1. PLANTS UNDER STRESS

2. desert
Arid zone
Salty soil
Antarctic region

3. What is Stress?
• A significant deviation from the conditions
optimal for life, and eliciting changes and
responses at all functional levels of the
organism.
• Two ways
Temporary stress
Permanent stress

4. What Happens During Stress?

5. How to Recognize Stress
Effects of Stress
1. Stressor-specific effect
involve a well- defined target within the
plant.
Ex. Intense radiation causes direct damage to the thylakoid
membrane
2. Non- specific effect
Stress responses within the plant is carried out
by phytohormones.

6. How to Recognize Stress
• Non- specific effects of stress
a. Alterations in membrane properties
(membrane potential, transport of substances)
b. Increased respiration
c. Inhibition of photosynthesis
d. Growth disturbances
e. Lower fertility
f. Premature senescence
g. Decrease of availability of energy

7. How to Recognize Stress
• Intracellular decrease in availability of energy.
(Due to metabolic impairment)
• Less ATP is formed.
• It can be calculated as an Adenylate Energy
Charge(AEC).
AEC = (ATP)+ 0.5(ADP)
(ATP)+(ADP)+(AMP)
• AEC < 0.6 indicates deterioration in the vitality
of a plant, and a plant under stress.

8. Survival of Stress
• Survival = Stress evasion, Resistance, Recovery

9. Natural Environmental Constraints
• Environmental stress factors
1. Abiotic factors – mainly include
climatic factors.
2. Biotic factors – Due to activity of
animals, microorganisms or human beings.

11. Multiple Stresses
• In nature frequently multiple stresses are
involved.
Ex. Stress arise due to combination of strong
radiation, overheating, drought in open
habitat.

12. Radiation Stress
• Two ways of radiation stress
1.Excessive quantities of photosynthetically
active radiation.
2.increased absorption of UV radiation.

13. Light Stress
• Strong light presents the leaf with more
photochemical energy than can be utilized for
photosynthesis.
• Overloading of the photosynthetic process.
• Extremely high irradiance destroys
photosynthetic pigments and thylokoid
structures is called “photodamage”
• Shade plants may be damaged breif exposure
of strong light.

14. Light Stress
Conostomum tetragonium exposed to the high light intensity

15. Photoinhibition
• Inhibition of photosynthesis caused by
excessive radiation.
• Strong light attack photosystem II
• Brake down of Protein sub units
• Photosynthetic electron transport is
interrupted.
• Reduce efficiency of photosystem II

16. Photoinhibition
As an protective measure,
• Excessive radiation energy is diverted to
fluorescence and heat.
• Surplus reductive capacity in chloroplast is
used by “Xanthophyll Cycle”

17. Xanthophyll Cycle
Thylakoid membrane
Lumen Stroma

18. A moss quenches high light energy with the pigment zeaxanthin.

19. a) Pellia endiviifolia did not
experienced a rise in de-
epoxidized Xanthophyll.
Liverworts
b) Flullania dilatata was a rise
in the concentration of de-
epoxidized xanthophylls
that can protect cell from
chlorophyll damage
a)
b)

20. Adaptation to Stress from Strong Light
• Positioning leaves at an angle to the incoming
light- Receive less radiation.
• Rolling up the shoots (mosses, pteridophytes)
• Dense coverings of trichomes on the upper
surface of the leaf.
• Thickened walls in the epidermis and hypodermal
tissue-act as diffusive filters (conifer needles &
cacti)
• Presence of Anthocyanin- act as darkening filters
& shields the mesophyll.

21. Ultraviolet Radiation
• Two types of UV radiation
UV-A (315-400nm)
UV-B (280-315nm)
• UV-A is mainly photooxidative.
• UV-B is in addition to photooxidative action
causes photolesions in biomembranes.

22. UV Damage
• Breaking down the disulfide bridges in protein
molecules.
• Dimerizing thymine groups of DNA- results in
defective transcription.
• Xanthophyll cycle is disrupted by inhibiting the
violaxanthine-deepoxidase

23. UV Damage
Can be identified by
• Changes in enzyme activity (increased
peroxidase activity, inhibition of cytochrome
oxidase).
• Poor energy status of the cell.
• Lower photosynthetic yield.
• Disturbed growth (reduced extension growth
& pollen tube elongation).

