Estimation of cardinal temperatures in germination data analysis

Seed germination is a complex biological process that is influenced by vari ous environmental and genetic factors. The effects of temperature on plant development are the basis for models used to predict the timing of germinat ion. Estimation of the cardinal temperatures, including base, optimum, and maximum, is essential because rate of development increases between base an d optimum, decreases between optimum and maximum, and ceases above the maxi mum and below the base temperatures. Nonlinear growth curves can be specifi ed to model the time course of germination at various temperatures. Quantil es of such models are regressed on temperature to estimate cardinal quantit ies, Bootstrap simulation techniques may then be employed to assure the sta tistical accuracy of these estimates and to provide approximate nonparametr ic confidence intervals. A statistical approach to modeling germination and estimation of cardinal temperatures is presented with reference to replica ted experiments designed to determine the effect of temperature gradient on germination of three populations of an introduced weed species, common cru pina (Crupina vulgaris Pers.).