Mineral Nutrition

Hydroponics as a method to study mineral nutrition


  • Organics and Inorganics which are supplied from outside to the organisms constitute their nutrition.
  • In 1860, Julius Von Sachs introduced the technique ‘Hydropnics’ or soilless growth, or Tank farming
  • The technique is to know about the interaction between different elements and their role.
  • All the elements can be classified into essential (C, H, O, N, K, S, P, Ca, Fe, Mg, Cu, Mn, B, Cl, Zn, Mo, Ni) & Non-essential elements (Na, Si, Al, Se, Sr, V)
  • Macronutrients are C, H, O, N, K, S, Ca, Fe, Mg, P, which must be supplied in the concentration of 1-10 μgL-1/10m mol Kg-1 of dry matter
  • Micronutrients are Cu, Zn, Mn, B, Cl, Mo, Ni, which must be supplied in the concentration of 0.1 to 1.0 μgL-1/ 10m mol Kg-1 of dry matter
  • The nutrient which satisfies a specific nutrient requirement of specific plants is called beneficial nutrient.
  • C; H; O; N – Biomolecules
  • Mg; P – Energy
  • Mg; Zn – Enzymes
  • K – Osmotic potential; stomatal movement
  • Na – Halophytes
  • Si – Grasses
  • Co – Leguminous plants
  • Se – Astragalus
  • Ca, K – Antagonistic role
  • Cofactors – Mg, Fe, Ca, Zn, Cu, K, Mn, Mo
  • Nitrogen (NO3): Role in Proteins, Nucleic acids, Vitamins and Plant hormones.
  • • Deficiency symptoms
  • • Chlorosis [from The older leaves]
  • • Purple colouration of stem
  • Sulfur (SO42-): Role in chlorophyll formation, Part of amino acids
  • • Deficiency symptoms
  • • Chlorosis [from the younger leaves]
  • • Tea-yellow disease
  • Phosphorous (PO43-): Role in phosphorylation, photosynthesis, Protein synthesis
  • • Deficiency symptoms
  • • Chlorosis with Necrosis [from the older leaves]
  • • Poor vascular tissues development
  • Calcium (Ca2+): Role in second messengers; detoxification of Na and K
  • • Deficiency symptoms
  • • Chlorosis and Necrosis [from the younger leaves]
  • • Blossom end rot of Tomato
  • Magnesium (Mg2+): Role in cell wall formation
  • • Deficiency symptoms
  • • Interveinal chlorosis (from the older leaves)
  • • Under development of phloem and pith.
  • Potassium (K+): Role in osmotic potential, turgidity and membrane permeability
  • • Deficiency symptoms
  • • Dieback disease
  • • Plastid disintegration
  • • Mottled I.V.C (first in older leaves)
  • Iron (Fe3+): Role in ETS, development of chloroplast & chlorophyll
  • • Deficiency symptoms
  • • IVC (first in young leaves)
  • Manganese (Mn2+): Role in activation of nitrite reductase, carboxylase and dehydrogenase
  • • Deficiency symptoms
  • • Marsh spot disease
  • • Sterile flowers.
  • Chlorine (Cl-): Role in osmotic potential and production of fruits
  • • Deficiency symptoms
  • • Bronze colouration in leaves
  • • Flower abscission and reduced fruiting
  • Zinc (Zn2+): Role in activating carbonic anhydrase, dehydrogenase and Carboxylase
  • • Deficiency symptoms
  • • White bud disease (Maize)
  • • Khaira disease (Paddy)
  • • Rosette formation (Walnuts)
  • Boron (BO3-): Role in sugar translocation; pollen tube formation
  • • Deficiency symptoms ;
  • • Black necrosis; Brown heart (Turnip)
  • • Internal Cork (Apple)
  • • Heart rot (Sugar beet)
  • • Browning of Cauliflower
  • Copper (Cu2+): Role in ETS, formation of Vitamin C and activation of RUBP Carboxylase.
  • • Deficiency symptoms
  • •Diebackk of citrus
  • • Exanthema
  • • Blackening of potato
  • Ion concentration that reduces the dry weight of tissue by 10% is considered as Toxicity.
  • Manganese induces a deficiency of Fe, Mg and Ca2+ and Causes Crickle leaf disease
  • Absorption of elements can be either Active or passive (without energy)
  • Passive transport is mediated by simple diffusion, mass flow and ion exchange
  • Active Transport is explained by Cytochrome pump theory and Carrier concept.
  • Nitella sp. Absorbs K+ ions against the Concentration gradient
  • Nitrogen is abundant in the atmosphere (78%) but plants don’t absorb the same and hence is the most Critical element.
  • Nitrogen exists as dinitrogen atoms connected by three covalent bonds (N ≡ N)
  • Nitrogen fixation is converting inert atm. N2 into its usable compounds (Nitrate, ammonia, amino acids, amides etc.,) through biological(microbes) and Abiological methods (electric discharges, ozonisation and combustion).
  • Several bacterial species live in soil but cannot fix N2 by themselves.
  • Steps involved are (i) Bacterial collection over root hairs (ii) Degradation of cell wall (iii) formation of infection thread (iv) Bacterial multiplication. (v) Bacteroid formation covered by pinkish Leg haemoglobin (Lb). (vi) Protection of Nitrogenase (vii) Nitrogen fixation
  • Nitrogenase has 2 active centers – iron and Molybdenun to which dinitrogen attaches and reduces further to dimide (N2H2) , Hydrazine (N2H4) and then ammonia (2NH3) , which is the first stable product of N2 fixation
  • Free living N2 fixation happens through Annonification and Nitrification.
  • Bocillus ramosus, B. Vulgaris , B. mesentericus act upon proteins and convert them into ammonia (NH3), later converted into nitrites by Nitrosococcus and Nitrosomonas by Nitrification.
  • Nitrocystis and Nitrobacter convert nitrites and nitrates in the next step. Aspergillus flavus can perform both the reactions of Nitrification.
  • P. denitrificans , Thiobacillus denitrificans and Micrococcus denitrificans reduce nitrates into gaseous N2 under anaerobic conditions (water logging)
  • The obtained nitrates and nitrites are assimilated in plants by FAD/FMN/Nitrate reductase and Ferredoxin/ Nitrite reductase respectively to form 2NH3 (Ammonia), which is then converted to ammonium ions (NH4+).
  • Amino acids are the first Organic compounds of Nitrogen, which are synthesized by reductive amination, catalytic amidation and Transamination.
  • Amides are double aminated keto acids, which are derivatives of amino acid Eg : glutamine and Asparagine, Niacinamide
  • Vreides are mediated as a means of N2 transport from nodules of legumes (soyabean), which have a high N/C.
  • Finally, Proteins are synthesized from amino acids using ribosomes through the translation process.
  • Free living N2 fixing becteria : Azotobacter , Beijerinckia, Klebsiella , Desulfovibrio
  • Free living N2 fixing cyanobacteria : Anabaena , Nostoc , Calothrix, Aulosira
  • Symbiotic N2 fixing Bacteria : Frankia , Rhizobium , Xanthomonas , Mycobacterium
  • Symbiotic N2 fixing cyanobacteria : Anabaena, Nostoc.
  • Highly mobile elements : N, P, K, Mg
  • Immobile elements : Ca, S

Part-1: View this video for the topic from 0:39 to 13:10

Part-2: View this video for the topic from 0:09 to 5:44

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