Chlorophyll content of spring wheat flag leaves grown under elevated CO2 concentrations and other environmental stresses within the 'ESPACE-wheat' project
1999
Ommen, O.E. | Donnelly, A. | Vanhoutvin, S. | Oijen, M. van | Manderscheid, R.
Spring wheat cv. Minaret was grown in open-top chambers at four sites across Europe. The effect of different treatments (CO(2)) enrichment, O(3) fumigation, drought stress and temperature) on the chlorophyll content of the flag leaf was investigated using the MINOLTA SPAD-502 meter. Under optimum growth conditions the maximum chlorophyll content, which was reached at anthesis, was consistent among the sites ranging from 460 to 500 mg chlorophyll m(-2). No significant effect of elevated CO(2) or O(3) was observed at anthesis. Leaf senescence, indicated by the chlorophyll breakdown after anthesis, was relatively constant in the control chambers. Under control conditions, thermal time until 50% chlorophyll loss was reached was 600 degrees C day. Elevated CO(2) caused a faster decline in chlorophyll content (thermal time until 50% chlorophyll loss was reduced to 500-580 degrees C day) indicating a faster rate of plant development at two experimental sites. The effect of ozone on chlorophyll content depended on the time and dose O(3) exposure. During grain filling, high O(3) concentrations induced premature senescence of the flag leaves (up to -130 degrees C day). This deleterious effect was mitigated by elevated CO(2). Drought stress led to faster chlorophyll breakdown irrespective of CO(2) treatment.
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