Calcium and bicarbonate effects on the growth and nutrient uptake of burley tobacco seedlings: Hydroponic culture

In soilless production systems, water quality can have a major impact on the growth of plants. It has become evident that moderately alkaline water is a problem for tobacco transplant growers in some regions of Kentucky. To determine the level of bicarbonate (HCO₃^-) alkalinity, which is detrimental to burley tobacco transplants, and to better understand the effect of calcium (Ca) and the interaction of HCO₃^- and Ca on the growth of burley tobacco transplants grown in a float system, three levels of CaCl₂ (25, 75, and 125 mg L^-1 Ca⁺⁺) in factorial combination with five levels of HCO₃^- (0, 122, 244, 366, and 488 mg HCO₃^-L^-1) were tested in nutrient solution culture. Four-week-old burley tobacco (Nicotiana tabacum L. var. KY-907) seedlings were transplanted to 18-L containers filled with aerated Hoagland's solution with the different levels of calcium and HCO₃^- for two weeks. High HCO₃^- alkalinity caused root system damage and plant growth inhibition, but did not induce iron (Fe) chlorosis. A significantly lower concentration of Zinc (Zn) was measured in the shoots as HCO₃^- levels in solution increased. In the presence of high calcium, plant growth was not significantly improved. No significant interaction of HCO₃^- and Ca on growth or nutrient uptake was observed in this study.