Cold stress by Alisha Dewangan botany.pdf

Brief description about cold stress
1. Chilling stress
2. Freezing stress

1. Govt. J. Yoganandam Chhattisgarh
Raipur ( C.G )
MSc Botany 2
nd
Semester
Topic –cold stress
Presented by :
Alisha Dewangan
Guided by :
Dr Shailesh kumar verma sir

2. Synopsis -
1.Introduction
2.temperature stress
types of cold stress :
A] Chilling stress
a] Chilling injuries and resistance
b] Symptoms
B] freezing/frosting stress
a] freezing injuries
b] freezing stress resistance
c] symptoms
3. Prevention and protection against cold stress

3. 1. Introduction
Stress in plants refers to “ any external condition or substances that adversely
affect its normal functioning of plants like blocking its metabolism , growth ,
development and productivity of plants . ’’
Various types of stress produce in plants due to following factors :Cold,
heat, drought, flood, salinity, etc.
2. Temperature stress : major environmental factors which affect
plants growth , development , yieldetc.
Temperature above optimal and below optimal adverse effect for plant
growth which ultimately reduce yield production

4. Cold Stress
Under natural condition , higher plants are also get affect or stress by
cold temp [ low temp. ]. In certain parts of the years like autumn and
winter season .
Therefore , there are 2 types of cold stress/injuries occur in plants :
A]. Chilling stress
“ when plants are exposed to a low temperature above 0 ºC, but below the
optimum temperature 10-15 ºC .”
B].Freezing stress
“ when plants are exposed to a low temperature below 0 ºC which forms an
ice within tissue . ”

5. A]. Chilling Stress
“Plants may develop physiological disorders when exposed to low temperature below 10-15ºC
but above non-freezing temperatures[ below 0ºC ] .’’
There is varying degree of tolerance to cold temperature among different plants .
some plants growing in warmer climate are injured when exposed to cold climate between
10-15ºC ,whereas some plants may be cold resistant as they tolerate temp.between 10-
15ºC.
a]. Chilling injuries and Resistance
oThe German plant physiologist Molischsuggested the term ‘chilling injury’
oMany species of plants especially to tropical and subtropical region are affected to chilling
injury .
oThe most common site implicated for chilling injury is the plasma membrane
oExposure to temperature of 1 to 5ºC for 24 to 36 hours is fatal orinjurious to crop plants
like rice , velvet beans , cotton and peanut but less injurious to maize , tomatoes , sorghum
and pumpkin.

6. —Plants response differently when exposure to low temperature :
1. Chilling sensitive plants
•“ the plants are seriously injured by temperature above 0ºC and below
15ºC .”
•Most of the tropical and subtropical region
•Ex : croton , coleus , Passiflora
•Larger the exposure of chilling sensitive plant to chilling temperature ,
the greater is the result of injuries .
2.Chilling resistance plants
•“ The plants which are able to tolerate chilling temp. [10-15ºC] and are
seriously injured when it expose to below 0ºC . Therefore , ice formation
take place in tissue . ”
•Ex : Arabidopsis

7. Asaresultofchillinginjuries,plantshowsomesymptoms:
i.Reducedplantgrowthanddeath
ii.Surfacelesionsonleavesandfruits
iii.Abnormalcurling,
Causeoftheseeffectplantinducesdisordertometabolic
activitiesandphysiologicalconditionwithincell:
i.Lossofmembranefunction:permeability
ii.Inhibitionofphotosynthesisandcarbohydrates:decrease
CO2exchangeandreductioninnetphotosynthesisthat
causesdestructionofchlorophyll
iii.Slowerrespiration
iv.Inhibitionofproteinsynthesis
v.Lossofvigor
vi.Internaldiscoloration[vascularbrowning]
b]. Symptoms of chilling injuries

8. B]. Freezing/frosting stress
“ When plants are exposed to a low temperature below 0
0
c.Freezing damage occurs
primarily due to the formation of ice crystals, which damage cell structure ’’
It is observe in temperate zone plants .
a]. Freezing injuries
Freezinginjuryinplantscanbefromtwosources:
1.Freezingofsoilwater
Thesoilwaterthatisavailabletoplantsisfoundintheporous
regionsbetweensoilparticles.Itfreezesatabout-2°C,depriving
theplantofitssourceofwater.
2.Freezingofthefluidswithintheplant
Freezingofwaterwithintheplantcancausedisruptionof
structureandfunctionofcellsandtissues.Iceusuallyformsfirstinthe
cellwallsandintercellularspaces.Damageoccurswhenicecrystals
growandpunctureintothecytoplasm.Itcausesdehydrationofcell.

