| Abstract: | Abstract Calcium seems to be required by higher plants (and in parts of higher plants) in variable concentrations and much confusion exists about plant requirements of it. When most heavy metal concentrations are low, the calcium requirement in plants can also be low. Levels of calcium of 800 or less and up to 2000 ppm of dry weight are adequate under some conditions. Even though the requirement may be low, these levels are not much above critical concentrations and deficiency problems are easily encountered. Some calcium deficiency problems seem to be related to this phenomenon. |
