widely for cooking and supplies the necessary Beta-carotene.

But careful screening and evaluation has now provided orange-fleshed types that give excellent harvests even in demanding conditions sub-Saharan Africa. They retain their Beta-carotene content when processed and are passing African consumer tests. Studies already show that a small amount of the new sweet pottoes added to the family diet can eliminate Vitamin A deficiency in both children and adults.

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