abiotic stress

1. AMAL JOSE
2017-11-131
COA VELLAYANI
KERALA AGRICULTURE UNIVERSITY

2.  Stress can be any factor that may produce an
adverse effect in individual organism,
populations or communities.
 Stress is also defined as the overpowering
pressure that affects the normal functions of
individual life or the conditions in which
plants are prevented from fully expressing
their genetic potential for growth,
development and reproduction (Levitt, 1980;
Ernst, 1993).

4.  Abiotic stress management is one of the most
important challenges facing agriculture
 Abiotic stress can persistently limit choice of
crops and agricultural production over large areas
and extreme events can lead to total crop failures.
 Abiotic stresses adversely affect the livelihoods of
individual farmers and their families as well as
national economies and food security.

5. Temperature
 Greaves (1996) defines suboptimal temperature stress as
any reduction in growth or induced metabolic, cellular or
tissue injury that results in limitations to the genetically
determined yield potential, caused as a direct result of
exposure to temperatures above or below the thermal
thresholds for optimal biochemical and physiological
activity or morphological development.

6.  Low temperatures can damage plants both by a
chilling effect, leading to physiological and
developmental abnormalities
 Injury that is caused by a temperature drop to
below 15℃ but above freezing point
 And by freezing, causing cellular damage(intra
cellular) directly or via cellular dehydration(extra
cellular)

7.  Chilling and freezing injury can directly affect
crop growth by causing physical damage or by
interfering with normal biochemical and
physiological functions, thus reducing yield.
Symptoms of cold stress in plants
o Desiccation or burning of foliage
o Water soaked areas that prolongs to necrosis
o Weakened root system or split bark

8.  Lyons (1973) described many symptoms of low-
temperature injury
 Some physiological processes such as flowering
in rice are extremely sensitive to low
temperatures and damage may occur at
temperatures as high as 20°C.
 According to Levitt, (1980), Witt and
Barfield,(1982) Commonly visible symptoms of
low-temperature injury to the leaves include
wilting, bleaching due to photo oxidation of
pigments, waterlogging of the intercellular
spaces, browning, and eventually leaf necrosis
and plant death

9.  Cell membrane damage:Normal lipid crystalline
membrane changes into solid state.
 Prevention of pollen formation :No sugar
translocation through tapetum
 Abnormal hormone metabolism
 Imbibitional chilling injury
 Reduction in photosynthesis:Low stomatal
activity,low electron transport and low enzymatic
activity

10.  Polyamines synthesis: Gives membrane stability
 Membrane-Lipid unsaturation: Production of
unsaturated fatty acids gives adaptation to cold
stress
 Phyto hormones:ABA accumulation- stomatal
maintenance,water balance, prevention of
chlorosis

11. Mitigation of Low temperature stress
 Foliar spray of 0.15 % Ammonium molybdate
reduces the low temperature stress effect.
 Pre-soaking treatment with GA3 and Proline
increase the Seed germination
 Application of Paclobutrazol increases the
activity of Scavenging enzymes
 Cryoprotectants also used for reducing the
stress effect.
 ABA has a role in induction of freezing
tolerance.

12.  Levitt (1980) classified plants into
psychrophiles, mesophiles, and thermophiles
according to whether or not they tolerate low,
medium, or high temperatures.
 Psychrophiles-15 to 20°C
 Mesophiles -35 to 45°C
 Thermophiles-45 to 100°C

13. Effects of Heat stress on Plants
 Seedling establishment is hampered
 Drying of leaf margins and scorching effect on leaves
 Reduction in plant growth
 Pollen development is affected
 Alteration in photosynthesis
 Total biomass is reduced
 Spikelet sterility
 Grain and fruit development and quality is affected

14.  Avoidance mechanisms –transpiration,leaf
pubescence,reduction of foliage.etc
 Production of heat shock protein
 Amylopectin can hold water
 Membrane stability by saturated fatty acids
 Plant growth hormones

