EFFECTS OF METHANOL ON PLANT RESPIRATION

This study examined the effects of methanol on respiration in tissues of pepper (Capsicum annuum), tomato (Lycopersicon esculentum), and pet unia (Petunia hybrida) as measured by metabolic heat rates. Metabolic heat rate increased on brief exposure to aqueous solutions containing less than toxic concentrations of methanol. The heat rate increase cor related with methanol concentration. Simultaneous measurement of metab olic heat, CO2, and O-2 rates of bell pepper leaf tissue suggested tha t exposure to methanol resulted in an increased carbon conversion effi ciency. Exposure of a single leaf to methanol resulted in a systemic r esponse throughout the plant within a few hours. The methanol-induced increase in metabolic rate in whole plants lasted for several weeks. B rief exposures to methanol concentrations greater than or equal to 30% were toxic to leaf tissue as shown by greatly decreased metabolic rat es and waterlogged appearance. Root tissue was more sensitive than lea f tissue, showing toxicity when briefly exposed to 10 % methanol solut ion. The increased metabolic rate and efficiency may explain previous reports of increased productivity seen in some field studies. The comp lexity of the exposure-respiratory response relationship and differing tissue sensitivities found in this study probably explains the inabil ity of others to reproduce the field responses originally reported.