Références sur les Plantes

Using radiation-based techniques to modify crop characteristics and traits, scientists and crop researchers at the Kenya Agricultural Research Institute (KARI), working closely with the International Atomic Energy Agency (IAEA), developed new wheat seeds over the past decade. The first mutant wheat variety, called Njoro-BW1, was released in 2001. It is tolerant to drought and uses limited rainfall efficiently. Moreover, it exhibits moderate resistance to wheat rust, has high yields and the flour is of good baking quality. Today, Njoro-BWI is cultivated on more than 10 000 ha in Kenya. It has become so popular among Kenyan wheat farmers that KARI‘s seed unit can hardly keep up with demand.

Another high-yielding mutant, codenamed DH4, is due to be released soon.

3.2 New Sorghum and Rice Varieties in Mali Mali‘s native sorghum has traits that give it some resistance to drought, but it still needs substantial rainfall for a good harvest. As sorghum production has not kept up with population growth, Malian scientists, especially at the Institut Polytechnique Rural, initiated a programme to improve the production of sorghum while conserving their essential traits. With the assistance of the IAEA, traditional varieties of sorghum were irradiated with gamma rays according to prescribed procedures. Initial field tests show increases of more than 10% in productivity.

It is worth noting that other traits of sorghum in Mali have also been altered using different gamma irradiation doses, as shown in Table 7.1.

Table 7.1: Altered traits of sorghum Dose Year Traits 300 Gy 1992 Increased lodging resistance 250 Gy 1998 Earliness 100 Gy 1998 Increased panicle size, increased yield and change in grain colour Rice has been grown in the flood plains of the Niger River for several centuries. Following irradiation of the local variety, new mutants have been developed with white colour characteristics and higher yields (> 15%).

White rice in Africa fetches double the price of red; so for farmers, the colour alone means a substantial increase in income.

3.3 Sesame in Egypt In Egypt, three mutant varieties of high-yielding, disease and insect-resistant sesame are bringing higher economic returns than standard varieties.

3.4 Cassava in Ghana Ghana‘s cassava variety ―Tek Bankye‘‘, with improved cooking quality, was released recently. Trials are underway to produce higher-yielding, disease-resistant cassava, with improved starch content.

3.5 Other New Radiation-Induced Varieties Several other radiation-induced varieties of crops with improved traits, higher yield and better nutrition value, which are adaptable to harsh environments have been released. These include, among many others, finger millet and cotton in Zambia and banana in Sudan.

3.6 Ongoing Activities Numerous research and development (R&D) activities are being carried out in African countries to develop improved varieties of various crops through the use of nuclear technology. These include the development of: a) A better lodging and higher-yield variety of tef in Ethiopia. b) An improved variety of rice at the Sokoine University of Agriculture, Morogoro, Tanzania. c) A disease-resistant variety of cocoa at the Cocoa Research Institute of Ghana (CRIG), Tafo, Ghana.

The cocoa swollen shoot virus (CSSV) is a major disease which has destroyed more than 40% of the cocoa production in Ghana. In fact, during the last 50 years, about 200 million cocoa trees have been destroyed in Ghana as a result of CSSV. Buds of cocoa plants are subjected to gamma radiation at the Ghana Atomic Energy Commission (GAEC) with a view to producing new plant strains with disease-resistant properties. Some of these new strains are being field-tested; if successful, the economic benefit to Ghana would be immense.

4 Conclusion Nuclear techniques can help to address the issues of food security in Africa. These techniques are highly competitive in relation to non-nuclear technologies and can be used to achieve better solutions to new challenges in Africa. Other regions have already derived huge economic benefits through the use of radiationinduced mutations.

In China, up to 2005, a total of 638 mutant varieties of 42 plant species have been released, covering 9 million ha of planting area. The economic benefit derived from increased cereal production alone is estimated to be about US$420 million a year.