GENETICS OF THRIPS (Megalurothrips sjostedti) RESISTANCE IN COWPEA (Vigna unguiculata (L.) WALP.)
GENETICS OF THRIPS (Megalurothrips sjostedti) RESISTANCE IN COWPEA (Vigna unguiculata (L.) WALP.)
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Date
2011-08
Authors
RICHARD, DORMATEY
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Abstract
Genetics of resistance of Megalurothrips sjostedti in cowpea was studied, field trial was
conducted at Savannah Agricultural Research Institute (SARI), Nyankpala, Ghana, involving
F1, F2, backcross populations and the five parental materials: four improved varieties; Sampea
8, Ife brown, Sampea 7, Padi-tuya and one local landrace, Sanzi obtained by bi-parental
mating design at the Institute for Agricultural Research (IAR), Samaru, Nigeria. Nyankpala is
located on (90 251 N: 00 581 W). The study was undertaken to validate the resistance status of
the parental materials, to elucidate the mode of inheritance of flower bud thrips resistance in
these genotypes and to establish the genetic relationships between the resistance genes. The
results showed Sanzi to be resistant and Sampea 8, moderately resistant whilst Ife Brown,
Sampea 7 and Padi-tuya were classified as susceptible. Maternal effect was implicated while
frequency distributions of the F2 and backcross generations revealed quantitative inheritance.
Additive, dominance and epistatic gene effects made major contributions. The effective
factors of 3 to 4 indicated an oligogenic inheritance of resistance genes for flower bud thrips.
The study suggested that some of the resistant genes in Sampea 8 and Sanzi are non-allelic.
Broad sense heritability estimates ranged from 53.00 % to 58.00 % and 85.00 % to 94.00 % in
Number of flower bud thrips per plant and pods per peduncle. Narrow sense heritability
ranged from 13.00 % to 28.00 % and 18.00 % to 41.00 % coupled with genetic advance of
3.64 to 4.78 respectively. The estimates of broad and narrow sense heritability with genetic
advance showed the possibility to increase and diversify resistance of cowpea to flower bud
thrips by using these two resistant genotypes as viable sources for resistant to Megalurothrips
sjostedti in high yielding commercial cultivars
Description
A thesis submitted to the post graduate School, Ahmadu Bello University, in
partial fulfilment of the requirement for the Degree of Masters of Science
in Plant Breeding
DEPARTMENT OF PLANT SCIENCE
FACULTY OF AGRICULTURE
AHMADU BELLO UNIVERSITY
ZARIA, NIGERIA
August, 2011
Keywords
THRIPS,, Megalurothrips sjostedti,, RESISTANCE,, COWPEA,, Vigna unguiculata,, WALP