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.
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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.
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