15. Mitigation for high temperature
 Plants need to be cultivated under shade
condition
 Overhead irrigation to avoid sunburn.
 Application of Gibberellic Acid Stimulate the α -
Amylase production for seed germination.
 BAP reduce the leaf senescence & Lipid
peroxidation
 Salicylic acid enhances the Thermo tolerance
capacity.
 Application of Ethylene enhance the seed
germination

16. Water Stress
 Among the environmental stress factors, one
of the most widely limiting for crop production
on a global basis is water
 On a global basis, water is a predominant
factor in determining the distribution of
species.,
 And the responses and adaptation of species to
water stress are critical for their success in any
environment and for their use and productivity
in agricultural ecosystems
 Can be either Drought(deficient) or Flood
(excess)

17.  Drought can be defined as an extended period
of deficient rainfall relative to the statistical
mean for a region.
Mechanism
. Functioning of stomata
In general, stomata lose their function and may
die, because wilting after certain limit denatures
the starch in the guard cells and also in the
mesophyll cells.
. Carbohydrates metabolism in green leaves
The very first effect of drought on
carbohydrates metabolism is that starch
disappears from the wilted leaves and sugar
accumulates simultaneously.

18. . Photosynthetic activity
CO2 diffusion into the leaf is prevented
due to decrease in stomatal opening and
there by reduces photosynthetic activity in
green cells
. Osmotic pressure
The reduced amount of water during
drought causes an increase in the osmotic
pressure of plant cell.
. Biochemical effects
Water shortage alters the chemical
composition. For example, starch is
converted to sugar, besides this, there is a
considerable increase in nitrate nitrogen and
protein synthesis is adversely affected

19. Effects of drought stress on
crops
 Reduced seed germination and seedling
development
 Poor vegetative growth
 Reproductive growth is severely affected
 Plant height and leaf area reduced
 Significantly reduction in leaf weight
 Reduced photosynthesis.
 Reduced stomatal conductance

20.  Drought Escape:Short duration,early maturity..etc
 Dehydartion avoidance:Water savers and water
spendes.,proline accuulation, osmotic adjutment
.etc
 Dehydartion tolerence

21.  Foliar spray of 2% DAP + 1% MOP during critical stages
of flowering and grain formation
 3% Kaoline spray at critical stages of moisture stress
 Mulching with 5 tonnes of sorghum / sugarcane trash
which saves 20% of irrigation water by reducing
evaporation loss of water
 Seed hardening with 1% KH2PO4 and other salts for 6 – 8
hours (depending upon nature of seed coat) soaked in
equal volume of water
 In cotton, nipping terminal portion of main stem beyond
15th node (at 70 - 80 DAS) and at 20th node (at 90 DAS)
in the case of hybrids and varieties respectively for
arresting transpiration loss of water)

22. Flood
 Flooding may be defined as any situation of excess
water.
 Sudden inundation following high rainfall events
also poses a severe physiological stress on crops
 In the water logged soils, water gets filled in the
pores of the soil which are previously occupied by
air. Such soils suffer O2deficiency. This O2
deficiency depresses growth and survival of plants
growing in it.

23.  Reduce gas exchange:Root system become
anaerobic
 Poor water uptake due to root injury
 Nutrient Imbalance
 Disturbance in root metabolism:Anaerobic
respiration

24. Effects of flooding stress on
plants
1. Decay and death of leaves
2. Wilting
3. Abscission
4. Epinasty
5. Lenticels formation

25. Nutrient deficiency & Toxicity:
Under the anaerobic condition Fe toxicity is high.
This leads to increase the polyphenol oxidase
activity, leading to the production of oxidized
polyphenols. It also causes leaf bronzing and
reduced root oxidation power
• Flood sensitive plants - Tomato,
soybean and sunflower
• Tolerant species- Rice

26. Mitigation of flooding stress
 1. Providing adequate drainage for draining
excessive stagnating water around the root
system.
 Spray of growth retardant of 500 ppm cycocel
for arresting apical dominance and thereby
promoting growth of laterals.
 Foliar spray of 2% DAP + 1% KCl (MOP).
 Spray of 0.5 ppm Brassinolide for increasing
photosynthetic activity.
 Apply sufficient K fertilizer
 Foliar spray of 0.3 % Boric acid + 0.5 % ZnSO4 +
0.5 % FeSO4 + 1.0 % urea during critical stages
of the stress

