Abstract:
The study was conducted at Haro Sabu Agricultural Research Centre (HSARC) during the
2015 main cropping season. The objectives of the study were to estimate combining ability
and to identify direction and magnitude of standard heterosis in mid-altitude maize test
crosses for grain yield and yield related traits. Eighteen inbred lines and four single cross
testers were crossed in line x tester mating design during the 2014 main cropping season
at Bako National Maize Research Center (BNMRC). The resulting 72 F1 crosses plus
three standard checks (BH543, BH546 and BH547) were studied at HSARC condition.
Data were collected on seventeen traits and analysis of variance was done accordingly.
The mean square indicated highly significant (p<0.01) genotypic differences for all traits
with the exception of shelling percentage, stand count at harvesting and common leaf rust,
suggesting the presence of wide genetic variation among genotypes for most of the traits
studied. The highest and significant mean performance of grain yield were recorded for
L3xT1, L5xT1, L5xT2, L8xT1, L11xT3, L8xT2, L10xT2, L8xT4, L12xT1 than high yielding
hybrid check BH-543 (9.36 t ha-1). GCA mean square due to lines and testers were
significant for all traits except tester GCA mean square for harvesting index, anthesis
silking interval, days to anthesis, days to silking and days to maturity. The mean square of
SCA effect of the crosses revealed significant difference for all traits except for number of
kernels per row, plant height, anthesis silking interval, days to silking, gray leaf spot and
tarcicum leaf blight. Significant GCA and SCA effects were indicative of the importance of
both additive and non-additive gene actions. However, the proportion of GCA sum of
square was higher than SCA sum of squares for most traits, indicating the preponderance
of additive gene actions in the control of most of the traits. As far as grain yield and yield
related traits were concerned; this study identified good inbred lines and testers desirable
GCA effects. L3, L5, L6, L8 and L11 inbred lines, and T1and T2 testers were good
combiner for more than one traits. For maturity related traits, L1, L4, L14, L15, L17 and
L18 were good combiners for earliness. The present study identified several elite inbred
lines for grain yield and yield related traits and high yielding test crosses possessing
positive and significant standard heterosis over the best check hybrid (BH543).These
crosses could be recommended for release or used in maize breeding program for
concerned traits after further confirmation of the result through evaluation over years and
locations.
