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. 2022 Jun 7;9:uhac124. doi: 10.1093/hr/uhac124

Table 1.

Calculations and definitions of water relations, gas-exchange and fluorescence (Strasser et al., 2000, 2004) parameters measured in the study with their broad classification

Phenotype category Phenotype Calculation Definition
Drought score and water relations
DS Drought scoring system based on the appearance characteristics of seedlings
Drought score RWC (fresh weight (FW) – dry weight (DW)) / (turgor weight (TW) – DW) Leaf relative water content (RWC)
Gas-exchange parameters
Pn Net photosynthetic rate (μmol CO2 m−2 s−1)
Tr Transpiration rate (mmol H2O m−2 s−1)
gs Stomatal conductance (mol H2O m−2 s−1)
Gas-exchange Ci Intercellular CO2 concentration (μmol CO2 mol−1 air)
parameters Ca Atmospheric CO2 concentration
WUEintri Pn/gs WUEintri in μmol CO2 mmol H2O−1
WUEinst Pn/Tr WUEinst in μmol CO2 mmol H2O−1
CE Pn/Ci An estimate of carboxylation efficiency of Rubisco
Fluorescence parameters
F0 F0 = F50μs Minimum Fluorescence, when all PSII RCs are open
FJ FJ = F2m Fluorescence intensity at the J-step (2 ms)
Primary FI FI = F60ms Fluorescence intensity at the I-step (60 ms)
fluorescence FM FM = F1s Maximum fluorescence, when all PSII RCs are closed
measurements FV FV = FM - F0 Variable fluorescence
VJ VJ = (FJ-F0)/(FM-F0) Variable Fluorescence at the J-step
VI VI = (FI-F0)/(FM-F0) Variable fluorescence at the I-step
FM/F0
Fluorescence ratios FV/F0 Maximum efficiency of photochemistry
FV/FM (FM - F0)/FM Maximum yield of primary photochemistry
M0 4(F300μs - F0)/(FM - F0) Rate of reaction center closure
N (Area/(FM - F0)) × M0 × (1/VJ) Turn-over number QA reduction events
between time 0 and FM
Ψ0 Ψo = ET0/TR0 = 1- VJ Likelihood that a trapped exciton can move
an electron further than QA
Derived parameters φEo ΦEo = ET0/ABS = (1-(F0/FM)) × Ψ Quantum yield of electron transport to intersystem electron acceptors (between photosystem II and I)
φDo ΦDo = 1- Φp0 = (F0/FM) Quantum yield at time 0 for energy dissipation
Φpav Φpav = Φp0(1-Vav) Average quantum yield of primary photochemistry
PIABS (RC/ABS) × (φPo/1- φPo) Performance Index of PSII normalized for equal absorption
ABS/RC ABS/RC = M0 × (1/VJ) × (1/Φp0) Energy absorption by antenna per reaction
center (indicator of antenna size for PSII)
Energy flux
parameters
TR0/RC TR0/RC = M0 × (1/VJ) Flux of excitons trapped per reaction center: reduction of Pheophytin and QA
ET0/RC ET0/RC = M0 × (1/VJ) × Ψ0 Energy flux for electron transport per reaction center: beyond QA
DI0/RC DI0/RC = (ABS/RC)-(TR0/RC) Flux ratio of energy dissipation per reaction center