Population breeding as a tool for germplasm enhancement

The genetic basisof Solanum tuberosum ssp.tuberosum has been discussed focusing on the importance of increasing its genetic variability. A review of the work on germplasm enhancement, using both cultivated, primitive and wildSolanum species, carried out by several institutions, has been made. Through these research efforts, mainly based on a population breeding strategy, new sources of genetic variability for yield, tuber quality factors, and pest, disease, and stress resistance or tolerance have been identified. The utilization of these new breeding resources has already started to produce results. In the last few years at least 30 new varieties, carrying resistance to one or more pests, diseases, or stresses, have been released in several countries.