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Key Elements for Plant Nutrition
When a house plant has not been repotted or fertilized for many years, you might find signs of distress, such as leaf yellowing. Like all living things, plants require specific nutrients to reproduce, photosynthesize, and maintain homeostasis. Which nutrients do plants require to thrive?
Healthy plants need organic, carbon-based compounds as well as inorganic nutrients, commonly called minerals.
There are about 17 nutrients that support all of a plant’s biochemical needs. These elements are called essential nutrients; no other elements can substitute for essential elements, and without them, a plant cannot complete its life cycle.
Among the essential nutrients are carbon, hydrogen, and oxygen, which are derived from the atmosphere and water. Most plants acquire all other essential nutrients from the soil in which they are rooted.
The two groups of essential nutrients are macronutrients and micronutrients. Macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Plants require these elements in relatively large amounts.
Carbon makes up about 45 percent of the dry mass of plants, and is a key component of proteins, nucleic acids, and carbohydrates. Nitrogen is likewise a critical constituent of nucleic acids, proteins, and the photosynthetic pigment chlorophyll. Potassium is vital for regulating gas exchange, a process critical for photosynthesis.
Essential plant nutrients needed in smaller amounts are called micronutrients; the micronutrients chlorine, iron, manganese, boron, zinc, copper, nickel, and molybdenum are required for proper plant functioning.
Some micronutrients function as cofactors, which are substances that help enzymes work properly. For example, iron is a cofactor for enzymes in the mitochondria and chloroplasts.
If a plant is deficient in an essential nutrient, it begins to show symptoms like chlorosis or yellowing leaves. The particular nutrient deficiency can often be determined by examining the plant’s appearance and the soil nutrient content.
Though essential nutrients account for a relatively small amount of a plant’s mass, they are crucial for plant growth and homeostasis.
34.18:
Key Elements for Plant Nutrition
Like all living organisms, plants require organic and inorganic nutrients to survive, reproduce, grow and maintain homeostasis. To identify nutrients that are essential for plant functioning, researchers have leveraged a technique called hydroponics. In hydroponic culture systems, plants are grown—without soil—in water-based solutions containing nutrients. At least 17 nutrients have been identified as essential elements required by plants. Plants acquire these elements from the atmosphere, the soil in which they are rooted, and water.
Nine of these essential nutrients—collectively called macronutrients—are needed by plants in more significant amounts. The macronutrients include carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, calcium, magnesium, and potassium. Critical plant compounds, such as water, proteins, nucleic acids, and carbohydrates, contain macronutrients. Macronutrients also regulate cellular processes. For example, potassium regulates the opening and closing of stomata for gas exchange.
Plants need micronutrients in smaller amounts. These include chlorine, iron, manganese, boron, zinc, copper, nickel, and molybdenum. Many micronutrients function as cofactors, which enable the activity of enzymes. Therefore, without micronutrients, plants are unable to perform critical functions.
A plant experiencing an essential nutrient deficiency may display symptoms, such as drying and yellowing leaves. Old and young leaves are susceptible to distinct nutrient deficiencies. For example, the younger leaves of a plant are often more affected by iron deficiency than the older leaves.
The effective treatment of nutrient deficiencies in plants is an integral part of agricultural and environmental practices. For example, optical sensors are used to measure the nitrogen content in soil. Nitrogen is critical for plants, but the excessive use of nitrogen-containing fertilizers (i.e., maintaining soil nitrogen levels that exceed what the plants can absorb) negatively influences ecosystem function and may contribute to global warming.
Suggested Reading
Padilla FM, Gallardo M, Peña-Fleitas MT, de Souza R, Thompson RB. Proximal Optical Sensors for Nitrogen Management of Vegetable Crops: A Review. Sensors (Basel). 2018 Jun 28;18(7). [Source]
Rouached H, and Phan Tran LS. Regulation of Plant Mineral Nutrition: Transport, Sensing and Signaling. Regulation of Plant Mineral Nutrition: Transport, Sensing and Signaling. Int J Mol Sci. 2015 Dec; 16(12): 29717–29719. [Source]