Effect of Alpha-Naphthalene Acetamide upon the Anatomical Structure of Cocklebur Grown in a Nutrient Medium Deficient in Calcium

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Abstract
Plants of cocklebur were grown with a complete nutrient culture medium and in one lacking Ca. One-half of these plants were treated with alpha-naphthalene acetamide. Symptoms of Ca deficiency, such as short upper internodes, downward cupping of the leaves, brown areas on the surface of the leaves and darkening of the margins, and drying of the stem tips, soon appeared on plants grown without Ca. Treatment with alpha-naphthalene acetamide had only a slight effect on delaying symptoms of Ca deficiency at 65[degree]F. At 75[degree]F, treatment of the plants with the acetamide greatly delayed the appearance of symptoms of Ca deficiency. At 75[degree] plants grown without Ca were dry except for a few of the lower leaves after 46 days. 74 days from the start of the treatment plants grown without Ca but treated with the acetamide first began to show slight symptoms of Ca deficiency. The 4th internode of plants grown without Ca had smaller and thinner-walled cells at both 65[degree] and 75[degree]F than the normal plants. When treated with alpha-naphthalene acetamide at 75[degree], the cells of Ca-deficient plants more nearly resembled those of the normal plants in size and degree of lignification, but at 65[degree] the treatment was less effective; some of the cells had collapsed, giving necrotic-appearing regions. Stems of plants given a complete nutrient and treated with the acetamide had an active cambium and more xylem elements than the controls. Sections of the stems were incinerated. As compared with control sections those from Ca-deficient plants contained the least ash. Sections from Ca-deficient plants treated with alpha-naphthalene acetamide contained nearly as much ash as the controls and those from the complete nutrient culture plus the acetamide appeared to contain more than the controls.