| dc.description.abstract | Eight parents Nyala and SB-8, SB-25, SB-93, SB-19, 915/5/12, 835/5/30 and
SB-98 were crossed in a diallel mating scheme to generate 28 F1 progenies in
a greenhouse at Kabete, University of Nairobi. The F1 and their parents were
evaluated at KALRO-Embu and Mwea Research Centers between December
2016 and May 2017. The trials were laid out in an alpha-lattice design
arranged in a 6 × 6 pattern with 3 replicates. Data was collected on maturity,
plant height, grain yield and pod shattering. General and specific combining
ability were determined according to Griffing’s diallel, Method 2. General
and specific combining ability (GCA and SCA) were significant (P<0.05) for
all the traits indicating that additive and non-additive gene action were
important in the inheritance of pod shattering and other traits. GCA/SCA
ratio varied from 0.00124 to 0.0742. Although the ratio was higher for pod
shattering (0.0742) compared to other traits (less than 0.0132), the ratio in
general was close to zero. This indicated that non-additive gene action
played a more important role over additive gene action in the inheritance of
these traits. Parents SB-93, SB-19, SB-98, 835/5/30 and Nyala, were the best
combiners for early maturity. SB-19, 915/5/12, Nyala, SB-93 and SB-98
significantly contributed towards reduced plant height. Parent 835/5/30
followed by SB-8 had the higher GCA gene action thus were the best
combiners for high grain yield. Parents SB-8 and Nyala had the highest
negative and significant GCA effects for pod shattering indicating that these
lines had favorable gene frequencies of resistance to pod shattering.
Progenies of SB-25 x SB-8 were the best combiners for pod shattering
resistance across environments. This study found non-additive gene action
to be more important over additive and suggested that heterosis breeding
and selection of late segregating generations would be effective to improve
pod shattering resistance ability and other agronomic traits in soybeans. | en_US |
