Close-Grown Tobacco: Yield, Alkaloids, and Sugar Content by Stalk Position

Flue-cured tobacco (Nicotiana tabacum L.) produced in a close-grown system may offer an alternative to use of synthetic smoking materials. In order to develop optimum production and handling practices for this system, information is needed on the chemical and physical contents of the harvested material. Tobacco (‘Sp C-28’) was produced in a close-grown system with varying plant populations (45,448, 90,896, 136,344 plants/ha), N-rates (84, 168, 252, 336 kg/ha), top ping (topped vs. nontopped), and row spacings (equidistant vs. twin). The research was conducted at the Oxford Tobacco Research Station on a Durham loamy sand (fine loamy, siliceous, thermic, Typic Hapudult). Yield, total alkaloids, and reducing sugars of lamina, midaib, and stalk from the upper, middle, and lower thirds of cured plants were compared. One-third of the total plant weight was in each stalk position. The upper third of the close-grown plant contributed most to total lamina weight and total alkaloid level. The proportion of lamina in the upper stalk position was higher in plants that were topped or when plant population was increased above 45,448/ha but it deoreased when N-rate was increased above 84 kg/ha. Total alkaloid concentration was highest in the upper stalk position and in lamina. Increased plant population resulted in decreased total alkaloids in the middle stalk position. Topping and increasing N-rate resulted in higher total alkaloids in all stalk positions. Reducing sugar content was approximately the same for all three stalk positions but highest levels in lamina and midrib were found in the upper two-thirds of the plant. Reducing sugar concentrations were highest in stalk. Plant population had no significant effect on reducing sugar content but increased N-rate lowered concentrations in the lower stalk position. Results indicate that agronomic practices offer a means for altering the physical and chemical content of closegrown tobacco.