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Mineral nutrition of plants
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  1. 1. ENVIRONMENTAL SCIENCE Dr. Thirunahari Ugandhar Head & Assistant Professor in Botany Dr. Thirunahari Ugandhar Head & Assistant Professor of Botany
  2. 2. SUBTOPICS Mineral nutrition important Classification of minerals Roles and properties 0f minerals Deficiency symptoms 0f minerals
  3. 3. Why Is Mineral Nutrition Important?  In most natural soils, the availability of mineral nutrients limits plant growth and primary productivity.  Nutrient limitation is an important selective pressure and plants face many special changes related to the need to acquire and use mineral nutrients efficiently.  “Plant nutrition” specifically does not refer to photosynthesis.
  4. 4. Classification Of Minerals:  On the basis of the amounts found in plants:  Macronutrients: N, K, Ca, Mg, P, S, Na, (Si)  Micronutrients: Cl, Fe, B, Mn, Zn, Cu, Mo, Ni
  5. 5. Essential Elements : What defines an “essential” element? 1. In its absence the plant cannot complete a normal life cycle 2. The element is part of an essential molecule (macromolecule, metabolite) inside the plant  Most elements fall into both categories above (e.g., structural vs. enzyme cofactor)  These 17 elements are classified as  9 macronutrients (present at > 10 mmol / kg dry wt.)
  6. 6.  Hydroponic culture can determine which mineral elements are actually essential nutrients. Essential Elements :
  7. 7. Classification of minerals:  Macronutrients are elements required by plants in relatively large quantities (9 total).  Organic compounds: Carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus.  The other three are potassium, calcium, and magnesium.
  8. 8.  Micronutrients elements are nutrients that the plants need in very small amounts (8 total).  Iron, chlorine, copper, zinc, manganese, molybdenum, boron, and nickel.  Most function as cofactors of enzymatic reactions. Classification of minerals:
  9. 9. Name Function in plant Chemical symbol Relative % in plant to N Primary macronutrients Nitrogen N 100 Proteins, amino acids Phosphorus P 6 Nucleic acids, ATP Potassium K 25 Catalyst, ion transport Secondary macronutrients Calcium Ca 12.5 Cell wall component Magnesium Mg 8 Part of chlorophyll Sulfur S 3 Amino acids Iron Fe 0.2 Chlorophyll synthesis Micronutrients Copper Cu 0.01 Component of enzymes Manganese Mn 0.1 Activates enzymes Zinc Zn 0.03 Activates enzymes Boron B 0.2 Cell wall component Molybdenum Mo 0.0001 Involved in N fixation Chlorine Cl 0.3 Photosynthesis reactions
  11. 11. CARBON (C): Roles and properties:  Basic structural element of life.  Although not very plentiful in the earth's crust (<0.1%), carbon is one of the most abundant elements in living things.  It occurs in plants combined with hydrogen and oxygen in the form of hydrocarbons., and in their geological derivatives, petroleum and coal.  Carbon also occurs in the atmosphere as CO2, and in rocks as carbonate minerals such as limestone. Deficiency symptoms:  Very serious, no growth!
  12. 12. OXYGEN (O): Roles and properties:  Powerful oxidizing agent .  Oxygen is the most abundant element in the earths crust on the basis of both mass and number of atoms (49.5% of the mass of the earths crust is oxygen atoms).  In the free state oxygen occurs in the atmosphere as O2 molecules (21% of air by mass).  In the combined state, oxygen occurs in many minerals, living things and water. Deficiency symptoms:  No Respiration.
  13. 13. HYDROGEN (H): Roles and properties:  Lightest element, and a powerful reducing agent.  Most abundant element in the universe.  In the earth's crust hydrogen is third in abundance on an atom basis. On a mass basis, it is ninth in order of abundance .  Free, uncombined hydrogen is very rare.  However, combined hydrogen is quite common (eg., water, and organic compounds).  Supplied in the mobile oxidized form of H2O, and made available as a reducing element by photosynthesis.  Forms covalent bonds with the electronegative elements C, N, O and H. Pretty important for hydrogen bonding!