27. Salinity stress
 Salinity is defined as the presence of excessive
amounts of soluble salts that hinder or affect
the normal functions of plant growth
 It is measured in terms of electrical
conductivity (EC),Exchangible sodium
percentage and pH.
 Therefore, saline soils are those that have
saturated soil paste extracts with an EC of
more than 4 dSm–1, ESP less than 15 percent,
and pH below 8.5 (Waisel, 1972; Abrol, 1986;
Szabolcs, 1994)
 Saline soils have a mixture of salts of Chloride,
Sulfates of Sodium, Magnesium and Calcium
ions with sodium chloride often dominant.

28.  There are two main sources of salinity:
 Primary or natural sources Resulting from
weathering of minerals and the soils
developed/derived from saline parent rocks.
 Secondary salinization Caused by human factors
such as irrigation, deforestation, overgrazing, or
intensive cropping (Ashraf, 1994)
 Salinisation affects the physical as well as the
chemical properties of the soil

29.  Plants are classified into two types based on the
tolerance to salt stress. They are halophytes and
glycophytes
Halophytes
Halophytes are the plants that grow under high
salt concentrations
Glycophytes
Glycophytes are the plants that cannot grow
under high salt concentration

30. Mechanism of salt stress on plants
 Osmotic effect or water deficit effect: Reduces
the plant‘s ability to take up water, and this
leads to slower growth. This is the osmotic or
water-deficit effect of salinity.
 Salt specific effect or Ion Excess Effect: Salts
enter the transpiration stream and eventually
injure cells in the transpiring leaves, further
reducing growth
 High salts can cause leaf burn, inhibit water
uptake, and can interfere with uptake of
certain essential elements (e.g., calcium).
 Stress at reproductive stages leads to spikelet
sterility in cause of rice
 Accumulation of Na+ and Cl- is toxic to cell in
terms of the effect in enzyme activity.

31. Effect of salt stress on plant growth and
yield
 Seed germination
Salt stress delays seed germination due to the
reduced activity of the enzyme, α-amylase
 Seedling growth
The early seedling growth is more sensitive. There is
a significant reduction in root emergence, root growth
and root length.
 Vegetative growth
When plants attain vegetative stage, salt injury is
more severe only at high temperature and low
humidity. Because under these conditions, the
transpiration rate will be very high as a result uptake
of salt is also high.

32.  Photosynthesis
Salinity drastically declines photosynthetic
process. Thylakoid are damaged by high
concentration of salt and chlorophyll b content is
drastically reduced
Tolerant crops: Cotton, sugar cane, barley
Semi tolerant crops: Rice, maize, wheat,
oats, sunflower, soybean
Sensitive crops: Cow pea, beans,
groundnut and grams

33. Mitigation of salt stress
 Seed hardening with NaCl (10 mM
concentration)
 Application of gypsum @ 50% Gypsum
Requirement (GR)
 Foliar application of ascorbic acid alone
increased number of leaves and leaf area,
while in combination with zinc sulfate increased
the plant height and total plant biomass
 Maintenance of high K/Na ratio by applying
potash and Ca‘ fertilization
 Application of PGRs like cytokinin,GA3, IAA,
cycocel, thiourea and polyamines (putrescine,
spermidine and spermine) either as seed
treatment or foliar spray

34. Low light and UV radiation stresses
Low Light Stress
In some places the light intensity might be
even up to 60000 lux in the first season but it
would be low up to 30000 lux in the second
season causing very poor productivity.
Light quality is also very poor by showing
about 400-440nm instead of the normal 600-
640nm. The abnormal light intensity and
quality causes reduced yield in any crops

35. UV radiation and plant stress
1. UV radiation slows down the growth of plants
2. Damage the process of photosynthesis
3. Prevent maturation and ripening process
4. Accelerate genetic mutation.

