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.
