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The effect of heat on the growth and recovery of Aspergillus spp. from the mycoflora of onion seeds
Author(s) -
HAYDEN N. J.,
MAUDE R. B.
Publication year - 1994
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.1994.tb01600.x
Subject(s) - biology , aspergillus , fungal growth , horticulture , botany , agronomy
Temperature optima for growth of Aspergillus niger and A. flavus on agar lay between 30°C and 35°C; the optimum for A. fumigatus was 40°C. A. flavus grew less rapidly in culture than the other two species. These fungi were recovered when a single sample of onion seeds, produced in Sudan, was plated out onto agar and incubated over a range of temperatures from 15°C to 45°C. In line with the growth optima of the fungus, the recovery of A. niger was greatest between 25°C and 35°C; recovery of A. flavus was greatest between 30°C and 35°C and recovery of A. fumigatus greatest between 40°C and 45°C. Hot‐water treatment for durations of up to 60 min at 50°C failed to reduce the incidence of recovery of seedborne A. niger and A. flavus from seeds incubated at 30°C on agar; A. fumigatus was not recovered from seeds treated in this way. However, when seeds were hot‐water treated at 60°C and incubated on agar at 30°C, A. niger was virtually eliminated by a treatment duration of 15 min or more; the incidence of recovery of A. fumigatus was significantly increased compared with the 50°C treatment and there was no change in the incidence of A. flavus. Hot‐water treatment at 60°C for more than 30 min significantly reduced seed germination.