Effect of Ionizing Radiations on Plant Tissues. III. Softening and Changes in Pectins and Cellulose of Apples, Carrots, and Beetsa

Abstract

SUMMARYA study was conducted of changes that occur in pectic and cellulose constituents of apple, carrot, and beet tissues as a result of treatment with gamma radiation. In apple tissues, degradation of both these constituents occurred at approximately the dose at which tissue softening could he first demonstrated, and progressed with increasing dose. The degradation of pectins was demonstrated by several criteria, such as the loss of viscosity in the individual fractions, the loss of specific viscosity calculated for a constant uronide or calcium pectate value, and by change in the soluble‐insoluble pectin ratio. Cellulose degradation was characterized by a decrease in the specific viscosity calculated for 0.15% cellulose solutions.Although these findings were corroborated in carrot tissues, the softening of beets does not seem to be as clearly accompanied by such marked changes in pectins and cellulose. Whereas previously published data indicated that beets have a higher softening threshold dose than either carrots or apples, this does not explain the differences found. It is suspected that other factors, such as cell turgidity, are involved in the softening process, and is here responsible for this phenomenon.