Table 1.
Planting and harvest dates and climatic parameters in the study years
Canopy temperature (in °C) is averaged for the time period from canopy closure (V5, fifth node stage) to R7 (beginning of maturity) developmental stages (Ritchie et al., 1993) on the control (c) and heated (h) plots under ambient (400 μmol m−2 s−1) and elevated (600 μmol m−2 s−1) [CO2] with periods of rain excluded for the calculations. ΔCanopy temperature (in °C) is the difference between heated and control plots within each CO2 treatment. Day is averaged from 6:00 h to 18:00 h and night from 18:00 h to 6:00 h.
| Year | 2013 | 2014 | 2015 |
|---|---|---|---|
| ø Annual air temperature (°C) | 10.7 | 9.8 | 11.6 |
| ø Air temperature June–October (°C) | 20.1 | 19.5 | 20.4 |
| Annual sum precipitation (mm) | 845 | 1012 | 1114 |
| Sum precipitation June–October (mm) | 363 | 525 | 536 |
| ø Canopy temperature (°C) c/h | |||
| Day: ambient [CO2] | 25.7/28.6 | 23.3/26.2 | 24.7/27.2 |
| Day: elevated [CO2] | 26.6/29.3 | 23.7/26.3 | 25.0/27.6 |
| Night: ambient [CO2] | 17.4/20.8 | 15.4/18.9 | 17.3/20.7 |
| Night: elevated [CO2] | 17.7/21.1 | 15.7/19.1 | 17.1/20.5 |
| ø ΔCanopy temperature (°C) ±SD | |||
| Day: ambient [CO2] | 3.0 ± 1.0 | 2.8 ± 1.0 | 2.5 ± 1.0 |
| Day: elevated [CO2] | 2.8 ± 0.8 | 2.7 ± 1.0 | 2.6 ± 1.1 |
| Night: ambient [CO2] | 3.4 ± 0.7 | 3.4 ± 0.4 | 3.4 ± 0.4 |
| Night: elevated [CO2] | 3.4 ± 0.6 | 3.4 ± 0.4 | 3.4 ± 0.5 |
| Planting date (DOY) | 158 | 169/170 | 156 |
| Canopy closure V5 (DOY) | 191 | 206 | 190 |
| Beginning maturity R7 (DOY) | 261 | 265 | 260 |
| Harvest date, DOY (treatment) | 275 | 281 (Ah, Eh) 292 (Ac, Ec) |
274 (Ac) 275 (Ec, Eh) 279 (Ec, Eh) 280 (Ah, Ec, Eh) |
Ø, average; DOY, day of year.