ABIOTIC STRESS MANAGEMENT IN VEGETABLE CROPS

1. ABIOTIC STRESS
MANAGEMENT IN
VEGETABLE
CROPS
LABEEBA RIYAZ SHAH
DIVISON OF VEGETABLE SCIENCE.
1

2. INTRODUCTION:
Phenotypic performance:
Environmental factors:
2
Genotype Environment
Biotic Abiotic

3. STRESS
ABIOTIC
WATER
DEFICIT
EXCESS
TEMPERATURE
HIGH
LOW
SALT/ION
TOXICITY
DEFICIENCY
OXIDATIVE
BIOTIC
Plant stresses are biotic and abiotic
3
STRESS:
When some factors of the environment interferes with the complete expression
of genotypic potential (Singh, B.D).
 Significant deviation from the ideal conditions, preventing plants from
expressing their full genetic potential for growth, development, and reproduction
(Rehman et al. 2005).

4. FRACTION OF WORLD’S
ARABLE LAND AFFECTED WITH
ABIOTIC STRESSES
4
DROUGHT
26%
MINERAL
TOXICITY
/DEFICIENCY
20%
FREEZING
15%
Drought accounts
alone for 50 % of
losses caused by
biotic and abiotic
stresses.

5. LOSSES CAUSED DUE TO
ABIOTIC STRESS
The estimated potential yield losses are 17 % due to drought, 20 % due to
salinity, 40 % due to high temperature, 15 % due to low temperature and 8 %
due to other stress (Ashraf et al.,2008).
World Bank projects that the climate change will depress crop yields by 20% or
more by the year 2050 (Narendra Tuteja, 2012)
It was estimated that approximately 70 % of yield reduction was due to abiotic
stress. ( Acquaah, 2007)
Abiotic stresses are main factors that limit the crop productivity . Drought
,salinity and heavy metal stresses caused yield losses annually to a great extent
(Nafees A khan and Sarvajeet Singh, 2008)
5

6. Plant responses to stress:
6
Stresses trigger a wide
range of responses:
 Altered gene expression.
 Cellular metabolism.
 Changes in growth rates
and crop yields.

7. 7
Stress resistance mechanisms:
1. Avoidance mechanisms
prevents exposure to stress.
2. Tolerance mechanisms
permit the plant to withstand stress.
3. Acclimation
alter their physiology in response to stress.

8. Water Stress:
It may result in two types of stresses:
8
Drought stress
Water logging

9. 9
Water depletion

10. DROUGHT:
 Inadequacy of water availability.
 It acts as serious limiting factor in agricultural production by preventing a crop from reaching the
genetically determined theoretical maximum yield.
INJURY MECHANISMS:
At cellular level, drought affects membrane structures of
macromolecules like protein, nucleic acids and enzymes.
At low water potential, stomata close due to the loss in
turgidity of the guard cells leading cease in transpiration.
In absence of transpiration, temperature of the leaves
increases to lethal level and the leaves die.

11. Injuries in vegetable crops:
11

12. TOLERANCE MECHANISMS:
• Mechanisms causing minimum loss of yield in a drought environment relative to
the maximum yield in a constraint free environment.
• It is grouped into three categories:
12
Drought Escape. Dehydration
Avoidance.
Dehydration
Tolerance.

13. DROUGHT ESCAPE
 It is an important strategy of matching phenological
development with the period of soil moisture
availability to minimize the impact of drought stress on
crop production (Turner, 1986).
 Early maturing is one of the most important attribute
of drought escape (Lewin and Sparrow, 1975). An
example of local cultivars of cowpea (Vigna
unguiculata L.) flower progressively earlier.
 It also involves aspects of seed germination. Dormant
seeds, quasi dormant or quiescent state seeds survive
dry spell (Thomas, 1997) and germinate only under
favorable conditions.
13

14. Tolerance mechanisms are complex traits, expression of which depends on
action and, interaction of different characters which are:
14
MORPHOLOGICAL
• Reduced leaf area,
Leaf angle.
• Leaf rolling e.g. rice,
wheat
• Cuticular wax e.g. oat,
rice.
• Increased root growth
e.g. bean
• Pubescence
PHYSIOLOGICAL
• Reduced transpiration
e.g. tomato, sorghum,
okra, brinjal.
• Osmotic adjustment
e.g. bean, tomato cv.
Arka saurabh, Pusa
early dwarf.
• Abscisic acid.
BIOCHEMICAL
• Accumulation of
proline, polyamines,
trehalose, LEA
protiens etc
• Increased storage of
carbohydrates that is
fructan.

