Environment of Earth

August 12, 2008

FACTORS AFFECTING PLANT SENSTIVITY TO AIR POLLUTANTS

Filed under: Air pollution,Environment — gargpk @ 12:58 pm
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Pollutant

Factor

Sensitivity

Comment

C2H4 pollution

Tissue age

Epinasty in immature leaves. Other symptoms on oldest leaves first.

Tissues with high natural C2H4 are more sensitive.

C2H4 pollution

High temperature

Sensitivity increased

C2H4 pollution

Other pollutants

Effects inhibited by high levels of SO2 or CO2

Cl2 pollution

Bright sunshine

Sensitivity increased

Cl2 pollution

Tissue age

Little effect; in conifers, current year’s needles most sensitive

Immature leaves tolerant in some species.

Cl2 pollution

Wet leaves

No effect

Cl2 pollution

Drought

Sensitivity decreased

Cl2 pollution

Low temperature

Sensitivity decreased in pines

Symptoms take longer to develop.

Cl2 pollution

Plat age

Seedling less sensitive than oleder plants

HCl pollution

Tissue age

Young, fully expanded leaves most sensitive

Immature leaves tolerant.

HCl pollution

Plant age

Seedlings less sensitive than mature plants

Older plants become more tolerant.

HCl pollution

High relat. Humidity

Sensitivity increased

HCl pollution

Ca-deficit

Sensitivity decreased

Effect shown for Nasturtium. May be different for other species.

HCl pollution

Ca-excess

Sensitivity increased

Effect shown for Nasturtium. May be different for other species.

HCl pollution

Cl-deficit

Sensitivity increased

Effect shown for Nasturtium. May be different for other species.

HCl pollution

Cl-excess

Sensitivity increased

Effect shown for Nasturtium. May be different for other species.

HCl pollution

Mg-deficit

Sensitivity increased

NH3 pollution

Concentration

Variable

Some conifers sensitive at moderate but tolerant at high levels.

NH3 pollution

Tissue age

Little effect

NH3 pollution

Darkness

Variable

NH3 pollution

Drought

Sensitivity decreased

NH3 pollution

Wet leaves

Sensitivity increased

Symptoms develop faster.

NOx pollution

Ca-excess

Sensitivity decreased

Opposite effect in some species.

NOx pollution

Tissue age

Immature leaves/needles most sensitive

NOx pollution

Cultivar

Highly variable; especially in gladiolus & tomato

In gladiolus, sensitivity related to flower colour

NOx pollution

High relat. humidity

Sensitivity increased

NOx pollution

Low temperature

Sensitivity decreased; symptom expression delayed

NOx pollution

Drought

Sensitivity decreased; symptoms induced in conifers needles previously exposed.

Sensitivity increased in some fruit trees.

NOx pollution

N-deficit

Sensitivity decreased

Opposite effect in some species.

NOx pollution

Ca-deficit

Sensitivity decreased

Opposite effect in some species.

NOx pollution

N-excess

Sensitivity decreased

Opposite effect in some species.

NOx pollution

P-excess

Sensitivity increased

Opposite effect in some species.

NOx pollution

Other pollutants

Interaction with SO2, NO2, O2 & hydrocarbons

Response varies with concentrations and relative proportions.

NOx pollution

K-deficit

Sensitivity increased

Opposite effect in some species.

O3 pollution

K-excess

Variable sensitivity

O3 pollution

N-excess

Variable sensitivity

O3 pollution

Plant age

Young plants most sensitive

O3 pollution

Tissue age

Intermediate leaves usually most sensitive

O3 pollution

Darkness

Sensitivity decreased

Plants grown in low light are more sensitive. High light during exposure increases injury.

O3 pollution

Wet leaves

Variable sensitivity

O3 pollution

Drought

Sensitivity decreased

O3 pollution

Other pollutants

Interactions with SO2, NO2, PAN & heavy metals

Response varies with species, concentration & relative proportions

O3 pollution

High soil salinity

Sensitivity decreased

O3 pollution

High relat. Humidity

Sensitivity increased

O3 pollution

S-excess

Sensitivity decreased

O3 pollution

N-deficit

Variable sensitivity

O3 pollution

P-deficit

Sensitivity decreased

O3 pollution

Low temperature

Sensitivity decreased

Sensitivity decreases again above 30 degree C. Response varies according to dose.

O3 pollution

K-deficit

Variable sensitivity

PAN pollution

High relat. Humidity

No effect

PAN pollution

Tissue age

Young, rapidly expanding leaves most sensitive

Sensitivity strongly affected by physiological age, results in bands of damage.

PAN pollution

Other pollutants

Interactions with O3 & SO2

Response varies with concentrations & pollutant.

PAN pollution

Drought

Sensitivity decreased

PAN pollution

Time of day

Sensitivity more in morning than after noon

PAN pollution

Darkness

Injury eliminated. Sensitivity increases with increased light intensity

Presence of light before, during and after exposure must for injury to occur.

PAN pollution

Low temperature

Injury decreased

PAN pollution

Plant age

Young plants more sensitive

SO2 pollution

Other pollutant

Interaction with O3, NO2, HF

Response varies with concentrations and relative proportions.

SO2 pollution

Time of day

More sensitivity when sugar content low

In many plants in the morning.

SO2 pollution

High relat. Humidity

Sensitivity increased

SO2 pollution

Drought

Sensitivity decreased

SO2 pollution

High wind

Sensitivity increased

SO2 pollution

Wet leaves

Variable; may increase

SO2 pollution

Darkness

Sensitivity decreased

Some plants e.g. Potato not closing stomata at night may be unaffected.

SO2 pollution

Low temperature

Sensitivity decreased

Susceptibility to frost injury increased by SO2 exposure

SO2 pollution

Plant age

Seedlings more sensitive than older plants

SO2 pollution

Season

Grasses more sensitive in winter; conifers more in April/May than in July/August

Not vry important for very short exposures.

SO2 pollution

N-deficit

Sensitivity decreased

SO2 pollution

S-deficit

Sensitivity decreased

SO2 pollution

P-deficit

Sensitivity decreased

SO2 pollution

N-excess

Sensitivity decreased

SO2 pollution

K-deficit

Sensitivity increased

SO2 pollution

S-excess

Sensitivity increased

SO2 pollution

Tissue age

Most in young, fully expanded leaves

SO2 pollution

Ca-deficit

Sensitivity increased

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HABITAT AND PLANT RESPONSE

Filed under: Environment,plants — gargpk @ 12:51 pm
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Cause

Common name

Botanical name

Plant part

Symptom

Cold area

Pea

Pisum sativum

Leaf

Bronzing

Cold area

Bean

Phaseolus vulgaris

Leaf

Bronzing

Cold area

Spinach

Spinacea oleracea

Leaf

Bronzing

Dry area

Pine

Pinus sp.

