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Unit: Plant Nutrition Nutritional Needs of Plants. 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)
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Unit: Plant Nutrition Nutritional Needs of Plants
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)
What makes an element essential? There are 3 established criteria for an “essential element”: • The plant cannot complete it’s 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.
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.
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.
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
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.
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
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
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
(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
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
Let’s 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
Micronutrients: • Iron: (Fe) • Function: • Involved in chlorophyll & protein synthesis and respiration • Deficiency: Immobile • New growth interveinal chlorosis • Toxicity: • If over-apply foliar necrotic spots
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
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
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.
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
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
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.
Let’s 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”.
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) Req’d for tea bush; toxic for most plants Nickel (Ni) Maybe req’d for N-fixers; toxic for other plants Selinium (Se) In milk vetches; toxic to most plants
Pictures from this presentation can be found at: www.plantphys.net/_article.php?ch=t&id=289 Plant Physiology online: Chapter 5.1 Visual symptoms of nutrient deficiencies in plants Dr. Wade Berry, UCLA