Mineral Nutrition

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Unit 1

• Chapter 5
• Mineral Nutrition

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Mineral nutrition

• Mineral nutrients are elements such as N, P, K
  that plants acquire primarily in the form of
  inorganic ions from the soil.
• Plants are miners of mineral nutrients through
  roots.
• Mycorrhizal fungi and nitrogen-fixing bacteria
  often participate with roots in the acquisition
  of mineral nutrients.

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Figure 5.1 Worldwide fertilizer consumption over
the past five decades
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• Typically, lt 50 fertilizer applied to the soils
  are used.
• Leaching or evaporation to the air cause
  pollution. Nitrate (NO3-) and ammonium (NH4).
• Because of the complex nature of
  plant-soil-atmosphere relationships, studies of
  mineral nutrition involve scientists in many
  fields.

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Essential nutrients

• Essential elements
• an intrinsic component in the structure or
  metabolism of a plant,
• its absence causes severe abnormalities in plant
  growth, development, or reproduction.
• There are a total of 16 essential mineral
  elements
• Macronutrients
• N, P, K, Ca, Mg, S, Si
• Micronutrient
• Cl, Fe, B, Mn, Na, Zn, Cu, Ni, Mo

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Figure 5.2 Various types of solution culture
systems
Solution culture Hydroponics
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Figure 5.3 Chelator and chelated cation
DPTA
EDTA

• To prevent Fe precipitation, often chelators as
  EDTA or DTPA are used to make chelated Fe

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Mineral deficiencies

• Deficiencies of several elements may occur
  simutaneously in different tissues
• Deficiencies or excessive amounts of one element
  may induce deficiencies or excessive
  accumulations of another
• Some virus-induced plant disease may produce
  symptoms similar to those of nutrient deficiencies

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Mineral deficiencies

• Nutrient deficiency symptoms in a plant are
  expression of metabolic disorders resulting from
  insufficient supply of an essential elements
• These disorders are related to the roles played
  by essential elements in normal plant metabolism
  and function (Table 5.2)

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Si, Ni, Mn ??
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Mineral deficiencies

• If an essential element is mobile, deficiency
  symptoms tend to appear first in older leaves.
• Deficiency of an immobile essential element
  becomes evident first in younger leaves.

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Nutrient deficiencies

• Essential elements have multiple roles in plant
  metabolism.
• Soil and plant tissue analysis can provide
  information on the nutritional status of the
  plant soil system and can suggest corrective
  actions to avoid deficiencies or toxicities.

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Extra reading

• Topic 5.1 Symptoms of Deficiency In Essential
  Minerals
• http//5e.plantphys.net/article.php?chtid289

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Nutrients

• Group 1. part of carbon compounds
• N component in amino acids, DNA Deficiency
  chlorosis in old leaves.
• S component in amino acids, vitamins. Deficiency
  chlorosis in mature and young leaves. Veins and
  petioles show a very distinct reddish color.

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Nutrition

• Group 2 energy storage or structural integrity
• P components in DNA, RNA, phospholipids, ATP,
  etc
• Deficiency stunted growth, dark green
  coloration containing necrotic spots slight
  purple coloration

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Silicon components of cell wall Deficiency
lodging and fungal infection Boron function
unclear (cell wall component) Deficiency
necrosis of young leaves and terminal buds
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Nutrition

• Group 3 nutrients in ionic form
• Potassium marginal chlorosis necrosis, shown
  first in old or mature leave. A more advanced
  deficiency status show necrosis in the
  interveinal spaces between the main veins along
  with interveinal chlorosis. This group of
  symptoms is very characteristic of K deficiency
  symptoms.

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Nutrition deficiencies

• Calcium necrosis around the base of the leaves.
  The very low mobility of calcium is a major
  factor determining the expression of calcium
  deficiency symptoms in plants.
• Classic symptoms blossom-end rot of tomato
  (burning of the end part of tomato fruits), tip
  burn of lettuce, blackheart of celery and death
  of the growing regions in many plants. All these
  symptoms show soft dead necrotic tissue at
  rapidly growing areas, which is generally related
  to poor translocation of calcium to the tissue
  rather than a low external supply of calcium.

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Group 3
Leaf chlorosis and necrosis
Small necrotic spots, chlorosis in young or old
leaves
Chlorosis in old leaves
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Nutrition
Dark green leaves, twisted or malformed
Intervenous chlorosis in young leaves

• Group 4 mineral nutrients involved in redox
  reactions
• Iron Zinc Copper Nickle
• Molybdenum associated with nitrate metabolism,
  chlorosis in leaves

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Nutrient deficiency

• Diagnosis of mineral nutrient deficiency
• Soil analysis
• Plant tissue analysis
• Crop harvesting removes nutrients from the soil
• Nutrients can be added back to the soil in the
  form of fertilizers
• Chemical fertilizers, organic fertilizers (plant
  and animal residues)
• Fertilizers can be applied to the soil or sprayed
  on leaves

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Figure 5.4 Relationship between yield and the
nutrient content of the plant tissue
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Figure 5.5 Influence of soil pH on the
availability of nutrient elements in organic soils

• Soil pH has a large influence on the availability
  of mineral nutrients to plants

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Figure 5.6 The principle of cation exchange on
the surface of a soil particle
Cation exchange capacity the degree to which a
soil can adsorb and exchange ions
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• The soil is a complex substrate physically,
  chemically, and biologically. The size of soil
  particles and the cation exchange capacity of the
  soil determines the extent to which a soil
  provides a reservoir for water and nutrients
• A soil with higher cation exchange capacity
  generally has a larger reserve of mineral
  nutrients

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Figure 5.7 Fibrous root systems of wheat (a
monocot)
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Figure 5.8 Taproot system of two adequately
watered dicots
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Figure 5.9 Diagrammatic longitudinal section of
the apical region of the root
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Figure 5.10 Formation of a nutrient depletion
zone in region of soil adjacent to plant root
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Roots

• Plants develop extensive root systems to obtain
  nutrients
• Roots have a relatively simple structure
• Roots continually deplete the nutrients from the
  immediate soil around them, and roots grow
  continuously.
• Different areas of the root absorb different
  ions
• in barley, Ca absorption is restricted to the
  apical region K, nitrate, and ammonium can be
  absorbed at all locations of the root surface.
• In corn, elongation zone has the maximum rate of
  K and nitrate absorption.

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Figure 5.11 Root biomass as a function of
extractable soil NH4 and NO3

• Excessive nutrients decrease root biomass, as
  carbohydrates become limited.

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Figure 5.12 Root infected with ectotrophic
mycorrhizal fungi

• Root infected with ectotrophic mycorrhizal fungi
  forming a dense sheath or mantle the hyphae
  also penetrate the intercellular space of the
  cortex to form the Hartig net.

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Figure 5.13 Association of arbuscular
mycorrhizal fungi with a section of a plant root

• Arbuscular mycorrhizal fungi grow into the
  intercellular space of the cortex and penetrate
  individual cortical cells

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Mycorrhizal fungi

• Plant roots often form associations with
  mycorrhizal fungi
• The fine hyphae of mycorrhizae extend the reach
  of roots into the surrounding soil and facilitate
  the acquisition of mineral nutrients,
  particularly those like phosphorus that are
  relatively immobile in the soil.
• Plant provides carbohydrates to the mycorrhizae.
  Plants tend to suppress mycorrhizal association
  under conditions of high nutrient availability.