RELATIVE RESISTANCE OF STORED SORGHUM (SORGHUM BICOLOR (L) MOENCH) VARIETIES TO THE RICE WEEVIL, SITOPHILUS ORYZAE (L) (COLEOPTERA.CURCULDAE)
RELATIVE RESISTANCE OF STORED SORGHUM (SORGHUM BICOLOR (L) MOENCH) VARIETIES TO THE RICE WEEVIL, SITOPHILUS ORYZAE (L) (COLEOPTERA.CURCULDAE)
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Date
1996-12
Authors
BAMAIYI, Lucius Joseph
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Abstract
Laboratory studies were carried out to evaluation 36
sorghum varieties maintained at the Institute for Agricultural
Research (I.A.R.) Samaru and ICRISAT Kano, for their relative
res, istance to the rice weevil, Sitoplilus oryzae (Linnaeus)
(Coleoptera: Curculionidae). The criteria used for the
evaluation of the sorghum varieties to postharvest infestation
and damage included Fl progeny emergence, median developmental
period (in days), index of susceptibility, percentage damage
to grains and poercentage weight loss. The effect of physical
characters like grain and biochemical compositions of the
grains on the relative resistance of the sorghum varieties to
S.oryzae were also investigated. The grains of the sorghum
varieties BES, ICSH89009NG, ICSV247, - ICSVII, and ICSV1079BF
supported fewer Fl progeny emergence, had longer median
developmental periods, lower index of susceptibility, suffered
less damage and weight loss than grains of varieties Singe-2,
SK5912, ICSV902NG, KSV8, 18495 and ICSV210. The former group
of sorghum varieties showed a higher degree of resistance than
the latter group. Singnificant positive correlations were
obtained between Fl progeny emergence and index of
susceptibility as well as with percentage damage and weight
loss, but all these parameters showed a negative correlation
with median developmental period of S.oryzae.
Biochemical analysis showed that carbohydrate, protein,
lipid, ash, fibre, tanning and phytic acid content of the
sorghum grains had a non-significant negative correlation with
the index of susceptibility.
Physical charateristics of the different sorghum grains
were investigated for their effect on the behavour including
seed-coat colour, seed-coat texture, and seed size. The grain
hardness of the various sorghum grains was also determined.
The results showed that even though there was preference for
certain grain characters (white and red seed coats, warty and
rough textured seeds and large-seeded grains) under choice
conditoons, no such preference show significant preference for
the various grain characteristics.
Grain hardness had significant negative correlation with
Fl progeny emergence, index of susceptibility, percentage
damage and percentage weight loss, but significant positive
correlation with median developmental period. There was
negative and non-significant correlations between grain
hard less and biochemical composition.
Grain hardness appeared to be the major factor
responsible for resistance of sorghum grains to S.oryzae. This
is evident by the fact that those sorghum varieties that
supported fewer S.oryzae emerging from them were simply
fragamented on grinding while those with more S.oryzae
emerging form them were finely crushed on grinding.
Description
A thesis submitted to the Postgraduate School,
Ahmadu Bello University, Zaria,
in partial fulfillment of the requirements
for the Degree of Master of Science in
Crop Protection
Department of crop protection
Faculty of Agriculture
Ahmadu Bello University, Zaria Nigeria
December, 1996
Keywords
RESISTANCE,, SORGHUM,, (SORGHUM BICOLOR (L),, MOENCH,, VARIETIES,, SITOPHILUS ORYZAE,, (COLEOPTERA.CURCULDAE)