Determining Factor in the Respiration of Potato Disks of Varying Thickness

Suimiiary. The effect of temperature on the respiration rate of potato tuber slices has been analyzed in terms of the Arrhenius equation. Freshly cut disks, irrespective of thickness, show a linear response to increasing temperature up to 300 with an activation energy (E) of approximately 12.0 Kcal. Aged disks less than 1.0 mm thick also give a linear response with E similar to that of fresh disks. With aged disks above 1.0 mm thick there is a loss of linearity above 200 and E falls to about 4.0 Kcal indicating that respiration becomes rate-limited by a diffusion process. This departure from linearity can be corrected by raising the oxygen tension or by subdivision of thick disks to give thin slices. It is concluded that the respiration of aged disks is rate-limited by oxygen deficiency and that the inverse relationship between respiration rate and disk thickness is in large part attriblutable to this factor.