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Table 1 Effects of low temperature treatments on chlorophyll fluorescence parameters of C. bifida and C. panzhihuaensis

From: Differences in lipid homeostasis and membrane lipid unsaturation confer differential tolerance to low temperatures in two Cycas species

Parameters Species Treatment    
   Control Cold Freezing Recovery
Fv/Fm C. bifida 0.826 ± 0.006a 0.782 ± 0.015b 0.717 ± 0.046c 0.001 ± 0.002d
  C. panzhihuaensis 0.857 ± 0.010a* 0.824 ± 0.004b* 0.819 ± 0.007b* 0.823 ± 0.009b*
Y(II) C. bifida 0.462 ± 0.068a 0.325 ± 0.052b 0.152 ± 0.040c 0 ± 0d
  C. panzhihuaensis 0.465 ± 0.050a 0.421 ± 0.044ab* 0.427 ± 0.018ab* 0.383 ± 0.026b*
Y(NPQ) C. bifida 0.315 ± 0.084a 0.321 ± 0.045a 0.076 ± 0.057b 0.052 ± 0.005b
  C. panzhihuaensis 0.260 ± 0.046b 0.288 ± 0.034ab 0.226 ± 0.030b* 0.313 ± 0.034a*
Y(NO) C. bifida 0.224 ± 0.016d 0.354 ± 0.014c 0.776 ± 0.104b 0.948 ± 0.005a
  C. panzhihuaensis 0.275 ± 0.016b* 0.291 ± 0.039b* 0.348 ± 0.023a* 0.304 ± 0.013b*
qp C. bifida 0.744 ± 0.044a 0.533 ± 0.061ab 0.241 ± 0.054b 0.8 ± 0.0447a
  C. panzhihuaensis 0.635 ± 0.048a* 0.644 ± 0.070a* 0.634 ± 0.019a* 0.588 ± 0.028a*
qN C. bifida 0.682 ± 0.106b 0.596 ± 0.043b 0.134 ± 0.100c 0.987 ± 0.029a
  C. panzhihuaensis 0.561 ± 0.050a* 0.602 ± 0.054a 0.490 ± 0.051b* 0.612 ± 0.043a*
rETR C. bifida 120.4 ± 17.501a 83.6 ± 13.390b 38 ± 9.925c 0 ± 0d
  C. panzhihuaensis 117.4 ± 12.740a 108.6 ± 11.127a* 108.6 ± 4.393a* 94.8 ± 6.686b*
  1. Different letters in the same row indicate significant differences between treatments within species and * indicates significant difference between species within treatment (P < 0.05). Data are mean ± standard deviation (n = 4)
  2. Fv/Fm The maximum quantum yield of photosystem II (PSII), qP Photochemical quenching coefficient, qN Non-photochemical quenching coefficient, rETR Relative electron transport rate, Y(II) Effective quantum yield of PS II, Y(NO) Non-regulated non-photochemical energy loss in PS II, Y(NPQ) Regulated non-photochemical energy loss in PS II