Table 1.
Comparison of three different leaf angle modelling approaches with respect to effect on light interception and photosynthesis
| Light intercepted (%) |
Photosynthesis with one set of parameters (μmol m−2 s−1) |
Photosynthesis with two sets of parameters (μmol m−2 s−1) |
||||
|---|---|---|---|---|---|---|
| Leaf-angle distribution | Diffuse | Direct | Diffuse | Direct | Diffuse | Direct |
| Fixed angle (CONST) | 77 (43) | 80 (41) | 20 (8·8) | 27 (12·3) | ||
| Ellipsoidal distribution (ELLIP) | 77 (48) | 80 (47) | 24 (10·3) | 29·2 (12·9) | 21 (10·7) | 29·6 (13·2) |
| Explicitly described leaf angles (EXPL) | 77 (52) | 80 (55) | 27 (10·6) | 30·3 (13·2) | 24 (10·9) | 30·9 (13·7) |
Values for light interception and photosynthetic rate are for the total canopy. Values in parenthesis refer to the middle of the canopy (0·75–1·25 m from the top of the plant) where differences were observed. Direct light was calculated for 21 June. The light intensity for direct light conditions was derived from the 10-yearly average of light incidence on these dates under Dutch conditions (4·6 µmol m−2 s−1at sunrise, 3109 µmol m−2 s−1 at noon and 23 µmol m−2 s−1 at sunset). For diffuse light conditions a light intensity of 460 µmol m−2 s−1 was considered. Calculations were done when it was assumed that all leaves of the canopy had the same photosynthetic properties or with two sets of photosynthetic properties, where the properties of the top layer differed from those of the middle and lower layers.