Mineral Composition of Young Rabbiteye and Southern Highbush Blueberry Exposed to Salinity and Supplemental Calcium

`Tifblue' and `Brightwell' rabbiteye blueberry ( Vaccinium ashei Reade) and `Sharpblue' southern highbush blueberry (primarily V. corymbosum ) were treated with 0, 25, and 100 m m Na + as Na 2 SO 4 or NaCl, and 0, 1, 3, and 10 m m supplemental Ca 2+ in sand culture in the greenhouse. For rabbiteye plants salinized with Na 2 SO 4 , leaf Na + concentrations increased 54-fold and the percentage of total plant Na + found in the leaves increased from 9% to 63% with increasing external Na + . Calcium supplementation reduced the Na + concentrations in leaves by up to 20%. Leaf Ca 2+ concentrations increased with Ca 2+ supplementation, but accounted for a decreasing percentage of the total Ca 2+ found in the plant, since root Ca 2+ concentrations were much higher. Root Na + concentrations increased with increasing Na + treatments to a smaller extent than in the leaves and were also reduced by Ca 2+ supplements. Potassium concentrations in leaves and roots decreased with increasing Na + treatment levels, particularly in roots, where K + concentration was about half at 100 m m Na + (as Na 2 SO 4 .) Leaf Na + concentrations were up to two times greater when Na was supplied as NaCl compared to Na 2 SO 4 . For plants salinized with NaCl, leaf Na + levels increased to 1.1% and did not decrease when supplemental Ca 2+ was applied. Leaf Cl - concentrations also increased greatly with NaCl, reaching >1.0% (dry weight basis.). Root Cl - concentrations also increased with increasing salinity and were not affected by Ca 2+ supplements. Ca 2+ supplementation led only to a greater Ca 2+ concentration in leaves and roots, but this did not alter Na + concentrations. Nutrient concentrations in `Sharpblue' leaves, stems, and roots were greater than those of the rabbiteye cultivars, but were influenced by salinity and Ca 2+ in essentially the same way. Excess Na + , Cl - , or both, together with lowered K + , were likely the cause of extensive leaf necrosis and may be indicative of a lack of a mechanism to control Na + influx into blueberry leaves.