Ever since human beings began to practise settled agriculture more than 8 000 years ago, they have selected which plants to grow -- first from the wild and then in cultivated fields. Early farmers chose plants that not only grew well but that seemed to have the best resistance to changing weather conditions, pests and diseases. The plant populations selected by these farmers are the basis of today's crops that feed the world. In addition to wild plants and landraces, there is a third type of agricultural plant: those bred on a research farm, either commercial or public. Plant breeders aim, through crossing and selection, to produce varieties that have desirable characteristics, such as higher yields, resistance to pests and diseases or better adaptation to their environment. The seed and planting material of these varieties are then supplied to farmers.

Breeders need access to plant genetic material with the characteristics they seek, including wild relatives and landraces - that is, to biodiversity. "The public needs to understand why biodiversity is so important," says Jose Esquinas-Alcazar, Secretary of FAO's Commission on Genetic Resources for Food and Agriculture. "It's not just about breeding more productive crops -- it's about protecting and improving our food security. In biodiversity, we can find the genes that confer resistance to new threats, such as pest epidemics and climate change, as they occur."

The Green Revolution

The impact of scientific crop breeding became more prominent after the 1960s. Around that time, Norman Borlaug, a US scientist working in Mexico, and his colleagues used it to breed new wheat varieties that had higher yield potential and were more responsive to inputs such as fertilizer and irrigation water. Until then, attempts to increase productivity of existing local varieties had been only partially successful, as giving them too much fertilizer made them outgrow their strength, so that they toppled over.

After years of painstaking work, Professor Borlaug crossed the local wheat with Japanese dwarf varieties to produce plants that could productively utilize greater amounts of fertilizer. The resulting wheat varieties were credited with averting the mass starvation that faced the developing world in the 1960s. Those wheat varieties have been adopted and grown widely, particularly in India, Mexico and Pakistan. Professor Borlaug won the Nobel Peace Prize in 1970. Meanwhile, scientists extended the principles of modern crop breeding to other staple crops, such as rice. The Green Revolution had begun.

An "Evergreen Revolution"?

Beyond any doubt the Green Revolution played a critical role at that time. Recently, however, the Green Revolution has been much analysed. Some argue that it led to unsustainable use of agrochemicals and a high level of inputs. It has also been said that new plant varieties displaced landraces in the fields and thus led to a loss of biodiversity.

Nevertheless the Green Revolution was a breakthrough that contributed to food security and the fight against hunger, particularly in Asia and Mexico. With new technologies, the science of plant breeding is changing rapidly. The genetic improvement of food crops needs to continue at a pace sufficient to meet the needs of the 8.3 billion people projected in 2025, and Professor Borlaug believes that both conventional breeding and biotechnology methodologies will be needed.

The time has come for the next step. M.S. Swaminathan, an Indian scientist and winner of the 1987 World Food Prize, who was the other driving force behind the Green Revolution, has called for an "evergreen revolution". This would address a wider variety of issues and would more closely target the poorest. Dr Swaminathan believes that this effort will require more science, not less.

March 2003