49th TWC, Tob. Work. Conf., 2020, abstr. 19

Effects of chloride application to nutrient assimilation and post-harvest measurements of flue-cured tobacco

North Carolina State University, Raleigh, NC USA

Chloride (Cl-) application in excess of 34 kg/ha has generally been discouraged in the production of US flue-cured tobacco, due to the negative effects the nutrient can have on cured leaf yield, quality, and smoke sensory. However, fertilizer blending errors or misapplication sometimes result in the exposure of flue-cured tobacco to sources of potassium that contain a high Cl- concentration, resulting in the possibility of excess Cl- absorption. Research was conducted to quantify the effects of Cl- application to nutrient assimilation, cured leaf yield, quality, value, and chemistry. Chloride application rates ranged from 0 to 112 kg/ha, increasing in intervals of 11 kg/ha, which were sidedress applied 10 days after transplanting. Potassium chloride (0-0-60-47% Cl-) was the source of Cl- and was blended with potassium sulfate (0-0-50) and calcium sulfate (18% SO42-) to ensure that K2O and SO42- application rates were consistent among treatments (168 and 60 kg/ha, respectively). Liquid urea-ammonium-nitrate (28% N) was utilized as the source of N fertilizer and was split-applied 10 days after transplanting and at layby. Cured leaf Cl- concentration was in excess of one percent as application rates increased from 34 to 112 kg Cl-/ha, thus demonstrating strong concern with applications beyond the recommended maximum. Despite relatively high Cl- concentration, traditional toxicity symptoms and stunting were not observed nor were cured leaf yield and value negatively affected. Cured leaf quality was reduced as application rate increased beyond 67 kg Cl-/ha. In addition, the total alkaloid to reducing sugar ratio increased with Cl- application. Flue-cured tobacco producers should apply no more than 22 to 34 kg Cl-/ha to ensure acceptable leaf quality and usability by leaf dealers and manufacturers, as smoke quality issues are likely to result from excess leaf Cl-. (Reprinted with permission)