Occurrence of Localized Intense Cation Uptake Sites in the Vascular Rings of Red Beet Storage Tissue 2

Abstract

Development and decline of cation uptake capacity in discs taken from the vascular and parenchyma rings of storage tissue of red table beet (Beta vulgaris L.) were observed during 12 d of ageing. Uptake capacity for Na+ and Rb+ showed a steady rise reaching maximums by the fourth to fifth days of ageing. Thereafter, there was a steady decline in the uptake rates. Vascular ring tissues were able to develop a greater uptake capacity for both Na+ and Rb+ than the tissues of parenchyma rings. This difference, which was more pronounced for Rb+ than for Na+ uptake, is attributed to a combination of variations in cell density and differences in the acquisition and retention of the cation uptake capacity. Respiration of tissue discs showed no significant rise during ageing, nor were there significant differences in the respiration of vascular and parenchyma tissues. Vascular tissues contained significantly more betacyanin than parenchyma tissues; and they retained their pigment, as well as their acquired cation uptake capacity, for a longer period during the ageing process.