Types of recurrent selection

Types of recurrent selection
Simple recurrent selection or recurrent selection for phenotype
  • In this a number of plants are self pollinated in a source population in first year.
  • At maturity, superior plants based on phenotypic performance are selected.
  • In the second year, seeds produced by self fertilization of the selected plants are planted and crossed in all possible combinations and the produce is bulked. This completes original selection cycle.
  • Since selection is based on the phenotype of the plant, it is useful only for characters with high heritability.
  • In case of cabbage and cauliflower, etc. where it is not possible to identity the desired selection before flowering, inter-crosses of selections may be made in the first year of each cycle and the second year may be eliminated from each cycle.
  • This, strictly speaking, selfing is not an integral component of simple recurrent selection, rather it is done to prevent crossing from the inferior pollen grains before the plants reach to selection stage.

Recurrent selection for general combining ability (gca)
  • Here a three year cycle involved.
  • In first year, a number of plants are self pollinated as well as crossed to a broad – based heterozygous tester stock to identify the so-called plants with good general combining ability.
  • In second year, the crosses are evaluated to identify those that are superior. Selfs of first year are kept in reserve.
  • In third year, the reserve selfed seeds of those superior genotypes which exhibited good performance in the evaluation of gca during second year are grown out, inter-crossed in all possible combinations, and a composite of inter – crossed seed is used to establish an improved population for further selection.

Recurrent selection for specific combining ability (sca)
  • This method is the same as that of recurrent selection for general combining ability except that the tester selected is a narrow base inbred line.
  • The recurrent selection for general and specific combining ability is equivalent to half sib progeny.

Reciprocal recurrent selection
  • Aims at simultaneous improvement of two heterozygous and heterogeneous population, one acts as a tester for another and vice versa. This method is as effective as recurrent selection for sca when non-additive effects are of major importance

Last modified: Monday, 11 June 2012, 6:16 AM