  14. 14. NITROGEN (N): Roles and properties:  About 1/3 as abundant as carbon. Occurs principally as diatomic N2 in the atmosphere.  Makes + charged groups possible.  Amine N is important in complexing metals (eg., binding Fe in cytochromes, or binding Mg in chlorophyll).  Acts as a donor atom in many enzymatically catalyzed reactions.  In living things, N is found almost exclusively in the fully reduced state.  Most of the N absorbed from the soil by higher plants is in the fully oxidized form of NO3, and must be reduced for
  15. 15. NITROGEN (N): Deficiency symptoms:  General chlorosis,especially of older leaves (mobile).  In severe cases these leaves yellow and die.  Younger leaves remain green longer, because they receive soluble forms of nitrogen transported from older leaves.  In many plants, excess nitrogen often stimulates shoot growth more than root growth and may favor vegetative growth over flowering and seed formation.
  16. 16. PHOSPHOROUS (P): Roles and properties:  Occurs and reacts as orthophosphate, the fully oxidized and stable form.  Participates in metabolism by forming water-stable phosphate esters and anhydrides. In these forms P has several fundamental roles:  Linkage (as in nucleic acids),  Source of free energy in bond formation (Carries chemical energy in ATP).  Component of sugar-phosphates; (in DNA & RNA)  Component of phopholipids (in membranes)  Mg++ (or Mn++) is a required cofactor in reactions involving phosphate transfer. Mg++ also commonly neutralizes polyphosphate compounds.
  17. 17. PHOSPHOROUS (P): Deficiency symptoms:  Phosphorous-deficient plants are stunted (stop growth) and , in contrast to those lacking nitrogen, are often dark green.  Phosphate is easily redistributed (mobile) in most plants from one organ to another and is lost from older leaves, accumulating in younger leaves, developing flowers and seeds. As a result, deficiency symptoms occur first in more mature leaves.
  18. 18. SULFUR (S): Roles and properties:  Occurs primarily in reduced form in living things.  Disulfides are more stable than dioxides (or peroxides), permitting -SH participation in redox reactions (-SH + HS- -- -- -S- S-).  SH groups are also form hydrogen bonds.  SH groups can be the reactive sites of enzymes or coenzymes (Coenzyme A) and are important for protein conformation.  Sulfate (SO4=) from the soil is the primary source of S, although some SO2 is absorbed from the atmosphere (too much SO2 can be quite toxic to plants.  Sulfate reduction is very energy intensive and occurs mainly
  19. 19. SULFUR (S): Deficiency symptoms:  General chlorosis of leaf, including vascular bundles.  Sulfur is not easily redistributed (immobile) from mature tissues in some species, so deficiencies are usually noted first in younger leaves.
  20. 20. POTASSIUM (K+): Roles and properties:  Dominant cation in plants.  K+ is an activator of many enzymes that are essential for photosynthesis and respiration, and it also activates enzymes needed to form starch and proteins.  K+ is quite mobile in the plant, because there are many membrane carrier systems adapted to K+.  It is a major contributor to the osmotic potential of cells and therefore to their turgor pressure.  K+ regulation of osmotic potentials forms the basis for turgor movements in plants (eg., stomate opening, leaf movements).
  21. 21. POTASSIUM (K+): Deficiency symptoms:  As with N and P, K+ is easily redistributed (mobile) from mature to younger organs, so symptoms first appear in older leaves.  Leaves develop necrotic lesions and light chlorosis.  The tips often die first.  K+ deficient cereals develop weak stems so they are easily fall.
