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

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Abstract
An inbred strain of Bonny Best tomatoes was grown in sand culture. The effects of 44 nutrient solns. which varied in the relative proportions of nitrate, sulfate, and phosphate 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. Not only differences in stem diam. and the actual area of each of the component tissue systems but differences in the relative proportion of phloem, xylem, and pith as well could be correlated with differences in nutrient supply. The actual areas as well as the relative areas of tissue systems in stem sections could also be significantly correlated with characteristics used as criteria of vegetative growth and fruitfulness. E.g., as the area of xylem in stem cross-sections increased, the height and dry wt. of the plant as well as the number of fruit produced per plant was greater. Also, as the relative proportion of cross-sectional area occupied by the area of the xylem increased, growth and fruitfulness of the plants were greater. Cellular differences in pith parenchyma, xylem vessels, and fibers, internal and external phloem, internal and external pericyclic fibers, and cortical cells are described and correlated with differences in nutrient supply.