HOST-PLANT RESISTANCE AND RESPONSE TO SELECTION IN SORGHUM TO HEAD BUGS (Eurystylus oldi. Poppius)
HOST-PLANT RESISTANCE AND RESPONSE TO SELECTION IN SORGHUM TO HEAD BUGS (Eurystylus oldi. Poppius)
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Date
1998-11
Authors
SHOWEMIMO, FRANCIS ABAYOMI
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Abstract
Three resistant sorghum cultivars used as males were crossed to three susceptible
sorghum cultivars used as females in a factorial mating system. The resultant nine F, hybrids
were advanced to F2 generation and screened for resistance by artificially infesting each sorghum
panicle with 10 pairs of head bugs (Eurystylus oldi (Poppius)) using the 'no choice' head cage
method. The best 10% of F2 genotypes were advanced to F3 and F4 generations. The six
parents, nine F,s, nine F2s, 25 F3 lines and 25 F4 lines were evaluated for resistance to E. oldi.
Randomized complete block design (RCBD) was used, while North Carolina design II was the
breeding design used.
The analysis of variance revealed highly significant effects (P=0.01) among entries (nonsegregating
and segregating populations), crosses, F2 generations, F3 lines and F4 lines for all
the traits measured that is; number of head bugs, grain damage rating, floaters percentage,
germination percentage, 1000-grain weight and grain yield. The parents also showed highly
significant effect (P=0.01) for all the traits except grain yield.
Estimates of genetic component of variance O2
A, O2
D and O2A/D ratio revealed the
preponderance of non-additive gene action for all the traits measured. High narrow-sense
heritability estimates were recorded for all traits in F4 lines, F3 lines, F2 generations and the F1S,
except for number of head bugs (47.00%) in the F1. High narrow-sense heritability estimates
were also recorded at F2 generations, F3 and F4 lines for all the traits measured
Description
A dissertation submitted to the Postgraduate School,
Ahmadu Bello University, Zaria in partial fulfillment
of the requirements for the degree of
Doctor of Philosophy in Plant Breeding.
Department of Plant Science
Faculty of Agriculture
Ahmadu Bello University
Zaria, Nigeria.
NOVEMBER, 1998
Keywords
HOST-PLANT RESISTANCE,, RESPONSE,, SORGHUM,, HEAD BUGS,, (Eurystylus oldi. Poppius)