Needle

Tip burn; sharp boundaary between necrotic and healthy tissue

Dry area

Spruce

Picea sp.

Needle

Tip burn; sharp boundaary between necrotic and healthy tissue

Dry area

Fir

Abies sp.

Needle

Tip burn; sharp boundaary between necrotic and healthy tissue

Dry area

Aspen

Populus tremula

Leaf

Tip necrosis with sharp boundary

Dry area

Plum

Prunus domestica

Leaf

Marginal/interveinal necrosis, boundary chlorotic & diffuse

Dry area

Wych elm

Ulmus glabra

Leaf

Tip necrosis with sharp boundary

Dry area

Willow

Salix sp.

Leaf

Tip necrosis with sharp boundary

Dry area

Cherry

Prunus avium

Leaf

Marginal/interveinal necrosis, boundary chlorotic & diffuse

Dry area

Oak

Quercus rubur (Q. pedunculata)

Leaf

Interveinal brown/bronzed lesions

Dry area

Apple

Malus sylvestris

Fruit

Dark lesions

Dry area

Cherry

Prunus avium

Fruit

Brown/black depression at tip

Dry area

Pear

Pyrus communis

Fruit

Brown/black depression at tip

Dry area

Tomato

Lycopersicum esculentum

Fruit

Blossom end rot

Water logged area

Lucerne (alfalfa)

Medicago sativa

Leaf

White stipple

Hot area

Onion

Allium cepa

Leaf

Tip necrosis; white/grey stipple

Hot area

Horse chestnut

Aesculus hippocastanum

Leaf

Marginal necrosis

Hot area

Lettuce

Lectuca sativa

Leaf

Brown stipple of veins

Hot area

Lucerne (alfalfa)

Medicago sativa

Leaf

White stipple

Cold area

Lucerne (alfalfa)

Medicago sativa

Leaf

Necrotic stipple

Cold area

Potato

Solanum tuberosum

Leaf

Black discolouration; necrotic stipple

NUTRIENT DEFICIENCY SYMPTOMS IN PLANTS

Filed under: Environment,plants — gargpk @ 12:43 pm
Tags:

Cause

Common name

Botanical name

Plant part

Symptom

K-deficit

Pear

Pyrus communis

Leaf

Upward curling

K-deficit

Pea

Pisum sativum

Leaf

Brown stipple

K-deficit

Potato

Solanum tuberosum

Leaf

Bronzing of lower surface; marginal, later interveinal necrosis

K-deficit

Tomato

Lycopersicum esculentum

Leaf

Marginal, later interveinal necrosis

K-deficit

Lucerne (alfalfa)

Medicago sativa

Leaf

Marginal, later interveinal necrosis

P-deficit

Cabbage

Brassica oleracea var. capitata

Leaf

Red/purple discolouration

P-deficit

Lucerne (alfalfa)

Medicago sativa

Leaf

Red/purple discolouration

P-deficit

Potato

Solanum tuberosum

Leaf

Curling or rolling

S-deficit

Tomato

Lycopersicum esculentum

Leaf

Very pale new leaf; Bleached old leaf

Ca-deficit

Tulip

Tulipa gesneriana

Leaf

Necrosis

Ca-deficit

Tulip

Tulipa gesneriana

Plant

Wilting

Mg-deficit

Pear

Pyrus communis

Leaf

Black necrosis

Mg-deficit

Potato

Solanum tuberosum

Leaf

Brown stipple

Mg-deficit

Tomato

Lycopersicum esculentum

Leaf

Curling & brittleness

Mn-deficit

Oats

Avena sativa

Leaf

Grey discolouration

Mn-deficit

Wheat

Triticum vulgare

Leaf

White dashes

Mn-deficit

Wheat

Triticum vulgare

Plant

Pale floppy appearance

Mn-deficit

Barley

Hordeum vulgare

Plant

Pale floppy appearance

Mn-deficit

Barley

Hordeum vulgare

Leaf

White dashes

Zn-deficit

Lucerne (alfalfa)

