Temperature Control and Metabolic Drifts in Ageing Disks of Storage Tissue

Abstract

The respiratory drifts of ageing disks of sugar-beet, red beet, carrot, swede, and potato maintained at different temperatures have been determined mano-metrically. The general pattern of the respiratory time-drift exhibited by all tissues is that of a hyperbolic curve but its exact form is largely determined by the temperature of pretreatment, higher temperatures causing a telescoping effect. Different respiratory time-drifts obtained by earlier workers from the same tissue are shown to be explicable in terms of the temperature of pretreatment. Except in swede disks, estimations of total and reducing sugar content of the disks throughout the experimental period revealed a very considerable conversion of sucrose (or starch in potato) to reducing sugars. In sugar-beet, red beet, carrot, and potato the concentration of reducing sugar is positively correlated with the rate of respiration. The character of the respiratory time-drift in the disks is discussed in relation to substrate concentration and other possible determinants.