Define the term - Sulphur  

Sulphur is found in small amounts in soil perhaps 0.15% only. A large part of sulphur used by plants comes from decomposing organic matter or from fertilizers. It is required for the synthesis of sulphur  containing amino acids, cystine, methionine and cysteine and proteins. Many reactions take place due to the presence of sulphydryl group (- SH) of enzymes.

Sulphur is also present in coenzymes such as coenzyme A, thiamine pyrophosphate and biotin. These coenzymes are involved in the metabolism of carbohydrates, fats and proteins. Sulphur is known to stimulate root growth, seed formation and nodule formation. Although not a constituent of chlorophyll, sulphur also helps in its formation.