Water Relations Bibliography

The experiment as conducted using potted seedlings of the shade-tolerant species Beilschmiedia pendula in open-top chambers in a forest clearing on Barro Colorado Island, Panama. Vesicular-arbuscular (VA) mycorrhizas (inoculated using feeder roots and soil from the palm Oenocarpus panamanus) increased relative growth rates (RGR) at both ambient and doubled CO₂ concentrations. RGR was correlated with the net assimilation rate (NAR) of the plants. Within this general correlation, in plants with similar RGR, NAR was reduced in VA-mycorrhizal plants compared with non-mycorrhizal plants. As RGR is the product of NAR and the leaf area ratio (LAR, the ratio of leaf area to plant mass), increases in RGR in VA-mycorrhizal plants were the results of increased LAR. Thus, VA-mycorrhizas increased growth rates of B. pendula by altering the morphology of the seedlings. Under increased CO₂ the amount of fungus within roots increased in VA-mycorrhizal plants compared with those grown under ambient CO₂, and this was associated with a greater post-inoculation depression in leaf growth. Post-inoculation depressions in leaf growth and the lower NAR (in plants with similar RGR) of VA-mycorrhizal plants indicate there is increased carbon transfer to soils under increased CO₂.