Indian Society of Genetics & Plant Breeding

BREEDING FOR QUANTITATIVE CHARACTERS IN LINSEED.-I. UTILITY OF DIALLEL CROSSES IN THE SELECTION OF PARENTS

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ONE of the chief problems which face the plant breeder, especially with regard to a
self-pollinated crop, is the choice of the parents to be included in his hybridization
programme. The choice of the parents is relatively straight-forward when a
qU'llitatively-inherited character stich as disease-resistance or awning in cereals is concerned. The manipulation of such genes with large and easily recognizable effects
has indeed become more or Jess a matter of routine. However, many of the economically important characters like earliness, maturity, yield, quality etc., do not allow
of such facile handling. For, these are controlled by a large number of genes which
do not have unique effects and cannot, therefore, generally be identified individually.
It must be confessed that, largely because of the technical difficulties involved,
geneticists have not been able to obtain as good an understanding as could be hoped
of the genetical basis of such continuously-varying characters. In the absence of such
information, the breeder of self-pollinated crops is often at a loss to know which particular combination of parents would' nick' to produce a large number of superior
offspring, allowing scope for rigorous selection with regard to the many other requirements which must be fulfilled if a variety acceptable to the grower is to result. Also,
unlike in the case of cross-pollinated crops, the breeder of self-pollinated crops is interested, not so much in the performance of the hybrid or early segregating generations as
in the performance of the pure-lines which can be ultimately selected out from the
progeny of such hybrids. The performance of the parents themselves or even of the
hybrids between them does not always nccessarily give him any indication of the
probable performance of the pure lines which can be selected out of the progeny of
such crosses. 

Info

Year: 1961
Volume: 21
Issue: 2
Article DOI: NA
Print ISSN: 0019-5200
Online ISSN: 0975-6906

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