1,280 kg per hectare to 2,750 kg per hectare. Within 10 years, as the hybrids improved, the yield had more than tripled to reach 3,810 kg per hectare. In a little over 20 years it had almost quadrupled to reach 4,190 kg per hectare. Seldom has there been such a rapid increase in grain yields in a cereal crop.

The hybrids were developed by crossing sorghums from southern Africa (the so-called kafir type) with others from Central Africa (caudatum types). The benefits come both from the hybrid vigor (which results when widely divergent strains of an organism are crossbred) and from the fact that the plant's heightened potentials and profits encouraged farmers to apply fertilizers and pesticides.

Hybrids have produced quantum jumps in production in India and Latin America as well, but so far, except in the Sudan, Zimbabwe, and South Africa, they are uncommon in Africa itself. In most of East Africa, for instance, only 5-10 percent of the crop is in the form of hybrids or other improved varieties, and in West Africa the percentage is even lower. This is not unexpected. Occasional U.S. hybrids, such as NK 300, prove productive over a wide range of conditions in Africa, but most do not. Also, most U.S. hybrids were developed for stock-feed and their grains make poor-quality foods. In addition, they lack the necessary resistance to striga, a parasitic plant unknown in most sorghum-growing areas of the United States.

These days, however, hybrids that produce food-quality grain are coming available. Moreover, it would appear that the problems of poor adaptability and striga resistance will be overcome. On the face of it, then, hybrid sorghums produced for sale rather than for subsistence should play a big role in Africa's future agriculture.

Of course, hybrids are not without drawbacks. They perform best under good production conditions and good quality control. They are suited only to sites where seeds and other materials can be readily delivered. (Farmers must purchase fresh seed for each planting.) Further, it has been found in Nigeria that during the rainy season the male-sterile plants used in making the hybrid seed are vulnerable to ergot.5

Some observers believe that problems such as these make hybrid sorghum appropriate for only a small part of Africa. This may be true, but as the following sections show, there are reasons for thinking that large-scale, efficient, productive, and very profitable sorghum production can indeed become a major part of Africa's agriculture mix.

5  

This fungal disease infects empty florets. It can be overcome by producing seed under irrigation during the dry season but, at least in West Africa, the areas where this is practical are limited.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement