Lecture # 13 Light Acclimatization Acclimatization

Lecture # 13Lecture # 13LightLight

AcclimatizatioAcclimatizatio

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ACCLIMATIZATION:ACCLIMATIZATION:

Adaptation of a SpeciesAdaptation of a Speciesto a New Environmentto a New Environment

What Is Acclimatization?What Is Acclimatization?

Favorable Favorable environment environment

for for maximum maximum

growthgrowth

Interior Interior environmentenvironment

low light,low light,low relative low relative

humidityhumidity

high light, high high light, high nutrition,nutrition,

high water supply, high water supply, high temperaturehigh temperature

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The Two Sides of AcclimatizationThe Two Sides of Acclimatization

* Light Acclimatization* Light Acclimatization* Soil Acclimatization * Soil Acclimatization

reduce nutrient application,reduce nutrient application,

reduce water frequency.reduce water frequency.

low light = less growthlow light = less growth= less need for nutrients= less need for nutrients

= less water need= less water need

Organ Level: LeafOrgan Level: Leaf

The Plant Leaf - An Overview of StructureThe Plant Leaf - An Overview of Structure

upper epidermisupper epidermis

lower epidermislower epidermis

palisade palisade mesophyllmesophyll

spongy mesophyllspongy mesophyll

xylemxylemphloemphloem

vascular vascular tissuestissues

vascular parenchymavascular parenchyma

stomatesstomates

chloroplastschloroplasts

Anatomical Differences Anatomical Differences BetweenBetween

'Sun' and 'Shade' Plants'Sun' and 'Shade' Plants

The Chloroplast - An Overview of The Chloroplast - An Overview of StructureStructure

Electron Micrographs Electron Micrographs Of ChloroplastsOf Chloroplasts

High LightHigh Light

Low LightLow Light

Organelle Level : ChloroplastOrganelle Level : Chloroplast

Internal OrganizationInternal Organization

High light chloroplastHigh light chloroplast Low light chloroplastLow light chloroplast

smaller chloroplastssmaller chloroplastsless thylakoids /less thylakoids / more stroma more stromaMore grana stacksMore grana stacksTaller stacksTaller stacksless chlorophyll per less chlorophyll per volumevolume

larger chloroplastslarger chloroplastsmore thylakoids /more thylakoids / less stroma less stromaFewer grana stacksFewer grana stacksSpreadout thylakoid Spreadout thylakoid more chlorophyll per more chlorophyll per volumevolume

Acclimatization

This This PeperomiaPeperomiawent from a lowwent from a lowlight environmentlight environmentto a high light to a high light environment. environment. Its appearance hasIts appearance haschanged due inhibition ofchanged due inhibition ofchloroplast development chloroplast development in light-sensitive cells.in light-sensitive cells.

Light Overload Can Cause Death!

Placing a low light adapted plant under very bright light will cause Placing a low light adapted plant under very bright light will cause chloroplasts to adsorb too much light energy. The will disrupt chloroplasts to adsorb too much light energy. The will disrupt biochemical pathways and they will cease to operate. Leaf scorch is the biochemical pathways and they will cease to operate. Leaf scorch is the result.result.

These three leaves were These three leaves were subject to increasing subject to increasing amounts of time for amounts of time for acclimatization. The acclimatization. The smaller leaf was most smaller leaf was most acclimatized and thus acclimatized and thus could better handle the could better handle the light load.light load.

Structural and PhysiologicalStructural and PhysiologicalDifferences BetweenDifferences Between

'Sun' and 'Shade' Plants'Sun' and 'Shade' Plants

Changes in Natural Light Penetration Changes in Natural Light Penetration Occur Within Interior Spaces Because of Occur Within Interior Spaces Because of

Changes in the Sun's InclinationChanges in the Sun's Inclination

Summer sunSummer sun

Winter sunWinter sun

General Characteristics ofGeneral Characteristics ofSun and Shade LeavesSun and Shade Leaves

Descriptive Sun leaves Shade leaves Descriptive Sun leaves Shade leaves level level

often, a mosaic often, a mosaic leaf leaf arrangement, arrangement, phototropic leaf phototropic leaf petioles, Thin petioles, Thin leavesleaves

leaves leaves thickerthicker

Due to cuticle Due to cuticle and denser and denser cell wallscell walls

MorphologicalMorphological


DescriptiveDescriptive level Sun leaves Shade leaves level Sun leaves Shade leaves

more stomatamore stomata

Linear leavesLinear leavesFewer palisadeFewer palisadelayers, shorter layers, shorter cells,cells,

tighter packingtighter packing

fewer stomatafewer stomataLeaves broader, Leaves broader,

More palisade layers, More palisade layers, longer palisade cells longer palisade cells

more intercellular more intercellular spaces spaces

AnatomicalAnatomical



smallersmaller chloroplasts, chloroplasts,fewer andfewer and smaller grana smaller grana

larger larger

chloroplastschloroplastsmore grana,more grana,phototactic - phototactic -

-chloroplasts -chloroplasts

UltrastructuralUltrastructural



lower chlorophylllower chlorophyll

high respiration high respiration high LCPhigh LCPhigh lighthigh lightsaturation levelssaturation levels

more chlorophyllmore chlorophyll

low respiration low respiration low LCP low LCP low light low light saturation levelssaturation levels

