Estimating genetic effects in maternal and paternal half-sibs from tetraploid-diploid crosses in <Emphasis Type="Italic">Musa</Emphasis> spp. |
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Authors: | Abdou Tenkouano Rodomiro Ortiz Dirk Vuylsteke |
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Institution: | (1) International Institute of Tropical Agriculture, P.M.B. 5320 Oyo Road, Ibadan, Nigeria;(2) Present address: Department of Plant Breeding and Biotechnology, Swedish University of Agricultural Sciences, Box 101, 230 53 Alnarp, Sweden; |
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Abstract: | Ploidy manipulations and interspecific crosses have allowed considerable genetic progress in Musa breeding, but estimation
of genetic parameters for parental selection remains a major challenge. This study aimed to determine the components of genetic
variance and the relative contribution of genetic effects to phenotypic variation of yield and phenological traits in secondary
triploid hybrids from tetraploid–diploid crosses. The hybrids were evaluated in two consecutive growth cycles on a tropical
forest site. Non-genetic effects accounted for a large fraction of the variation observed for most traits, except bunch weight.
Partitioning of genetic variance into additive and dominance components confirmed the predominant role of additive genetic
effects on the expression of bunch weight, fruit filling time, fruit length, plant height, and number of leaves while primarily
non-additive effects accounted for suckering behavior and fruit circumference. Maternal general combining ability (GCA) effects
accounted for the additive genetic variation in plant height and number of leaves, suggesting that selection for these traits
should be carried out in tetraploid clones. Conversely, paternal GCA effects were the primary causes of genetic variation
for fruit filling time, bunch weight, and fruit length, suggesting that these characters should be selected for in diploid
clones. Specific combining ability (SCA) effects were observed for all traits, except fruit filling time, suggesting that
additional genetic gain could be achieved through recombinative heterosis for these traits. |
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