24. PLANT STRESS DUE
TO EXTREME
TEMPETURES
24

25. KINETIC ENERGY OF MOLECULES= HEAT
KINETIC
ENERGY OF
MOLECULES
HIGH ENERGY
LOW ENERGY
HEAT
COLD
25

26. Temperature balance on earth by,
Solar radiation
air current
Heat and Cold effect
• Metabolic activity
• Growth
• Viability
• Distribution,
of a plant.
26

27. Critical temperature Thresholds
• Activity limit
(5-25 0C)
• Lethal limit
– Cold
– Heat
27

28. 28

29. Heat
Highest temperature on earth- 80oC
Lethal limit- 40-70oC
High temperatures arise by,
• Higher solar radiation
• Volcanic phenomena
• Hot pools
• Fires
29

30. Functional disturbance of heat
• Damage physiochemical state of bio
membranes and the conformations of protein
molecules.
– Disturbance in photosynthesis
– Disturbance in transport
– Disturbance in mitochondrial respiration
30

31. Heat Tolerance
• Evasion of strong sunlight
– Thick cutine layer
• Heat insulating bark
– Thick fibrous bark
– Rough suberized bark
– Silica in cell walls
– Peripheral cambium layer
• Dense leaf sheaths covering the basal buds
• Withdrawal to underground organs
• Transpirational cooling
31

32. Most effective form of heat
protection is provide by,
Heat shock proteins
32

33. Type of heat resistance
Three types
• Heat sensitive species
• Relatively heat resistant eukaryotes
• Heat tolerance prokaryotes
33

34. Cold
lowest temperature on earth= -90oC
Lethal limit= +5 - -90oC
low temperatures arise by,
• Low solar radiations
34

35. Functional disturbance of cold
Above the freezing point
By Decrease the speed of chemical reactions
• Uptake of water and nutrients restricted
• Less metabolic energy
• Less biosynthesis
• assimilation reduced
• Growth stops
35

36. The first main detectable result of
low temperature is,
cessation of cytoplasmic
streaming
36

37. Mostly effect on chilling sensitive
plants. It happens in stepwise
37
Primary effect:-
LIQUID CRYSTALINE BIO MEMBRANES → SOLID GELL
Initial reversible processes:-
DAMAGE TO THE FUNCTIONALITY OF ORGANS
CLOROPLAST- INHIBIT PHOTOSINTHESIS
MITOCHONDRIA- INCREASE RESPIRATION
Final irreversible processes:-
INSUFFICIENT CARBOHUDRATES
IMPAIRED ION BALANCE
IMBALANCE IN METABOLISM
ACCUMILATION OF TOXIC SUBSTANCES
INJURY AND DEATH OF CELLS

38. Type of chilling sensitive plants
• Partially sensitive plants
• Totally sensitive plants
38

39. Below the freezing point
FROST OCCUR PERIODICALLY AND
EPISODICALLY ON EARTH
by the ice formation
• Cytoplasm destroy by ice crystals
• Block the vascular bundles
• Ice nucleation active bacteria attack
39

40. By ice formation less water in the
plant = Desiccation condition
arise
40

41. It results,
• Unfrozen solution reach abnormally
high concentration
• Toxic effect
• Enzymes get inactive
• Bio membranes are overtaxed both
osmotically and by the volume reduction
41

42. Freezing of cells
• intercellular • Extracellular
42

43. Low temperature tolerance
• No thermal insulation (no heat losses)
– Dense growth surrounding the regenerative buds
– Giant rosette
• Abscission of sensitive organs
• Depression of freezing point
• Super cooling
• Trans located ice formation (extra tissue
freezing)
43

44. Categories of cold resistance
• Chilling sensitive plants
• Freezing sensitive plants
• Freezing tolerance plants
44

45. EVOLUTION OF VASCULAR PLANTS
FOR FROST
Happen in a stepwise process
45
First step:
COLD ADAPTATION OF ENZYMES AND MEMBRANES
Second step:
IMPROVING THE SUPERCOOLING CAPACITY

