Anatomical Responses of Tomato Stems to Variations in the Macronutrient Cation Supply

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Abstract
An inbred strain of Bonny Best tomatoes was grown in sand culture. The effects of 43 nutrient solns. varying in the relative proportions of macronutrient cations (Ca, K, and Mg) were studied in relation to the anatomy of plant stems. Measurements of stem diam. and the actual area of each of the component tissue systems were recorded. The data were reduced and analyzed by statistical methods. Great differences in stem diam. and the actual area of each of the component tissue systems were positively correlated with K and negatively correlated with Ca supply to the plant. In addition, significant differences between treatments occurred with respect to the relative areas of the constituent tissue systems in the stem sections. These differences could also be correlated with nutrient composition. Cell size and relative thickness of cell walls in pericyclic fibers could be associated with Ca-ion supply. Cellular differences were also observed in pith parenchyma, internal and external pericyclic fibers, internal and external phloem, and in cortical chlorenchyma and collenchyma. They are described and correlated with the supply of one or more ions in the nutrient medium. Many differences in the anatomy of the tomato stems are significantly correlated with characteristics used as criteria of vegetative growth and fruitfulness. E.g., the relative amt. of phloem in stem sections is positively correlated with vegetative growth, while the relative amount of xylem is positively correlated with fruitfulness.