Genetic analysis of new maize hybrids for yield and resistance to aflatoxin accumulation

Authors: OPPONG, ALLEN - Csir-Crops Research Institute; DADZIE, ABU - University Of Ghana; IFIE, BEATRICE - University Of Ghana; ASANTE, MAXWELL - Csir-Crops Research Institute; PREMPEH, RUTH N. - Csir-Crops Research Institute; ABROKWAH, LINDA - Csir-Crops Research Institute; KUBI, ZIPPORAH - Csir-Crops Research Institute; MARFO, ESTHER - Csir-Crops Research Institute; ANANNG, ESTHER - Csir-Crops Research Institute; Warburton, Marilyn

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/3/2021
Publication Date: 9/15/2021
Citation: Oppong, A., Dadzie, A.M., Ifie, B.E., Asante, M.D., Prempeh, R.A., Abrokwah, L.A., Kubi, Z.A., Marfo, E.A., Ananng, E.A., Warburton, M.L. 2021. Genetic analysis of new maize hybrids for yield and resistance to aflatoxin accumulation. Journal of Agricultural Science. 13(10):15-30. https://doi.org/10.5539/jas.v13n10p15.
DOI: https://doi.org/10.5539/jas.v13n10p15

Interpretive Summary: Maize (Zea mays L.) is the most important cereal crop in sub-Saharan Africa and provides food for many of its 1.2 billion inhabitants. In Africa, maize production is plagued by low yields and presence of aflatoxin, which are toxins produced by the fungus Aspergillus flavus. Breeding can create hybrids with higher yield and higher resistance to A. flavus, and the first step in creating hybrids is to measure how inbred parental lines behave when crossed as a hybrid. Resistant maize inbred lines from other breeding programs were crossed with locally adapted and good yielding inbred lines and grown in the field to see which formed good hybrids. Many good inbred lines and hybrids were identified in this study, some of which can be used directly by farmers, and all of the information in this study can be used to identify and create other new, improved hybrids.

Technical Abstract: Maize (Zea mays L.) is the most important cereal crop in sub-Saharan Africa and provides food for many of its 1.2 billion inhabitants. However, production is hampered by many factors including low yields and aflatoxin contamination. The toxin contaminates maize pre-harvest as well as during storage. Grains with contamination levels above 20 ppb are not for human consumption in the USA while EU and Japan allow only 2-4 and 0 ppb respectively. Ghana lacks regulatory infrastructure for monitoring and detecting aflatoxin in grains prior to market, and most of the local maize varieties have been found to be susceptible to aflatoxin accumulation. At present, there are only a few, relatively expensive mitigating activities to reduce aflatoxin accumulation in grains by growers. Host resistance is envisaged as a key approach in addressing the aflatoxin menace. Sixteen aflatoxin resistant inbreds from international (exotic) sources were crossed as males to six local inbreds, two populations, one OPV and one three-way cross (hybrid) in a North Carolina II design to generate 160 new hybrids. These were planted together with 9 checks using a 13 x 13 lattice with three replications. The new hybrids were evaluated across six environments in two seasons. Five plants each per hybrid were inoculated with a local strain of Aspergillus flavus at a concentration of 9 x 107conidia/ml. Statistical analysis showed significant effect of environment and genotypes for all traits especially aflatoxin accumulation resistance and yield. The general combining ability effect of males for all traits were found significant (P<0.05) whereas that of the females were not significant for all traits. Inbreds with consistent significant negative GCA effect for aflatoxin reduction were identified (MP715, TZI8, MP719) as well as hybrids which combined high yields with reduced aflatoxin levels below 20 ppb. Furthermore, the underlying genetic control for the aflatoxin accumulation resistance trait was found to be via both GCA and SCA effects. Heritability estimates were moderate, suggesting permissible transfer of traits during selection to create high yielding aflatoxin resistant hybrids for consumers.