The experimental design was a completely randomized block design. Wheat (Triticum aestivum L. cv. Yitpi) was grown in eight
[aCO2] rings (384 lmol CO2 mol1, 4 m diameter) and eight
[eCO2] rings (550 lmol CO2 mol1, 4 m diameter), completely randomized
with two different sowing times: ‘‘normal’’ or TOS1 (late May or early June) and ‘‘late’’ or TOS2 (mid or late June).