Combining Ability And Heterosis Of Maize (Zea Mays L.) Inbred Lines Under Low And Optimum Soil Nitrogen

Abstract

ABSTRACT Maize is the most relevant food crop in Ghana, and it accounts for the majority of millions of people's diets. Despite this, smallholder farmers still obtain low grain yields in maize as a result of low soil fertility. Low soil nitrogen (low N) threatens maize production in Ghana. Therefore, maize cultivars tolerant to low nitrogen will lessen the use of nitrogen inputs and expand maize production. Combining ability can be used to select parental lines with desirable genes and identify superior hybrid combinations. The objectives of this study were to (1) determine the general combining ability (GCA) effects of the parental maize inbreds, (2) identify the best performing hybrids based on their specific combining ability (SCA) effects, and (3) identify the gene action controlling the inheritance of grain yield under low N soil. Nine inbred lines were crossed in a half-diallel cross fashion to generate thirty-six (36) hybrids. The 36 hybrids plus four local (4) checks (GH110, Tintim, Afriyie, and Apraku) making a total of 40 genotypes were planted using 8 x 5 alpha lattice design in three replications on the low nitrogen soil (30 kg N ha-1) and optimum N soil condition (90 kg N ha-1). The hybrids were planted in the 2021 major season in Fumesua and Ejura. Significant GCA and SCA effects for grain yield and agronomic traits displayed the preponderance of GCA effects over SCA effects, showing that additive gene action controlled the inheritance of grain yield and other related traits. CRIZEQ-25 was the best general combiner under low N conditions. The single-cross hybrids, CRIZEQ-44 X CRIZEQ-14, CRIZEQ-25 X CRIZEQ-24, CRIZEQ-45 X CRIZEQ-25, CRIZEQ-46 X CRIZEQ-25, CRIZEQ-46 X CRIZEQ-42, and CRIZEQ-46 X CRIZEQ-45 were the best hybrid combinations but CRIZEQ-25 X CRIZEQ-24 and CRIZEQ-46 X CRIZEQ-45 were high yielding and tolerant to low N. These cultivars should be further tested in several locations for possible release and commercialization.