Università°li&Studi&di&Trieste!

Università°li&Studi&di&Udine!

Casolo&V.,&Tomasella&M.,&De&Col&V.,&Braidot&E.,&Savi&T.,&Nardini&A.&&&

Spar%na'patens&(Poaceae)&

Func&onal!plas&city:!wide!ecological!amplitude!of!the!genus!!

•  Role!played!by!plant!hydraulics!in!driving!plant!adapta&on!to! saline!habitats!and/or!plas&city!of!invasive!plants?! Solidago(canadensis:!capability!of!hydraulic!acclima&on!to!contras&ng!water!availabili&es! (Nolf!et!al.,!2014)!

Effect!of!xylem!sap!salt!concentra&on!on!plant!hydraulic!efficiency! (Zwieniecki!et!al.,!2001;!Nardini!et!al.,!2011;!…)!

•  Can!halophytes!successfully!use!salts!to!enhance!their!xydraulic! efficiency/safety?!! Xylem!sap![Na+]upSregula&on!in!saltSstressed!plants!(Munns,!1985)! Modula&on!of!xylem!sap!sodium!content!in!mangroves!(LopezSPor&llo!et!al.,!2005)! No!studies!on!eventual!effects!of!salt!on!xylem!hydraulics!in!leaves!and/or!halophy&c!grasses!

Study&site&&&&contrasBng&salinity&levels&

Methods&

Salt&marsh& (45°38’2,06”!N,!13°04’21,87”!E)! • 88,5!cm!a.m.s.l.!

Dune& (45°38’3,42”!N,!13°04’41,95”!E)! • !202,5!cm!a.m.s.l.!(highest!height)!

Summer!2012:!severe!drought!period!

Leaf!water!poten&al!and!conductance!to!water!vapour!(gL,!mmol!mS2!sS1)! Methods& Leaf!water!poten&al!isotherms!(PV!curves):!Ψtlp;!π0;!εmax! ! Starch!concentra&on!in!leaves! N!concentra&on!in!soil!and!leaves! !

Leaf!hydraulics!

•  Whole!leaf!hydraulic!conductance!and!vulnerability!to!drought!stress! (rehydra&on!kine&cs!technique):! Kleaf_area=!Cleaf_area!x!ln!(Ψ0 Ψf-1) t-1! ! •  Hydraulic!efficiency!of!leaf!xylem:!! kleaf_xylem!(mmol!sS1!MPaS1!mS1)! ! •  Role!played!by!Na+!in!the!regula&on!of!leaf!hydraulics:! increase!of!kleaf_xylem!(%)!at!different!NaCl!concentra&on! (Xylem!sap!enrichment!with!ions:!electrical!conduc&vity!of!sample!fluid)! !

Leaf!anatomy!

diameter!of!metaxylem!vessels!in!primary!veins! N°!major!veins!per!sec&on! Distance!between!adjacent!vascular!bundles! ! Aboveground!biomass!

Results&&&Discussion&

Soil!salinity! mS!cmS1! *!

Leaf![starch]! mg!gS1! n.s.!

Aleaf! cm2! n.s.!

LMA! mg!cmS2! n.s.!

Marsh! 6390!±!3556! 1.10!±!0.44! 10.6!±!1.9!

24.6!±!8.0!

9.3!±!1.8!

12.1!±!1.7!

Dune!

19.1!±!7.4!

10.7!±!2.5! 11.6!±!1.5!

570!±!38!

Soil![N]! mg!gS1! *!

0.34!±!0.10!

Leaf![N]! mg!gS1! *!

7.0!±!1.8! +&50%&

Invariant!leaf!morphological!traits!and!total!biomass!accumulated!

Data!shown!as!mean!±!SD! *,!P!
Results&&&Discussion& 2.0

**

Marsh Dune

* 1.0

Minimum&leaf&water& potenBal&and&conductance& to&water&vapour&

!

leaf,

-MPa

1.5

0.5

0.0 120

n.s.

*

80

-2

gL, mmol m s

-1

100

Marsh!plants:!effec&ve! acclima&on!responses!to!salt/ water!stress!

60 40 20 0

July

September

Data!shown!as!mean!±!SD! *,!P!
Results&&&Discussion&

Seasonal&changes&in&Ψtlp and π0& 4

Marsh Dune

*

Substan&al!osmoregula&on! in!marsh!plants! ! ! No!seasonalS/popula&onS based!difference!in!ɛmax!

$ , -MPa tlp

3 n.s. 2

1

0 4

(datas!not!shown)!!

*

2

n.s.

0

! "#MPa

3

1

Data!shown!as!mean!±!SD! *,!P!
0

July

September

Marsh!plants:!! ! !

important!seasonal!downSregula&on!of!TLP! decrease!of!π0!!!!!!!!!!!!!!!!!!!higher!leaf![N]! ! ! ! predominant!role!played!by!osmoregula&on!in!Ψtlp adjustment! (Bartley!et!al.,!2012)!

Results&&&Discussion&

Whole&leaf&hydraulic&conductance&&

Diameter!of!metaxylem!vessels:! ! Marsh:!16.0!±!2.2!µm! Dune!18.5!±!1.1!µm!

