ISSN:
1435-0653
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
2 . This study investigated whether the effects of an episode of high air temperature (HT, 43°C as a daily maximum), water deficit (WD), or both, had the same effect on the recovery of photosynthesis and on leaf water relations of soybean [Glycine max (L.) Merr., cv. Fiskeby V] grown at ambient CO2 (aCO2) or elevated CO2 (eCO2). An 8-d period of HT, WD, or both (HTWD) were imposed during early seed filling of soybean grown in glasshouses at either 362 or 685 μmol mol-1 CO2. Photosynthesis (Amax), stomatal conductance (gs), and water relations were measure in fully expanded upper-canopy leaves. Immediately after the 8-d treatments at 60 d after sowing (DAS), Amax was reduced by 31, 48, and 64% in aCO2 and by 28, 39, and 49% in eCO2 under HT, WD, and HTWD, respectively, but no significant interactions were detected. At 60 DAS, gs was reduced by WD and HTWD in aCO2 but not by HT while there was little change in gs by WD, HT, and HTWD under eCO2. Amax fully recovered under WD in eCO2 by 66 DAS, while Amax remained reduced under WD in aCO2. Under each CO2 concentration, almost fully recovery of Amax occurred under HT by 75 DAS but under HTWD Amax never attained control values. At 60 DAS, early morning leaf water potential (ψ) was lower after HT, WD, and HTWD and Amax was a negative function of ψ, at each CO2 concentration. The results suggest that full recovery of Amax from WD was only possible under eCO2, because at aCO2, immediately after the stress episode, ψ was below the threshold for chloroplast damage.
Type of Medium:
Electronic Resource
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