The Effects of Ectomycorrhizal Status on Carbon Dioxide Assimilation Capacity, Water-Use Efficiency and Response to Transplanting in Seedlings of Pseudotsuga menziesii (Mirb) Franco

1990

9 Abb., 2 Tab.

Unselbständiges Werk

2819

200041212

One year-old Douglas fir seedlings, mycorrhizal with Laccaria laccata or with Thelephora terrestris and grown at two levels of phosphorus in the nutrient solution (10 and 40 mg.l-1P), were compared for water relations and gas exchange before and after transplanting in non-limiting water conditions. The results showe that i) L. laccata is more efficient than T. terrestris in increasing photosynthesis and water use efficiency, ii), phosphorus deficiency reduces photosynthesis and water use efficiency, iii), the stimulating effect of L. laccata on photosynthesis and water use efficiency is, at least partly, due to the improvement of phosphorus nutrition, iv), the photosynthesis reduction resulting from transplanting is due to a non-stomatal mechanism, and v), the recovery of photosynthesis involves the regrowth of the external mycelium of mycorrhizas. These results are discussed from the viewpoint of the plant-fungus relationships.