Pedigree breeding

Pedigree breeding
  • If the two original parents do not provide all of the desired characters, a third parent can be included by crossing it to one of the hybrid progeny of the first generation (F1).
  • In the pedigree method, superior types are selected in successive generations, and a record is maintained of parent–progeny relationships.The F2 generation (progeny of the crossing of two F1 individuals or selfed F1) affords the first opportunity for selection in pedigree programmes.
  • Starts with the crossing of two genotypes, each of which have one or more desirable characters lacked by the other.
  • In this generation, the emphasis is on the elimination of individuals carrying undesirable major genes.
  • In the succeeding generations the hybrid condition gives way to pure breeding as a result of natural self-pollination, and families derived from different F2 plants begin to display their unique character.
  • Usually one or two superior plants are selected within each superior family in these generations.
  • By F5 generation the pure-breeding condition (homozygosity) is extensive, and emphasis shifts almost entirely to selection between families.
  • The pedigree record is useful in making these eliminations.
  • At this stage, each selected family is usually harvested in mass to obtain the larger amounts of seed needed to evaluate families for quantitative characters.
  • This evaluation is usually carried out in plots grown under conditions that simulate commercial planting practice as closely as possible.
  • When the number of families has been reduced to manageable proportions by visual selection, usually by the F7 or F8 generation, precise evaluation for performance and quality begins.
  • The final evaluation of promising strains involves
  1. Observation, usually in a number of years and locations, to detect weaknesses that may not have appeared previously;
  2. Precise yield testing; and
  3. Quality testing. Many plant breeders test for five years at five representative locations before releasing a new variety for commercial production.

Last modified: Sunday, 1 April 2012, 10:52 PM