abiotics mobility and symptoms, Plsc 350, Plsc 350 environmental stressors

Potassium (K) in the soil

Moderately immobile in soil; held on cation exchange sites

Magnesium (Mg) in the soil

Relatively mobile in soil; leaches in sandy soils

Nitrogen (N) in the plant

Highly mobile in the plant (deficiency appears first on older leaves)

Potassium (K) in the plant

Highly mobile in the plant (deficiency appears first on older leaves)

Magnesium (Mg) in the plant

Mobile in the plant (deficiency appears first on older leaves)

Phosphorus (P) in the plant

Somewhat mobile in the plant (older leaves affected first)

Calcium (Ca) in the plant

Immobile in the plant (deficiency appears on young leaves and meristems)

Sulfur (S) in the plant

Immobile or weakly mobile in the plant (young leaves affected first)

Zinc (Zn) in the plant

Somewhat immobile in the plant (new growth affected first)

Copper (Cu) in the plant

Immobile in the plant (new growth affected first)

Iron (Fe) in the plant

Immobile in the plant (new growth affected first)

Manganese (Mn) in the plant

Low mobility in the plant (new growth affected first)

Boron (B) in the plant

Immobile in the plant (except in a few species)

Nickel (Ni) in the plant

Mobile in the plant (species dependent)

Molybdenum (Mo) in the plant

Highly mobile in the plant (moves in xylem and phloem)

Nitrogen (N) in the soil

Highly mobile in soil as nitrate; prone to leaching

Sulfur (S) in the soil

Highly mobile in soil as sulfate; easily leached

Calcium (Ca) in the soil

Somewhat mobile in soil but often chemically unavailable

Phosphorus (P) in the soil

Immobile in soil; binds to iron/aluminum at low pH and calcium at high pH

Zinc (Zn) in the soil

Immobile in soil; strongly adsorbed and unavailable at high pH

Copper (Cu) in the soil

Immobile in soil; tightly bound to organic matter and minerals

Iron (Fe) in the soil

Immobile in the soil; availability decreases sharply as pH rises above 6.5

Manganese (Mn) in the soil

Immobile in the soil; availability decreases at high pH and increases in acidic or waterlogged soils

Boron (B) in the soil

Highly mobile in soil; easily leached from sandy soils

Nickel (Ni) in the soil

Relatively mobile in soil; availability increases at low pH

Molybdenum (Mo) in the soil

Mobile to moderately mobile in soil; availability increases at higher pH

Nitrogen (N) deficiency symptoms

Uniform yellowing of older leaves; whole plant chlorosis

Sulfur (S) deficiency symptoms

Uniform pale chlorosis of young leaves; resembles nitrogen deficiency

Potassium (K) deficiency symptoms

Marginal chlorosis progressing to brown leaf-edge scorch on older leaves

Calcium (Ca) deficiency symptoms

Tip burn, blossom end rot, distorted young leaves, poor root tips

Magnesium (Mg) deficiency symptoms

Interveinal chlorosis on older leaves with dark green veins

Phosphorus (P) deficiency symptoms

Dark green to purple older leaves; stunting and small leaves

Zinc (Zn) deficiency symptoms

Interveinal chlorosis of new leaves; little leaf; rosetting

Copper (Cu) deficiency symptoms

Dieback of growing tips; chlorosis and distorted young leaves

Iron (Fe) deficiency symptoms

Bright interveinal chlorosis on young leaves; sharply defined green veins

Manganese (Mn) deficiency symptoms

Interveinal chlorosis on young leaves; necrotic spotting

Boron (B) deficiency symptoms

Death of growing points; thickened or leathery young leaves; cracked stems

Nickel (Ni) deficiency symptoms

Chlorosis and small leaves; mouse-ear symptoms in pecan

Molybdenum (Mo) deficiency symptoms

Interveinal chlorosis and marginal necrosis of older leaves; whiptail in cauliflower

Micronutrients

B, Cl, Cu, Fe, Mn, Mo, Ni, Zn

Macronutrients

N,P,K,Ca,Mg,S

nitrogen, phosphorus, potassium, calcium, magnesium, sulfur

ideal ph for plant growth

5.5 to 7

Mobility of macronutrients

Leaf Scorch

Transpiration failure where water loss exceeds root uptake, causing marginal and tip necrosis beginning on older leaves.

Key Diagnostic Feature of Leaf Scorch

Necrosis limited to leaf margins and tips of older leaves, progressing inward.

Abiotic Causes of Leaf Scorch

Heat, low humidity, wind, soil compaction, overwatering, salinity, natural gas leaks.

Biotic Causes Mimicking Leaf Scorch

Verticillium wilt, nematodes, Pierce's disease (Xylella fastidiosa), vascular discoloration.

Winter Sunscald

Bark injury caused by winter sunlight warming tissue followed by rapid freezing, leading to elongated dead bark on south/west trunk sides.

Sunscald Prevention

White trunk paint, tree wrap, avoid over-pruning, retain lower branches, proper irrigation.

Photo-Oxidative Sunburn

UV (shortwave) radiation injury causing white, bleached tissue at normal temperatures.

Sunburn Browning

Heat-related (longwave) injury at 110-115°F causing bronze/yellow discoloration while cells remain alive.

Sunburn Necrosis

Severe heat injury causing epidermal and underlying tissue death on sun-exposed side.

Daily Light Integral (DLI)

Total moles of light received per square meter per day; determines biomass production.

Light Compensation Point

Light level where photosynthesis equals respiration (no net carbon gain below this point).

Etiolation

Stretching growth under low light with pale leaves, thin stems, weak growth, delayed flowering.

Variegation Reversion

Loss of variegation in low light as plant increases chlorophyll production.

Oedema

Blister-like corky lesions caused when roots absorb water faster than leaves transpire under low light and high humidity.

Rapid Freeze Damage

Ice crystals form inside cells causing rupture and severe tissue injury.

Slow Freeze Damage

Ice forms between cell walls causing dehydration injury rather than rupture.

Chill Hours

Hours between 32-45°F required for proper dormancy break and uniform bloom; hours above 60°F subtract from total.

Insufficient Chill Symptoms

Delayed bud break, irregular flowering, reduced fruit production.

Lightning Strike Injury

Steam explosion from heated sap causing bark splitting or circular scorched crop patterns.

Drought Stress Hormone

Abscisic acid (ABA) triggers stomatal closure to reduce water loss.

Early Drought Symptoms

Wilting, leaf drooping, dull bluish-green color, midday leaf rolling.

Late Drought Symptoms

Marginal leaf necrosis, leaf drop, blossom drop, stunting, small misshapen fruit.

Osmotic Salinity Stress

Salt in soil reduces plant water uptake, mimicking drought.

Ion Toxicity Salinity Stress

Accumulation of Na, Cl, or B in older leaves causing marginal necrosis.

Waterlogging

Oxygen deprivation from excess soil water causing wilting in wet soil, chlorosis, root death, and disease susceptibility.

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