ABSTRACT
Plant breeding involves the systematic production of crop populations exhibiting genetic segregation and selection within that population to establish lines with favourable allele combinations. For cross-pollinating plants this is accomplished by recurrent selection of heterozygous plants, whereas for self-pollinating crops, pure-line breeding is preferred. Breeding of vegetatively-propagating species presents special challenges and relies heavily on culture techniques and induction of somatic mutations. The achievements of plant breeders are numerous, but may be grouped into several major areas of impact - yield increase, enhancement of compositional traits, crop adaptation and the impact on crop production systems. Plant breeders are interested in centers of plant domestication as regions of genetic diversity, variability being critical to the success of crop improvement. Conventional breeding is often constrained by the availability of limited number of disease resistance genes that are present and identified in various crop varieties.
