Calcium and bicarbonate effects on the growth and nutrient uptake of burley tobacco seedlings: Float system¹

Contribution paper no. 98–060154 of the Kentucky Agricultural Experiment Station, published with the approval of the director.

Abstract

High levels of bicarbonate (HCO₃ ⁻) alkalinity have been shown to affect the growth and nutrient uptake of tobacco seedlings in solution culture. The objective of this study was to determine the effect of HCO₃ ⁻ on the nutrient uptake of burley tobacco seedlings grown in a float system. Float bays of a size to accommodate individual float trays were filled with 40 L of deionized water. A commercial 20–10–20 (20% N, 10% P₂O₅,20% K₂O) water soluble fertilizer was added to give 100 mg N L⁻¹. Sodium bicarbonate and calcium chloride were added to provide a factorial combination of 5 levels of HCO₃ ⁻ (0, 122, 244, 366, and 488 mg L⁻¹) and three levels of calcium (Ca²⁺) (25, 50, and 75 mg L⁻¹). Pelleted burley tobacco seed (var. KY 907) were sown into 200‐cell float trays filled with peat‐vermiculite medium. Plants in all treatments appeared normal. HCO₃ ⁻ alkalinity above 244 mg L⁻¹ limited the growth of tobacco seedlings. Total nitrogen (N), phosphorus (P) and potassium (K) concentration in the shoot portion of tobacco seedlings the lowest at 244 mg L⁻¹ HCO₃ ⁻, as compared to lower or higher HCO₃ ⁻ levels. Calcium concentration in shoots increased with increased HCO₃ ⁻, but zinc (Zn) decreased and magnesium (Mg) and iron (Fe) were not significantly changed. Added Ca²⁺had no significant effect on transplant growth. High nitrite‐N concentrations were observed in the float water solution three weeks after seeding. Nitrite‐N accumulation increased at high levels of HCO₃ ⁻ _. Increased HCO₃ ⁻ alkalinity resulted in lower shoot nutrient concentrations, but the growth restriction due to HCO₃ ⁻ did not appear to be related to nutrient deficiency. However, transient levels of nitrite‐N may have been sufficiently high to result in stunting of the tobacco seedlings.

Notes

Contribution paper no. 98–060154 of the Kentucky Agricultural Experiment Station, published with the approval of the director.