Author : Meity Suradji Sinaga

Summary : 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 show that C. truncatum either on infested or infected soybean seeds can survive during storage at either room temperature (29-36 degree C) or at low temperature (5 degree C). There was no significant difference (P>0.05) in C. truncatum infection percentage during storage at room temperature and at 5 degree C. Untreated-seeds had a higher percentage of C. truncatum infection than seeds treated with 1 percent NaOCl. C. truncatum 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 5 degree C. However, longevity of storage of treated seeds had 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 1 percent NaOCl seed-treatment can minimize the spread of the fungus. Three types of seed and seedling damage were exhibited by artificially-inoculated soybean seed. These were seed-rot, seedling blight, and cotyledon or stem infection. The first two reducted 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 longevity x storage temperature x seed-treatment interaction factors. The highest percentage of seed-rot (84.5 percent) was recorded four months after storage at room temperature. Seedling-blight symptom was influenced only by longevity of storage.