Mineral deficiency & organic constituents in tobacco plants. III. Plant growth & alkaloid contents related to gradual development of calcium or boron deficiency symptoms.

In the preceding papers (7, 8) of this series we presented the effects of certain mineral deficiency on the organic constituents of tobacco plants. Changes in the organic composition were associated with the development of typical symptoms resulting from an abnormal supply of a specific mineral. Mineral deficiency symptoms, in general, appear initially in a localized area and are very mild. They gradually extend to other portions of the plant and cause further characteristic effects. The severity of the symptoms increases with age and development of plants. In the case of calcium or boron deficiency, initial symptoms appear at the tip of a tobacco plant. Further abnormalities or symptoms gradually advance toward the midd(le portion and finally to the whole plant if the specific nutrient is withdrawn at an early stage of the plant growth. In tobacco plants, calcium or boron deficiency causes, in addition to other symptoms, natural decapitation which is physically similar but physiologically different from manual topping in tobacco cultivation. The present and following reports (in preparation) provide data on the corresponding changes in organic constituents including alkaloids, sugars, organic acids, andl amino acids relating to the gradual development of Caor B-deficiency svmptoms. In this paper results are reported on the plant growth and the alkaloid content in the leaves at various degrees of severity of deficiency symptoms and at different stalk positions.