Genetic Analysis of Resistance to Pod Shattering in Soybean (Glycine Max. (L) Merrill).

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April, 2010
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Genetic analysis of resistance to pod shattering was undertaken on three soybean crosses with reciprocals involving resistant and susceptible varieties to examine broad sense (h2bs) and narrow sense (h2ns) heritability, minimum number of genes involved (MNG), mid-parent heterosis (MPH), cytoplasmic inheritance and allelic relationship between shattering and non-shattering. Two sets of experiments were conducted. The first experiment was a non-replicated crossing block in plastic pots to develop F1 populations at the plant house of the Faculty of Agriculture – Kwame Nkrumah University of Science and Technology, Kumasi (Latitude 06o 41′ N and longitude 01o 33′ W). F1 plants were selfed to produce F2 generations. The F1 progenies were backcrossed to both parents to produce BC1 and BC2 progenies. The second experiment was a replicated trial laid in a randomized complete block with three replications to determine genetic ratios for levels of pod shattering resistance at F2 and this was used to determine allelic relationship between shattering and non-shattering genes using chi-square test. Mean h2bs was 0.30 (range 0.00 – 0.90) and mean h2ns was 0.92 (range 0.00 – 1.72) indicating the importance of both additive and non additive variances, suggesting that improvement in resistance can be achieved through breeding. Mean MNG was two genes (range 1 – 3) indicating that genes for resistance differed among parental lines. Mean MPH was -3.7% (range -44.1 – 55.7%) indicating that heterosis did not influence the expression of resistance to pod shattering in soybean. There was no difference between the mean of any F1 population and it’s reciprocal, indicating lack of maternal influence and that the character could be under nuclear gene control. Observed ratios at F2 population revealed that, inheritance of resistance to pod shattering is quantitative and under the influence of either duplicate recessive or dominant and recessive epistasis depending on the parental genotypes used in the cross.
A Thesis Submitted to the Department of Crop and Soil Sciences, Faculty of Agriculture of the College of Agriculture and Natural Resources, Kwame Nkrumah University of Science and Technology, Kumasi, in Partial Fulfillment of the Requirements for the Award of Msc. Agronomy (Plant Breeding Option).