Table 2.
Leaf segment | Observed δ18O, ‰ | Craig–Gordon model-predicted δ18O, ‰ | Gat–Bowser model
|
|||
---|---|---|---|---|---|---|
Nonvariable E
|
Fitted E
|
|||||
E, mmol⋅m−2⋅s−1 | Predicted δ18O, ‰ | E, mmol⋅m−2⋅s−1 | Predicted δ18O, ‰ | |||
Base 1 | −7.4 | 11.0 | 7.14 | −7.5 | 7.40 | −7.4 |
2 | 1.0 | 11.0 | 7.14 | −2.4 | 12.25 | 1.0 |
3 | 9.6 | 11.0 | 7.14 | 3.2 | 10.60 | 9.6 |
4 | 16.1 | 11.0 | 7.14 | 9.4 | 6.05 | 16.1 |
5 | 23.2 | 11.0 | 7.14 | 16.4 | 5.70 | 23.2 |
6 | 27.7 | 11.0 | 7.14 | 24.6 | 2.40 | 27.7 |
Tip 7 | 41.7 | 11.0 | 7.14 | 35.3 | 5.60 | 37.3 |
Mean | 16.0 | 11.0 | 7.14 | 11.3 | 7.14 | 15.4 |
δ18Osource was −12.5‰, and all other environmental parameters were as mentioned in Table 1. In the Gat–Bowser model, the mean value of E for the entire leaf remains constant. However, the proportion of E within a segment was either held constant (nonvariable E) or was varied (fitted E). The calculated variations in fitted E across the length of the leaf are less than those of sugarcane (20).