Abstract:
The objective of the study was to compare the effectiveness of pedigree and independent culling levels methods for early selection in the F3 and late selection in the F5 generations. The experiments were conducted at South Valley University Experimental Farm at Qena during 2007 through 2010 summer seasons. The F3, F4, F5 and F6 generations of the grain sorghum hybrid (Giza 15 x Dorado) were studied. Highly significant differences were observed among F3 families for all studied traits. After three cycles of selection, the genetic variability retained after independent culling level was larger and more pronounced than that after single trait selection. However, the genetic variability retained in the F6 was larger after late than after early selection. Late pedigree selection in the F5 increased grain yield/plant by 9.57% compared to 12.70% from the bulk sample after three cycles of selection for this trait started early in the F3. Selection for early flowering and 1000-grain weight improved these traits but decreased yield in both early and late selection. Late selection in the F5 generation in these materials was more efficient than early selection in the F3 families. Pedigree selection though proved to be an efficient selection procedure for improving the selected traits. However, it was accompanied with some deleterious effects in some unselected related traits. ICL caused moderate increases in most measured traits that were comparable for early and late selection.
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