Journal article

Publication year: 2000

Pages: 74-82

Journal: Journal of applied botany = Angewandte Botanik

Volume number: 74

Issue number: 1-2

ISSN: 0949-5460

Publisher: Blackwell

Abstract: 

Spring wheat (Triticum aestivum L. cv. Minaret) was exposed to ambient (A-NF) and ambient + 320 ppm CO2 (A320-NF) in non-filtered (NF) open-top chambers. Wheat plants were grown in pot culture and were supplied with 300 kg N ha(-1).

For a diagnosis of photosynthetic acclimation to elevated CO2 A/C-1-curves were measured at youngest fully emerged leaves using a closed loop photosynthesis measurement system. Wheal plants that grew under elevated CO2 did not show a modification of the A/C-1-curves at tillering and stem elongation and thus did not exhibit any photosynthetic acclimation before anthesis. A widely used photosynthesis model was parameterized from the A/C-1-curves. Within model inaccuracies the key model parameters carboxylation efficiency CE and maximum e(-)-transport rate J(max) were linearly dependent on total leaf N concentration irrespective of the treatment.

However, total leaf nitrogen content declined in flag leaves of A320-NF plants. Using the N-dependence of the key photosynthesis model parameters it was calculated that a photosynthetic acclimation due to N-dilution was likely to occur in flag leaves. Besides, an increase of water-soluble carbohydrate (WSC) content due to CO2 enrichment occurred exclusively in flag leaves during grain filling. From the flag leaf area of the whole plant, the calculated photosynthetic rate of the unit leaf area and the modeled sink strength of the ears a source-sink imbalance was estimated at the organ level. Direct feedback limitation due to disturbed carbohydrate translocation probably inhibited photosynthesis in A320-NF beyond the N-induced inhibition. Source-sink imbalance primarily was provoked by wheat plants inflating their flag leaf area under elevated CO2.

At the whole plant level a functional growth analysis was carried out to characterize the growth response of wheat to elevated CO2. Aboveground dry weight was not increased due to elevated CO2 until grain filling began. The CO2-induced stimulation of the relative growth rate diminished with time. However, this behaviour was not a consequence of photosynthetic acclimation, since the normally occurring decline of the relative growth rate with increasing plant size wholly accounted for this effect (before anthesis). Absolute growth rare in A320-NF always was above A-NF.

Harvard Citation style: Grüters, U., Fangmeier, N. and Jäger, H. (2000) Scaling the response of wheat to elevated CO2: Comparison of photosynthetic acclimation and organ/plant growth, Journal of applied botany = Angewandte Botanik, 74(1-2), pp. 74-82

APA Citation style: Grüters, U., Fangmeier, N., & Jäger, H. (2000). Scaling the response of wheat to elevated CO2: Comparison of photosynthetic acclimation and organ/plant growth. Journal of applied botany = Angewandte Botanik. 74(1-2), 74-82.