Irrigation scheduling in a high-density olive orchard from estimated stomatal conductance

Stomatal conductance (g_s) is one of the possible good plant-based indicator, because it reflects finely the level of water stress and photosynthesis limitations.
We conducted an experiment to schedule a regulated deficit irrigation (RDI) strategy for high density olive orchards, using modeled g_s (summer 2017, Spain). We had three treatments with four replicated plots: two control treatments, one of them irrigated with the K_c method (100C_Kc) and the other one from the estimation of g_s as a function of air vapor pressure deficit (D) and radiation (100C_gs). We also had one RDI treatment (45RDI), in which 45% only of the water supplied to the 100C_gs treatment was applied.
Stomatal conductance modeled for 100C_gs was compared to g_s estimated using sap flow measurements.
We found a good correlation between g_s estimated with the two methods (R²=0.9, p<0.0001). The total water supply in 100C_gs (3722.6 m³ ha^‑1) was lower than in 100C_Kc (4103.2 m³ ha^‑1), with no effect (p>0.05) either on the trees water status (average predawn leaf water potential was -0.67 MPa in 100C_gs) or in fruit yield (12633±3448 and 13290±1256 kg ha^‑1 in 100C_gs and 100C_Kc, respectively). Yield in 45RDI was significantly reduced (7399.7±276 kg ha^‑1) as it was the estimated g_s, which decreased around 30% in relation to 100C_gs. We conclude that it is possible to schedule irrigation in olive from automated estimations of g_s. This estimation model and further supplement and related research might be opens the possibility for determining targeted levels of stress as a function of g_s.

XXX International Horticultural Congress IHC2018: International Symposium on Water and Nutrient Relations and Management of Horticultural Crops

V. Hernandez-Santana, J.E. Fernández, A. Diaz-Espejo

regulated deficit irrigation, fruit yield, virgin olive oil

https://doi.org/10.17660/ActaHortic.2019.1253.59