Details

Autor(en) / Beteiligte

• Grant, R.F
• Kimball, B.A
• Wall, G.W
• Triggs, J.M
• Brooks, T.J
• Pinter, P.J. Jr
• Conley, M.M
• Ottman, M.J
• Lamorte, R.L
• Leavitt, S.W

Titel

Modeling elevated carbon dioxide effects on water relations, water use, and growth of irrigated sorghum

Ist Teil von

• Agronomy journal, 2004-11, Vol.96 (6), p.1693-1705

Ort / Verlag

Madison, WI: American Society of Agronomy

Erscheinungsjahr

2004

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Elevated concentrations of atmospheric CO2 (C(a)) are believed to raise sorghum Sorghum bicolor (L.) Moench productivity by improving water relations. In ecosys, water relations are simulated by solving for the canopy water potential (psi(C)) at which water uptake from a model of soil-root-canopy water transfer equilibrates with transpiration from the canopy energy balance. Simulated water relations were tested with psi(C), water uptake, and energy exchange measured under ambient (363 micromol mol(-1)) and elevated (566 micromol mol(-1)) C(a) and high vs. low irrigation in a free air CO2 enrichment experiment during 1998 and 1999. Model results, corroborated by field measurements, showed that elevated C(a) raised psi(C) and lowered latent heat fluxes under high irrigation and delayed water stress under low irrigation. Changes in psi(C) modeled under ambient vs. elevated C(a) varied diurnally, with lower psi(C) causing earlier midafternoon stomatal closure under ambient C(a). Modeled changes in sorghum water status caused elevated C(a) to raise seasonal water efficiency under high and low irrigation by 20 and 26% (vs. 20 and 13% measured) in 1998 and by 9 and 27% (vs. 6 and 26% measured) in 1999. Ecosys was used to generate an irrigation response function for sorghum yield, which indicated that yields would rise by approximately equal to 13% for a range of irrigation rates if air temperatures were to rise by 3 degrees C and C(a) by 50%. Current high sorghum yields could be achieved with approximately equal to 120 mm or approximately equal to 20% less irrigation water if these rises in temperature and C(a) were to occur.