MORPHOLOGICAL, CULTURAL AND PATHOGENIC VARIATION IN TOLYPOSPORIUM PENICILLARIAE BREF, THE CAUSAL AGENT OF SMUT OF PEARL MILLET IN NIGERIAN SAVANNA
MORPHOLOGICAL, CULTURAL AND PATHOGENIC VARIATION IN TOLYPOSPORIUM PENICILLARIAE BREF, THE CAUSAL AGENT OF SMUT OF PEARL MILLET IN NIGERIAN SAVANNA
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Date
1985-12
Authors
ORJI, CHRISTIANA NCHETA
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Abstract
Twenty isolates of the pearl millet smut pathogen,
Tolyposporium penicillariae, were collected from pearl millet
growing ecological savanna zones of Nigeria and studied for
morphological, cultural and pathogenic variations. All the
isolates were used for morphological and cultural studies while
10 isolates were selected for pathogenicity tests.
The dimensions of the sporeballs of T. penicillarlae of the
different isolates varied. The mean lengths and widths of 100
sporeballs from Jaji were the greatest (118.90 x 93.65 urn) while
those of the isolate from Bakura were the smallest (87.20 x 70.00
um). The sporeballs were dark brown and their shapes varied from
circular to near polyhedral. The mean number of teliospores
aggregated in a sporeball ranged from 549 for Jaji isolate to 758
for Bakura isolate. Teliospores were oval or spherical and
yellowish brown. The mean lengths end widths of 100 teliospores
varied from 8.36 x 7.46 um for Kano isolate to 10.9? x 9,57 um for
Jaji isolate. Germination of aggregated teliospores
(sporeballs) in water occurred at 6 to 12 hours of incubation
at 30°C.. The mode of germination was similar in all the isolates
and the following patterns were observed within the isolates:
sporidia borne laterally or/and terminally on promycelium;
sporidia produced in clusters on promycelium and sporidia
produced in branched chains directly by the teliospores without
the
formation of promycelium, Sporidia were spindle shaped and
hyaline and the mean lengths of 50 sporidia varied from
11.1+7 um to 19.15 um for Jalingo end Gombe isolates
respectively. Mean incidence (percentage) of germination
of aggregated teliospores (sporeballs) varied from 25.67 per
cent for Karfi isolate to 64.33 per cent for Maigana isolate.
Some variations were observed in cultural
characters of the pathogen grown on five different media.
At 30 C maximum growth of T. penicillariae occurred on
potato dextrose agar while minimum growth was observed on
potato agar. Growth of the fungus remained sporidial and
yeas-like even after several subculturing.
In the pathogenicity tests carried out with sporidial
inoculum (2 x 10 ) sporidial/ml) from 1 - 1 0 day-old cultures
and five pearl millet varieties, four pathogenic groups were
identified, namely highly virulent, virulent, moderately
virulent and weakly virulent. In general, no definite
correlation could be established between the pathogenicity
of the different isolates and their morphological or
cultural characteristics.
Description
A thesis submitted to the Department of Crop Protection,
Faculty of Agriculture, Ahmadu Bello University in partial
fulfillment of the requirement for the degree of
MASTER OF SCIENCE
Ahmadu Bello University
Zaria, Nigeria,
December-, 1985.
Keywords
MORPHOLOGICAL,, CULTURAL,, PATHOGENIC,, VARIATION,, TOLYPOSPORIUM,, PENICILLARIAE,, BREF,, CAUSAL,, AGENT,, SMUT,, PEARL,, MILLET,, NIGERIAN,, SAVANNA.