  22. 22. CALCIUM (CA++): Roles and properties:  Often the most abundant divalent cation in plants.  Important component of cell walls.  It stabilizes the polysaccharides by forming intermolecular complexes with -COO- groups of pectins.  Calcium is also important for maintaining the safety of membranes, especially the plasma membrane.  Free calcium concentration in the cytosol is normally very low, about 10-7 M. Some hormonal or environmental signals raise the free Ca++ concentration to 10-6 to 10-5 M.  Because changes in calcium are associated with hormonal
  23. 23. CALCIUM (CA++): Deficiency symptoms:  Meristematic regions die.  Margins of younger leaves become chlorotic then necrotic.  Young leaves are distorted.  Symptoms appear first in young tissues since Ca++ is not very mobile.
  24. 24. MAGNESIUM (MG++): Roles and properties:  Most important divalent cation in enzymatic catalysis.  Involved in most reactions involving ADP and ATP.  Activates enzymes for DNA and RNA synthesis.  Constituent of chlorophyll.  Activates key enzymes involved in CO2 fixation.  Has structural roles in membranes, especially in organelles.
  25. 25. MAGNESIUM (MG++): Deficiency symptoms:  Deficiency causes extensive interveinal chlorosis which starts with basal leaves (older) and progresses to younger leaves (mobile).
  26. 26. IRON (Fe++): Roles and properties:  Important for its oxidation-reduction properties (Fe+++ to Fe++).  Iron forms a locus for electron transfer in many enzymes (eg., cytochromes, peroxidases, catalyses).  It is also required for chlorophyll synthesis.  Iron is a difficult cation for plants to handle since it readily precipitates.
  27. 27. IRON (FE++): Deficiency symptoms:  Extensive interveinal chlorosis, starting with younger leaves (iron is relatively immobile).  Similar to Mg deficiency except in younger leaves.
  28. 28. COPPER (CU++): Roles and properties:  Important for its oxidation-reduction properties (Cu++ to Cu+)  Copper is an important component of several critical enzymes (eg., plastocyanin for photosynthesis and cytochrome oxidase for respiration).
  29. 29. COPPER (CU++): Deficiency symptoms:  Plants need very little copper so they are rarely deficient in it (usually sufficiently available in soil).  Experimentally, copper deficiency leads to distorted and dark green younger leaves. (immobile)
  30. 30. MOLYBDENUM (MO6+): Roles and properties:  Important for its oxidation-reduction properties.  It is a key component of nitrate reductase where it functions as an e- carrier for nitrate reduction.  It is also important in organisms that can carry out nitrogen fixation (from N2).
  31. 31. MOLYBDENUM (MO6+): Deficiency symptoms:  Most plants require less molybdenum than any other element, so deficiencies are rare.  Symptoms often consist of interveinal chlorosis, first in older leaves. (mobile)  Young leaves may be severely twisted (whiptail disease).
  32. 32. MANGANESE (MN++): Roles and properties:  Important for its oxidation-reduction properties.  A major role for manganese is in the removal of electrons from water during photosynthesis (wate r oxidation).  Manganese also is essential in respiration and nitrogen metabolism.  It can function effectively in some metal catalyzed enzymatic reactions which require magnesium.
  33. 33. MANGANESE (MN++): Deficiency symptoms:  However, deficiencies are rare since low amounts are required and it is usually in plentiful supply in soil.  The absence of Manganese causes disorganization of chloroplast thylakoid membranes.  Plants become chlorotic.
  34. 34. ZINC (ZN++): Roles and properties:  Important in enzymes with oxidation-reduction properties. Deficiency symptoms:  Interveinal chlorosis and inhibition of stem growth.  Leaf margins are distorted and puckered.
  35. 35. BORON (B(OH)3): Roles and properties:  Specific function unknown. However, boron is found in cell walls complexed with raffinose- containing polymers.  It is also found in phloem complexed with sorbitol.  pollen tubes can't elongate without boron.  Some research suggests a role for boron during synthesis of nucleic acids. Deficiency symptoms:  Several disorders related to disintegration of internal tissues such as "heart rot" of beets and "stem crack" of celery .
