GENETICS OF SUICIDAL GERMINATION OF Striga hermonthica (Del.) Benth, BY COTTON (Gossypium hirsutum L.)
GENETICS OF SUICIDAL GERMINATION OF Striga hermonthica (Del.) Benth, BY COTTON (Gossypium hirsutum L.)
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Date
1998-03
Authors
JOMIA, BOTANGA CHRISTOPHER
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Abstract
The germination of "giant witchweeds" (Striga hermonthica (Del.) Benth),
a noxious root parasite of many cereal crops, is stimulated by exudates from the
roots of both host and non-host ("trap") plants. Forty genotypes of cotton
(Gossypium spp.), a "trap" crop, were screened in the laboratory, using the cut
root technique, to investigate the variability among these genotypes for their ability
to stimulate the suicidal germination of S. hermonthica and to select materials for
a genetic study.
The genotypes exhibited significant differences for the trait. Striga
germination percentages ranged from 13.33 to 50.00% for the cotton genotypes
compared with 47.33% for the sorghum variety CK60B, the susceptible control.
Three cotton genotypes were selected based on their Striga seed germination
stimulation and used as parents in crosses of the combination; low x high Striga
germination stimulation. The F1s, F2 s and parents for these crosses,
(RASA(78)11b x SAMCOT-10 and RASA(78)11b x TX-CABS-1-83) were
evaluated in separate experiments.
Broadsense heritability estimates for the trait from both crosses ranged
from 71.8 to 78.5% indicating a high genetic influence for the trait. Gene number
estimates gave values of less than 1. This was reflected by a discrete frequency
distribution of the F2 populations into two classes of high and low Striga seed
germination stimulation, fitting into classical phenotypic ratio of 3:1.
These results tend to suggest that Striga germination stimulation by cotton
(G. hirsutum L.) is a qualitative trait, and that the gene controlling this trait is
monogenic and simply inherited, with high Striga germination stimulation dominant
over low Striga germination stimulation. It should be possible to select and breed
cotton genotypes that produce highly active germination stimulants in large
amounts, while incorporating other good agronomic attributes.
Description
A thesis submitted to the Postgraduate School, Ahmadu Bello University in
partial fulfillment of the requirements for the award of the degree of Master of
Science in Crop Breeding.
DEPARTMENT OF PLANT SCIENCE
Faculty of Agriculture
Ahmadu Bello University, Zaria
Nigeria
MARCH, 1998
Keywords
GENETICS,, SUICIDAL GERMINATION,, Striga hermonthica,, COTTON,, (Gossypium hirsutum L.)