Marsh

6

+35%&

5 4

2.0

-1

min&Ψleaf&

0 0 6

1

2

3

Dune

min&Ψleaf&

5 4 3

r2 = 0.29 P50 = -3.5 MPa

1

P!
1.5

1.0

0.5

Marsh

0 0

&

0.0

2 1

P < 0.05

-1

1

-1

r2 = 0.65 P50 = -2.9 MPa

2

kleaf_xylem, mmol s MPa m

-1

Kleaf_area ,mmol s-1 MPa m

-2

3

2

! leaf, -MPa

3

Dune

Xylem&specific& hydraulic&conducBvity&

Results&&&Discussion&

Hydraulics&

One!of!the!first!studies!on!whole!leaf!hydraulic!efficiency!and!safety! of!an!halophy&c!grass! ! !

Leaf!hydraulic!system!of!S.(patens(well!protected!against!risk!of! droughtSinduced!failure:!!! Min!Ψleaf!values!!!!!!!!!!!!!!!!!!24S16!%!loss!of!Kleaf_area! !

! !

marsh!plants:!lower!kleaf_xylem!!(narrower!xylem!conduits)! compensated!by!higher!efficiency!of!extraSvascular!pathway!

Results&&&Discussion& Marsh Dune

%

10

Role&played&by&Na+& in®ulaBon&of&leaf& hydraulics&

!k

15

leaf_xylem,

20

5

0 0

10

20

30

[NaCl], mM

40

50

Xylem!sap!enrichment! with!ions!(electrical! conduc&vity!of! collected!perfused! water):!

! Marsh:!0.20!±!0.09!mS!cmS1! Dune:!0.16!±!0.07!mS!cmS1! (n.s.)!

Results&&&Discussion&

Ca&onSmediated!enhancement!of!xylem!hydraulic!efficiency! !

S.(patens:!

Inverse!rela&onship!!between!NaCl!availability!and!sensi&vity!of!xylem! to!changes!in!xylem!sap!concentra&on! ! ! marsh!plants:!higher!NaCl!availability,!higher!ions!upload!!in!xylem!sap! ! ! possible!compensa&on!of!lower!kleaf_xylem!! ! ! ! dune!plants:!reduced!NaCl!availability!in!the!soil!compensated!by! higher!sensi&vity!to!Na+!

Substan&al!invariance!of!seasonal!gas!exchange!rates!and!primary! produc&vity!under!contras&ng!salinity!condi&ons:! • !osmoregula&on! • Leaf![N!]! • Hydraulic!efficiency!and!safety!mechanisms!!

FuncBonal&plasBcity&of&leaf&water&relaBons&and&xylem&hydraulics:&key& ! trait&in&the&compeBBve&ability&and&invasive&potenBal&of&S.'patens' ! ! !!

na&ve!species?!

Technische Universität München

KROOF&Z&Kranzberg&forest&ROOF&experiment& Ecophysiological&contribuBon&

C. Blanck, M. Tomasella, M. Goisser, T. Grams, K-H Häberle, R. Matyssek , Ecophysiology of Plants, TU München, Freising, Germany

Mixing!effects!among!European!beech!and!Norway!spruce! Hypothesis:& •  Growth!of!spruce&is&limited&by&reduced&carbon&uptake&upon!stomatal!closure!under!incipient! drought,!reflec&ng!its!more!isohydric&strategy! •  Growth!of!beech&is&limited&by&hydraulic&failure&and/or!impeded!longSdistant!C!transport!under! advanced!drought!reflec&ng!a!more!anisohydric&strategy! •  Will&beech&benefit&from!the!higher!soil!water!availibility!when!growing!in!neighborhood!of!spruce! (belowground!water!repar&&oning)?!

KROOF!–!Kranzberg!forest!throughfall!exclusion!experiment! KROOF!site!!!!!!!!!!!!!!!!!!!!! C: Control plot T: Drought plot

Crane!

Crane!access!

Establishment!of!plots! Impossible d'afficher l'image. Votre ordinateur manque peut-être de mémoire pour ouvrir l'image ou l'image est endommagée. Redémarrez l'ordinateur, puis ouvrez à nouveau le fichier. Si le x rouge est toujours affiché, vous devrez peut-être supprimer l'image avant de la réinsérer.

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Main!points!to!be!inves&gated!

! ! !Responses!to!drought!in!terms!of!vulnerability!to!cavita&on:! in!the!Kranzberg!forest:!! • differences!between!species,!! • inside!of!a!species,!in!mixed!vs!pure!stand!trees! • Follow!the!developement!of!drought!treatment:!safety!margins..! in!poyed!plants:! • Induced!water!stress!!in!European!beech,!Norway!spruce,!Quercus(petrea,!Poplar!(hybrid)! !  Belowground!water!repar&&oning:!(hydraulic!redistribu&on)! Split!root!aproach!in!poyed!plants! ! ! !

Mechanisms!of!tree!vulnerability!to!drought!

tree‘n‘ing& Ecophysiology!of! Plants! ! R.!Matyssek! T.!Grams! K.SH.!Häberle! M.!Tomasella! M.!Goisser! C.!Blanck! Funded(by(TUM( Interna;onal( Graduate(School(of( Science(and( Engineering((IGSSE),( Focus(Area(„Water“(

Process!Engineering!of! Disperse!Systems! ! P.!Först! M.!Meixner! ! ! Process!systems! engineering! ! H.!Briesen! M.!Kuhn!

20!