Recovery of flue-cured tobacco from magnesium deficiency: changes in leaf magnesium content and effects on leaf quality

Abstract

Twenty-four days after being transplanted into sand culture outdoors, tobacco plants were supplied with nutrient solutions with and without magnesium. Magnesium at two levels was resupplied to some deficiency-stressed plants 6, 11, 16, or 26 days later, and all plants were grown to maturity.

The value of cured leaf was affected adversely when the period without magnesium exceeded 6 days. Quality of top leaf, but not of cutters, was improved when resupply was made at the rate necessary for maximum leaf value when supplied throughout. Addition of magnesium at a higher level improved the quality of leaf lower on the stalk, but led to an accumulation of magnesium in top leaf with subsequent impairment of quality.

It appeared that the leaf concentration of magnesium had to fall below 0.2% for a period of between 5 and 10 days for leaf deficiency symptoms to appear. The application of magnesium, even at a high rate, upon the appearance of the first symptoms of deficiency resulted in a loss of over 25% in the value per plant.