Tuff trenches improve sap flow in avocado trees affected by long-term irrigation with treated wastewater

D.B. Nemera, A. Bar-Tal, G. Levy, V. Lukyanov, J. Tarchitzky, S. Cohen
Reduced orchard performance following long-term irrigation with treated wastewater (TWW) in clayey soils and orchard performance are well documented. This study evaluates the effects of tuff trenches to mitigate damage to soil and avocado orchards following long-term irrigation with TWW. The treatments studied included TWW, fresh water (FW) and TWW-irrigated tuff trenches (TUF) with six replications. Trenches 30 cm deep and 30 cm wide, ~30 cm away from the stem on both sides of the tree rows, were dug and filled with volcanic tuff. Climate data and tree sap flow were measured to determine tree responses to treatments. Wind speed, solar radiation, temperature and relative humidity were measured at about 1 m above the treetops. The daytime courses of sap flow (F) measured in 10 trees per treatment during selected days with high VPD (≥2.00 kPa) shows the peak in FW (7.31 L h‑1 tree‑1) and TWW (5.19 L h‑1 tree‑1) an hour earlier (at 11:15 am) than on low VPD (≤1.5 kPa) days (at 12:15 pm). The observed midday F was significantly higher in TUF and FW compared to TWW. Daily average F in FW and TUF during higher midday VPD was 31.70 and 28.47%, respectively higher than TWW when midday VPD was low. The treatment effect on tree F is tangible at about midday (10:00 am-15:00 pm) indicating tree water demand is regulated by VPD and other environmental variables. F in FW and TUF was enhanced probably due to the leaching of salt and/or toxic ions from the rhizosphere and improved soil aeration. Based on the sap flow response, tuff trenches may be a reliable candidate treatment for prevention and mitigation of TWW adverse effects on tree performance.
Nemera, D.B., Bar-Tal, A., Levy, G., Lukyanov, V., Tarchitzky, J. and Cohen, S. (2020). Tuff trenches improve sap flow in avocado trees affected by long-term irrigation with treated wastewater. Acta Hortic. 1300, 7-12
DOI: 10.17660/ActaHortic.2020.1300.2
salinity, vapor pressure deficit, soil aeration, water uptake

Acta Horticulturae