Analytic studies in plant respiration VI—The relation of the respiration of potatoes to the concentration of sugars and to the accumulation of a depressant at Low temperatures Part 3—The relation of the respiration to the concentration of sucrose

Abstract

In Parts 1 and 2 of this investigation (Barker, 1933), an analysis was presented of the relation between the rate of respiration of potatoes and the concentration of extractable sugar, the latter being varied by changes in the temperature of storage over the range —1° C to +15° C. The relation between respiration and sugar was found to be complicated by a new type of temperature effect, which was called " low temperature depression ". When the depression was believed to be negligible the respiration/sugar relation— i.e. , the relation between the rate of respira­tion plotted as ordinate axis and concentration of sugar as abscissa axis-showed a general approximation to the form of an "enzymatic rectangular hyperbola" such as expresses the rate of reaction/substrate concentra­tion relation for an enzyme reaction in vitro , suggesting that the sugar concentration in some way determined the concentration of the respirable substrate. From the data then available it could not be decided whether respira­tion were more closely related to sucrose or to one of the hexose sugars, and, pending a more precise analysis the concentration of total sugars was provisionally adopted as the measure of the respirable substrate.