36.  Dheeraj Chatti(2015)-CO2 Enrichment induced
drought tolerence response in tomato and
amaranthus
 Study the physical and varietal response of
tomato and amaranthus to water stress condition
and their modification under elevated CO2
environment
 The technology used for CO2 enrichment is Open
Top Chamber (OTC) system
 Plants were maintained under irrigated condition
for one week . Stress condition imposed by
withdrawing irrigation

37.  Higher values are observed for total drymatter
production,shoot wight, root weight, relative
water content,total chlorophyll content etc. under
elevated CO2 condition
 Elevated CO2 condition have a positive impact on
recovery response
 In the present study CO2 enrichment was
revealed to have a role in improving the stress
tolerence and recovery response in the case of
tomato and amaranthus

38.  Lini Jacob(2006)-Effect of abiotic stress factors
on growth and secondary plant metabolism in
Ashwagandha
 Study analyzed effect of abiotic stress on
growth,physiological ,biochemical parameters
and withanolide content (secondary metabolite )
 Application of 3 levels of light stress-25% ,50%
and 75% shade and 3 levels of water stress
25%,50% and 75% FC
 The present study shown that the exposure of
abiotic stress factors leads to decrease in growth
parameters but the accumulation of secondary
metabolite was increased and activity of free
radical,scavenging enzymes also increased

39.  Sethulashmi V.S (2017)- Organic preparations
and biostimulats for moisture stress mitigation
in container grown okra
 The treatments was comprised of application of
organic preparations and biostimulants including
fermented cow urine,citric acid,salicylic acid
,moringa leaf extract ,yeast extract and water
 All treatments except water have done in
moisture stress condiotion
 Results shown that moringa leaf extract gave
maximum plant height and root volume
 The spraying of citric acid to the container
growing okra found to be ideal treatment for
moisture stress tolerence and reducing
irrigation requirement

40.  Dinesh Jinger et al (2017) -Silicon in mitigating
biotic stress in rice
 Silicon is probably the only element which is
able to enhance the resistance to multiple
stresses
 Providing appropriate amounts of Si to the
plants cultivated in Si deficient soils could
considerably improve the rate of plant growth
and its resistance against biotic and abiotic
stresses.

41.  Silicon depleted soils have been associated with
lower resistance to insect-pests and fungal
diseases as well as crop lodging
 Recent studies shows that Silicon contribute to
biotic stress managagement by controlling the
disesases through the production of low
molecular weight metabolites, which include
flavonoid, phytoalexins

42.  Hasheem Abeer et al (2015) – Induction of
salt stress tolerance in cowpea [Vigna
unguiculata (L.) Walp.] by Arbuscular
Mycorrhizal Fungi
 The present study shows that AMF possesses
the potential to enhance salt tolerance of
cowpea
 AMF induce Proline secreation in plants
 AMF allayed the salt stress by preventing the
excess uptake of Na+ and at the same time
causing further enhancement in activities of
antioxidant enzymes thus ensuring better
scavenging of ROS

44.  Vibhuti et al (2015) –Assessment of salt stress
tolerance in three varieties of rice (Oryza sativa
L.)
 Made an analysis on 3 rice varities (Narendra-
1, Sabarmati and Hybrid-312) for salt stress
 The results showed that with increasing salt
stress, germination in all the varieties was
delayed and decreased from 100 % in control to
16.7% in highest (20 dsm-1) salt stress level
 Maximum germination percentage was
observed in Narendra-1 and Sabarmati
varieties under salt stress levels

46. THANK YOU

47.  Abeer H,Abdulla E.F.2015Induction of salt stress
tolerance in cowpea [Vigna unguiculata (L.) Walp.] by
arbuscular mycorrhizal fungi. Botany and
Microbiology Department, Faculty of Science, Saudi
Arabia.
 Paul M.M,Kumar R. Classification of cereal proteins
related to abiotic stress based on their
physicochemical properties using support vector
machine
 Gaiser T,Rezaei E.2014. Heat stress in cereals:
Mechanisms and modelling. University of Bonn,
Institute of Crop Science and Resource Conservation,
D-53115 Bonn, German