Statistical Studies Using AIC Method to Decide the Question of "Break" or "Straight" in Arrhenius Plots of Water Proton NMR Relaxation Times in Chilling-Sensitive Vigna and Insensitive Pisum Seedlings

The question of "break" or "straight" in Arrhenius plots forthe temperature dependency of NMR relaxation times (T₁) of waterprotons in etiolated intact seedlings for chilling-sensitivetwo Vigna species and chilling-insensitive Pisum was statisticallystudied using the Akaike's Information Criterion (AIC), a versatileprocedure for statistical model identification. Among sevenmodels, the most appropriate was based on the following assumptions:individual k (preparation numbers) two-half lines connectingat the break point (TCB) and imposing no restrictions for thegradient and the break point (Model 7). The worst two modelswere one straight line or one TCB (Model 1 or 4). Thus, thedata obtained from replicated preparations should not be treatedas a whole but as individual in each sample case. Break pointsdetermined with Model 7 ranged around 11-5°C for V. radiataand 17-10°C for V. mungo. The implication of the occurrenceof "break" for Pisum clearly differed from Vigna judging bythe model fitness based on the AIC values. The question of "break"or "straight" in Arrhenius plots is therefore fairly dependenton the validity of the model selection in the statistical analysis,and the AIC method is a useful procedure for the resolutionof the problem of the "use" or "misuse" of Arrhenius plots inplant physiology. (Received November 2, 1988; Accepted January 17, 1989)