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- Survival Spread and Pathogenicity of Colletotrichum truncatum (Schw....
Survival Spread and Pathogenicity of Colletotrichum truncatum (Schw.) Andrus and W. D. Moore on Seeds of Soybean (Glycine max (L.) Merr.)
Thesis Abstract:
Three experiments were conducted to evaluate the effects of seed inoculation, storage longevity, storage temperature, seed treatment, and their interactions on the survival, spread, and pathogenicity of C. truncatum on soybean seeds, variety UPL- SY2.
Results showed that C. truncatum either on infested or infected soybean seeds can survive during storage at either room temperature (29-36ºC) or at low temperature (5ºC). There was no significant difference (P>0.05) in C. truncatum infection percentage during storage at room temperature and at 5ºC. Untreated seeds had a higher percentage of C. truncatum infectlon than seeds treated with one percent NaOCI, C. truncutum from artificially-inoculated seeds can infect other healthy seeds. The fungal spores can be also disseminated by adherence on surface of inoculated seeds. There was no significant difference(P>0.05) in the spread of C. truncatum among the seeds stored at room temperature and at 5ºC. However, longevity of storage of treated seeds significantly affected the spread of C. truncatum. The highest percentage of spread of the fungus was noted at 0-month storage wherein 35.50 percent of seeds were infected with C. truncatum. The use of one percent NaOCI seed treatment can minimize the spread of the fungus.
Three types of seeds and seedling damage were exhibited by artificially-inoculatcd soybean seed. These were seed-rot, seedling blight, and cotyledon or stem infection. The first two reduced seed germination, whereas seedling with cotyledon or stem infection still developed after 14 days of planting. The percentage of seed-rot was significantly (P<0.01) affected by storage longevity, storage temperature, storage longevity x storage interaction, and storage longeviity x storage temperature x seed treatment interaction factors. The highest percentage of seed-rot (84.5%) was recorded four months after storage at room temperature. Seedling blight symptom was influenced only by longevity of storage: four months of storage resulted in the lowest percentage (3.75) of this incidence.
Cotyledon or stem infection was significantly (P<0.01) affected by storage longevity, storage temperature, seed treatment, and interaction of storage longevity x storage temperature. Unstored seeds and those stored for four months showed lower percentage of this type of infection than those that were stored for one, two, and three months. Seeds which were stored at room temperature and testedd without one percent NaOCI treatment had lower percentage of cotyledon or stem infection than those stored at 5ºC.