Roles of Nutrients in Plants

HomeRoles of Nutrients in Plants

Each essential element has at least one specifically defined role in plant growth so that plants fail to grow and reproduce normally in its absence. Most of the essential elements have several functions in the plant.

Carbon, from carbon dioxide (CO2) in the atmosphere, is assimilated by plants in the photosynthetic process. It is a component of organic compounds such as sugars, proteins, and organic acids. These compounds are used in structural components, enzymatic reactions, and genetic material.

Oxygen, derived from CO2, also is a part of organic compounds such as simple sugars. Atmospheric oxygen is necessary for all oxygen-requiring reactions in plants including nutrient uptake by roots.

Hydrogen derived from water (H2O) is incorporated into organic compounds in the photosynthetic process. Hydrogen is involved in electrochemical reactions and maintain electrical charge balances across all membranes.

Nitrogen (N)

  • essential role in the synthesis of chlorophyll
  • essential part of forming plant proteins
  • influences tillering and seed formation in grasses

Phosphorus (P)

  • vital role in energy storage and transfer during photosynthesis and respiration
  • required for cell division and enlargement, especially at growing points
  • may help improve tolerance to drought

Potassium (K)

  • photosynthesis and respiration
  • protein synthesis
  • may improve tolerance to diseases
  • activates enzyme systems
  • can improve tolerance to cold and drought
  • may reduce lodging

Sulphur (S)

  • assists nitrogen fixation by legumes
  • important part of amino acids that form proteins
  • necessary for chlorophyll formation and photosynthesis

Calcium (Ca)

  • Required for cell division and elongation
  • Required for cell wall development
  • Nitrate uptake and metabolism
  • Activates enzyme activity
  • Starch metabolism
  • can help delay leaf senescence and slow down leaf and fruit fall

Magnesium (Mg)

  • important for chlorophyll
  • aids phosphate metabolism
  • aids respiration
  • aids protein synthesis
  • important in the formation of seeds with high oil content

Copper (Cu)

  • Pollination & seed set
  • Carbohydrate and protein metabolism.
  • Formation of lignin in plant cell walls which contributes to the structural strength of the cells, and the plant.
  • A catalyst in photosynthesis and respiration.
  • It is a constituent of several enzyme systems involved in building and converting amino acids to proteins.
  • Cu:N Balance: High N uptake in the presence of marginal Cu levels can lead to a reduction of Cu transport into the growing tips of plants
  • Copper also affects the flavour, the storage ability, and the sugar content of fruits.
  • may improve tolerance to fungal attack

Zinc (Zn) 

  • Production of Auxins, an essential growth hormone.
  • Activates enzymes in protein synthesis, plus is involved in the regulation and consumption of sugars
  • Starch formation
  • Root development.
  • Influences the rate of seed and stalk maturation.
  • It is necessary for the formation of chlorophyll and carbohydrates.
  • Adequate amounts of zinc aid’s the plant to withstand lower air temperatures.

Manganese (Mn)

  • important for chlorophyll synthesis, enzyme systems, and carbohydrate and nitrogen metabolism
  • Photosynthesis

Iron (Fe)

  • catalyst for chlorophyll synthesis
  • oxygen carrier


Molybdenum (Mo)

  • important in nitrogen metabolism and protein synthesis
  • required in root nodules of legumes for nitrogen fixation

Boron (B)

  • important in the processes of pollination, fruit and seed set (e.g. legumes), fruit development and quality
  • important for the translocation of sugars
  • influences cell wall development
  • nodule formation in legumes

Chlorine (Cl)

  • involved in transport of nutrients within plants
  • helps regulate opening and closing of stomata

Silicon (Si)

  • contributes to cell wall structure, drought tolerance and tolerance to insects and diseases


The following chart shows nutrient solubility at a range of pH levels. For example, if we look at iron, it becomes more soluble in an acidic soil, and in the case of iron, has a strong influence on soil acidity and solubility of some other nutrients (aluminium is very similar to iron). We can also see phosphorus become less soluble in an acidic soil thus less available to the plant. In fact, using this example, the phosphorus becomes and aluminium phosphate or an iron phosphate product.

In and alkaline soil, most often calcium becomes the dominant element, the phosphate become less soluble between pH 8 and 8.75, often forming calcium phosphate product.

Nutrient antagonism and synergism

An excess of one nutrient can mean a deficiency of another

The aim of nutrient application is to provide an amount of nutrient in a manner which contributes to soil and crop performance. Over application of a nutrient may be wasteful or inhibit soil and crop performance.

Using calcium as an example we can see that this element reacts with numerous other elements being Manganese, phosphorus, zinc, boron, magnesium, iron and potassium. By using soil tests to understand the soil type, we can make informed decisions about rate and frequency of applications and improve management outcome of soils, crops and livestock.