RA 00110.pdf - OAR@ICRISAT

Table 5. Prediction equations for interpopulation improvement methods—Reciprocal Half-sib Selection and Reciprocal
Full-sib Selection.
Half-sib Selection (RHS)
Reciprocal Full-sib Selection (RFS)
Note: = genetic variance among A x B full-sibs = in AB population.
=genetic variance among half-sibs.
line from the other population. Thus, every entry has
one elite line parent and therefore, is a potential
commercial hybrid, assuming further inbreeding
and selection in the selected S, lines. Comstock
(1979) concludes that RHS using the counterpart
populations as testers is superior to RIS using pure
line testers for improving the population cross. The
RIS scheme has an advantage from a line development
point of view and has been used by some
commercial breeders.
The major advantages and disadvantages of RRS
procedures are outlined in Table 6.
Response to Selection
This section concentrates primarily on a comparison
of S, line per se with reciprocal full-sib selection
(RFS) because considerable data on these methods
is available and because of their expected contrasting
responses. Line per se selection would be expected
to perform best only if additive types of effects were
involved while reciprocal selection schemes like
RFS would be best able to capitalize on nonadditive
(especially overdominance) effects.
A very large and comprehensive comparison of
Table 6. Advantages and Disadvantages of Reciprocal Recurrent Selection (RRS) Procedures.
Advantages
1. Dominance types of relationships are important in cross-fertilized crops, and basing selection on crossed families seems
the most logical way to take advantage of this heterotic vigor.
2. Some forms of RRS can be integrated into applied line-development programs.
3. The ultimate selection limit may be highest for this type of selection because any type of genetic variation that can
contribute is exploited, though it may take a long time to make use of epistatic combinations on a population basis.
Disadvantages
1. Requires considerable labor for hand pollinations, both in making up families for testing and for recombination.
2. Expensive, requires many yield-trial plots (especially for RHS and RIS).
3. As in most other family schemes (with exception of intra-population full-sib selection) requires 3 growing seasons per
cycle.
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