Research note: Can decreased transpiration limit plant nitrogen acquisition in elevated CO2?

• DOI: 10.1071/fp02007
• Publication Date: 2002-09-16T04:40:11Z
• Authors: Evan P. McDonald; John E. Erickson; Eric L. Kruger
• Keywords: Stomatal Conductance; Ecophysiology

N acquisition often lags behind accelerated C gain in plants exposed to CO2-enriched atmospheres. To help resolve the causes of this lag, we considered its possible link with stomatal closure, a common first-order response elevated CO2 that can decrease transpiration. Specifically, tested hypothesis declines transpiration, and hence mass flow soil solution, delivery mobile root thereby limit plant acquisition. We altered transpiration by manipulating relative humidity (RH) atmospheric [CO2]. During 7-d period, grew potted cottonwood (Populus deltoides Bartr.) trees humidified (76% RH) non-humidified (43% glasshouses ventilated either or non-enriched air (~1000 vs ~380μmol mol-1). monitored effects and/or on conductance, whole-plant biomass gain, accumulation. facilitate latter, NO3- enriched 15N (5 atom%) was added all pots at outset experiment. Transpiration accumulation decreased when were elevated. The disparity between led 19% shoot concentration ambient CO2. Across treatments, positively correlated (P<0.0001), significant portion remaining variation (44%) related per unit mass. At given humidity, leaf area conductance. Thus, content under enrichment may be attributable part associated decreases conductance