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Zhi LiDepartmentofEnvironmentalHorticulture

University of Florida

SeedPrimingEffectsonLongevity

Overview

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1. IntroductionSeedPrimingSeedLongevity

2. ProjectOverview3. MaterialsandMethods

SeedsSolidMatrixPrimingQ2Analysis

4. Results

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SeedPriming

3Lutts,Stanley,etal."SeedPriming:NewComprehensiveApproachesforanOldEmpiricalTechnique."(2016).

Methods:

Ø Hydropriming

Ø Osmopriming

Ø SolidMatrixPriming

Ø etc.

SeedPrimingFactorsaffectpriming:

• Temperature

• Waterpotential

• Primingduration

“Hydrothermalprimingtime”Model

Effectsofpriming:

• Increasegerminationrateanduniformity

• Developseedlingrootsystemsrapidly

• Breakdormancy,overcomesomeadverseconditions,e.g.hightemperature

• Reduceseedlongevity,especiallyathighmoisturecontent

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SeedLongevityafterpriming

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Watertreatmentsandprimingaffectseedlongevity.

Tarquis,A.M.andBradford,K.J.(1992)Prehydration andprimingtreatmentsthatadvancegerminationalsoin-creasetherateofdeteriorationoflettuceseeds.JournalofExperimentalBotany

LettuceSeedsControlledDeterioration@10%MC+40C

WaterIncubation Osmopriming @-1.5MPa

controlcontrol

primingWatertreatment

Reductionofseedlongevityinstoragecomparedtonon-primedseed

ProjectDesign– Activitiesperformed

PrescreeningPriming

PrimingTestsMCTests

ControlledDeteriorationTests

DryingwithDryingBeadsto

30%RH

Q2Tests

Incubationat47%RH

GerminationTests

Objective:

Developandevaluateprimingtreatmentsonseedlongevity

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MaterialsandMethods

Seeds

SeedswereobtainedfromHM.Clause company,including:• Twoseedlotsoftomato(cv.PonyExpressE89224(T1)andE57272(T2))• Oneseedlotofpepper(cv.SequoiaPepperE65965)

• Oneseedlotofonion(cv.MissionStarE46851).

MaterialsandMethods

SolidMatrixPriming

ClaymixturematerialA.G.Taylor,D.E.KleinandT.H.Whitlow(1988)SMP:SolidMatrixPrimingofSeeds.ScientiaHorticulturae,37KeithKubick – HM-Clause

+fixedamountofseedsandincreasingamountofwatertoobtainthresholdseedwatercontentforpriming.

Ratioseed:media:waterrange1:2:1- 2

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MaterialsandMethods

Q2OxygenSensingTechnology

The Q2 equipment provides a quick and precisemeasurement of the oxygen consumption of eachindividual seed, so that it can give us respiration (oxygendepletion) time courses.

http://www.astec-global.com/q2-technology

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Agar0.4%+Fungicide

Curves of O2 depletion

MaterialsandMethods

Q2Analysisoxygenconsumptionmeasurementsat30-minuteintervals

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MaterialsandMethods

• PODcurvesarevisuallysimilartogerminationtimecourses.

• Seedoxygenconsumptionratesonanindividualseedandpopulationbasisarehighlycorrelatedwithgerminationtiming.

• Potentialmaixumum longevity(Pmax)ofseedscanbeestimatedaging-timemodelbasedonPODdata.

Population Oxygen Depletion (POD)Curves

Bello,P.,andBradford,K.J. (2016).Single-seedoxygenconsumptionmeasurementsandpopulation-basedthresholdmodelslinkrespirationandgerminationratesunderdiverseconditions.SeedScienceResearch26,199-221.

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Results

Initialseedgerminationat25C.

FinalGermination:

Onion85%

Tomato-T194%

Tomato-T294%

Pepper85%

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Results- PrescreeningofPriming

2.5gofseed+5gofclaymedia+differentamountofwater.

Amountofdaysrequiredtostartofgerminationaddingincreasingamountofwateronbags(2.5-4.75ml).3mlchosenforprimingonallspecies.

Daysforgermination

ProjectDesign– Activitiesperformed

PrescreeningPriming

PrimingTestsMCTests

ControlledDeteriorationTests

DryingwithDryingBeadsto

30%RH

Q2Tests

Incubationat47%RH

GerminationTests

ControlledDeteriorationTest:50°Cwithdifferentagingdurations,rangingfrom 10-40Days

Q2Test:PopulationOxygenDepletion(POD)Curves

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Results– PrimingDuration

Pepper Onion

Tomato– T1 Tomato– T2

Pepper– littlechangeinratesforfirst4daysofpriming,increasingspeedafterthat.

Onion– moregradualreductionintimewithincreasingprimingduration.

Tomato-T1– Similargradualresponseexceptwithlongestduration.

Tomato-T2– 1and2daysdurationresponsestrongaslongerprimingduration.

Figure.Population OxygenDepletion(POD)curvesforpepper(A),onion(B),tomato-T1(C)andtomato-T2(D)withdifferentdaysofpriming(legendsineachpanel).ThecurvesareplottedforR50(thetimesatwhicheachseedconsumedhalfoftheoxygenavailableintheQ2vial).

Results– ControlledDeteriorationTomato- T1

0

40

80

120

160

200

0 10 20 30 40

R50

(50)

(h)

Aging duration (days)

TomatoT1

0 1 2 4 60

10

20

30

40

50

60

70

0 1 2 4 6

Pmax

(day

s)

Priming Duration (days)

Primingduration(days)

A B

Longevity declined sharply between 0 and 2 days of priming, then recovered somewhat at longer priming times.

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0

10

20

30

40

50

60

70

80

90

0 1 2 3 4 5 6P

max

(day

s)Priming Duration (days)

Tomato- T2- PrimingDurationandPmax

Tomato – T2 – Priming durations + Aging Series -

Q2 Tests

0

50

100

150

200

250

0 10 20 30 40

R50

(50)

Aging duration (days)

Tomato- T2- PrimingDurationandAging

0 1 2 3 4 5 6

Results– ControlledDeteriorationTomato-T2

Similar pattern to T1, with the least potential longevity occurring after 2 days of priming

Take-homeMessagesPerformanceenhancedbypriming:

• Increasegerminationrateanduniformity• Developseedlingrootsystemsrapidly• Breakdormancy,overcomesomeadverseconditions

Disadvantage:

• Reduceseedlongevity