POTASSIUM AND MAGNESIUM NUTRITION EFFECTS ON YIELD AND CHEMICAL COMPOSITION OF BURLEY TOBACCO LEAVES AND SMOKE

A field experiment was conducted to determine the effects of varying levels of K and Mg fertilization on the yield, value, and chemical composition of burley tobacco (Nicotiana tabacum L. cv. Ky-14) leaves and smoke. Potassium was applied at rates of 0,112, 224, and 448 kg K/ha as K2SO4 and KNO3, and Mg was applied at rates of 0, 56, 112 and 224 kg Mg/ha as MgO. Potassium fertilization (112 kg K/ha) increased the cured leaf yield and its market value about 12% over the control. Additional increases in market value were observed where 224 and 448 kg K/ha were applied. Magnesium did not significantly affect leaf yield and market value; there was no Mg × K interaction for these characters. Potassium fertilization reduced protein-N, total volatile nitrogenous bases (TVNB), amino-N, Ca, and Mg contents of leaf by 12, 10, 25, 23, and 32%, respectively, from the control when applied at the rate of 448 kg K/ha. In contrast, K fertilization increased leaf K and Mn contents 5.6- and 1.2-fold, respectively. Magnesium application depressed leaf amino-N content and increased Mg content. Total particulate matter (TPM), nicotine, and gas phase cyanide delivered from all-burley cigarettes were decreased by 24, 7, and 50% from the control when plots were supplied with 448 kg K/ha. However, the gas phase aldehyde content of the smoke was increased by K application. Magnesium fertilization had no measurable effects on the chemical composition of burley tobacco smoke.