Medicago sativa

Leaf

White stipple on lower & Bronzing of upper surface

Zn-deficit

Tomato

Lycopersicum esculentum

Leaf

Interveinal chlorosis, later necrosis

Mn-excess

Cauliflower

Brassica oleracea var. botrytis

Leaf

Brown/purple stipple

Mn-excess

Potato

Solanum tuberosum

Leaf/stem

Black stipple or streaks

MINIMUM EXPOSURE TO AIR POLLUTANTS FOR PLANT INJURY

Filed under: Environment — gargpk @ 9:28 am
Tags: ,

Plant name Pollutant
ppm hours tolerance
Alder HCl 6.00 4.00 Middle
Aster HCl 9.00 0.40 Low
Barley HCl 7.00 0.40 Very low
Bean HCl 4.00 0.40 Very low
Beech HCl 1000.00 1.00 Very high
Cherry HCl 9.00 4.00 High
Chrysanthemum HCl 9.00 3.00 High
Cornflower HCl 20.00 0.40 Middle
Cosmos HCl 9.00 0.40 Low
Douglas fir HCl 10.00 4.00 High
Marigold HCl 9.00 0.40 Low
Nasturtium HCl 9.00 0.40 Low
Norway maple HCl 7.00 4.00 High
Norway spruce HCl 19.00 4.00 Very high
Oak HCl 1000.00 1.00 Very high
Tomato HCl 5.00 2.00 Low
Tulip tree HCl 3.00 4.00 Low
Weymouth pine HCl 8.00 4.00 High
Zinnia HCl 9.00 0.40 Low
Annual poa NH3 12.00 4.00 Middle
Buckwheat NH3 16.60 4.00 Middle
Chickweed NH3 12.00 4.00 Middle
Dandelion NH3 12.00 4.00 Middle
Apple SO2 0.40 6.00 Middle
Aspen SO2 0.40 3.00 Middle
Barley SO2 1.30 1.00 Very low
Bean SO2 0.80 3.00 Low
Begonia SO2 0.30 1.00 Very low
Broad bean SO2 2.00 4.00 High
Broccoli SO2 0.30 4.00 Low
Buckwheat SO2 0.70 1.00 Very low
Cabbage SO2 1.00 4.00 Low
Chrysanthemum SO2 2.50 3.00 Very high
Cocksfoot SO2 3.10 6.00 Very high
Cucumber SO2 0.80 4.00 Low
Dandelion SO2 2.00 4.00 High
Douglas fir SO2 0.70 4.50 Middle
French marigold SO2 2.00 2.00 High
Geranium SO2 2.00 2.00 High
Ginkgo SO2 2.80 3.00 Very high
Gladiolus SO2 0.50 8.00 Middle
Iris SO2 0.50 8.00 Middle
Italian ryegrass SO2 1.90 6.00 High
Larch SO2 0.30 8.00 Low
Lettuce SO2 1.00 2.00 Low
Locust tree SO2 2.00 4.00 High
Lucerne SO2 0.10 4.00 Low
Lilac SO2 0.30 6.00 Middle
Tomato NH3 8.30 5.00 Low
White clover NH3 100.00 0.10 Middle
African marigold C2H4 0.01 20.00 Low
Cattleya orchid C2H4 0.00 24.00 Very low
Aspen O3 0.15 2.00 Low
Bean O3 0.06 8.00 Low
Begonia O3 0.13 3.00 Low
Bindweed O3 0.20 4.00 Low
Apple C2H4 0.01 48.00 Middle
Buckwheat C2H4 0.05 48.00 Middle
Carnation C2H4 0.10 6.00 Low
Chrysanthemum C2H4 1.00 9.00 High
Cucumber C2H4 100.00 6.00 Very high
Fat hen C2H4 0.05 48.00 Middle
Forsythia C2H4 0.70 20.00 High
Narcissus C2H4 0.40 1.00 Very low
Pepper C2H4 0.10 8.00 Low
Rose C2H4 10.00 24.00 Very high
Snapdragon C2H4 0.50 1.00 Very low
Strawberry C2H4 1.00 24.00 High
Sunflower C2H4 0.05 48.00 Middle
Tomato C2H4 1.00 24.00 Middle
Tulip C2H4 0.40 1.00 Very low
Norway maple SO2 2.50 3.00 High
Oats SO2 1.00 1.00 Low
Onion SO2 1.00 4.00 Low
Pea SO2 1.00 1.00 Low
Petunia SO2 2.00 4.00 High
Pine SO2 0.30 2.00 Low
Plantain SO2 0.80 6.00 Middle
Poplar SO2 2.00 4.00 High
Potato SO2 4.20 1.00 Middle
Radish SO2 0.50 1.00 Low
Red fescue SO2 1.20 6.00 Middle
Rose SO2 0.70 6.00 Middle
Rye SO2 0.70 3.00 Low
Ryegrass SO2 1.00 6.00 Low
Fat hen NH3 12.00 4.00 Middle
Lettuce NH3 2.00 24.00 Low
Ryegrass NH3 100.00 0.20 Middle
Smooth-stalk meadow grass NH3 12.00 4.00 Middle
Silver birch SO2 0.90 2.00 Low
Smooth-stalk meadow grass SO2 0.20 2.00 Low
Snapdragon SO2 4.00 2.00 High
Spruce SO2 3.00 6.00 Very high
Spinach SO2 1.00 4.00 Low
Sweet pea SO2 0.80 3.00 Low
Swiss chard SO2 1.00 1.00 Low
Timothy SO2 0.80 1.00 Low
Tomato SO2 0.50 4.00 Low
Turnip SO2 1.00 2.00 Low
Wheat SO2 0.80 1.00 Low
Annual poa HF 0.10 4.00 Low
Apple HF 0.40 4.50 Middle
Azalea HF 0.10 48.00 High
Bean HF 0.70 2.30 Middle
Buckwheat HF 0.70 2.30 Middle
Celery HF 0.10 48.00 High
Chickweed HF 0.10 4.00 Low
Corn HF 0.10 4.00 Low
Dandelion HF 0.10 4.00 Low
Dock HF 0.50 8.00 High
Fat hen HF 0.10 4.00 Low
Gladiolus HF 0.06 6.00 Very low
Iris HF 0.50 8.00 High
Lucerne HF 0.10 48.00 High
Nettle-leaved goosefoot HF 0.10 4.00 Low
Norway spruce HF 0.20 5.80 Low
Pine HF 0.07 4.00 Very low
Polygonum HF 0.50 8.00 High
Rose HF 0.50 8.00 High
Smoot-stalk meadow grass HF 0.10 4.00 Low
Sunflower HF 0.10 4.00 Low
Tomato HF 0.30 3.00 Low
Tulip HF 0.50 8.00 High
Azalea Nox 13.00 1.00 Middle
Awnless brome Nox 4.00 0.50 Very low
Bean Nox 6.00 2.00 Low
Beet Nox 30.00 1.00 High
Begonia Nox 16.00 0.50 Middle
Broccoli Nox 16.00 0.50 Middle
Buckwheat Nox 4.00 4.00 Low
Chrysanthemum Nox 4.00 0.50 Very low
Corn Nox 4.00 0.50 Very low
Cocksfoot Nox 4.70 6.00 Low
Cucumber Nox 6.00 2.00 Low
Erica heather Nox 1000.00 1.00 Very high
Sunflower NH3 3.00 4.00 Very low
Italian ryegrass Nox 4.70 6.00 Low
Lettuce Nox 30.00 1.00 High
Lucerne Nox 6.00 8.00 Low
Oats Nox 4.00 0.50 Very low
Pea Nox 6.00 4.00 Low
Plantain Nox 3.30 6.00 Low
Potato Nox 30.00 1.00 High
Radish Nox 4.00 0.50 Very low
Rape Nox 30.00 1.00 High
Rye Nox 30.00 1.00 High
Ryegrass Nox 4.70 6.00 Low
Red fescue Nox 4.70 6.00 Low
Smooth-stalk meadow grass Nox 4.70 6.00 Low
Spinach Nox 6.00 2.00 Low
Swiss chard Nox 1.00 1.00 Very low
Timothy Nox 4.70 6.00 Low
Tomato Nox 8.00 1.00 Low
Wheat Nox 5.00 0.50 Very low
Azalea Cl2 0.80 4.00 Low
Azalea Cl2 0.80 4.00 Middle
Bean Cl2 1.30 0.50 Low
Begonia Cl2 1.00 4.00 High
Buckwheat Cl2 0.50 1.00 Low
Carnation Cl2 0.50 4.00 Middle
Clover Cl2 35.00 2.00 Middle
Corn Cl2 0.10 4.00 Very low
Cucumber Cl2 0.50 4.00 Middle
Dahlia Cl2 0.50 4.00 Middle
Dandelion Cl2 0.50 4.00 Middle
Fat hen Cl2 1.00 4.00 High
Geranium Cl2 0.80 4.00 High
Lucerne Cl2 0.10 2.00 Very low
Maple Cl2 0.10 4.00 Very low
Nasturtium Cl2 0.50 4.00 Middle
Onion Cl2 0.80 4.00 High
Petunia Cl2 0.10 4.00 Very low
Pine Cl2 1.00 3.00 High
Polygonum Cl2 1.00 4.00 High
Radish Cl2 0.10 2.00 Very low
Rose Cl2 1.00 0.50 Low
Ryegrass Cl2 35.00 0.20 Middle
Squash Cl2 0.80 4.00 High
Sunflower Cl2 0.10 2.00 Very low
Tomato Cl2 0.50 4.00 Middle
Zinnia Cl2 0.10 4.00 Low
Buttercup O3 0.20 4.00 Low
Chrysanthemum O3 0.26 3.00 Low
Corn O3 0.10 2.00 Low
Corsican pine O3 0.25 4.00 Low
European larch O3 0.25 4.00 Low
Grape O3 0.40 4.00 Middle
Lettuce O3 0.15 2.00 Low
Lucerne O3 0.15 4.00 Low
Oats O3 0.10 2.00 Very low
Pea O3 0.10 2.00 Very low
Poplar O3 0.18 4.00 Low
Radish O3 0.08 2.00 Very low
Red clover O3 0.15 4.00 Low
Scots pine O3 0.25 8.00 Middle
Smooth-stalk meadow grass O3 0.10 17.50 Very high
Spinach O3 0.13 3.00 Low
Tobacco O3 0.05 5.00 Very low
Common vetch O3 0.20 4.00 Low
Weymouth pine O3 0.07 4.00 Very low
Wheat O3 0.23 3.00 Low
White clover O3 0.15 4.00 Low
Bean PAN 0.05 4.00 Low
Petunia PAN 0.01 8.00 Low
Tomato PAN 0.01 4.00 Low
Lettuce PAN 0.05 12.00 High
Small nettle PAN 0.05 35.00 Very high
Annual poa PAN 0.05 42.00 Very high
Phalaenopsis orchid C2H4 0.00 24.00 Very low

AIR POLLUTANTS AND PLANT RESPONSES

Filed under: Environment — gargpk @ 9:14 am
Tags: ,

Cause Common name Botanical name Plant part Symptom
Acid mist pollution Begonia Begonia sp. Leaf Necrotic spots on upper surface at point of contact
Swiss chard Beta vulgaris var. cicla Leaf Shot holing
Boron pollution Honeysuckle Lonicera periclymenum Leaf Brown marginal necrosis; interveinal necrosis; cupping & distortion
Norway maple Acer platanoides Leaf Brown marginal necrosis; interveinal necrosis;necrotic stipple; abscission
Silver maple Acer saccharinum Leaf Brown marginal necrosis, interveinal necrosis; cupping & distortion
Spiraea Spiraea sp. Leaf Abscission
Br2 pollution Bean Phaseolus vulgaris Leaf Marginal necrosis
Beech Fagus sylvatica Leaf Black spots, later whole leaf black/brown
Corn Zea mays Leaf Yellow tip, later necrotic
Dahlia Dahlia pinnata Leaf Brown discolouration; marginal necrosis
Fir Abies sp. Needle Red/brown discolouration, later grey/brown
Larch Larix decidua Needle Yellow/white tip
Pea Pisum sativum Leaf Marginal necrosis
Pea Pisum sativum Tendril Necrosis
Rose Rosa sp. Leaf Brown discolouration
Rye Secale cereale Leaf Yellow tip, later necrotic
C2H4 pollution Apple Malus sylvestris Flower Intumescence formation
Apple Malus sylvestris Bark Hypertrphy, especially around lenticels
Azalea Rhododendron sp. Flower Necrosis
Beet Beta vulgaris Old leaf Red/purple discolouration
Carnation Dianthus caryophyllus Flower Closing of flowers; ‘sleepiness’
Cattleya orchid Cattleya sp. Sepal Drying/bleaching from tip to base
Cucumber Cucumis sativus Flower Conversion of male into female
Daffodil Narcissus pseudonarcissus Leaf Inwards roll, curl or twist
Hibiscus Hibiscus sp. Stem Hypertrophy of lenticels
Hyacinth Hyacinthus sp. Flower Delayed opening; abnormal colour
Hyacinth Hyacinthus sp. Leaf Inwards roll, curl or twist; abscission
Lettuce Lectuca sativa Young leaf Dark green colouration
Lilac Syringa vulgaris Bark Hypertrphy, especially around lenticels
Lily Lilium sp. Leaf Inwards roll, curl or twist; abscission
Marigold Tagetus sp. Stem Root induction
Pea Pisum sativum Young leaf Dark green colouration
Petunia Petunia hybrida Flower Flowering inhibition
Phalaenopsis orchid Phalaenopsis sp. Sepal Drying/bleaching from tip to base
Poplar Populus sp. Bark Hypertrphy, especially around lenticels
Radish Raphanus sativus Old leaf Red/purple discolouration
Radish Raphanus sativus Young leaf Dark green colouration
Rose Rosa sp. Flower Premature opening
Rose Rosa sp. Old leaf Chlorosis, later necrosis
Rose Rosa sp. Young leaf Dark green colouration
Snapdragon Antirrhinum majas Flower Loss of petals
Tomato Lycopersicum esculentum Stem Root induction
Tulip Tulipa gesneriana Leaf Inwards roll, curl or twist; abscission
Tulip Tulipa gesneriana New leaf Continued folding
Willow Salix sp. Bark Hypertrphy, especially around lenticels
Wych elm Ulmus glabra Bark Loss of bark
Cement pollution Bean Phaseolus vulgaris Leaf Margin rolling; interveinal necrosis; growth inhibition
Oats Avena sativa Leaf Yellow spots
Cl2 pollution Apple Malus sylvestris Leaf Abscission; marginal necrosis
Azalea Rhododendron sp. Leaf Necrotic margins
Barberry Berberis vulgaris Leaf Marginal cholrosis
Cherry Prunus avium Leaf Necrotic stipple; abscission
Chrysanthemum Chrysanthemum sp. Leaf Necrotic stipple
Dahlia Dahlia pinnata Leaf Black marginal discolouration
Dandelion Taraxacum officinale Leaf Red discolouration
Douglas fir Pseudotsuga menziesii Needle Necrosis
Fir Abies sp. Needle Red/brown necrosis; narrow band of necrotic stipple between necrotic and healthy tissue
Ginkgo Ginkgo biloba Leaf Necrotic stipple
Hibiscus Hibiscus sp. Leaf Marginal cholrosis
Horse chestnut Aesculus hippocastanum Leaf White stipple
Horse chestnut Aesculus hippocastanum Leaf Marginal necrosis
Larch Larix decidua Needle Chlorotic mottle
Lettuce Lectuca sativa Leaf Necrotic margins; bronzing of lower surface
Lucerne (alfalfa) Medicago sativa Leaf Necrotic margins
Oak Quercus rubur (Q. pedunculata) Leaf Necrotic stipple; bronzing
Onion Allium cepa Leaf Tip necrosis
Pear Pyrus communis Leaf Black necrosis
Peony Paeonia sp. Leaf Necrotic margins
Pine Pinus sp. Needle Dull grey/green, later necrotic; orange necrosis; chlorotic mottle; narrow band of necrotic stipple between necrotic and healthy tissue
Plum Prunus domestica Leaf Necrotic stipple; marginal necrosis
Rhododendron Rhododendron Leaf Dark stipple, more on upper surface
Rose Rosa sp. Leaf Dark stipple, more on upper surface
Spruce Picea sp. Needle Red/brown necrosis; narrow band of necrotic stipple between necrotic and healthy tissue
Squash Cucurbita Leaf Cupping
Sycamore Acer pseudoplatanus Leaf Marginal necrosis
Sycamore Acer pseudoplatanus Leaf Black necrosis
Tomato Lycopersicum esculentum Leaf Cupping; epinasty
Tulip Tulipa gesneriana Leaf Bleached lower surface
Wych elm Ulmus glabra Leaf Marginal necrosis
Yew Taxus baccata Needle Black necorsis
Fluoride pollution Apple Malus sylvestris Leaf Interveinal necrotic stipple; red/brown necrosis
Bilberry Vaccinium sp. Leaf Red tip & margin discolouration
Buckwheat Fagopyrum esculentum Leaf Leaf cupping
Cherry Prunus avium Fruit Necrosis of stylar end
Colorado spruce Picea pungens Young needle Purple necrosis
Corn Zea mays Leaf Marginal chlorotic mottle; necrotic stipple, later necrotic streaks
Cyclamen Cyclamen Sepals & petals Marginal necrosis
Dahlia Dahlia pinnata Leaf Black necrosis
Dandelion Taraxacum officinale Leaf Ivory necrosis
Gladiolus Gladiolus sp. Leaf Glazed upper surface; red/brown necrosis
Lilac Syringa vulgaris Leaf Necrotic bands; red margin discolouration
Lucerne (alfalfa) Medicago sativa Leaf Marginal necrosis
Oats Avena sativa Leaf Ivory necrosis
Peach Prunus persica Fruit Premature ripening & suture rotting
Pear Pyrus communis Fruit Necrosis of stylar end
Petunia Petunia hybrida Sepals & petals Marginal necrosis
Pine Pinus sp. Young needle Reddish necrotic bands
Poplar Populus sp. Leaf Ivory necrosis; tip notching
St. Johns Wort Hypericum perforatum Leaf Red/brown necrosis
Sunflower Helianthus annuus Leaf Brown necrosis
Tomato Lycopersicum esculentum Leaf Edge curling; ivory necrosis
Tulip Tulipa gesneriana Leaf Glazed upper surface
Wheat Triticum vulgare Leaf Bleached tip; ivory necrosis
H2S pollution Aster Callistephus chinensis Flower Necrosis of bracts
Buckwheat Fagopyrum esculentum Leaf Upward rolling
Sunflower Helianthus annuus Leaf Distortion; orange interveinal necrosis
HCl pollution Aspen Populus tremula Leaf Chlorotic mottle
Aster Callistephus chinensis Leaf Bronzing/glazing of lower surface
Bean Phaseolus vulgaris Leaf Ivory necrosis; bronzing/glazing of lower surface; upward curling or rolling
Beech Fagus sylvatica Leaf Interveinal bleaching; necrotic stipple
Cherry Prunus avium Leaf Chlorotic mottle
Cornflower Centaurea cyanus Leaf Necrotic stipple; upward curling or rolling
Cosmos Cosmos bipinnatus Sepal Tip burn
Cosmos Cosmos bipinnatus Leaf Upward curling or rolling
Cosmos Cosmos bipinnatus Petal Discolouration
Dahlia Dahlia pinnata Leaf Black marginal discolourationg; black necrosis
Maple Acer sp. Leaf Necrotic stipple
Marigold Tagetus sp. Sepal Tip burn
Nasturtium Tropeolum majas Leaf Necrotic stipple; bleaching
Oak Quercus rubur (Q. pedunculata) Leaf Interveinal bleaching
Pear Pyrus communis Leaf Marginal necrosis
Rose Rosa sp. Leaf Black marginal discolourationg; marginal necrosis
Silver birch Betula pendula Leaf Marginal necrosis
Tomato Lycopersicum esculentum Leaf Bronzing/glazing of lower surface; bifacial bronzing, later necrotic
Zinnia Zinnia angustifolia Leaf Bronzing/glazing of lower surface; upward curling or rolling
Zinnia Zinnia angustifolia Petal Necrotic stipple
Hg pollution Privet Ligustrum sp. Leaf Browning of interveinal tissue
Rose Rosa sp. Petal Colour loss, later brown at margins
Rose Rosa sp. Stamen/pistil Black
Rose Rosa sp. Bud Remain closed, later necrosis
Rose Rosa sp. Peduncle Brown/black
Rose Rosa sp. Flower Abscission
NH3 pollution Apple Malus sylvestris Fruit Purple/black/brown discolouration around lenticels
Azalea Rhododendron sp. Leaf Brown/black necrosis
Azalea Rhododendron sp. Flower Brown & white marks on white and red flowers respectively
Barley Hordeum vulgare Leaf Bleaching
Bean Phaseolus vulgaris Leaf Red discolouration; red/brown/purple margins of necrotic areas
Beech Fagus sylvatica Leaf Bronzing/glazing of upper surface
Broad bean Vicia faba Leaf Yellow discolouration; later black
Buttercup Ranunculus sp. Leaf Yellow discolouration; later black
Carrot Daucus carota Leaf Brown/black necrosis
Cauliflower Brassica oleracea var. botrytis Leaf Ivory necrosis; black spots on lower surface
Celery Apium graveolens Leaf Red discolouration
Clover Trifolium sp. Leaf Red/brown/purple margins of necrotic areas
Cocksfoot Dactylis glomerata Leaf Ivory necrosis
Cotoneaster Cotoneaster sp. Leaf Yellow discolouration
Dandelion Taraxacum officinale Leaf Brown/black necrosis; red discolouration
Forsythia Forsythia intermedia Leaf Dark pigmented spots spreading & coalescing untill leaf becomes dark green/brown/black
Gladiolus Gladiolus sp. Leaf Ivory necrosis
Hawthorn Crataegus monogyna Twig Dieback
Horse chestnut Aesculus hippocastanum Leaf Dark pigmented spots spreading & coalescing untill leaf becomes dark green/brown/black
Iris Iris sp. Leaf Yellow discolouration
Leek Allium porrum Leaf Glazing; ivory necrosis
Onion Allium cepa Leaf Glazing; ivory necrosis
Parsley Petroselinum crispum Leaf Ivory necrosis
Pea Pisum sativum Leaf Purple/black/brown discolouration around lenticels
Pear Pyrus communis Leaf Dark pigmented spots spreading & coalescing untill leaf becomes dark green/brown/black
Poplar Populus sp. Leaf Bronzing/glazing of upper surface
Potato Solanum tuberosum Leaf Ivory necrosis
Rhubarb Rheum rhaponticum Leaf Red/brown/purple margins of necrotic areas; reddish necrosis
Rye Secale cereale Leaf Reddish necrosis
Sorrel Rumex acetosa Leaf Red/brown/purple margins of necrotic areas
Sprouts Brassica oleracea var. gemisera Leaf Black spots on lower surface
Spruce Picea sp. Young needle Red/yellow discolouration
Spruce Picea sp. Needle Pale green, becoming white and then red
Stinging nettle Urtica dioica Leaf Brown/black necrosis
Strawberry Fragaria vesca Leaf Red discolouration
Sycamore Acer pseudoplatanus Leaf Dark pigmented spots spreading & coalescing untill leaf becomes dark green/brown/black; yellow discolouration
Wheat Triticum vulgare Leaf Ivory necrosis
Willow Salix sp. Leaf Bronzing/glazing of upper surface
Nox pollution Alder Alnus glutinosa Leaf Red/brown necrosis
Annual poa Poa annua Leaf Glazing
Apple Malus sylvestris Leaf Red/brown necrosis
Apple Malus sylvestris Leaf Herringbone necrosis
Aspen Populus tremula Leaf Ivory necrosis, often with dark brown border
Aster Callistephus chinensis Leaf Orange/brown necrosis
Azalea Rhododendron sp. Leaf Orange/brown necrosis
Barley Hordeum vulgare Awn Tip necrosis
Bean Phaseolus vulgaris Leaf Marginal necrosis
Beech Fagus sylvatica Leaf Red/brown necrosis
Beech Fagus sylvatica Leaf Herringbone necrosis
Begonia Begonia sp. Leaf Shot holing with coloured margin
Cabbage Brassica oleracea var. capitata Leaf Necrotic stipple; bronzing/glazing
Carnation Dianthus caryophyllus Leaf Tip necrosis
Carrot Daucus carota Leaf Tip necrosis
Clover Trifolium sp. Leaf Marginal necrosis
Cocksfoot Dactylis glomerata Leaf Yellow/orange necrosis
Dahlia Dahlia pinnata Leaf Orange/brown necrosis
Fir Abies sp. Old needle Abscission after several months; sharp red/brown band between necrotic and healthy tissue
Gooseberry Ribes uva-crispa Leaf Tip necrosis
Hazel Corylus avellana Leaf Ivory necrosis, often with dark brown border; herringbone necrosis
Kohlrabi Brassica oleracea var. gongylodes Leaf Necrotic stipple
Larch Larix decidua Old needle Abscission after several months
Lettuce Lectuca sativa Leaf Necrotic stipple; ivory necrosis; shot holing with coloured margin
Lucerne (alfalfa) Medicago sativa Leaf Marginal necrosis
Lupin Lupinus angustifolium Leaf Marginal necrosis
Maple Acer sp. Leaf Red/brown necrosis
Oak Quercus rubur (Q. pedunculata) Leaf Red/brown necrosis; marginal necrosis; ivory necrosis, often with dark brown border
Ox-eye daisy Chrysanthemum leucanthemum Leaf Orange/brown necrosis
Parsley Petroselinum crispum Leaf Tip necrosis
Pea Pisum sativum Leaf Marginal necrosis
Pear Pyrus communis Leaf Black necrosis
Pine Pinus sp. Old needle Abscission after several months
Pine Pinus sp. Old needle Bleaching, later necrosis
Pine Pinus sp. Old needle Ring of white spots close to base
Pine Pinus sp. Old needle Sharp red/brown band between necrotic and healthy tissue