46. Survival capacity
• Younger plants are more sensitive
• Reproductive organs are more sensitive
• Underground organs are also quite sensitive
• Above ground shoot is the least sensitive part
46

47. Winter desiccation
Winter conditions may result in damage due to
desiccation.
This happen by,
• Frozen soil
• Snow and ice
47

48. Effects of winter desiccation
• Plants can not take up enough water and
nutrient
• Loss water by stomatal transpiration
• Xylem transpiration make cavities of the water
columns in the conducting vessels
• Block the passage of water through the xylem
• Chronic damages in plant tissues
48

49. Harmful effect of long periods beneath
ice or snow
• Low CO2 and O2 permeability of ice sheets
• Stop the gas exchange of plant
• Respiratory CO2 increase and O2 decrease with
in the plant
• Hypoxia
• Toxic substances accumulate
• Pathogenic effect
49

50. Oxygen Deficiency in the Soil.
Drought
Salt Stress

51. Oxygen Deficiency in the Soil.
Lack of sufficient oxygen in the soil.
Extensive areas of land are temporarily inundate by
flood waters of large rivers, small rivers or streams
repeatedly overflow their banks.
the plants cover of valley soils is often buried of long
period of times.
Soils are compacted and become impermeable as a result
of construction activities.

52. The soil atmosphere is low in Oxygen in any
case,
Anaerobic microorganisms take over .
Creating a strongly reducing milieu which Fe2+ ,Mn2+
, H2S, Sulphides ,Lactic acid ,Butyric acid are present in
toxic concentration.
Nitrogen turnover in the soil.

53. Functional Disturbances and Patterns of
Injury
roots are capable of respiring anaerobically,
continuous for some hours irregularities in metabolism
occur.
partial pressure of Oxygen drops to 1-5 kPa (Hypoxia)
Alternative respiratory pathway is activate.
The energy status of the adenylate system drops
substantially.

54. Root growth stops.
Root tips entering the low Oxygen zone die off
Adventitious root developed.
Older part of the root systems often develop corky
intumescences and swollen lenticels.

56. Total and near total Oxygen deficiency (anoxia)
Respiration switches to anaerobic dissimilation
In the absence of terminal oxidation
Acetaldehyde and ethanol accumulate.
Abscisic acid, ethylene and ethylene precursors are
formed in larger amount.
Evoking in the leaves partial stomatal closure.
Epinasty and often abscission.
Cellular membrane systems brake down.
Mitochondia and microbodies disintegrate and their enzymes
are partially inhibited.

57. Fig. 6.51

58. Surviving Oxygen Deficiency
Many plants can germinate, roots and grow in oxygen deficient
soil because they have developed certain adaptations to meet
conditions in an toxic environment.
Functional adaptation Morphological
adaptation

59. Functional adaptation
increase in alcohol dehydrogenase (ADH) during
anaerobiosis.
Protein metabolism is adjusted within a few hours
after gene activation

60. Morphological adaptation
A hypoxic milieu consist in the development in ventilating
tissue (aerenchyma) with a continuous systems of
intercellular spaces.
The volume of intercellular system in the root parenchyma,
swamp plants – 20%-60%
well-aerated plant – <10%
Well aerated roots may even loss oxygen to the surrounding
soil, It can detoxify harmful reducing substances :
Fe2+ Fe111- oxide.
Aeration is also furthered by temperature gradients.

61. Plants growing on very dense and poorly aerated soils develop
a system of laterally spreading roots near the surface.
In the flooded regions submerged parts of trunks and
branches put out dense bundles of water roots.
poplar, willow, alder, ash

62. In mangrove plants,
In the form of lenticels-covered respiratory roots
(pneumatophores) with a large amount of aerenchyma.
Knee roots that produced above the surface of the soil and
standing water.

63. Drought
A period without appreciable precipitation, during with the
water content of the soil is reduced to such an extent that
plants suffer from lack of water.
Low precipitation and high evaporation.
Strong evaporation caused by dryness of the air and
high levels of radiation.

