Transcript loew_matyssek

CASIROZ Fall Meeting
Antwerp 2003
What I did last summer
Markus Löw (PhD student)
Ecophysiology of Plants, Freising, Germany
Working Team: Löw, Häberle, Matyssek
TU Munich
In this presentation:
• Assessments e.g. Flush, Senescence and Symptoms
• Climatic issues
• gas exchange measurements:
Photosynthesis, Conductance
• Chlorophyll fluorescence
Quantum Yield of PS II, Imaging PAM
• Any Changes for next year?
• Timetable for next year
Conductance H2O [mol/m2s]
conductance during CASIROZ sampling leaf 482 sun
0.180
0.120
0.060
0.000
16. Jun
29. Jul
15. Sept
date
14. Okt
Assessments: e.g. senescence
Senescence:
endin
ofnets
growing
25.10.2003until
• 20 branches
enclosed
from season:
end of September
November
per tree one shade and one sun branch
• 14 assessments
Climatic issues
Available water for roots (mm)
• extremely dry summer in 2003!
• this summer was worse than 1947 or 1976
Data from „Waldzustandsbericht Bayern 2003“
Porometry, conductance
Measured under ambient light conditions
during CASIROZ sampling days 11am –
1pm always at the same leaf
0.18
0.12
0.06
conductance during CASIROZ sampling leaf 482 sun
0.00
0.18
29. Jul
15. Sept
14. Okt
date
predawn water potential
0.12
0.06
0.00
n.v.
0.0
n.v.
Conductance H2 O [mol m- ²s-1 ]
16. Jun
predawn water potential [MPa]
Conductance H2 O [mol m- ²s-1 ]
conductance during CASIROZ sampling leaf 482 sun
-0.6
-1.2
16. Jun
29. Jul
15. Sept
Bu 1xO3
14. OktBu 2xO3
LiCor 6400 Portable Photosynthesis
System
date
-1.8
June
July
August
Date
September
October
Porometry, photosynthesis
1x O3 n= 38
2x O3 n= 58
Lammas shoots n=22
Steady state measurement August
• saturating light
• 360 ppm CO2
• Temperature ~ 25°C, rH ~ 45%
photosynthesis rate ± SD
Photosynthesis reduced by at least 50%
compared to previous years!
photosynthesis rate [µmol m-2s-1]
5
4
3
2
1
0
1xO3 sun
2xO3 sun
treatment or kind of leaf
lammas shoot
Porometry & Fluorescence
Steady state measurement August
• saturating light
• 360 ppm CO2
• Temperature ~ 25°C, rH ~ 45%
New LiCor Leaf Chamber
Fluorometer: simultaneous
gas exchange and
chlorophyll fluorescence
MaximumYield:
Quantum
Yield (Fv/Fm)
± SDFv'/Fm'. ± SD
Maximum Quantum
comparison
Fv/Fm and
0.7
0.7
ratio ratio
Fv/FmFv/Fm
or Fv'/Fm'
0.6
0.6
Fv/Fm
Fv'/Fm'
new developed test:
-25% light cond.)
first measurement of Fv’/Fm’ (Fv/Fm under
0.5
0.5
0.4
0.4
-18%
-2%
second measurement of Fv’/Fm’
Lammas shoot leaves have
4 min
at saturating light
until gas leaves 2are
min at less
saturating
light
Lammas
shoot
tolerant
exchange
stable
best
capacity
of PS II (quantum yield)to
high
light
than
other
sunleaves
leaves
But quantum
yield
still high
in
all leaves:
compared
toisother
sun
no drought effects visible in terms of PS II
0.3
0.3
0.2
0.2
0.1
0.1
0.0
0.0
1xO3
1xO3sun
sun
2xO3
2xO3sun
sun
treatment
treatmentor
orkind
kindof
ofleaf
leaf
lammas
lammasshoot
shoot
Imaging PAM
New technique: shows Chlorophyll Fluorescence
values as a 2D false color picture:
Zangerl, A. R., Hamilton, J. G., et. al. (2002)
Impact of folivory on photosynthesis is
greater than the sum of its holes.
Proceedings of the National Academy of Sciences of the United States of America 99, 1088-1091.
• Non invasive diagnostic method on PS II
“… on average,
indirectlychanges
affected area
wastime
six times
that of the area directly
• observe
over
(months)
affected by tissue removal.”
•
e.g.
calculate
affected
area
“... indirectly affected area remained
photosynthetically
active, but at a reduced
rate, its contribution to photosynthesis reduction […] was three times that of
the directly affected area.”
Imaging PAM
Compare visible symptoms with fluorescence findings:
In contrast to findings on folivory:
surrounding area is not affected
Does ozone injury develop like this?
1
3
?
2
4
Differences young / old trees
Old Trees: few large stipples,
diffuse area
Holes
Young trees: many small destinct
stipples
Changes & Improvements 2004
• combine Imaging PAM and Porometer in the field to get a
picture of actual ozone uptake in the leaf
• measure dark adapted leaves to determine quantum yield:
LiCor „Leaf Chamber Fluorometer Dark adapting clips“ are
needed
• measure more leaves to improve observation of forming
necroses
but no major changes in the time schedule for
next year:
Timetable