S influences a wide range of metabolic processes. Therefore, it is essential in order to achieve high yield and good quality.
The SO42- taken up via the root system needs to be reduced (Sulphate assimilation) prior incorporation into AAs, proteins and coenzymes.
Visible deficiency symptoms are first paling of young leaves than leaf chlorosis seen as uniformly distributed yellowing of the plant and crop stunting.
Typical S deficiency symptoms on oilseed rape leaves.
Metabolic process
Function of S
Photosynthesis
S is required for assimilating CO2
Trapping light energy in chloroplasts
Sugar formation
S containing coenzymes incorporate assimilated CO2 into sugars
Starch formation
In plants well supplied with S, enhanced protein synthesis reduces starch accumulation in leaves
Amino acids formation and protein synthesis
S is a structural element of cysteine and methionine, which are needed to synthesise other AAs and protein
Oil and fat synthesis
S is a structural element of coenzymes, the Vitamins B and H, which are needed for the fatty acid synthesis