64. The dry region of the earth

65. Functional disturbance and patterns of Injury
Decrease in turgor and a slowing down of growth process
Decrease in cell volume
Most strongly inhibited enzyme is nitrate reductase.
plants that have been treated with nitrogen containing
fertilizer in drought.
Nitrogen fixation is more sensitive to drought.
Increase in concentration of the cell sap.
Progressive dehydration of the protoplasm

66. Protein metabolism and synthesis of amino acids are
impaired.
Supresses cell division
Slow down mitosis- S phase being affected most.
During pollen development, the meioses exhibit
chromosome anomalies- specially metaphase and anaphase.
Drought lower pollen fertility.

67. During drought,
Initiate stomatal closer
Under the influence of hormone synthesized in the
leaves and roots in response to drought
Changes occur in the allocation of assimilates
The ratio of shoot to roots growth is altered
Characteristic morphogenetic features develop
Reproductive processes become predominant
Senescence is accelerated
Older leaves dry out and shed

68. In wilt,
The reduction of cell volume
Increasing concentration of the intercellular solutes-ions
In the final phase preceding cellular disruption
The central vacuole splits up into small fragmentary
vacuoles
The thylakoids in the chloroplasts and the mitochondrial
cristae first of all swell and are later break down
The nuclear membrane becomes distended and the
polyribosome disintegrate
Drought stress in tobacco

69. Fig. 6.62

70. Survival of Drought
Drought resistance
the capacity of a plant to withstand period of dryness, and is
a complex characteristics.
xerophytes

71. Desiccation Avoidance
desiccation is delayed by all those mechanisms
that enable the plant to maintain a favorable tissue water
content as long as possible despite dryness of air and
soil.
uptake of water from the soil
reduced loss of water

72. Water uptake
extensive root system with a large active surface area is
improved further by rapid growth into deeper soil layer
the seedling of woody plants in dry regions may have
tap roots ten times as long as the shoot
grasses in such places develop a dense root system and
send their threadlike roots to depths of some meters.

73. Fig 6.64

74. Reduction of transpiration
Modulative adptation
timely closure stomata
when leaves growing under conditions of water
deficiency develop smaller but more densely distributed
stomata.

75. Fig 6.65

76. The leaves have more densely cutinized epidermal walls
Covered with thicker layer of wax.
Stomata are present only on the under side of the leaves
smaller
often hidden beneath dense hair or in depression
Boundary layer resistance is increased and the air outside the
stomata become moisture
Rolling the leaves

77. Salt stress
Salt stress may have be a first chemical stress
factor encountered during the evolution of life on earth.
Saline habitats
the presents of an abnormally high content of
readily soluble salt
Aquatic saline habitat: Oceans, salt lakes, saline ponds
In land: saline soil

78. Effect of high salt concentration on plants
The burden of high salt concentrations for plant is due to
osmotic retention of water and to specific ionic effect on
the protoplasm.
An excess of Na+ and Cl- in the protoplasm lead to
disturbance in the ionic balance
Ion specific effects on enzyme protein and
membrane.

79. Too little energy is produced by photophosphorylation
and phosphorylation in respiratory chain
Nitrogen elimination is impaired
Protein metabolism is disturbed
Accumulation of diamines such as putrescine
cadaverine,polyamines

80. Functional disturbance
Photosynthesis is impaired
Stomata closure
Effect of salt in chloroplast in particular on electron
transport and secondary process
Respiration increased or decreased – root
Enzyme system of glycolysis and the tricarboxylic acid
cycle are more sensitive than alternative metabolic
pathways.
When the NaCl content of the soil is high the uptake of
mineral nutrients NO3
- , K+ , Ca2+ is reduced.

81. Extreme salt stress
Inhibition of root growth
Bud opening is delayed
Shoot are stunted
Leaves are small
Cell die and necrosis appear in roots, buds, leaf margins and
shoot tips
The leaves become yellow and dry before the growing
season has ended and whole portion of the shoot dry out.
Lower level of cytokinin
Increased abscisic acid senescence

82. Survival of Saline habitats
plant growing in saline habitat cannot evade the
effects of salt and must therefore develop at least some
degree of resistance to it.
Salt resistance is ability of a plant either to avoid,
salt regulation
excessive amount of salt from reaching the
protoplasm
to tolerate the toxic and osmotic effect associated
with the increased ion concentration.

