GGE-Biplot and genetic diversity analysis of maize hybrids and inbred lines from the breeding programme at UKZN.
Makongwana, Mandisa Precious.
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Maize (Zea mays L.) is the most important cereal crop in southern Africa. It is classified as a major staple food for human consumption. It is also used for animal feed in the livestock industry. Therefore, maize plays a crucial role in ensuring food security. However, production of maize is outstripped by consumption. Therefore, there is a yield gap that needs to be closed by increasing maize yields. Unfortunately, the adequate production of the crop is affected by lack of highly stable and highly productive hybrids. Hybrids that combine these two attributes are highly desired in the small scale sector where resources are usually limiting. Hybrids can be exploited to increase productivity of maize; however, a study of diversity between the parent lines is required because hybrid heterosis is obtained when the lines are divergent and complimentary. Therefore, the current study investigated genetic diversity and genetic gains that were realized by the breeding program at the UKZN. Thirty-one experimental hybrids from the program were tested alongside eleven commercial hybrids across 6 locations in South Africa. Hybrids 11C3201, 13C7082, 11C3417, 14XH149 and 14XH146 were among the best four hybrids across 6 locations. They combined high levels of stability and productivity, qualifying them as potential candidates for advancement. The study indicated that the program was successful at breeding new hybrids with the potential to compete with current commercial hybrids. With respect to diversity, 51 inbred lines were genotyped with 396 SNP markers at the LGC genomics, UK. Therefore, PIC, genetic diversity, availability, inbreeding coefficient, heterozygosity and genetic distance were determined. SNP markers indicated there was large diversity between the lines as reflected by two major clusters at the truncation level of 0.14 in the coefficient scale. Under the second major cluster, there were eight sub-clusters (sub-cluster B-J) identified which indicated wide range of the genetic diversity within inbred lines. Genetic distance between lines ranged from 0.05 to 0.35. This indicates the program was successful at generating new inbred lines that can be used to breed new hybrids.