Unit: Plant Nutrition

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Unit Plant Nutrition Nutritional Needs of Plants
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Plants and mineral nutrients Plants require
certain elements in order to grow and stay
healthy. 16 Elements essential to plant
growth

• Macronutrients
• Carbon (C)
• Hydrogen (H)
• Oxygen (O)
• Nitrogen (N)
• Phosphorous (P)
• Potassium (K)
• Sulfur (S)
• Calcium (Ca)
• Magnesium (Mg)

• Micronutrients
• Chlorine (Cl)
• Iron (Fe)
• Manganese (Mn)
• Boron(B)
• Zinc (Z)
• Copper (Cu)
• Molybdenum (Mo)

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What makes an element essential?
There are 3 established criteria for an
essential element

1. The plant cannot complete its life cycle without
   the element.

2. Action of the element must be specific- no
other element can substitute for it.
3. The element must be directly involved in the
nutrition of the plant.
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Macro vs. Micro

• Macronutrients nutrients required in large
  amounts and absorbed from the soil or hydroponic
  solution.
• Micronutrients nutrients required in small
  amounts and absorbed from a soil or a hydroponic
  solution.
• Does NOT imply importance. All of the essential
  nutrients are required for growth and function.

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Mobile vs. Immobile
These nutrients are further divided into the
mobile and immobile nutrients. Mobile A plant
will always supply more nutrients to its younger
leaves than its older ones, so when nutrients are
mobile, the lack of nutrients is first visible on
older leaves. Immobile When a nutrient is less
mobile, the younger leaves suffer because the
nutrient does not move up to them but stays lower
in the older leaves.
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Macronutrients

• Carbon (atmosphere)
• Hydrogen (Water)
• Oxygen (atmosphere)
• These 3 nutrients make up 95 of a plants fresh
  tissue.
• Typically not limiting factors except for
• Drought
• Disease
• Extreme cold
• Poor drainage

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N - Nitrogen

• Function Nitrogen stimulates growth, increase of
  fruit production and gives plants a healthy green
  color.
• Toxicity dark green plant with restricted root
  system and fruit set.
• Deficiency Mobile. Growth restricted. Leaves
  become light green and yellow then die.

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• K - Potassium
• Function
• Catalyst/activator for enzymes
• Encourages vigor/health
• Deficiency Highly mobile older growth
• Poor growth, chlorosis, necrosis reduced gas
  exchange
• Toxicity Hi K may cause Ca, Mg, Mn, Zn, Fe
  deficiencies

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• P - Phosphorus
• Function for the energy molecules ATP, ADP,
  AMP
• Deficiency Very mobile (old growth)
• Lower leaf surfaces turn purple
• Leaves curl downward
• Poor leaf, root, flower development
• Toxicity Not usually a problem

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• Ca -Calcium
• Function
• As an activator of enzymes
• Plant strength vigor
• As a neutralizing agent
• Deficiency Immobile (new growth)
• Misshapen, poor or no growth
• Blossom end rot of fruit
• Toxicity Not usually a problem

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• (Mg) Magnesium
• Function
• heart of the chlorophyll molecule
• Enzyme activator (ATP, DNA, RNA)
• Deficiency Highly mobile
• Older leaf interveinal chlorosis
• Upturned leaves
• Toxicity
• Not known

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• Sulfur
• Function
• Form disulfide bonds that aide in the
  folding of proteins and effect their function
• Deficiency Moderately mobile
• Less chlorophyll ? chlorosis and
• purplish veins in mid/young leaves
• Thin, brittle stems

• Toxicity
• Red. Growth, interveinal chlorosis, leaf burn

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Lets review the macros (all result in poor
growth) Mobile Functions Def.
Symptoms N Y protein, RNA, DNA, Chl chlorosis,
necrosis P Y ATP, etc. purple underleaf
K Y Catalyst/activator for enzyme red.
Transpiration Ca N cell walls, enzyme act. poor
new growth blossom end rot in
fruit Mg Y Chlorophyll, enzyme act.
Interveinal chl. brittle upturn
leaf S Mod 2 amino acids mid/new
growth chlorosis,
purple veins, thin brittle stems
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• Micronutrients
• Iron (Fe)
• Function
• Involved in chlorophyll protein synthesis and
  respiration
• Deficiency Immobile
• New growth interveinal chlorosis
• Toxicity
• If over-apply foliar ? necrotic spots

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• Manganese (Mn)
• Function
• Enzyme activator (chl, RNA, DNA)
• carbohydrate metab., O2 prod.
• Deficiency Relatively immobile
• Newer growth interveinal chlorosis
• Necrotic spots/leaf drop
• Upward leaf curl

• Toxicity
• Reduced growth
• Hi Mn ? Low Fe and interveinal chlorosis

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• Boron (B)
• Function
• Related to metabolism of Ca, K
• Regulates carbohydrate
• Involved in RNA synthesis
• Deficiency Mobile in leaf not in plant
• Stems abnormal/slow growth, brittle
• Shoot/root die back
• Young leaves thick, curled
• Low flowering, fruiting fruit rots
• Toxicity
• Def. sym. leaf tip chlorosis/necrosis

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• Zinc (Zn)
• Function
• Enzyme activator
• Synthesis of proteins, hormones,
• RNA, DNA
• Deficiency Not very mobile
• Abnormal and stunted growth
• Leaves interveinal chlorosis, necrosis
• Toxicity
• Similar to def. symp.

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• Copper (Cu)
• Function (70 of Cu in leaf in chloroplasts)
• Chlorophyll synthesis
• Deficiency Immobile
• Leaf stunting, twisting dark green
• Reduced turgor (firmness)
• Reduced flowering/fruiting
• Toxicity Do not use Cu tube/fixtures
• Overall stunting thick, dark roots

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• Molybdenum (Mo)
• Function
• Involved in carbohydrate metabolism.
• Deficiency Mobile
• Leaf interveinal chlorosis, mottling,
  scorching, inward cupping
• Severe puffy leaf areas stunting
• Toxicity
• Not usually seen
• Leaves can turn yellow

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• Chlorine (Cl)
• Function
• Enzyme activator
• Promotes healthy growth of plants
• Hi NaCl ? stress ? flavor, nutrition
• Deficiency Mobile
• Leaf chlorosis then necrosis
• Low transpiration, wilting
• Plant stunting, die back
• Toxicity Leaf tip burn.

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Lets review the micros Some are mobile,
some are not ALL are involved in plant
metabolism Enzyme activators Parts of
enzymes In electron transfer As oxygen
carriers Invovled in synthesis/metabolism of
proteins, hormones, RNA/DNA, carbohydrates,
chlorophyll, ion balance, etc. KEY mainly
move around assisting in reactions, etc.
Therefore, not needed in large amounts for
structure.
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Other nutrients Found in some but not all
plants possibly required by those plants Sodium
(Na) C4 plants Silicon (Si) C4 CAM Cobolt
(Co) N-fixing bacteria Vanadium (V) Essential in
green algae toxic in hp in hi conc Iodine
(I) Stimulates growth in low conc toxic in hi
conc Bromine (Br) Can substitute for Cl Fluorine
(F) Toxic some plants accumulate hi in
teas! Aluminum (Al) Reqd for tea bush toxic for
most plants Nickel (Ni) Maybe reqd for
N-fixers toxic for other plants Selinium (Se) In
milk vetches toxic to most plants
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Pictures from this presentation can be found
at www.plantphys.net/_article.php?chtid289 Pl
ant Physiology online Chapter 5.1 Visual
symptoms of nutrient deficiencies in plants Dr.
Wade Berry, UCLA
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Questions?