83. Regulation of the salt content
1. Salt exclusion: In some mangrove- transport barriers of the
roots prevent the salinity of the water in the conducting
system from becoming too high.
Prosopis farcta
crop plants
halophorbic species
2. Salt elimination : A plant can rid itself of excess salt ,
releasing volatile methyl halides –
 exclusion by glands
 excretion of salt at the shoot
 shedding parts heavily loaded with salt
marine phytoplankton
macro algae

84. 3. Salt redistribution:
Na+ and Cl- can be readily translocated in the
phloem , so that the high concentration arising in actively
transpiring leaves can be diluted by throughout the plant.
4. Salt tolerance : the protoplasmic compartment of
resistance to salt stress.

85. Anthropogenic stress
Man made pollutants and their impact on the
phytosphere.
Due to human activities plants exposed to greater
amounts of harmful substances.

86. Human activities…
• Results of industrial processes.
• Traffic.
• Chemicals used in agriculture and household,
fertilizers, pesticides.
• Excessive consumption of fossil fuels-
emmission of green house gases.
• Catastrophic accidents-nuclear reactor
activities, oil spills.

87. • Pollutant
A contaminant of air, water or soil that has an
adverse effect on an organism.
1.Naturally occurring pollutants
2.Anthropogenic pollutants
Instead of one pollutant activity combined
activity of pollutants.
Ex: Photo oxidant complex + SO2 (g),+ heavy
metals

88. Naturally occurring harmful substances in higher
concentrations.
• SO2 (g),NO2 (g),H2S (g),O3 (g)
• Dust.
• Heavy metals.
Ultimate result is environmental stress.
Ecosystems
Countries
Continents
Entire globe

89. • High input of pollutants within a short period
of time = acute damages
• Exposure to low concentrated pollutants for a
longer period of time = Chronic damage
Pollution Injury
The extent which vital(physiological &
biochemical) functions are affected.

90. Visible damage depend on many
factors of the plant.
1. Plant species.
2. Growth form.
3. Age of the plant.
4. Phase of activity.
5. General vigour(physical strength & good health.
6. Climatic and edaptic condition.
7. Chemical nature.
8. Concentration of the pollutant.
9. Time and duration of the action of the pollutant.

91. Air born pollutants
• SO2 (g),NOx (g), PAN (peroxyacetyl
nitrate),Hydrogen
helides, NH3(g), hydrocarbons, tar
fumes, soot, dust.
Symptoms of damage
• Non specific.
• Many symptoms interact with other plant
stress factors.

92. • At noon stomata are fully open atmospheric
pollutant concentration is high in noon
damage is higher.
• At night plants recover from the injurious
immisions.

93. Early recognition of pollution damage
1. Accumulation of toxic compounds/substances in the
plant tissues.
2. Reduction of buffering capacity of tissues.
3. Erosion of epicuticular wax .
4. Decreation /incretion of certain enzyme activities.
5. Qualitative and quantitative shifts among
metabolites.
6. Appearance of stress hormones– Ex: ethylene
7. Respiration incretion/decreation
8. Photosynthetic disturbance.
9. Alteration of stomatal opening and closure.
10. Diminished allocation of photosynthetes to the root
system.

94. When the pollutant in immediate
vicinity..
1. Occurrence of chlorosis.
2. Leaf discoloration.
3. Tissue necrosis.
4. Death of entire plant.
•Reduce productivity and
defective fertility.
•Less growth in cambial tissues.
•Foliage become sparser.
•Water transpiration interfered.

