A sound breeding program for maize improvement is very important to meet the demands of the growing population. Therefore, combining ability and heterosis were studied in a 4 x 4 full diallel cross in maize for growth attributes, yield and its contributing traits. Randomized Complete Block Design (RCBD) with four replicates was used to study the general combining ability of parents, specific combining ability of F1s (including reciprocals) and heterosis of the F1s over commercial check variety on selected agronomic characters. Genotype was highly significant for all the traits studied. The combining abilities (GCA and SCA) and reciprocal mean squares were highly significant for most studied characters. The ratio of GCA/SCA was not less than unity for studied traits excepted for days to anthesis and ear height. The results indicated that the additive genetic effects were more important and played major role in studied traits. Thus, results revealed GCA effects for the parental lines (PL). Where ‘PL2’ was excellent combiner for number of tassels and cob circumference and ‘PL3’ was good combiner for days to silking and grain yield (t.h-1). While ‘PL4’ for short height. Majority of the F1s from the GCA effects showed high SCA effects. This F1 (PL2 x PL3) performed best amongst. However, several reciprocals were not desirable. Heterosis estimation was carried out using a commercial check, Oba super II. When commercial check was used, the percent heterosis especially on grain yield varied from -8.89 to 22.62%. Among the twelve F1s, nine of the crosses exhibited significant positive heterosis for grain yield (t.h-1). Those F1s that showed significant positive and/or negative desirable traits for SCA effects and significant positive heterosis could be used for varietal development in maize breeding. And conservation of those parents that exhibited high GCA effects be considered as well.

In the maize producing regions of Sub-Saharan Africa (SSA), compounding effects of genotype-by-environment interaction have necessitated breeding maize for outstanding performance and stability across varying environments. This study was conducted to assess the performance and stability of late-maturing cultivars and their respective hybrids evaluated under contrasting environments in the tropical rainforest region. We evaluated 108 genotypes in field trials under three different growing conditions in 2018 involving 14 open-pollinated parents and their hybrids derived from a diallel mating design. The genotypes were evaluated under field conditions using 9 × 12 alpha lattice design with three replications in six environments. The genotypes were divided into three groups, containing either the parents, hybrids or checks, for estimating the stability variance and grain yield. The difference between the lowest and highest yielding environment was 3.9 t ha−1, while the repeatability of the grain yield trials ranged from 39 to 80%. The average grain yield of the hybrids (2.33 t ha−1) was significantly higher than that of the parents (2.19 t ha−1) and the check varieties (2.03 t ha−1). The hybrids were more stable than both the parents and the checks. They also showed a higher stability against a common group of the parents and checks. The results of this study suggest that high yielding and stable population hybrids can be utilized in breeding programmes aiming to provide improved varieties for the large number of rural maize farmers in the SSA zone, who often lack access or the capacity to purchase commercial hybrids.

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B. (2022). Identification of a UDP -glucosyltransferase conferring deoxynivalenol resistance in Aegilops tauschii and wheat. Plant Biotechnology Journal. Portico.