AGRONOMIC PERFORMANCE AND HERITABILITY OF GRAIN YIELD AND OTHER YIELD-RELATED TRAITS OF STRIGA-TOLERANT MAIZE HYBRIDS UNDER STRIGAINFESTED AND STRIGA-FREE ENVIRONMENTS

Abstract

Striga hermonthica, an obligate root-parasitic weed is a major constraint to maize production in West Africa causing significant yield losses, sometimes up to 100%. Host-plant resistance is considered the most economical and feasible method of Striga control. In 2014 and 2015, seventeen single-cross Striga-tolerant maize hybrids and a local check were evaluated at Nyankpala and Manga for grain yield (GYLD) and agronomic performance under Striga-infested and Striga-free environments. Combined analysis of variance across Striga-infested and Striga-free environments revealed significant effects of genotype and environment on GYLD and most agronomic traits. The genotype-by-environment interaction effect was
not significant for most traits, including GYLD, under individual test environments or across
environments. This suggested that the GYLD and agronomic performance of the hybrids would be stable across both Striga-infested and Striga-free environments. Striga-free environments had higher heritability for GYLD and other traits (0.42-0.89%) than Striga-infested environments (0.01-0.73%). Grain yield under Striga-infested environments was positively genetically correlated with GYLD under Striga-free environments (rg = 0.63). This confirmed that GYLD performance under Striga infestation can be predicted from GYLD performance under Striga-free environments. The hybrids' mean GYLD in Striga-free
environments was 4.2 t/ha, with a 31% yield reduction in Striga-infested conditions. Ears per plant decreased by 16% as a result of the Striga infestation, but anthesis-silking interval increased by 34%. The most outstanding hybrids based on a selection index for Striga tolerance were M1462-15, M1462-6, and M1462-4. They can be grown in Striga-free and Striga-endemic conditions and also be used to create new Striga-tolerant varieties.