Soil Fertility and Nutrient Management

Functions and deficiency symptoms of Nitrogen

 
• Nitrogen plays a key role in the nutrition of plants. It is one of the principal growth promoting nutrient elements. Green plants are more markedly influenced by the deficiency of nitrogen than by any other element. It is absorbed by plants in the ionic form of NO3-, by most of the plants. Some plants require NH4+ form (rice). When applied as foliar nutrition, NH2 (amide from) is also absorbed. It has got most recognized role in the plant metabolism as it performs the following vital functions.

  Functions of Nitrogen in plants

  1. The Nitrogen is mainly involved in Photosynthesis of plants as it is essential constituent of chlorophyll, a green pigment essential in photosynthesis.
  2. It is very basic constituent of plant life, because, it forms essential constituent of proteins, nucleotides phosphatides, alkaloids, enzymes, hormones, vitamins etc.,
  3. It promotes better Vegetative growth and adequate supply of nitrogen promotes rapid early growth and imparts dark green color to plants, improves quality and succulence of leafy vegetables and fodder crops.
  4. It stimulates the formation of fruit buds; increases fruit set, and improve quality of fruits.
  5. It governs the better utilization of Potassium, Phosphorus & other elements.

  Deficiency symptoms of Nitrogen in plants: Nitrogen is highly mobile element in plants and so deficiency is exhibited in older/ bottom leaves. The striking deficiency symptoms are

  ¥ Yellowing of older leaves due to inhibition of chloroplasts and chlorophyll synthesis. As the deficiency of Nitrogen becomes severe “Chlorosis” of leaves is observed.
  ¥ Plants become dwarfed or stunted growth.
  ¥ Tends to advance the time of flower bud formation and reduce yield.
  ¥ Fruits become hard, small, low bearing capacity of trees,
  ¥ Reduces fertilization, premature dropping and fruits may become seed less.
  ¥ Severe deficiency leads to Necrosis of plant leaves (complete death of leaf)
  ¥ Excessive N in plants leads to more vegetative growth. Leaves become more succulent and more susceptible to pest and disease attack. Lodging of plants may occur. Reduces the sugar content of plant, storage and keeping quality of fruits or leaves and prolong the growing period and delay the reproductive phase of plant and crop maturity.

  N-Deficiency in coffee

Healthy coffee plant Deficient coffee plant

(Symptom: Entire plant becoming pale green, with sparse vegetative growth; leaves becoming yellow-green at advanced stages; whitish veins may be present in lower leaves).

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