Table 4.
Parameters for the two piece-wise linear function fitted for each of the three-leaf gas exchange variables in response to salinity as indicated in equation 1.
| Genotype | Net photosynthesis rate (μmol CO2 m−2 s−1) |
Transpiration rate (mmol H2o m−2 s−1) |
Conductance (g H2o m−2 s−1) |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Eccr | α1 | α2 | R2 | RMSEn (%) | Eccr | α1 | α2 | R2 | RMSEn (%) | Eccr | α1 | α2 | R2 | RMSEn (%) | |
| BRRI Dhan47 | 4.82 | 0.04 | −0.71 | 0.96 | 7.0–10.7 | 4.057 | 0.25 | −0.34 | 0.91 | 7.0–33.4 | 1.04 | −0.6 | −0.01 | 0.93 | 26.0–39.2 |
| IR64 | 7.58 | −0.11 | −1.45 | 0.99 | 3.0–17.7 | 4.26 | −0.04 | −0.29 | 0.99 | 1.0–15.7 | – | −0.04 | – | 0.89 | 9 |
| IR29 | 6.54 | −0.32 | −1.5 | 1 | 0.0–39.5 | 6.427 | −0.76 | −0.15 | 0.99 | 0.0–16.4 | 5.19 | −0.096 | −0.019 | 0.95 | 1.0–54.5 |
ECcr, critical level of salinity (dS m−1) to cause change in response; α1, α2, slopes of the two-piecewise linear regression; R2, coefficient of correlation; and RMSEn, normalized root mean square error between the observed and calculated values from the greenhouse experiments (Experiments 1, 2 and 3) and the field experiment (Experiment 4). Fitted data were obtained from 4 to 6 plants in each experiment (1–4) for each genotype and each Treatment (control, 1, 2 and 3) measured at three times (7, 14 and 21 d after start of salinity treatment).