Visual Deficiency and Toxicity Symptoms of Some Nutrients Nutrient Type Visual Symptoms Nitrogen Deficiency Toxicity Light green to yellow leaf color, older leaves, stunned growth. Dark green foliar color, excess vegetation, vascular browning in roots and stems. Phosphorus Deficiency Toxicity Leaves develop purple color, stunned growth, delay in plant development. Excess phosporus may induce zinc and iron deficiency. Potassium Deficiency Toxicity Older leaves turn yellow initially around margins.
Excess potassium induces magnesium and calcium deficiency.
Calcium Deficiency Reduced growth or death of growing tips, poor fruit development, blossom-end rot, tissue collapse in fruit. Excess calcium may cause magnesium and potassium deficiency. Magnesium Deficiency Toxicity Initial yellowing of older leaves between leaf veins spreading to younger leaves, poor fruit development. Imbalance with calcium and potassium may reduce growth. Sulfur Deficiency Initial yellowing of young leaves spreading to whole plant, similar symptoms to nitrogen deficiency, but occur on new growth.