GENOTYPE BY ENVIRONMENT INTERACTION AND INTERNATIONAL BREEDING PROGRAMS

This paper addresses the issue of genotype by environment (G x E) inte raction in relation to the distribution of germplasm from internationa l to national breeding programmes. Theoretical aspects of G x E intera ction and of the selection versus the test environment are reviewed. T he importance of specific adaptation to maximize yield and yield stabi lity under stress conditions is highlighted in barley and lentil. We c onclude that repeated cycles of selection at a few sites have a high p robability of reducing the frequency of genotypes specifically adapted to environmental and/or agronomic conditions not represented at those sites. Therefore a wider and earlier devolution of the selection work done by International Agricultural Research Centres (IARCs) to plant breeders in national programmes will increase the chances of exploitin g positive G x E interactions. It will also address the needs of small , resource-poor, subsistence farmers and reduce the danger of narrowin g genetic diversity within crops and regions. This is an efficient way of making breeding programmes in less developed countries more self-r eliant, which is a major objective of International Agricultural Resea rch Centres.