Capturing heterosis

Millions of farmers will reap the rewards of a new project to develop self-reproducing hybrid crops. Such crops could sustainably improve the productivity and incomes of smallholder farmers across Sub-Saharan Africa.

The Challenge

Food security challenge

Over 200 million people in Sub-Saharan Africa are impoverished and undernourished. Most are smallholder farmers living in rural environments and relying on agriculture as their major source of food and income.

Yields of the major staple crops which provide food, fodder and fuel are low due to poor quality seed, poor soils, drought and high disease pressure. Reliable production of greater quantities of staple crops would ensure greater surety of food supply, and sale of what cannot be consumed would improve smallholder income.

Our Response

Focusing on sorghum and cowpea

Sorghum and cowpea originated in Africa and are important staple food crops, but suffer from low yields. Increased yields of cowpea and sorghum could change these crops from subsistence crops to increasingly important sources of income for smallholder farmers.

Cowpeas originated in Africa but suffer from low yields.

Conventional genetic improvement to increase yield is slow. Sorghum and cowpea hybrids could provide significant increases in crop yields (~30 per cent) via heterosis, i.e. an increase in yield, uniformity, and vigour that is observed in offspring resulting from a cross between distinct inbred parental lines.

Hybrid crops offer partial solution

Heterosis or hybrid vigour causes the progeny (children) derived from a cross or mating of plants and animals to out perform their parents in such characteristics as size, growth rate, fertility, and yield.

While the first generation offspring out perform both parents, this vigour is not passed on to the next generation. This relates to features of the sexual reproductive process which causes trait segregation and the loss of the vigourous traits. Hybrid seed must be made anew and purchased each year.

Hybrid sorghum crops could sustainably improve the productivity and incomes of smallholder farmers.

The technically difficult and labour-intensive nature of hybrid seed production requires specialist enterprises, and hybrid seeds command a higher price. The requirement to purchase hybrid seed each growing season is a disincentive for cash-poor smallholder farmers.

In Africa, the gains conferred by heterosis remain limited to a single major crop, maize. While Guinea-race sorghum hybrids are being developed, cowpea hybrids are absent.

Self-reproducing hybrid crops

This five year humanitarian project aims to develop tools to generate self-reproducing hybrid sorghum and cowpea hybrids from which seeds can be saved and grown by smallholder farmers without loss of yield or quality.

If hybrid cowpea and sorghum crops could make their seed asexually instead of the way current hybrids do, via sexual reproduction, heterosis should be preserved. This would enable smallholder farmers to self-harvest high-quality seed, providing a more secure food supply and potentially increasing income through the sale of surplus harvest and seed.

The Results

Global effort to capture heterosis

Supported by the Bill & Melinda Gates Foundation we have brought together a team of other world leading scientists from the Universities of California Davis, and Georgia in the USA, the University of Zurich, the IPK in Germany (a Leibniz Institute), Langebio in Irapuato, Mexico and DuPont-Pioneer.

The initial stage of the project will be devoted to developing the techniques to enable cowpea and sorghum plants to reproduce asexually. If successful future stages of the project would involve African breeders and institutes.


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