Introgression of sugary su1 gene from sweet corn into obatanpa using backcross breeding approach

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AUGUST, 2015
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Biofortification of maize which is the major cereal consumed in Ghana will help alleviate malnutrition primarily among children. The study was conducted to further biofortify QPM by introgression of sugary gene. It was conducted at the Finatrade field at Faculty of Agriculture, KNUST. The parental materials used were Obatanpa (source of opaque-2 gene) as the first parent and Stowell’s evergreen (source of sugary gene) as second parent. The F1 produced was selfed to obtain F2 to obtain segregation ratios. The F1 was again backcrossed to both parents to obtain BC1P1 and BC1P2. Opaque seeds were selected and selfed to obtain BC1S1. Cobs of BC1S1 that segregated into 3:1 of non-shrunken opaque to shrunken opaque were again selected. The shrunken opaque (new) seeds were then evaluated with the two parents for both vegetative and output traits. Output traits of sucrose content, starch yield and protein content were analysed biochemically. From the study, the sugary gene was found to be inherited monogenically and all the vegetative traits of percentage emergence, ear leaf width, ear height, plant height and stem girth were highly heritable. Mid parent heterosis was positive for all vegetative traits measured. Among all the three seed type, it was only the new seed that obtained positive estimate for both mid and high parent heterosis for sucrose content which suggest some synergistic influence of opaque-2 and sugary genes. Harvesting should be done at 20 and 25DAP for sweet corn; 25, 30DAP for obatanpa and 25, 30 and 35DAP for new seed in similar studies. Also the best times for harvesting when sucrose content is of priority should be 20, 25 and 30DAP for sweet corn, obatanpa and new seed respectively. Sugary gene is thus fixed into the genetic background of obatanpa as the highest sucrose content obtained in sweet corn was insignificantly different from that obtained in new seed whilst maintaining their quality of protein.
A thesis submitted to the Department of Crop and Soil Sciences of the Faculty of Agriculture, Kwame Nkrumah University of Science and Technology, Kumasi in partial fulfilment of the requirement for the award of a Master of Philosophy Degree in Agronomy (Plant Breeding).