15. 15

16. Abscisic acid (ABA) synthesis :
16
1.Zeaxanthin epoxidase (ZEP,)
2. 9-cis-epoxycarotenoid
dioxygenase (NCED).
3.ABA-aldehyde oxidase (AAO)
4.Molybdenum
cofactor sulfurase (MCSU)

17. Osmotic adjustment:
17

18. Water logging
• Inhibition of gas exchange of roots with the
atmosphere.
18
Water logging
Gas diffusion
limitations
Oxygen
deficit
Carbon
dioxide
excess
Ethylene
excess
Mineral
nutrient
deficiency
Leaching
induced on
deficit
Anaerobic
respiration
Metabolic
toxins
Reduced
transpiration
Reduced root
conductivity
to water
Setter and Waters, 2003

19. Injury mechanisms:
• Reduced gas exchange.
• Water deficit in aerial parts.
• Nutrients imbalance.
• Change in phytohormone concentration
and activity.
• Disturbance in root metabolism.
• Decreased leaf epidermal conductance
• Morpho-physiological changes
 Photosynthesis
 Respiration
Pyruvate
Glycolysis
Anaerobic
respiration
Aerobic
respiration
CO2 and H2O + 36 ATP Ethanol or lactate
or alanine + 2 ATP

20. Tolerance mechanisms:
 Morphological and Anatomical Mechanisms
of Tolerance:
• Root porosity
• Adventitious roots
• Formation of aerenchyma tissue
• Changes in root geotropism
Metabolic rescue mechanisms of tolerance.
20

21. Temperature stress
21
Heat
stress
Cold
stress

22. Heat stress:
A transient elevation in temperature, usually 10-15°C above ambient, is
considered heat shock or heat stress (Wahid et al., 2007) .
22

23. Injury mechanisms:
• Effect of high temperature
on growth and
development:
It is associated with death of cells,
tissues, organs. It is known to cause
death of seedlings and flower
abscission, pollen sterility and poor
fruit set at reproductive stage and
yield reduction.
• Physiological effects:
It results in denaturizing of proteins,
enzymes, disrupts membrane
composition and stability and decrease
photosynthesis.
23
Flower development of tolerant (left)
and sensitive tomato genotypes (right):-
Anthers showed deformation, dark
coloration of the anther tipe pist.

24. Tolerance mechanisms
Heat Avoidance
mechanisms
Transpiration
Leaf pubescence
Reduction in the amount of
foliage
Adaptation
Heat Tolerance
mechanisms:
Molecular chaperones interacted to
protect against heat.
Amylopectin content.
Membrane stability.
Osmoregulators content.
Plant growth regulators.
Thermo stability of photo system 2
Repairing of injured cells.
24

25. Tolerance to heat stress
Heat shock proteins (HSPs)
HSP100 HSP90 HSP70 HSP60 SmHSP
Members appear to function as molecular chaperones.
Individual heat shock proteins have been transformed into plants in order to
enhance heat tolerance.
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26. Cold stress:
It can be categorized into two parts.
26
Injury caused
when temperature
is above freezing
point (> 00C)
Chilling
injury Injury caused at
temperature
below freezing
point (<00C)
Freezing
injury

27. Injury mechanisms of chilling stress:
• Membrane damage.
• Imbibational chilling injury.
• Reduction in photosynthesis.
• Oxidative stress and chilling injury.
• Low chlorophyll content.
27

28. Tolerance mechanisms for chilling
stress:
Biochemical and
Physiological basis
of tolerance.
• Polyamines
• Membrane lipid
unsaturation
• Phytohormones
• Vernalization
Morphological
basis of tolerance:
• Floral part
variation
• Cell size
• Pollen fertility
28

