Genetically Modified crops
The potential of GM crops to raise field yields
4.26 As a seed variety is adopted, learning takes place. Farmers gradually raise their field yields to the proportion of 'potential' that is most profitable (allowing for risk). Unless the plant, and hence the next new variety, shows increasing yield potentials, the growth of field yields must eventually slow down. GM crops may offer the best route both to higher yield potentials and resistance to stresses which have proved hardest to tackle by conventional plant breeding techniques alone. These recalcitrant problems include some biotic stresses such as viruses and fungi (in addition to birds, weeds and some insects, nematodes and bacteria); and abiotic stresses such as moisture and temperature stress (and in some conditions salt, iron and aluminium).
4.27 GM research should not, however, divert resources from conventional plant breeders where these efforts offer better promise of success. New conventionally bred varieties continue to seek improved crop robustness against pests and to increase yield potentials of food staples, for example through F1 rice and wheat hybrids, or biological nitrogen fixation. That these latter examples have proved disappointing is probably due in part to the greater concentration of GM crop research in developed countries. This indicates that the main risk at present is that without adequate GM inputs, conventional plant breeding will not greatly increase the growth of yield potentials in the main tropical food staples, so that field yields will be increasingly sluggish. This will seriously imperil employment, income and food access for the world’s poorest people.