Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/3/2003
Publication Date: 11/6/2003
Citation: WALL, G.W., KIMBALL, B.A., ORT, D.R., BERNACCHI, C.J., OLIVIERI, L.M., LONG, S.P., HARRISON, M. 2003. UNIVARIATE EFFECT OF ELEVATED CO2 OR O3 ON WATER RELATIONS OF SOYGBEAN AND CORN LEAVES. AGRONOMY ABSTRACTS. CD-Rom (A03-Wall866009-oral). Interpretive Summary:
Technical Abstract: Reported herein is the independent univariate effect of either atmospheric CO2 or O3 concentration on upper most sunlit leaf stomatal conductance (gs), transpiration rate (T), total water (TWP), osmotic (OWP) and resultant turgor (PWP) potentials, tissue concentration of osmotica (i.e., simple sugars, free amino acids, inorganic ions), and biophysical characteristic of leaf tissue. Soybeans (Glycine max) and corn (Zea maize) crops were exposed to ambient (control; 370 ppm CO2; 40-70 ppb O3) and either free-air CO2 (ambient +180 ppm) or O3 (ambient + 50%) enrichment (FACE) under a typical mid-western (USA) rainfed production system during 2002. At midday (solar noon) both elevated CO2 and O3 reduced gs, thereby, reducing T. Compared with control, elevated CO2 increased the concentration of total leaf osmotica and enhanced biophysical characteristics of leaf tissue, whereas O3 had the inverse effect. Elevated CO2 caused less negative (improved) TWP and more negative OWP, resulting in higher PWP. Elevated O3 had only a nominal, or slightly inverse effect, as that of CO2 on TWP, OWP and PWP. Hence, in a future high-CO2 world improved water relations are anticipated in a herbaceous C3 indeterminate dicot such as soybean, and a determinate warm-season C4 monocot grass such as corn. Nevertheless, a concomitant rise in atmospheric O3, along with CO2, will tend to mitigate any ameliorating effect that elevated CO2 will impart on plant water status.