Fluorescence data was collected using a MINI-PAM-II fluorometer (Walz Heinz GmbH, Effeltrich,
Germany). To conduct measurements, the leaf clip was attached to a leaf and measurements of
Germany).
**To conduct measurements:**
- The leaf clip was attached to a leaf and measurements of
photosynthetically active radiation (PAR) and the photosynthetic efficiency of photosystem II (PhiPSII) were
recorded. This was repeated ~10 times per plot. Each FI plot was followed by its RI plot counterpart. Plots of
blocks 1 and 4 were measured 49 days after sowing between 14:45 and 15:45. Plots of blocks 2 and 5 were
recorded.
- This was repeated ~10 times per plot.
- Each FI plot was followed by its RI plot counterpart.
>**Plots of blocks 1 and 4 were measured 49 days after sowing between 14:45 and 15:45. Plots of blocks 2 and 5 were
measured 48 days after sowing between 15:00 and 17:00. All blocks were measured 50 days after sowing
between 10:24 and 12:49. The fluorescence kinetics of saturation pulse analyses for measurements wereinspected using WinControl-3 Software (version 3.29-rev.1112) (Walz Heinz GmbH, Effeltrich, Germany).
between 10:24 and 12:49.**
The fluorescence kinetics of saturation pulse analyses for measurements were inspected using WinControl-3 Software (version 3.29-rev.1112) (Walz Heinz GmbH, Effeltrich, Germany).
Measurements that did not pass inspection were discarded from subsequent analyses.
PhiPSII values were clustered according to genotype, treatment and PAR level using custom R scripts.
PAR was divided into four levels: low (<500 μmol photons m -2 s -1 ), mid-low (500-1000 μmol photons m -2 s -1 ),
mid-high (1000-1500 μmol photons m -2 s -1 ) and high (>1500 μmol photons m -2 s -1 ). Agglomerative hierarchical
clustering was applied on the scaled PhiPSII means for all plots using the ‘agnes’ function of the R package
‘cluster’ [100] with a cut-off of five clusters.
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**PAR was divided into four levels:**
- low (<500 μmol photons m -2 s -1 ),\
- mid-low (500-1000 μmol photons m -2 s -1 ),
- mid-high (1000-1500 μmol photons m -2 s -1 ) and
- high (>1500 μmol photons m -2 s -1 ).
Agglomerative hierarchical clustering was applied on the scaled PhiPSII means for all plots using the ‘agnes’ function of the R package ‘cluster’ [1] with a cut-off of five clusters.
Reference:
[1] Maechler, M.; Rousseeuw, P.; Struyf, A.; Hubert, M.; Hornik, K.; Studer, M.; Roudier, P.; Gonzalez, J.; Kozlowski, K.; Schubert, E.; et al. “Finding Groups in Data”: Cluster Analysis Extended Rousseeuw et al. Available online: https://cran.r-project.org/web/packages/cluster/cluster.pdf (accessed on 26 February 2021).
