Function of Nutrients in Plants

Notes for RHS Level 2: Unit 1: Element 2 Role of Nutrients: AO1: Function of Nutrients in Plants

The essential nutrients required for plant growth and development are divided into two categories: macronutrients and micronutrients.

Macronutrients are elements that plants require in larger amounts, with the elements used in the highest quantities gained from the air, being carbon, hydrogen, and oxygen. Erosion slowly releases all the other minerals from the Earth’s rocks.

Whether minerals are obtained from organic sources, such as composted vegetable matter, or inorganic sources, such as liquid blends of chemicals, does not matter to the plant as the mineral elements are the same.

However, the main difference is that organic sources slowly release small quantities of minerals into the soil, whereas inorganic fertilisers use concentrations of specific elements prepared for defined and immediate usage.

N-P-K ratios on fertiliser display the ratios between nitrogen, phosphorus, and potassium (K refers to the now obsolete neo-latin kalium). For example a formulation using a ratio of 0-10-10 would promote flower and fruit set.

The following table lists the macronutrients and their functions in plants:

 

Nutrient               Function

Nitrogen             Essential for the production of chlorophyll, amino acids, and nucleic acids.

Phosphorus        Involved in the production of ATP, DNA, and cell membranes.

Potassium           Regulates water balance, activates enzymes, and helps in the production of ATP.

Calcium              Essential for cell wall formation, cell division, and cell elongation.

Magnesium         A component of chlorophyll, and is involved in photosynthesis and enzyme activation.

Sulfur                  Required for the production of amino acids, proteins, and enzymes.

Carbon                Required for photosynthesis, the process by which plants produce their own food.

Oxygen               Required for respiration, the process by which plants convert food into energy.

Hydrogen            Required for the formation of organic compounds, such as carbohydrates and proteins.

 

In addition to macronutrients, plants also require micronutrients in smaller amounts for their growth and development. The following table lists some of the essential micronutrients and their functions in plants:

 

Nutrient               Function

Iron                    Essential for the production of chlorophyll and involved in photosynthesis.

Boron                 Required for cell wall formation, pollen tube growth, and seed production.

Manganese         Involved in photosynthesis, respiration, and enzyme activation.

Molybdenum      Required for nitrogen fixation and the production of enzymes.

 

Plants lacking macronutrients and micronutrients will find their growth and development adversely affected, leading to mineral nutrient deficiencies and disorders. The symptoms of nutrient deficiency can vary depending on the nutrient that is lacking. For example:

Nitrogen deficiency:        Plants may exhibit stunted growth, yellowing of leaves, and reduced leaf size.

Phosphorus deficiency:   Plants may exhibit stunted growth, dark green leaves, and reduced root growth.

Potassium deficiency:     Plants may exhibit yellowing of leaf margins, wilting, and reduced growth.

 

Deficiencies will be explored further in a future post.