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Long-term selection experiments provide germplasm to study the effects of selection in a closed population. Recurrent selection
to enhance grain yield in oat has been ongoing at the University of Minnesota since 1968. The objectives of this study were:
(i) estimate the GCA and SCA effects for three agronomic traits in the seventh cycle of selection, (ii) assess the effect
of the current methods of selection on parental contribution and unselected traits, and (iii) determine the direct and indirect
responses to seven cycles of recurrent selection for grain yield. Progeny of the Cycle 6 parents and parents for Cycles 0
through 7 were grown in two separate tests. Grain yield, heading date and plant height were evaluated in each test. Grain
yield was increased by 21.7% after seven cycles of selection. Evaluation of Cycle 6 progeny showed that GCA effects were significant
for all three traits studied, and SCA effects were significant only for grain yield. Four Cycle 6 parents did not have any
progeny selected as Cycle 7 parents. Results from this study indicate that long term recurrent selection has continued to
increase grain yield. Alternative selection strategies may be necessary to maintain the genetic variability in this population,
particularly when improvement of secondary traits is required.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献