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Verification of a Model of Spore Germination at Variable, Moderate Temperatures. Paul E. Waggoner, The Connecticut Agricultural Experiment Station, New Haven 06504; J. Y. Parlange, The Connecticut Agricultural Experiment Station, New Haven 06504. Phytopathology 64:1192-1196. Accepted for publication 9 April 1974. DOI: 10.1094/Phyto-64-1192.

A concept of the development of germ tubes as f steps taken at P per hour produced the half-time (t1/2) and variance (s2) that characterize the sigmoid course of germination of wet Alternaria solani spores at steady temp. At steady temp from 4 to 29 C, the number of steps f was constant, and the isothermal P increased linearly with warmth. At variable temp from 10 to 29 C, because f was constant and the spores promptly took on the isothermal P at whatever temp they had, the t1/2 of germination could be calculated from an integration of P or even a simple heat-sum during development. The s2 could be calculated from the ratio f/P2 where P is the isothermal rate at the temp prevailing near t1/2. Although little development occurred at 4 C, exposure to 4 C on wetting did speed subsequent development somewhat.

Additional keywords: Alternaria solani, mathematical model.