Plantain Plantago sp. Leaf Ivory necrosis; bronzing/glazing
Potato Solanum tuberosum Leaf Black marginal stipple
Rhododendron Rhododendron Leaf Necrotic stipple
Rye Secale cereale Awn Tip necrosis
Silver birch Betula pendula Leaf Ivory necrosis, often with dark brown border
Spinach Spinacea oleracea Leaf Bronzing/glazing; shot holing with coloured margin
Spruce Picea sp. Old needle Immediate abscission
Sweet William Dianthus barbatus Bracts Tip necrosis
Sweet William Dianthus barbatus Sepals Tip necrosis
Timothy Phleum pratense Leaf Basal necrosis
Tulip Tulipa gesneriana Leaf Basal necrosis
O3 pollution Apple Malus sylvestris Fruit Tissue collapse around lenticels
Apple Malus sylvestris Leaf Bronzing by very dense small lesions, mostly on upper surface
Ash Fraxinus excelsior Leaf Dense to sparse purple/reddish stipple of upper surface, bounded by smallest veins
Barley Hordeum vulgare Leaf Fine chlorotic/white/tan streaks between large veins, more at leaf bendings & seedling tips/margins
Bean Phaseolus vulgaris Leaf Brown necrotic lesions on upper surface, darker on first trifoliate leaf
Bean Phaseolus vulgaris Fruit Rows of necrotic lesions
Citrus Citrus sp. Fruit Premature drop
Corn Zea mays Leaf Light tan/white bifacial irregular necrotic streaks severe on margins occurring at tips in young leaf pregressively downwards on old leaf; bands of small silver grey/light tan necrotic steaks
Grape Vitis vinifera Leaf Dense to sparse purple/reddish stipple of upper surface, bounded by smallest veins
Lilac Syringa vulgaris Leaf Curling with drying of tip & margin
Lime Tilia cordia Leaf Bronzing by very dense small lesions, mostly on upper surface
Lucerne (alfalfa) Medicago sativa Leaf White/light yellow-green/silvergrey/tan variable necrosis on all or limited area
Maple Acer sp. Leaf Dense to sparse purple/reddish stipple of upper surface, bounded by smallest veins
Oats Avena sativa Leaf Fine chlorotic/white/tan streaks between large veins, more at leaf bendings & seedling tips/margins
Onion Allium cepa Leaf White fleck, later brown tips
Pea Pisum sativum Leaf Fawn lesions
Pine Pinus sp. Needle Chlorotic mottling, later tip burn
Plane Platanus sp. Leaf Dense to sparse purple/reddish stipple of upper surface, bounded by smallest veins
Poplar Populus sp. Leaf Dark brown bifacial necrotic lesions
Silver birch Betula pendula Leaf Bleaching of upper surface except at margins
Snowberry Symphoricarpos albus Leaf Bleaching of upper surface except at margins
Spinach Spinacea oleracea Leaf Dull white/tan lesions; large bifacial necrosis
Tobacco Nicotiana tobacum Leaf Numerous small white/tan bifacial lesions on upper surface, larger and more on more sensitive varieties
Weymouth pine Pinus strobus Needle Chlorotic flecks, later pink lesions and then orange-red tip necrosis
Wheat Triticum vulgare Leaf Fine chlorotic/white/tan streaks between large veins, more at leaf bendings & seedling tips/margins
Salts pollution Hawthorn Crataegus monogyna Branch Tip-dieback
Maple Acer sp. Leaf Yellow necrosis
Poplar Populus sp. Leaf Abscission
Willow Salix sp. Leaf Brown necrosis
So2 pollution Apple Malus sylvestris Leaf Reddish necrosis; red discolouraion
Azalea Rhododendron sp. Leaf Reddish necrosis
Beech Fagus sylvatica Leaf Brown/orange necrosis; red discolouraion; necrotic stipple
Begonia Begonia sp. Leaf Shot holing
Blackberry Rubus fruticosus Leaf Brown necrosis
Bracken Pteridium aquilinum Frond Orange/red marginal necrosis
Broad bean Vicia faba Leaf Black necrosis
Cabbage Brassica oleracea var. capitata Leaf Red discolouration around necrotic areas
Carrot Daucus carota Leaf Tip necrosis
Cherry Prunus avium Leaf Red discolouraion
Chrysanthemum Chrysanthemum sp. Leaf Brown necrosis
Corn Zea mays Leaf Red discolouration
Daffodil Narcissus pseudonarcissus Leaf Light brown necrosis; sharp band between necrotic and healthy tissue
Dandelion Taraxacum officinale Leaf Brown necrosis
Fir Abies sp. Old needle Immediate abscission
Fir Abies sp. Middle age needle Sharp boundry between necrotic and healthy tissue ater 3 wks of exposure
Fir Abies sp. Young shoot Twist
Fuschia Fuschia hybrida Leaf Distortion, puckering, curling
Geranium Pelargonium sp. Leaf Distortion, puckering, curling; grey necrosis
Gladiolus Gladiolus sp. Sepal Tip necrosis
Gooseberry Ribes uva-crispa Leaf Red stipple on upper surface; tip necrosis
Hazel Corylus avellana Leaf Brown/orange necrosis
Hydrangea Hydrangea macrophylla Leaf Red discolouration around necrotic areas
Larch Larix decidua Middle age needle Necrosis
Lettuce Lectuca sativa Leaf Dark spots on lower surface; shot holing
Lily of the Valley Convallaria majalis Leaf Sharp band between necrotic and healthy tissue
Lime Tilia cordia Leaf Brown/orange necrosis
Lucerne (alfalfa) Medicago sativa Leaf Bronzing of lower surface
Lucerne (alfalfa) Medicago sativa Leaf Ivory necrosis
Maple Acer sp. Leaf Distortion, puckering, curling
Marigold Tagetus sp. Sepal Tip necrosis before leaf injury
Marigold Tagetus sp. Leaf Large, bifacial necrotic spots on margin; distortion, puckering, curling
Oak Quercus rubur (Q. pedunculata) Leaf Ivory necrosis
Oats Avena sativa Leaf Ivory necrosis
Parsley Petroselinum crispum Leaf Tip necrosis
Pea Pisum sativum Leaf Ivory necrosis
Pear Pyrus communis Leaf Black necrosis
Pine Pinus sp. Terminal bud Necrosis
Pine Pinus sp. Young needle Chlorosis
Pine Pinus sp. Middle age needle Sharp boundry between necrotic and healthy tissue ater 3 wks of exposure
Pine Pinus sp. Old needle Abscission after several months
Pine Pinus sp. Young shoot Necrosis
Poplar Populus sp. Leaf Reddish necrosis
Raspberry Rubus idaeus Leaf Marginal necrosis
Red currant Ribes rubrum Leaf Red stipple on upper surface
Rose Rosa sp. Leaf Red stipple on upper surface
Rowan Sorbus aucuparia Leaf Ivory necrosis
Silver birch Betula pendula Leaf Distortion, puckering, curling
Silver birch Betula pendula Leaf Ivory necrosis
Spinach Spinacea oleracea Leaf Shot holing
Spruce Picea sp. Middle age needle Necrosis
Strawberry Fragaria vesca Leaf Red discolouration around necrotic areas; brown necrosis
Sweet William Dianthus barbatus Leaf Tip necrosis
Tulip Tulipa gesneriana Leaf Ivory necrosis
Violet Viola sp. Leaf Ivory necrosis
Wheat Triticum vulgare Leaf Red discolouration
Willow Salix sp. Leaf Ivory necrosis
Zinnia Zinnia angustifolia Leaf Ivory necrosis

