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Maize is one of the most important cereal crops used as source of food and feed. Identification of suitable maize inbred lines and testers for the development of stable maize hybrids can be challenging. The assessments of the combining ability of selected maize inbred lines and testers, agronomic performance and yield stability of the resultant topcross hybrids would provide useful information that would guide the breeding program for optimum yield. Nine yellow maize inbred lines and two open-pollinated varieties (Early LN-Y and TZE-31DMRSRLNSYN) were crossed in a line × tester mating scheme. The resultant eighteen topcross hybrids together with two commercial hybrids and two candidate hybrids as checks were evaluated across eight locations in Nigeria. Significant differences were detected among the genotypes, lines, testers, line × tester and their interactions with the environment for most traits studied. Four inbred lines (TZEEIOR-197, TZEI-13, TZEI-17 and TZEIORQ-44) had significant General Combining Ability (GCA) effects for grain yield (GY), whereas TZEIORQ-44, TZEI-8 and TZEI-17 had significant GCA effects for earliness. Five topcrosses (TZE-31DMRSRLNSYN × TZEEIOR-197, TZE-31DMRSRLNSYN × TZEI-129, Early LN-Y × TZEI-13, TZE-31DMRSRLNSYN × TZEI-17 and Early LN-Y × TZEI-8) had significant specific combining ability effects for GY. The best eight topcross hybrids had comparable GY with the commercial checks. Four each of the eight hybrids were of either tester. Based on the GGE-biplot, TZE-31DMRSRLNSYN × ENT 13 was the most stable genotype across the test environments. The inbred lines with significant GCA effects and superior testcrosses were identified for future breeding programs. Key words: Grain yield, inbred lines, line × tester, testers, topcross maize hybrids.
Anthony et al. (Thu,) studied this question.