95. SO2 (g) –cause most of the damage
Natural sources-volcanic emissions, S containing
ores, biological decay and forest fires.
Man-made sources-fossil fuel combustion,
smelting, manufacture of sulfuric acid.
SO2 (g) is there in the environment since the plants
beginning.-Plants have been adapted to tolerate
SO2 (g) for some extent.
Entry into plants.
1. Enter the leaf through opened stomata.
2. By over-coming the cuticular resistance.(if the
stomata are closed)

96. Damage by SO2 (g)
SO2 (g)
low external
concentration
Trigger a loss of turgor in
epidermal cells
Stomata open
Transpiration high
• High external
concentration
• Stomata closure
• Low transpiration

97. • SO2 (g) diffuse similar as CO2 (g) .
Atmospheric SO2 (g)
Dissolved in guard cell wall water SO2 (g) +H2O(l)
HSO3
-
(aq) + SO3
2-
(aq)
Chloroplast: Cytosol: Vacuole
96 : 3 : 1

98. Sulphur compounds
(SO2(g),H2S (g) )detoxification
01.) SO3
2-
(aq) SO4
2-
(aq)
SO3
2-
(aq) remaining will effected by the
photosynthetic sulphur metabolism
Covert to sulphur containing amino
acids.(cysteine, methionone)
Call wall peroxidases.

100. Harmful effects of SO2 (g)
1. SO3
2-
(aq) Level in chloroplast rise.
2. SO2(g) ,occupies binding sites in RUBP
carboxylases.
secondary process of photosynthesis inhibits.
3.The tertiary structure of the enzymes are
disturbed.
4. SO3
2-
(aq) SO4
2-
(aq)
Super oxide radicals generate, if not excluded
rapidly chlorophyll will be destroyed.
photooxidation

101. Mechanisms of resistance of SO2 (g)
stress
* can be passive or active processes
Passive
Non specific, not usually related
to a particular pollutant.
1. Regular development of new
leaves with short functional
life span.
Ex:
deciduous
woody plants
• Thallophytes also have
structural, chemical
characteristics reduce the
entry of SO2
Active
Stressor specific processes.
1. High buffering capacity-from
increased uptake of alkali &
alkali earth cations.
2. Binding to 2ry products of
metabolism.
3. Metabolic use of Sulphur and
detoxifying oxidative
reactions.
4. C4 syndrome.
Ever
green
trees with
needles

102. Ever green tree s with needles Deciduous woody plants

103. C4 syndrome
C4 grass
1.Miscanthus sinensis
2.Andropogon virginicus
Moderate resistant C3
1.Polygonaceae
2.Metrosideros collina in Hawaii
Some plants have the
ability to grow in the
vicinity of volcanic
vents

104. Species-specific sensitivity to immissions.
• Different species
• Individual varieties and ecotypes
• Different life stages
SO2 (g) Resistant plant species introduce to
polluted areas.
Highly sensitive plants to SO2 (g) Indicator
organisms to
indicate SO2 (g)
pollution.

105. Atmospheric oxidants and secondary
photooxidants.
• O3(g) ,NOX(g) (NO(g) ,NO2(g)),peroxy radicals.
• NO2(g) NO(g) + O.
(g)
• O.
(g) + O2 O3(g)
• NO(g) + O3(g) NO2 (g) + O2(g)
Peroxy radicals +
hydro carbon compounds
UV 300-400 nm
Peroxyacetyl nitrtes.
Peroxybutyl nitrates.
Peroxybenzyl nitrates.

106. Uptake by the plant
• Through opened stomata.
• NO2(g) diffuse through cuticle, much faster
than SO2(g) .
• O3 (g) dissociate to O2(g) in the outer wall of the
epidermis.
• NO(g) ,NO2 (g) NO3
-
(aq) ,NO2
-
(aq) with water
taken up actively by living cells

107. Events within the cell.
• NO3
-
(aq) amino acids.
* SO2 (g) inhibit the action
of Nitrite reductase.
• Additional source of nitrates-advantageous.
• Acidification of cells/leaves-disadvantageous.
Nitrite reductase enzyme
Toxicity of nitrates

108. O3(g)
• O3(g) O2(g) + O.
• Peroxides,
-effect on plasma membrane.
-other bio membranes.
Transfer process
impaired.
Necrosis,growth
reduction,less
yields

109. Heavy metal
contamination of soil,
water
Create long term problems
metals = Zn,Pb,Ni,Co,Cr,Cu
Metalloids = Mn,Cd,Se,AS
Accumulation in
organisms, circulate
in food chains.

