Abstract:
Maize (Zea mays L.) is an important cereal crop of the World and major food crop in
Ethiopia especially, in Jimma Zone and south West areas of Oromia region. But due to
shortage of high yield and disease tolerant improved maize variety its productivity on
farmers’ field is low throughout the country. Knowledge of heterosis and combining ability is
precondition for developing a good economically viable open pollinated or hybrid variety.
The study was carried out at Jimma Agricultural Research Center during 2015 cropping
season. The objective was to evaluate combining ability and standard heterosis for grain
yield and other agronomic traits in maize inbred lines, for future use in breeding program.
Ten selected inbred lines were crossed in a half diallel mating method Griffing’s Model 1,
Method4 and the resulting 45 F1 hybrids (excluding parents) and four commercial check
hybrids were evaluated s in 7x7 alpha lattice designs with three replications. Data collected
on days to 50% anthesis, days to 50% of silking, plant height, ear height, lodging percent,
TLB, GLS and CR disease severity index, days to maturity, number of ear per plant, ear
aspect, ear length, ear diameter, number of rows per ear, number of kernel rows per ear,
number of grain per row, thousand grain weight and grain yield. Analysis of variance
indicated significant differences for all traits except for number of ear per plant, ear aspect
and thousand grain weights. Among the hybrids L7 x L9 (9.6 t/ha), L7x L10 (9.2 t/ha), L2 x
L9 (9.2 t/ha), L6 x L7 (9.1t/ha), L2 x L10 (8.9 t/h) and L3 x L9 (8.8 t/ha) revealed maximum
grain yield when compared with the best standard check BH546 (8.3 t/ha). Mean square due
to GCA was highly significant (P ≤ 0.01)) for all traits, whereas SCA mean squares were nosignificant except for grain yield, days to 50% tasseling, days to 50% of silking, days to
maturity and lodging percent. This indicated the importance of additive types of gene action
in controlling all traits studied. Among inbred lines, L2, L7, L9 and L10 manifested positive
and significant GCA effects for grain yield, indicating that this lines were good general
combiners for grain yield. Of the 45crosses evaluated, only L6 x L7 revealed positive and
significant SCA effect for grain yield. Among the crosses L6 x L7 (8.9%), L7 x L10 (10.7%),
L2 x L9 (11.1%) and L7 x L9 (15.6%) exhibited highest standard heterosis for grain yield
over the best commercial check (BH546).Therefore, maize breeding program that is engaged
inthe hybridization and synthetic variety formation can make use of the inbred lines with
high GCA for grain yield and diseases tolerant traits, such lines can contribute favorable
alleles to the new recombination. However, hybrids with the highest grain yield than the best
commercial check can be advanced for multi-location trail for possible released, since this
experimental study was carried out only at one location.
