The effect of manganese on tobacco leaf quality and on the inorganic cation levels of tobacco

Abstract

In a series of field and pot experiments, quality of cured leaf of tobacco plants Nicotiana tabacum, was adversely affected by increasing leaf levels of manganese. The quality decline manifested itself as a leaf 'greying' effect. Leaf manganese concentrations were readily increased by either foliar or substrate application of manganese. The increase in leaf manganese content was associated with a significant increase in potassium concentration and a significant decrease in calcium concentration in leaves. Sodium and magnesium leaf concentrations were not greatly affected by manganese. It is suggested that the decline in cured leaf quality was associated primarily with a change in the K : Ca : Mg ratio, which occurred at relatively low concentrations of manganese in the leaves. The results of this investigation indicate that the use of manganese-based fungicide sprays could cause a further quality decline of tobacco produced on soils containing high levels of exchangeable manganese.