August 11, 2008

PLANTS AS AMELIORATORS (MITIGATORS) OF POLLUTION

Filed under: Environment — gargpk @ 1:02 pm
Tags:

Many types of higher and lower plants and microorganisms have the capability to tolerate and absorb large amounts of gaseous, liquid and solid pollutants from the environment and decompose them into harmless substances. This ability of such organisms can be usefully exploited in the control of environmental pollution.

Plants cover about one third of the land area as forests and grasslands and another one third as agricultural crops. Large surface area of ponds, lakes, rivers and sea coasts is also covered with aquatic flora. All this vegetation provides huge surface area that can be gainfully used to trap pollutants from the environment. In this large vegetational cover, those plant species that can absorb large quantities of pollutants and accumulate them in their tissues without damage (tolerant-accumulator species) provide natural storehouses or sinks of various pollutants without any cost. Such plants are very important resource materials in environmental pollution control strategies. Generally, woody plants absorb more pollutants than herbaceous plants. Actively growing tissue of wood absorbs larger amounts of pollutants than dormant tissues. Therefore, trees are comparatively more useful than herbaceous plants in pollution control.

Use of tolerant-accumulator plats in the control of air and soil pollution involves:

  1. Identification of pollutant(s) present in the area,
  2. Identification of tolerant-accumulator plant species suitable for the climate and the pollution problem of the area and then
  3. Plantation of identified plant species in the area on available bare lands, fallow lands, community lands, waste lands, along roads, railway lines, canal banks as well as green belts, shelter belts, wind breaks, city forests, parks etc.

Trees reduce the velocity of air passing through them thus facilitating the absorption of pollutants by the foliage. Establishment of tolerant-accumulator epiphytic mosses and lichens on the trees may also help in absorption of pollutants. Many microorganisms that can degrade pollutants to harmless substances are also established on the leaves as phyllosphere. Many plants absorb pollutants from the soil and thus check their runoff into water bodies or their leaching into the groundwater.

Use of plants in the control of water pollution mostly involves treatment of sewage an industrial effluents before their release into lakes or rivers and treatment of polluted water bodies. Introduction and maintenance of accumulator aquatic plants like Eichhornia, Azolla, Cladophora, Fontinalis squamosa etc. in the ponds is very effective in cleaning polluted water and keeping them free of organic, chemical and metal pollution. Most important sewage and effluent treatment systems using plants are:

Peat moss treatment systems: Many types of systems have been designed to treat urban sewage and industrial effluents using Sphagnum moss. These can treat upto 91,000 litres of effluent per day. Effluents are passed through columns containing the moss, which absorbs metals and the used up moss is then destroyed. Pre-treatment of moss with CaCO3 increases the metal absorption.

Eichhornia treatment systems: Diluted sewage or industrial effluent is passed through a zig-zag system of ponds and canals in which Eichhornia plants are grown. These plants asorb pollutants and retain them in their rhizomes. Plants from these hyacinth lagoons are regularly harvested and can be used to produce biogas in suitable digesters or after extraction of absorbed metals, can be used in making paper, boards etc. In the lagoons, the growth and death rates of plants are continuously monitored and managed by regulating the dissolved oxygen, biological oxygen demand and chemical oxygen demand, pH, turbidity and conductivity of the water at different stages of cleaning.

Microbial treatment/biogas systems: Treatment systems for organic sewage use suitable aerobic/anaerobic decomposer bacteria, ammnifying and sulphur bacteria in anaerobic lagoons. The organic matter in he polluted water is decomposed producing methane and carbon dioxide. In such systems, combination of decomposer bacteria and algae like Spirulina, Scendesmus, Clorella etc. can also be used. The decomposed organic matter is used up by algal growth. These protein-rich algal cultures can be regularly harvested and used as cattle feed. In the biogas systems, anaerobic bacterial decomposition of organic matter produces combustible gas. The freed metals and other pollutants are removed and clean effluent is used as rich fertilizer.

Many bacteria can absorb metals (e.g. Thiobacillus ferrooxidans and T. thiooxidans absorb copper), degrade petroleum oil (Pseudomonas sp.) or other chemicals. Genetic engineering is being applied to create new and more efficient strains of bacteria for use in mining and industries to control metal pollution, to clean oil spills, to degrade herbicides and pesticides in the soil and to absorb SO2 from chimney gases before their release into the atmosphere. Pseodomonas, Staphylococcus and a cornybacterium that accumulate metal bearing particles like silver, Aspergillus and Penicilium that concentrate uranium and phosphate are examples of such useful bacteria. Sulphur bacteria like Chlorobium, Chromatium and Thiospirillum may be helpful in control of SO2 pollution of air.

August 4, 2008

PLANTS AS INDICATORS AND MONITORS OF POLLUTION

Filed under: Environment — gargpk @ 1:03 pm
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Plants can effectively be used as cheap and naturally available monitoring systems or bioassays of the level and type of air, soil and water pollution in an area. The type and concentration of a pollutant can be reliably found out by various characteristics damage symptoms produced in the plants because such damage symptoms are pollutant specific as well as concentration specific. For example, in young needles of Pinus, chlorois indicates SO2 pollution, necrosis indicates HF pollution, beaching indicates NO2 pollution while chlorotic mottle indicates Cl2 pollution in the atmosphere. These characteristic symptoms of damage in young pine needles appear only when concentration is 0.3 ppm for SO2, 0.07 ppm for HF and 1.0 ppm for Cl2. Similarly, browning in moss leaves due to fluoride accumulation is 5% in 65 ppm dry weight accumulation but rises to 90% in 4500 ppm dry weight accumulation. However, certain precautions have to be taken while using plants as pollution indicators.

Precautions in use of plants as pollution indicators

  1. The damage symptoms in plants should preferably be studied in the local native species. Cultivated and introduced species should be avoided.

  2. The species sensitive to pollutants should be first identified in the local flora and then used for pollution monitoring. Tolerant species should be identified and avoided in such work.

  3. Damage symptoms for a particular pollutant should be studied in different species sensitive to that pollutant so that presence of the pollutant in the area may be cross-checked. For example, grey necrosis in Geranium, ivory necrosis in Zinnia, brown necrosis in Chrysanthemum and reddish necrosis in Azalea indicates absolutely certain presence of SO2 pollution in the area.

  4. Many types of damage symptoms viz. morphological, anatomical, ultra-structural physiological, biochemical etc. should be studied in one or more sensitive plant species to ascertain the presence of a particular pollutant in the area.

  5. Samples should be taken from as many different sites in the area as possible. From such data the extent of pollution can be determined and the possibility of symptoms being due to some pathogen is also excluded because the intensity of damage symptoms due to pollution varies in different sites according to the distance from the source of pollution while it is same in all sites in case of a pathogenic disease.

  6. The possibility of damage symptoms in plants occurring due to some cause other than pollution e.g. due to pathogen, environmental condition or nutritional deficiency/excess should be thoroughly checked and ruled out.

Important characteristics of plant species used in pollution monitoring

The plant species used to monitor pollution in an area should have certain important features for the success of such programme. Most important such features are:

  1. Species should be easy to identify in the field and easy to handle for damage analysis.

  2. Species should have a wide range of distribution so that it can be used in different areas.

  3. Species should be sensitive to many types of pollutants so that it can be used to monitor different types of pollutants in the area.

  4. Species should produce highly specific damage symptoms in response to particular types and concentrations of pollutants.

Plants commonly used as pollution indicators

Though all types of sensitive species can be used in monitoring pollution, most useful and commonly used plants include sensitive species of lichens, mosses, plankton algae, aquatic ferns and angiosperms, other ferns, conifers oaks and many crop plants. Mosses, lichens, ferns algae and aquatic plants are generally more useful in pollution monitoring because their range of pollutant specificity is usually much higher than that of higher vascular plants. Examples of some common types of plants useful as pollution monitors are given below.

Plant type

Plants

AIR & SOIL POLLUTION

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