BiochemicalBiochemical

Differences Between Acclimatized And Differences Between Acclimatized And Non-acclimatized PlantsNon-acclimatized Plants

AcclimatizedAcclimatized

Medium to dark green Medium to dark green leavesleavesLarge leavesLarge leavesFlat leavesFlat leavesThin leavesThin leavesLeaves widely spacedLeaves widely spaced

Non-acclimatizedNon-acclimatizedYellowish to light green Yellowish to light green leavesleavesSmall leavesSmall leavesPartially folded leavesPartially folded leavesThick leavesThick leavesLeaves crowded togetherLeaves crowded together

High Sun Grown,

AcclimatizedAcclimatized Non-acclimatizedNon-acclimatized

Internodes longInternodes longThin to medium stemsThin to medium stemsLeaf position horizontalLeaf position horizontalor slightly reflexedor slightly reflexedFew new leavesFew new leavesWide branch anglesWide branch angles

Internodes shortInternodes shortThick stemsThick stemsLeaf position uprightLeaf position uprightMany new leavesMany new leavesAcute anglesAcute angles

Differences Between Acclimatized And Differences Between Acclimatized And Non-acclimatized PlantsNon-acclimatized Plants

Nursery:Nursery:6000-1000ft-c6000-1000ft-c

85-95% RH85-95% RH

Greenhouse:Greenhouse:1500-2000ft-c1500-2000ft-c

90-97% RH90-97% RH

Lighted Lighted Warehouse:Warehouse:300-500ft-c300-500ft-c40-50% RH40-50% RH

ToTo Job: Job:

1/2 x1/2 x xy weeksxy weeksTime = xTime = x

Light Acclimatization PathwaysLight Acclimatization Pathways

Initial Response.Initial Response. Improving Acclimatization Level.Improving Acclimatization Level. Reverse Acclimatization.Reverse Acclimatization.

highhighlightlight

lowlowlightlight

PS ratesPS rates

R ratesR rates

Stored reservesStored reserves

beginning of acclimatization:beginning of acclimatization:reorientation of chloroplast and grana;reorientation of chloroplast and grana;increase in chlorophyll levels;increase in chlorophyll levels;reduction in respiration rate;reduction in respiration rate;production of new foliage.production of new foliage.

1 - 2 wks1 - 2 wks

acclimatization completeacclimatization complete

changes lead to changes lead to lower lower

compensation compensation pointpoint

changes do not changes do not lead to lead to lower lower

compensation compensation pointpoint

plant livesplant lives plant diesplant dies

2 - 8 wks2 - 8 wks

Time Required for AcclimatizationTime Required for Acclimatization

Depends on species, plant size, previous Depends on species, plant size, previous treatment and magnitude of the change. treatment and magnitude of the change.

1 - 10 weeks or more;1 - 10 weeks or more; Examples: Examples:

Philodendron, AglaonemaPhilodendron, Aglaonema - very little time - very little time required;required; Sun - grown Sun - grown Ficus benjamina Ficus benjamina and and BrassaiaBrassaia

in 40 to 80 % shade - approx. 5 wks;in 40 to 80 % shade - approx. 5 wks; Ficus nitidaFicus nitida in 50 % shade - 10 wks. in 50 % shade - 10 wks.

Acclimatization StrategiesAcclimatization Strategies

fertilized w/ fertilized w/ slow release slow release

fertilizerfertilizer

remove pellets remove pellets from the from the surface;surface;leach leach

thoroughlythoroughly

continue continue with the with the

new new fertilization fertilization and water and water scheduleschedule

continue with the new continue with the new fertilization fertilization

and water scheduleand water schedule

continue with the continue with the new fertilization new fertilization

and water and water scheduleschedule

fertilized w/ fertilized w/ soluble soluble fertilizerfertilizer

underfertilizedunderfertilized

ACCLIMATIZATIONACCLIMATIZATION

60 %60 % 75%75% 100 %100 %

Field ProductionField Production ON SITEON SITEGreenhouse Greenhouse ((INTERIM ACCLIMATIZATION)INTERIM ACCLIMATIZATION)

Time lineTime line

0 6 12 18 240 6 12 18 24

Photo

synth

esi

s (r

ate

)Photo

synth

esi

s (r

ate

)

Leaf life span (months)Leaf life span (months)

Leaf life span varies with Leaf life span varies with species and cultivarspecies and cultivar

DieffenbachiaDieffenbachia

PalmPalm

0 50 100 150 200 2500 50 100 150 200 250

Photo

synth

esi

sPhoto

synth

esi

s

Light intensity (ft-c) 12 hours per dayLight intensity (ft-c) 12 hours per day

+2+2

+1+1

00

-1-1

LCPLCP

Ficus benjaminaFicus benjamina(nonacclimatized)(nonacclimatized)

Ficus benjaminaFicus benjamina(acclimatized)(acclimatized)

Summary Tips:Summary Tips:

* * Learn as much as possible about the Learn as much as possible about the extentextent

of acclimatization of the purchased plants.of acclimatization of the purchased plants.

** Provide necessary conditions : Provide necessary conditions :

Light is the most important factor.Light is the most important factor.

** Apply fertilizer and water at reduced Apply fertilizer and water at reduced rates.rates.

!!

The Cheapest PlantThe Cheapest PlantTo Buy IsTo Buy Is

An Acclimatized PlantAn Acclimatized Plant

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Lecture # 13 Light Acclimatization Acclimatization