Teaching Documents by Richard Dormatey
– Genetics of flower bud thrips (Megalurothripssjostedti) resistance in cowpea was studied by cro... more – Genetics of flower bud thrips (Megalurothripssjostedti) resistance in cowpea was studied by crossing two resistant cowpea genotypes, Sampea 8 and Sanzi, to three susceptible genotypes Ife Brown, Sampea 7 and Padi-tuya. Sufficient seeds of the parental, F 1 , F 2 and backcross populations were generated and evaluated under natural thrips infestation at the Savannah Agricultural Research Institute (SARI), Nyankpala (9 0 25 1 N: 0 0 58 1 W), Ghana. The results confirmed Sanzi to be resistant and Sampea 8, moderately resistant, whilst Ife Brown, Sampea 7 and Padi-tuya were classified as susceptible. Maternal effects were implicated while frequency distributions of the F 2 and backcross generations revealed quantitative inheritance. Additive, dominance and epistatic gene effects made major contributions. The effective factors of 3 to 5 indicated an oligogenic inheritance of resistance to flower bud thrips. The study indicated that the resistance genes in Sampea 8 and Sanzi were non-allelic. Broad sense heritability estimates for number of thrips per plant, thrips damage rating and pods per peduncle ranged from 53.00 to 58.00%, 49.70 to 58.32% and 85.00 to 94.00%, respectively. Narrow sense heritability estimates for the same traits ranged from 13.00 to 28.00%, 12.69 to 20.86% and 18.00 to 41.00% respectively. Genetic advance of reduction of susceptibility from 4 to 6 thrips per plant at 10 % selection intensity was predicted. The broad and narrow sense heritability estimates with the genetic advance showed the possibility to increase and diversify resistance of cowpea to thrips by using the two resistant genotypes, Sanzi and Sampea 8.
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Teaching Documents by Richard Dormatey