I. Goldringer et al., DIVERGENT EVOLUTION OF WHEAT POPULATIONS CONDUCTED UNDER RECURRENT SELECTION AND DYNAMIC MANAGEMENT, Agronomie (Paris), 18(5-6), 1998, pp. 413-425
The effects of artificial selection in a recurrent selection programme
(RS) and natural selection in a dynamic management programme (DM) wer
e studied in a wheat composite population. The initial population, pop
ulations of different cycles of RS and four populations of DM were com
pared for agromorphological traits. It is shown that DM and RS led to
divergent evolution of the populations that could be sharply distingui
shed by fen traits: plant height, earliness, frequency of bearded plan
ts and susceptibility to powdery mildew and leaf rust. Except for plan
t height, genetic variability was maintained in the DM system either w
ithin the populations or through the differentiation between populatio
ns. Variability was also preserved in the RS programme except for leaf
rust resistance for which the strong increase of resistance level led
to a loss of genetic variability. Compared with RS, DM could have sel
ected more multigenic resistances and conserved a larger diversity of
resistance genes. Conditions for the possible use of the DM population
s as a source of variability for the RS programme are discussed. We su
ggest the introduction of artificial selection in some DM populations
in order to preserve their 'cultivated' phenotype. In DM, the benefit
of multiplication sites with high and contrasting parasitic pressures
is emphasized. ((C) Inra/Elsevier, Paris.).