Stomatal control and hydraulic conductivity in 'Manzanilla' olive trees under different water regimes

8 pages, 4 figures, 15 references.-- International Symposium on Olive Irrigation and Oil Quality, Nazareth, Israel.

We studied the response of leaf water potential (Ψ1), stomatal conductance (gs), leaf specific hydraulic conductivity (Kl) and percentage loss of hydraulic conductivity (PLC) in current-year shoots of 40-year-old 'Manzanilla' olive trees under three water treatments: Rainfed, in which rainfall was the only source of water; FAO, in which the trees were under localized irrigation to replace crop water demand; Pond, in which the whole root zone of the trees was maintained under non-limiting soil water conditions throughout the irrigation season. In the FAO trees, some roots were left in drying soil during the irrigation season. Results suggest near-isohydric behavior of olive trees. FAO trees maintained Ψ1 values similar to those of Pond trees by increasing stomatal closure. In Rainfed trees, gs values were smaller than in the irrigated trees, but stomatal closure did not prevent Ψ1 values from falling below those of the irrigated trees, likely because of the dramatic decrease in soil water content observed in the Rainfed treatment. Values of Kl and PLC showed no differences between treatments throughout the irrigation season. During that period, the PLC values ranged from 38% to 50%, which shows that even the well-irrigated Pond trees were unable to maintain their hydraulic efficiency, likely because of the high atmospheric demand in the area.

This work was funded by the Spanish Ministry of Education and Science, research project No.AGL2006-04666/AGR, and by the EU, research project ref. STREP 023120.

Peer Reviewed