Effects of foliar application of magnesium sulphate on the quality and magnesium content of flue-cured tobacco

Abstract

Tobacco seedlings were not damaged by sprays containing up to 20 per cent magnesium sulphate, but deleterious effects on leaf were observed when several applications of three per cent or more were applied to full-sized plants. In an outdoor trial with tobacco in sand culture plants were supplied with nutrient solutions with and without magnesium. The effects of foliar application of two per cent magnesium sulphate on quality and magnesium concentration in the cured leaf were studied. Seven sprays applied at about seven day intervals raised the magnesium concentration in leaves by 0.30 to 0.40 per cent Mg. Five sprays applied after the onset of deficiency symptoms raised the concentration in leaves by 0.1 6 to 0.25 per cent Mg, and improved quality greatly compared with leaves from deficient plants. Application of one spray several days prior to picking increased the concentration in leaves by approximately 0.08 per cent Mg, but had an adverse effect on value. The value of the leaf from sprayed plants was never as good as that from the best plants supplied with magnesium via the roots only even though the magnesium concentrations in leaf were similar. The difference in quality was not attributable to deleterious effects of high sulphur content.