Effect of nitrogen fertilization on distribution profiles of selected macronutrients in oriental field-grown tobacco plants

As nitrogen (N) fertilization is considered incompatible with oriental toba cco agricultural practice, we studied the influence of N fertilization [no fertilization or ammonium nitrate (NH,NO,) fertilizer applied at either 50 or 100 kg N ha(-1)], the growth stage (plant age) and the stalk position (b asal, middle, and upper) on the macronutrient phosphorus (P), potassium (K) , calcium (Ca),and magnesium (Mg) concentration distribution in leaves of t he oriental tobacco cv. Myrodata Agriniou. The distribution profiles of lea f P showed an increasing trend from the lower to the upper nodes in all tre atments during the vegetative stage up to the fruit set while almost unifor m profiles were detected after that. Leaf K, Ca, and Mg accumulation profil es showed decreasing trends from the base to the top over the season. All o f the examined macronutrients were accumulated in the lower leaves of the h igher fertilized plants late in the season. Leaf dry matter accumulation in creased by N fertilization and plant age,and decreased by stalk position. L eaf P concentration increased with N fertilization and stalk position and d ecreased with plant age. Leaf K concentration decreased with N fertilizatio n, plant age, and stalk position while leaf Ca and Mg concentrations decrea sed with N fertilization and increased with plant age and stalk position. T he interaction of N fertilization x stalk position affected with a weaker s trength leaf K, Ca, and Mg and did not affect leaf P. The interaction of N fertilization x plant age x stalk position had a strong effect on leaf K an d Ca, and did not affect leaf P and Mg concentrations. Stem P, Ca, and Mg c oncentrations were lower and K concentration was higher than in the leaves. Calcium and Mg concentration dependence from N fertilization was weaker fo r leaves than for stems. Stem P and K concentrations were reduced with plan t age. Stem Ca concentration did not change while stem Mg concentration was significantly reduced with plant age. Stem concentrations of all the exami ned nutrient elements significantly increased at higher nodes.