29. 29
Injury mechanisms
of freezing stress:
Ice formation can
be intracellular or
intercellular.
Membrane
disruption
Tolerance mechanisms of
freezing stress
Osmotic adjustment.
Bound water
Cell wall properties
Cold responsive proteins

30. 30
Mineral stress

31. Salt stress
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• Increased salinization of arable land is expected to
have devastating global effects, resulting in 30% land
losses within next 25 years and up to 50% by 2050 (
Wang et al 2003).
• Salt affected soils are mainly of two types:
 Saline
 Alkaline

32. Injury mechanisms
• Reduced water potential.
• Increased energy utilization .
• Ionic imbalance.
• Inhibition of enzyme activities.
• Change in physiological
parameters.
32

33. Tolerance mechanisms:
• Cell membrane stability
• Osmotic adjustment: Some
of the organic osmolytes
are
 Glycinebetaine
 Manitol
 Proline
• Phytohormones
• Enzymes
• Ion accumulation and ion
balance
• Ion exclusion
• Leaf characteristics
33

35. List of vegetables based on their degree of salt tolerance
Vegetable crops Threshold level (dS /m) Rating
Potato 1.7 MS
Onion 1.2 S
Asparagus 4.1 T
Turnip 0.9 MS
Broccoli 2.8 MS
Cabbage 1.8 MS
Squash 3.2 MS
Carrot 1.0 MS
Pepper 1.5 MS
Sweet potato 1.5 MS
Lettuce 1.3 MS
Tomato 2.5 MS
Bean 1.0 S
Radish 1.2 MS
35
*MS: Medium susceptible, S: Susceptible, T: Tolerant

36. Mineral toxicity
Mineral Injury mechanism Tolerance mechanism
Aluminum Reduced root growth
 Effects nutrient uptake
Effects pollen
germination
Chromosomal
abnormality and reduced
DNA synthesis.
Effects cell and cellular
organelles.
Plant exudation.
Cell wall composition
Uptake and accumulation
Nutrients.
Root induced ph change
Iron Inhibition of nutrient
absorption
Oxidative damage
Inhibition of
photosynthesis
Rhizosphere oxidation
Sap exudation
Physiological avoidance
36

37. Oxidative stress
• Stresses such as high temperature, high light intensity, osmotic
stress, metals and toxins lead to over production of reactive oxygen
species causing extensive cellular damage and inhibition of
photosynthesis.
37

38. Reactive oxygen species
(ROS)
• Formed during certain redox reactions and
during incomplete reduction of oxygen or
oxidation of water by the mitochondrial or
chloroplast electron transfer chain.
• Singlet oxygen, hydrogen peroxide, superoxide
anion, hydroxyl and per hydroxyl radicals.
38

39. How do they cause damage?
O -
2 H2O2 OH*
Protein Membrane Lipids Other Cellular
components
Amino acid
residues Lipid peroxide Nucleic Acids
Carbonyl Derivatives
Breaking Intra-molecular
Cross linking lipid per oxidation
Protein degradation
(Malondialdehyde(MDA) and
4-hydroxynonenal )
Degradation

40. Ozone and oxidative stress
• Hydrocarbons and oxides of nitrogen (NO, NO2) and sulfur
(SOx) react with solar UV radiation to generate ozone (O3).
• Ozone is a highly reactive oxidant.
40
Injury mechanism Tolerance mechanism
alters ion transport
increases membrane permeability
inhibits H+-pump activity
collapses membrane potential
increases Ca2
+ uptake from the apoplasm
Oxidative damage to bio molecules.
Utilizes either avoidance or tolerance.
Avoidance involves physically excluding the
pollutant by closing the stomata, the principal
site at which ozone enters the plant.
Tolerance - biochemical responses that induce
or activate the antioxidant defence system
and possibly also various repair mechanisms.

41. 41
Breeding and
Biotechnology in
management of
abiotic stresses

42. BREEDING METHODS:
Selection
Hybridization
42
Breeding requires certain considerations:
What is the effect of the abiotic stress on the crop to be improved?
What germplasm is available that contains the necessary genetic variation to initiate
improvement?
What breeding scheme will be used to facilitate improvement?
What will be the specific goals of the breeding effort?