  36. 36. CHLORIDE (CL-): Roles and properties:  Plants frequently contain a good deal of chloride but very little is required as a nutrient.  It has important functions in photosynthesis.  It may play a general role in maintaining electrical equilibrium. Deficiency symptoms:  The leaves have abnormal shapes, with distinct interveinal chlorosis.
  37. 37. ROLES AND PROPERTIES: Sodium (Na+):  Essential for some halophytes.  Sodium can replace potassium where it is deficient.  Exact functions unknown. May be important for maintaining electrical equilibrium. Silicon (Si4+):  Abundant in soils. Absorbed from soils as silicic acid (H4SiO4).  Is used by some plants to strengthen cell walls (eg., rice, oats, equisetum). Cobalt:  Not required by plants, but required by the bacteroids of
  38. 38. Element Function C,H,O Throughout the plant, organic compounds, sugars, cellulose, starch, lipids, . . . N Component of amino acids (required for protein synthesis), nucleic acids (DNA, RNA), chlorophyll K Regulates osmotic balance, especially in stomatal Opening/closing; enzyme activator Ca Major component of the cell wall; enzyme cofactor; component of calmodulin (signal transduction component); mediates membrane permeability P Carries chemical energy in ATP, sugar- phosphates; component of DNA & RNA; A summary of the functions of inorganic nutrients in plants.
  39. 39. Element Function Mg Cofactor of chlorophyll; enzyme activator S Component of 2 amino acids (forms disulfide bonds in proteins); cofactor of enzymes (coa) Fe Cofactor of cytochromes (electron transfer proteins); required for chlorophyll synthesis Cl Regulates osmotic balance; component of photosynthetic reaction center (PSII) Cu Cofactor of photosynthetic electron transfer protein (Plastocyanin), respriratory electron transfer protein (Cytochrome c oxidase) and of other enzymes A summary of the functions of inorganic nutrients in plants.
  40. 40. Element Function Mn Component of photosynthetic reaction center (PSII); cofactor of some enzymes Zn Enzyme cofactor Mo Required for nitrogen fixation and nitrate (NO3 -) Reduction B Mediates ca utilization, nucleic acid synthesis, and lignin synthesis Ni Constituent of the enzyme urease Na Regulates osmotic balance in some plants; required for C4 photosynthesis Si Cell wall structural element in rice & equisetum A summary of the functions of inorganic nutrients in plants.
  41. 41. Element Deficiency symptoms Symptoms in older leaves first N Stunted growth; pale green, yellow, or brown leaves; slender stems; anthocyanin accumulation K Mottled or chlorotic leaves (faded green/yellow) with dead spots (necrosis); curling or crinkling P Stunted growth, dark green leaves with dead spots (necrosis); some anthocyanin accumulation Mg Mottled or chlorotic leaves (interveinal); tips & edges of leaves curl upward Common mineral deficiency symptoms observed in plants.
  42. 42. Elemen t Deficiency symptoms Symptoms in younger leaves first Ca Young leaves at bud hooked, then die back at edges, stalk dies at bud B Young leaves of the terminal bud light green, leaves twisted, stalk dies at bud S Chlorosis, young leaves light green; some anthocyanin accumulation Fe Young leaves chlorotic (interveinal) Cu Young leaves wilted, wilted terminal bud, dark green leavesw/necrosis Common mineral deficiency symptoms observed in plants.
  43. 43. Element Deficiency symptoms Symptoms in younger leaves first Mn Chlorosis (interveinal), necrosis Zn Rosette growth, leaves small, puckered (makes less auxin) Mo Interveinal chlorosis, necrosis; poor flowering; can cause N deficiency Cl Wilting at leaf tips; general chlorosis & necrosis, bronzing, stunted Common mineral deficiency symptoms observed in plants.