Role of S in Pant Growth and Development

Sulphur is one of the 17 essential plant nutrients. It is essential for the growth and development of all crops, without exception. Most of a plant's requirement for S is absorbed through the roots in the sulphate (SO4-2) form. Like any essential nutrient, sulphur also has certain specific functions to perform in the plant. Thus, S deficiencies can only be corrected by the application of S fertilizer.
 
Some key functions of S in plants are:

  • Formation of chlorophyll that permits photosynthesis through which plants produce starch, sugars, oils, fats, vitamins and other compounds.
  • Protein production. S is a constituent of three S-containing amino acids (cysteine, cystine and methionine), which are the building blocks of protein. About 90% of plant S is present in these amino acids.
  • Synthesis of oils. This is why adequate sulphur is so crucial for oilseeds.
  • Activation of enzymes, which aid in biochemical reactions in the plant.
  • Increases crop yields and improves produce quality, both of which determine the market price a farmer would get for his produce.
  • With reference to crop quality, S improves protein and oil percentage in seeds, cereal quality for milling and baking, marketability of dry coconut kernel (copra), quality of tobacco, nutritive value of forages etc.
  • It is associated with special metabolisms in plant and the structural characteristics of protoplasm
  

 

When plants have inadequate S, first they suffer from hidden hunger. When the S deficiency becomes severe, the plant shows typical S deficiency symptoms. Crop growth suffers at such levels and respond well to  S application. The critical level varies with the crop and the stage of development ...Click here for more

S Deficiency Symptoms

Sulphur deficiency symptoms in many ways resemble those of N that is, the leaves become pale-yellow or light green. Unlike N, S-deficiency symptoms appear first on the younger leaves, and persist even after N application. In cotton, tobacco and citrus, some of the older leaves are affected first. Plants deficient in S are small and spindly with short and slender stalks, their growth is retarded, maturity in cereals is delayed and fruits often do not mature fully and remain light green in colour. Nodulation in legumes may be poor and N-fixation reduced. Forages have undesirably wide N:S ratio and thus are of lower nutritive value. For S deficiency symptoms in various crops, ...Click here for more

S Deficiency Diagnosis

Visual observations, knowledge of the past history of the fertilizer practices followed on a field, soil analysis and tissue testing are all important  for diagnosing S deficiency...Click here for more

(2e)S Requirement of Crops

Crops in general require as much S as they require P on element basis. The S requirement can exceed the P requirement in the case of oilseeds in general and cruciferous plants in particular.. For critical concentration of S in 55 day old plants, ...Click here for more
Sulphur uptake by crops can range from 5 kg to 80 kg S/ha/year depending on type of crop, yield and cropping intensity. Sulphur uptake is generally 9% to 15% of N uptake and similar to P uptake. As a thumb rule, S uptake per tonne of grain production can be taken as:

  • Cereals:  4 kg (range 1-6)
  • Pulses :  8 kg (range 5-13)
  • Oilseeds:  12 kg (range 5-20) 

The current annual uptake of S by crops grown in India present is close to 1.3 million tonnes S. For uptake of S and its comparison with NPK in a number of crops, ... click here for more

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