Preliminary photosynthesis measurements of selected wheat cultivars prior to inoculation

Dr. Ferenc HorváthDr. Barnabás Wodala

The LI-6400 Portable Photosynthesis System

The LI-6400 Portable Photosynthesis System

The LI-6400 Portable Photosynthesis System

An open system

In an open system, photosynthesis and transpiration are computedfrom the differences in CO2 and H2O between in-chamber conditions and pre-chamber conditions.

Schematic without a CO2 mixer

Schematic with a CO2 mixer

IRGA (InfraRed Gas Analizator)

Infrared light source

(wide spectrum)

Gas inlet Gas outletMeasuring box Detector

Filter

CO2 measurement: 4,26 μm

H2O measurement: 2,59 μm

Signal processingIndicator

Matching

Incoming concentrations must be stable

breath, for example, is typically 30 000 μmol CO2 (mol air)-1

Ambient air contains 360 μmol CO2 (mol air)-1

Light

PSII PSI

Reflected light

Transmitted light

Heatdissipation

Chlorophyll a fluorescence

ETRΦPSII

Photosynthesis

Mehlerreaction

Photorespiration

PRELIMINARY MEASUREMENTSSetting up the instrument (Licor 6400, an open path gas exchange system)4 selected wheat genotypes (1 week before the infection)

PARout: sunny, depends on angle, 600 – 1800 µmol photon m-2 s-1

PARin: fixed, 1000 µmol photon m-2 s-1 (10% blue, 90% red)Tair: 27-29 °CTleaf: 25-27 °C

Calculated parameters

474 501 488 4830

0.1

0.2

0.3

0.4

0.5

0.6

ΦPS

II

474 501 488 48320

21

22

23

24

25

26

27

A (µ

mol

s-1

m-2

)

474 501 488 4830

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Gs (

mol

s-1

m-2

)

Thank you for your attention!