110. Common heavy metal sources
1. Industrial zones.
2. Heavy vehicle traffic.
3. Sewage sludge.
4. Emissions of dust from metal processing
industries.
5. Waste water-Cd,Zn,Fe,Pb,Cu,Cr,Hg

111. Uptake and toxic effects
• Uptake is mainly by roots.
-can’t stop the enter of heavy metal completely.
-need to plants as micro elements.

112. Toxicity due to..
1. Interference with electron transport in
respiration an photosynthesis.
2. Inactivation of vital enzymes.

113. Possible mechanisms of resistance
• Natural heavy metal exposures, plants growing on,
a. Metal ores.
b. Serpentine soils.
c. Strongly acidic soils.
Adaptations.
1. Immobilization in cell wall.
2. Obstruct permeation across the cell membrane.
3. Formation of chelates.
4. Compartmentalization in vacuoles.
5. Active export.

115. 6. Characteristic patterns of iso-enzymes-
element specific resistance.
7. Genetic plasticity, with several resistance
genes-resistant to several heavy metals.
*these plant can be used to re-vegetation of strongly
heavy metal contaminated area.
Ex:
Agrostis tenuis Festuca ovina Silene vulgaris

116. Bioindicators of pollution impact
• Bioindicators are organisms or communities of
organisms that are sensitive to pollution stress and
respond by alteration in their vital processes or by
accumulation of the pollutant.
Bioindicators
•Indicator organisms- respond to their
surroundings, depending on their specific requirements
•Test organisms- high degree of sensitivity to certain
pollutants.
•Monitor organisms- specific responses to pollutants can be
con be used for qualitative & quantitative detection of
stress situations.

117. Indicator organisms

118. Accumulation of heavy metals influenced
by ..
1. Meteorological factors
2. Edaphic factors -Influenced by the soil rather than by the
climate.
3. Habitat related factors- growth form and rooting pattern.
Heavy metal indicators= metallophytes.
Ex: Eichhornia crassipes

119. Reasons for forest decline
1. Ageing of the stand.
2. Episodic damage by pests.
3. Extremes of climate.
4. Inappropriate management.
5. Interruption of mineral recycling.
6. Exhaustion of soil nutrients.
7. Toxicity caused by identifiable local emitters.

120. forest decline
• Depend on the,
1. Tree species.
2. Growth form.
3. The site.
4. Type of the soil.
5. Geological origin.
6. Superimposition of various stress types.

121. Symptoms of forest decline
1. Anomalous growth.
2. Discoloration of needles and leaves.
3. Necrosis of isolated areas of needles, leaves,
branches.
4. Shedding of leaves.(thinning of crown, bareness
of the hanging branches).
5. Dieback of leader and branch tips.
6. Increasing the shallowness of the root system.

123. Causes of forest decline.
• Acidic effect of precipitations.
Direct acid damage
1. necrosis of margin of leaf
2. destruction of the cuticle and cuticular waxes.
3. acidification of the apoplast– affect the distribution
of phytohormornes.
4. fine root chromosome anormalities during cell
division.
5. cells damage dissolution of cell walls tissue
disruption.

124. Effect of atmospheric pollutants on the
ecosystems and at the global level.
1. Acid precipitations

126. Green house effect
• provides temperature necessary to support
the life on earth.
• Green house gases
1. CO2(g)
2. H2O(g)
3. CH4(g)
4. O3(g)
5. N2O(g)

128. Green house effect

130. References:
1. http://www.hindawi.com/journals/jb/2012/872875/
(15.10.2012)
2. http://lqma.ifas.ufl.edu/Publication/BB-02.pdf (15.10.2012)
3. http://www.hokkaido-
ies.go.jp/seisakuka/acid_rain/Acidrain-e.html (15.10.2012)
4. Larcher W., Physiological plant ecology, 3rd edition,Springer
publications,Berlin. pp 321-449.