43. Screening techniques for various stresses:
Characteristic Measurement Inference
Yield potential Screening in artificially created
environments.
Genotypes performing well in such
environments can be selected.
Leaf rolling Visually scored. High scored genotype is selected.
Mainly done in drought stress.
Water retention Measured as dehydration rate. Genotypes with high water retention
can be selected
Membrane stability Conductometer Plants with solute leakage should not
be selected. 43
Selection:
Natural
selection
Artificial
selection.
In Artificial selection characters with
high heritability
High correlation with yield should be selected.

44. Leaf necrosis and death. Visual evaluation Mineral stress causes necrosis and
death.
Pollen tube growth, pollen fertility. Pollen grain screening. Pollen tube growth rate is a selection
criteria used in salt stress. Meiotic
stage of pollen mother cell is very
sensitive to chilling therefore if
genotype shows tolerance it can be
selected.
Leaf ion content Based on ion exclusion or ion inclusion,
in case of salt stress, mineral stress.
Chlorophyll content SPAD. Used especially in cases of water
logging, cold stress e.g. Tomato,
Cucumber.
Sensitivity of reproductive phase Flower/ pod/ fruit/ seed production. Plants tolerant during reproductive
phase should be selected.
Root colour and shape Root decolourization and deformation. Aluminum toxicity sensitive plants
produce deformed and decolourized
roots.
Root length Relative root length Deep root system is a identified as a
target for selection especially in case of
drought stress, mineral stress.
Germination percentage Germination test Seedling that emerge and
establish first escape stress.
Photosynthetic rate Respirometer infrared gas
analyzer.
Plants with high photosynthetic
rate can be selected.
44

45. Determination of High Temperature Tolerance via Screening of
Flower and Fruit Formation in Tomato
Nuray, C., Mustafa, K.S., 2010
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Percentage of seeded fruit set at three
temperature regimes
Percentage of parthenocarpic fruit at three
temperature regimes

46. 46
The results showed that four domestic tomato genotypes (U-4-10, U-64-16, U-2-29,
and U-117-2) could be valuable source of heat-tolerant germplasm for tomato.
Percentage of undeveloped Flower/Fruit at
three temperature regimes
Percentage of aborted flower at three
temperature regimes

47. 47
Screening of heat tolerant potato

48. Hybridization:
Intraspecific hybridization.
48
Interspecific hybridization
Methods used:
Pedigree method
Back cross method
Mass selection
Recurrent selection

49. Sources of resistance:
Cultivated varieties
Land races
Wild relatives
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50. Sources of tolerance
2/17/2021 5:15 AM 50
S.No. Crops Genotypes references
1 Tomato Solanum habrochaites, S. esculentum var. cerasiforme, S.
hirusutum, S.cheesmani, S.chiloense
Rai.et.al (2011)
2 Brinjal S. Microcarpon, s.gilo, S.macrocarpon, S. integerifolium Rai.et.al (2011)
3 Chilli C. Chinense, C. bacctum var. pendulum, C. eximum Singh (2010)
4 Potato S,acuale, S.demisum, s.stentomum Arvin and Donelly
(2008)
5 Okra A. Callei, A.rugosus, A.tuberosus Charller (1984)
6 Onion A.fistulosum, A.munzii. Arka Kalayan Singh (2010)
8 Watermelon C. colocynthis, Dane et.al (2007)
9 Frenchbean P.acutifolius Kaver et.al (2011)

51. Crop Variety Tolerance
tomato Pusa Sadabahar,
Pusa Sheetal
Pusa Hybrid-1
Tolerant to high and
low temperatures
Arka saurabh,pusa ruby,pusa early dwarf Moisture stress
raddish Pusa Chetki Better root formation
under high
temperature regime,
carrot Pusa Vrishti Form root at high
temperature and high
humidity
cauliflower Pusa Meghna can form curd at high
temperature
brinjal Ph-4,R-34 High temperature
okra DOV-26, DOV-27, DOV-29, DOV-62 High temperature
chilli Musalawadi,bhaskar Moisture stress

