Role of calcium in micronutrient stresses of plants

When calcium carbonate was added to an acid soil, it induced or alleviated a micronutrient stress, depending on the genotype and the soil. Calcium carbonate added to Richland soil (pH 5.2) corrected Mn‐toxicity symptoms in Bragg soybean (Glycine max L.) Merr.) but induced B‐deficiency symptoms in Coker 71–5089 cotton (Gossypium hirsutum L.). The latter did not develop Mn‐toxicity symptoms. Absorption and transport of Ca may enhance P uptake and induce Fe‐deficiency symptoms on Fe‐inefficient genotypes. Cereals differ in their response to Cu stress and the degree to which Cu deficiency depresses the transport of Ca to top leaves affects the expression of the Cu‐deficiency symptoms (withertip). Manganese‐efficient oat genotypes took up more Ca than Mn‐inefficient oats. In contrast, Fe‐efficient oat genotypes took up less Ca than Fe‐inefficient oats. Calcium is universally important as a competing metal ion in chelation and transport of elements in plants and the differential uptake of Ca may affect use of these micronutrients.