Glossary Plant Breeding

tester are propagated from the selfed seed and intercrossed in all combinations to
establish a population for the next cycle of selection. The population so improved can
be used as a source population for extraction of superior inbred lines.
Recurrent Selection (for SCA). AsystemofbreedinginwhichanumberofS 1 lines
based on the testcross performance with a homozygous tester (inbred line) of original
selections (S 0 ) are selected and crossed in all combinations to form the new
population for the next round of selection. The inbred derived from such improved
population must be crossed with the homozygous tester for effective exploitation of
non-additive gene action.
Recurrent Selection. A cyclical scheme of plant selection designed to increase
systematically the frequency of desirable genes in a population primarily for
quantitatively inherited traits. The method involves repeated selection in each
generation among the progeny produced by intercrossing in all possible combinations
of the selected individuals (or their selfed progeny) of the previous generation. Since
intercrosses are made in each cycle of selection, appreciable heterozygosity (and
hence, genetic variability) is maintained. Thus opportunity for continuous selection is
enhanced because new recombinants are continually generated. Inbreeding depression
also remains within limits.
Rediscoverers of Mendel’s Principles. Carl Correns (of Germany), Hugo de Vries (of
Netherlands), and Tschermak (of Austria). However, some scientists credit principally
Carl Correns as the rediscoverer of Mendelian principles of heredity.
Reduction Division. The first nuclear division during meiosis that produces daughter
nuclei each having one-half as many centromeres as the parental nucleus.
Redundant DNA. Also called repetitive DNA; the DNA sequences that are present in
many copies per chromosome set.
Registered Seed. The progeny of foundation seed normally grown to produce certified
seed. This class of seed is not produced in India.
Regression Coefficient. A numerical measure of the rate of change of the dependent on
the independent variable. It measures the magnitude of change in a dependent variable
for a unit change in independent variable. It is mathematically the slope of the straight
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