Limitations of Glutamic Acid Decarboxylase Activity for Estimating Viability in Beans (Phaseolus Vulgaris L.)1

Abstract

Glutamica cid decarboxylase activity (GADA) in whole beans stored at 32.2 C and 85 to 90% relative humidity, and on the axes and cotyledons of viable and deteriorated seeds of five varieties of beans, was determined by a manometric method for measuring the evolution of CO2. GADA in some varieties remained at a high level in seeds which had lost viability. Correlation between GADA and germinations yielded coefficients ranging from +0.39 N.S. for ‘Tendercrop’ to +0.89** for ‘Taylor’. Determinations of GADA on the cotyledons and axes showed that the cotyledons contributed 87% of the activity in viable seeds and 91% in deteriorated seeds. The low correlation coefficients and the continuing high activity in the cotyledons limit the use of GADA in determining quality in the varieties used.