Interactive effects of elevated CO2, O-3, and soil water deficit on springwheat (Triticum aestivum L-cv. Nandu)

This study investigated the interactive effects of elevated carbon dioxide (CO2), ozone (O-3), and soil water deficit on spring wheat (Triticum aestiv um L. cv. Nandu). Plants were grown in open-top chambers (OTCs) which were arranged in a 2 x 2 factorial design consisting of two O-3 levels (ambient and 1.5-times ambient) in combination with two CO2 levels (ambient and ambi ent plus 320 mu mol mol(-1) CO2) Subplots in each OTC were subjected to two levels of watering, well-watered and restricted water supply. Total leaf c onductance (g(L)), growth and biochemical analyses were determined to asses s plant responses. The relative reduction in g(L) due to CO2, soil water de ficit and/or O-3 depended on plant growth stage. However, complex interacti ons between the experimentally controlled factors occurred on many days. Re duced water supply resulted in growth reduction but provided some protectio n against the loss in dry weight caused by O-3. Elevated CO2 stimulated pla nt growth, but no interactive effects between CO2, soil water deficit and/o r O-3 were observed, suggesting that elevated CO2 reduced the adverse effec ts of O-3 and/or soil water deficit in an additive manner. The complex natu re of the multiple stress interactions involved was also illustrated by the responses of specific biochemical variables (carbohydrates, proline, pigme nts). (C) 1999 Inra/Editions scientifiques et medicales Elsevier SAS.