LABELED SODIUM (NA-22(-CHLORIDE AND SUPPLEMENTAL CALCIUM()) UPTAKE AND TRANSLOCATION IN RABBITEYE BLUEBERRY EXPOSED TO SODIUM)

'Tifblue' rabbiteye blueberry (Vaccinium ashei Reade) plants grown in complete nutrient solution were supplied with 25 mM NaCl and with eith er 0, 3, or 10 mM supplemental Ca2+ added as a mixture of the sulfate, nitrate, and chloride salts. Uptake and partitioning of Na-22(+) into leaves, stems, and roots from labeled nutrient solutions and subseque nt translocation in the absence of additional labeled Na+ (pulse-chase experiment) was determined. Plants were harvested at intervals follow ing the uptake period. At 28 days, plants supplied with 10 mM Ca2+ acc umulated 35% to 68% more Na-22(+) in the 3rd-18th leaves from the apex and in herbaceous stems than plants not supplied with Ca2+. Leaf Naconcentrations followed a similar trend. There was a preferential tran slocation of Na+ to the shoots compared to the other plant parts, whic h accounted for 30 % of the total plant Na+ immediately following the uptake period and 45 % at 28 days. Blueberry plants supplied with 3 mM Ca2+ did not have greater leaf or stem Na-22(+) concentrations or tot al Na+ content than plants not supplied with Ca2+. The Na-22(+) conten t did not decrease with 3 mM Ca2+ treatments, It is proposed that the failure of a high level (10 mM) of Ca2+ to protect against Na+ uptake and translocation to the herbaceous shoots is due to metabolic dysfunc tion, Abnormally high levels of Ca2+ in the cytoplasm may lead to an i nability to sequester or exclude Na+.