Labeled Sodium (22Na+) Uptake and Translocation in Rabbiteye Blueberry Exposed to Sodium Chloride and Supplemental Calcium

`Tifblue' rabbiteye blueberry (Vaccinium ashei Reade) plants grown in complete nutrient solution were supplied with 25 m m NaCl and with either 0, 3, or 10 m m supplemental Ca 2+ added as a mixture of the sulfate, nitrate, and chloride salts. Uptake and partitioning of 22 Na + into leaves, stems, and roots from labeled nutrient solutions and subsequent translocation in the absence of additional labeled Na + (pulse-chase experiment) was determined. Plants were harvested at intervals following the uptake period. At 28 days, plants supplied with 10 mM Ca 2+ accumulated 35% to 68% more 22 Na + in the 3rd-18th leaves from the apex and in herbaceous stems than plants not supplied with Ca 2+ . Leaf Na + concentrations followed a similar trend. There was a preferential translocation of Na + to the shoots compared to the other plant parts, which accounted for 30% of the total plant Na + immediately following the uptake period and 15% at 28 days. Blueberry plants supplied with 3 m m Ca 2+ did not have greater leaf or stem 2 Na + concentrations or total Na+ content than plants not supplied with Ca 2+ . The 2 Na + content did not decrease with 3 mM Ca 2+ treatments. It is proposed that the failure of a high level (10 m m ) of Ca 2+ to protect against Na + uptake and translocation to the herbaceous shoots is due to metabolic dysfunction. Abnormally high levels of Ca 2+ in the cytoplasm may lead to an inability to sequester or exclude Na + .