Water uptake dynamics in apple trees assessed by an isotope labeling approach

Improving our knowledge on the relative contribution of irrigation water, precipitation, and groundwater to tree transpiration is necessary for an efficient sustainable use water resources in agriculture. For this purpose, we applied deuterium (2H) enriched trace uptake by apple trees under field pot conditions. 2H-enriched was supplied Alpine valley mimicking sprinkler irrigation. Labeled infiltration soil presence shoots measured over a week. An ancillary experiment using potted performed elucidate role after saturation with water. Under conditions, infiltrated maximum depth 0.6 m, where most fine roots were present, mixed pre-irrigation Sprinkler taken up 2–4 h its supply shoot content increased first 24 h, then it leveled off. Tree absorbed from layer represented average 48 ± 3% 26 2% total axes leaves, respectively. The results confirmed allowed us speculate that conditions (ca. 0.9 m deep, capillary rise expected depth) did not significantly contribute uptake. Results indicate large fraction (52–74%) derive recent uptake, suggesting rather limited mixing within organs.