By: Isabella Colucci
Overview
Plants require nutrients to properly grow and function. In order for these “essential” nutrients to be taken up they must be in a chemical form available to the plant. Suitable soil moisture, temperature, and pH are also necessary. When essential nutrients are absent or unavailable in the soil, plant leaves show visible symptoms of deficiencies.
Using Leaf Morphology to Identify Nutrient Deficiencies
We can use leaf symptoms to identify plant nutrient deficiencies. These leaf symptoms can be explained by how two different categories of nutrients move in plants. Mobile nutrients, such as nitrogen, phosphorus, potassium, magnesium, chloride, and molybdenum, are nutrients that can be moved from one area to another by the plant as needed. Immobile nutrients include boron, sulfur, calcium, copper, iron, and magnesium, which once used cannot be reused in another part of the plant.
Symptoms from mobile nutrient deficiencies will first appear in older, lower leaves, as the plant moves the nutrients to new areas of need in the growing plant. Symptoms of immobile nutrient deficiencies tend to develop in the younger or upper leaves as these nutrients are not able to relocate once used. Leaf symptoms can provide important clues, but many things affect leaf development. When plants are only slightly deficient, it is hard to visually diagnose the problem. Leaf symptoms from different nutrient deficiencies can sometimes appear similar, or the same plant species may have different responses. Issues unrelated to fertility can also cause leaf symptoms. A soil test can verify what is happening in your soil so you can address any nutrient deficiencies.
Key Concepts
Identifying leaf symptoms of plant nutrient deficiencies can help you diagnose problems with your crops. Understanding nutrient availability in your crop system will also help you to make informed decisions about your soil management practices so that you can choose the most appropriate amendment method for your needs.
Leaf Morphology Indicators
There are five general types of leaf symptoms that can help with identifying nutrient deficiencies.
Stunted growth is when the plant and leaves experience reduced size. This results in shorter plants and smaller leaves than a healthy plant. This response is commonly seen with the following nutrient deficiencies: potassium, molybdenum, copper.
Chlorosis occurs when there is an absence of chlorophyll, and the plant is widely yellowing. This response is commonly seen with the following nutrient deficiencies: copper (younger leaves), nickel (younger leaves), sulfur (younger leaves), potassium (older leaves), nitrogen (older), chloride, molybdenum, and boron.
Interveinal chlorosis is when the leaf veins stay green and the plant tissue surrounding the veins (called the lamina) turns yellow. This response is commonly seen with the following nutrient deficiencies: nickel (younger leaves), manganese (younger leaves), zinc (in the middle of the leaves), magnesium, and iron.
Purplish-red coloring happens when there is an increase of the purple pigment anthocyanin that can build up when the plant is stressed or when normal plant function is interrupted. This category may be hard to diagnose due to climatic factors that influence the plant’s anthocyanin content. Also, some healthy plants express this pigment and are naturally more purple in color. This response is commonly seen with phosphorous deficiencies.
Necrosis is when plant tissues turn brown and die from an extended period of nutrient deficiency. This response is commonly seen with the following nutrient deficiencies: phosphorus, potassium, nitrogen, chloride, boron, iron, and nickel.
Additional Resources
For a more in-depth bulletin on plant nutrient deficiencies and toxicity, here is Montana State University’s Plant Nutrient Functions and Deficiency and Toxicity Symptoms.
For more information about the nutrients themselves, look at The University of Arizona’s Guide to Symptoms of Plant Nutrient Deficiencies bulletin.
For further information or if you have any questions, contact your local Cornell Cooperative Extension office or contact us at soil3@cornell.edu.