ADAPTATION TO LOW HIGH INPUT CULTIVATION

Many areas of world, particular those where agriculture is largely pra cticed by resource-poor farmers with little or no use of external inpu ts, have not benefitted from the spectacular yield increases achieved by the combination of modern breeding technologies and use of inputs. The paper argues that because breeding is mostly conducted in presence of high inputs, it has systematically missed the opportunity to explo it genetic differences at low levels of inputs. Many studies show that these differences do exist, particularly in the case of fertilizers, and that these differences can only be identified is selection is cond ucted under the target level of inputs. Although this was predicted by theory more than 40 years ago, and has been supported by a large body of experimental data, very few breeders select in sub-optimal or stre ss conditions. The most common justification is the high environmental variation, and hence the lower heritability expected in low input con ditions. While this is not supported by experimental evidence, the pap er shows that in the case of a typical crop grown in low-input and cli matically marginal conditions such as barley, genetic gains are possib le by using locally adapted germplasm and by selecting in the target e nvironment. Similar conclusions, in relation to the use of a low-input selection environment, have been reached recently in maize. It is con cluded that the best avenue to a sustainable increase of agricultural production in low-input agricultural systems is through locally based breeding programs.