Effect of Fertilizing Potassium on Leaf-Quality of Bright Yellow Tobacco

Experiments were made with Wagner's 1/2000-are pots, the soil being fertilized with ammonium sulphate calcium superphosphate normally. Potassium was supplied in the form of sulphate, the quantity of which varied according to the plot from 0 to 8 grams per pot, expressed as K2O. Seedlings of a variety of American yellow-leaf tobacco were transplanted in these pots in May, 1950, and were harvested in July. It was observed, that the height of the plant, the total number of useful leaves on a plant and the mean length of stem-internode altogether decreased as the potassium supply was increased. Number of cells per unit area of the leaf epiderm were larger in the plants grown with greater amount of potassium. The leaf thickness measured on the middle leaves was maximum in the plant supplied with 4 grams of potassium fertilizer; with larger amount or potassium, the thickness decreased. The fresh weights of the middle and top leaves were reduced by excessive amount of potassium. Potassium content of leaves increased in parallel with the amount of potassium fertilizer. Total nitrogen, nicotine and glucose content showed no definite relations with the amount of potassium supply. The nicotine/total-nitrogen ratio was found highest in the samples taken from the middle leaves grown with 2 grams of potassium fertilizer, with larger amount of the fertilizer the ratio becoming lower. The ash content and its water soluble alkali degree showed maximum values in the leaves from the 4 grams fertilizer plots.