52. Biotechnological methods
Tissue culture
Somaclonal variation
Transgenic development
Embryo rescue
Marker assisted selection
52

53. F2
P2
F1
P1 x
Tolerant
Susceptible
Selection based on presence of marker
Marker Assisted Selection (MAS)
large populations consisting of
thousands of plants

54. Genetic transformation

55. SOURCES OF RESPONSIVE GENES
• Arabidopsis thaliana
• Nicotiana tabacum, N. Plumbaginifolia
• Spinach
• Holomonas elongata
• Saccharomyces sp.
• E. Coli
• Arthrobacter globiformis
( Grover et al.,2003,Current Science.)
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56. Winter Flounder Fish- Antifreeze
protien
17-02-2021 56
Hordeum vulgare- Hb gene
Oriza sativa- Cu/Zn SOD
Vitroscilla stercoraria- VHb gene
Anasystis nidulans- Fatty acid
desaturase gene

57. GENES INDUCED BY ABIOTIC STRESSES
The product of genes whose expression is induced by
abiotic stresses are classified in two groups.
Proteins that protect cell from stress.
a- Enzyme involved in production of osmoprotectants
b- Late embryogenesis abundant proteins
c- Antifreeze proteins
d- Chaperones
e- Detoxifying enzymes
Proteins involved in inducing transcription of
stress responsive genes.
a- TFs
b- Protien kinases
c- Enzymes involved in phosphoinositide metabolism
57

58. 58

59. 59

60. Recovery growth after 13 days of stress
Transgenics expressing AVP1 showed enhanced
drought recovery in tomato
WT AVP1
AVP1 enhances the root growth and hence better survival at the
end of stress and high recovery growth on stress alleviation
Park et al., 2005; PNAS 102: 52
60

61. (Zhang et al., 2004)
Drought and freezing tolerance in transgenic
Brassica napus through constitutive expression of CBF1
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62. 17-02-2021 62

63. Use of anti transpirants:
Anti transpirants
 Reduce the rate of transpiration.
Improve water use efficiency.
These have been classified as
 Film forming type
Reflecting type
Metabolic inhibitors.
63

64. 64
Table 13 : Effect of anti transpirants on fruit yield of brinjal
Treatment Fruit set (%) Number of fruits / pl. Yield (t/ha)
Control (T1) 29.52 12.4 12.62
Stress (T2) 23.62 6.3 5.69
Stress + Cycocel (T3) 24.91 8.6 7.13
Stress + Lime wash
(T4)
22.10 6.7 5.79
Stress + Potassium
chloride (T5)
27.90 8.0 6.84
C.D.
(p= 0.05)
0.43 1.13 1.34
Prakash et al,(1992)

65. Grafting:
 Use grafted tomato may give certain degree of
resistance against thermal stress. (Rivero et al, 2003)
Grafted plants have more content of Linolenic acid,
which helps in the survival of plants under low
temperature (Pandey and Rai, 2003).
Chilli grafted on sweet pepper rootstocks has given
highest yields under high-temperature conditions.
(Palada and Wu, 2008)
Inter-generic grafting imparts flood tolerance in
cucurbits. (Pandey and Rai, 2003 IIVR, Varanasi)
Grafting improved flooding tolerance of bitter gourd
(Momordia charanthia L. cv.) when grafted onto sponge
gourd (Luffa cylindria Roem cv. Cylinder). (Liao and Lin,
1996)
65

66. Use of micro organisms:
• VAM influences leaf water potential, solute
accumulation in plants under drought stress.
• Bacillus subtilis, Bacillus cereus, serratia spp,
have been reported to impart drought tolerance
in cucumber.
• VAM inoculated plants were protected against
drought shown by higher leaf water potential
and proline content.
66

67. Conclusion:
 Abiotic stress’ are major cause of concern for the
global food security.
 Conventional knowledge has almost saturated in
finding the solutions for the sprawling abiotic stress’
resulting due to climatic change and other causes.
 GE has proved its worth in tweaking the plants’ ability
to cope with the various abiotic stresses.
 The main advantage of GE is that it can transcend
across the species barrier.
 Much needs to be done to realize the full potentiality
of latest technologies.
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