EFFECTS OF CA AND SR ON ZEA MAYS SEEDLING PRIMARY ROOT GROWTH

Either Ca or Sr in a mineral nutrient medium prevented toxic effects of other nutrient ions on aerated primary roots of maize; other monovalent or divalent, cations substituted for Ca did not. Calcium in the complete nutrient solution, or as CaCl₂ alone, stimulated the division of apical meristem cells in these roots, as compared to division in water alone, but Sr did not. However, the replacement of Ca in the nutrient medium by Sr resulted in the development of additional secondary roots, probably in part by decreasing the rate of cell division in the apical meristem of the primary root and thereby diminishing apical dominance.