The effects of magnesium deficiency on the quality and magnesium content of flue-cured tobacco leaf

Abstract

In an outdoor trial with tobacco in sand culture, two levels of magnesium were supplied initially in the nutrient solution. The effects on quality and magnesium concentration in the cured leaf when magnesium was withheld from the nutrient were studied. When the magnesium supply was inadequate the reduction in magnesium concentration in leaves was largely accounted for by the diluting effect of increase in dry weight, and was accentuated under conditions of extreme deficiency by transference of magnesium from older leaves to actively expanding tissues nearer the apex. The effects of deficiency on quality depended partly on the amount of magnesium the plant had absorbed before the cessation of magnesium supply. To avoid loss of quality, magnesium in the nutrient solution had to be maintained at 20 % at least of the total cations (equivalent basis) until plants had been 'topped' (i.e. inflorescence removed) and the total leaf area of the plant had reached c. two-thirds of its final size.