Effects of elevated carbon dioxide on three grass species from montane pasture II. Nutrient uptake, allocation and efficiency of use

• Published in: Journal of Experimental Botany
• Main Authors: Baxter, R., Gantley, M., Ashenden, T.W., Farrar, J.F.
• Format: Text
• Language: English
• Published: Oxford University Press 1994
• Subjects: Articles; Poa alpina
• Online Access: http://jxb.oxfordjournals.org/cgi/content/short/45/9/1267; https://doi.org/10.1093/jxb/45.9.1267

Agrostis capillaris L.4 Festuca vivipara L. and Poa alpina L. were grown in outdoor open-top chambers at either ambient (340 μmol mol−1) or elevated (680 μmol−1) CO2 for periods from 79 to 189 d. Under these conditions there is increased growth of A. caplllarls and P. alpina , but reduced growth of F. vivipara . Nutrient use efficiency, nutrient productivity (total plant dry weight gain per unit of nutrient) and nutrient allocation of all three grass species were measured in an attempt to understand their individual growth responses further and to determine whether altered nutrient-use efficiencies and productivities enable plants exposed to an elevated atmospheric CO 2 environment to overcome potential limitations to growth imposed by soil fertility. Total uptake of nutrients was, in general, greater in plants of A. capillaris and P. alpina (with the exception of N and K in the latter) when grown at 680 μmol mol−1 CO 2 . In F. vivipara , however, uptake was considerably reduced in plants grown at the higher CO 2 concentration. Overall, a doubling of atmospheric CO 2 concentration had little effect on the nutrient use efficiency or productivity of A. capillaris . Reductions in tissue nutrient content resulted from increased plant growth and not altered nutrient use efficiency. In P. alpina , potassium, magnesium and calcium productivities were significantly reduced and photosynthetic nitrogen and phosphorus use efficiencies were doubled at elevated CO 2 with respect to plants grown at ambient CO 2 F. vivipara grown for 189 d showed the most marked changes in nutrient use efficiency and nutrient productivity (on an extracted dry weight basis) when grown at elevated CO 2 , F. vivipara grown at elevated CO 2 however, showed large increases in the ratio of non-structural carbohydrate to nitrogen content of leaves and reproductive tissues, indicating a substantial imbalance between the production and utilization of assimilate.