Elevated [CO2] increased root respiration and the effects of
drought were significantly modulated by the level of [CO2]
(Fig. 2). Thus, soil respiration was dramatically reduced after severe
drought stress under standard [CO2] and the observed decrease
(65%) was similar for both AT-sprayed and non-sprayed plants.
Additionally, high [CO2] increased soil respiration by 54.7%, but
no AT effect was found when plants were fully irrigated. However,
a significant difference was found when AT was applied
at high [CO2], and roots of these plants showed a respiration of
16mol CO2m−2 s−1, higher than non-sprayed plants under the
same stress conditions, but also higher than control plants at standard
[CO2]: 11mol CO2m−2 s−1.