9. In plants cells and tissue , 2 types of freezing take place :
1.Vitrification
“ the process of freezing so rapidly that the water molecule do not have time to
form ice crystal and instead instantaneously solidify into glass like structure .’’
2.Crystallization
Crystallization of ice occur either extracellularly or intracellularly [ gradual
cooling or drop in temperature ]
Formationoficeintracellularlymaybedueto:
•Byinternalnucleation(certainlargepolysaccharides/proteinsserveasnucleatingagentsto
formice)
•Bypenetrationofexternalicecrystalsintothecells
•Intracellulariceformationisverylethalwhichcausesimmediatedisruptionofcells.
•Itspreadsfromcelltocellthroughplasmodesmata
Thelowerthetemperature,thegreatertheproportionofwaterthatfreezesinintercellularspaces
andthelarger,theicecrystalbecame

10. Plant response differently when exposure to very low temperature below its freezing
point :
1.Freeze sensitive plants –
•“ some plants get injured when they are exposed to a freezing
temperature [below 0°C ] even for a short period .”
•Ex –potato , tomato , maize
2. Freeze tolerance plants –
•“ some plants can survive when expose to temperature of -20°C to -
30°C or even lower without causing apparent injury .”
or
•“ The plant which tolerate exposure to below 0ºC which is a freezing
temperature .”
•it is also called cold acclimation plants .
•Ex –non acclimated rye [ Secale cereals ] , drimys winteri

11. b]. Freezing stress resistance
•On the basis of frost resistance plants , it has a certain
properties in their protoplast that is during acclimation of plants
to freezing certain proteins are synthesis in their cell are called
antifreeze protein.
•These protein binds to the intercellular spaces and check their
proliferation .
•Some of the protein are also believe to stabilize other protein
and cell membrane during dehydration of cell induced by cold
temperature .
•During acclimation of winter cereals such as wheat , sugars
[chiefly sucrose] are known to accumulate in cell walls where
they may check the enlargement of ice crystal . Because theses
protein and sugar have cryoprotectivefunction , they are called
cryoprotectants.

12. c]. Symptoms of freezing stress
•Desiccationoffoliage
•Water-soakedareasthatprogressto
necroticspotsonleaves,stemsorfruitand
deathofsectionsoftheplantortheentire
plant.
•Closeexaminationofwoodyplantsseveral
daysorweeksafterfreezingmayreveala
deadorweakenedrootsystemorsplit
barkonstemsorbranches.
•Obvioussymptomsonplantfoliagemay
notbepresentuntilaftertheplanthas
beenstressedbywarmtemperatures.
•Wiltingand/ordesiccation,ascausedby
directdroughtstress.

13. 3. Prevention and protection against cold stress
There are some method to prevent cold stress among
cold sensitive plants :
1.Soil banking –it consist of placing a mound of soil
around the tree trunk to protect the trunk from cold
.one of the most efficient cold protection methods for
young trees and has been used with success for many
years .
2. Wrapping–
•Most tree wraps can be attached anytime during the
year and left on the tree throughout the year or even
for several years.
•It is important to cover the entire lower trunk,
especially at the base for best result .

14. 3. Sprinkling -It can be used to moderate temperatures
above freezing because of sensible heat in water and can
maintain plant leaf temperature at 1 to 2°C degrees or
more.
4.Fogging–
•Fogalsoretardsthelossofheatfromsoilandplant
surfacestotheatmosphere.
•Fogcanprovideupto4°C(8°F)ofprotectionoutdoors
duringradiationalcooling.
•Theappliedwateraddsheattotheplantenvironment
and/orbufferstemperaturechangebyincreased
humidity.

15. Reference :
1.Plant physiology by Dr. V.K Jain
2.Plant physiology by S Mukerji and A K Ghosh
3.Plant physiology by S N Pandey and B K Sinha
4.Source of internet
Thank you
-For your attention