Use of plant sap flow rate and stomatal conductance techniques to determine water stress in olive trees

The study was carried out in the mature olive trees of Memecik variety in 2018 at the Ministry of Agriculture and Forestry, Bornova Olive Research Institute. In this study, changes in stomatal conductivity (gs) and plant sap flow throughout the season were observed in olive trees under deficit irrigation conditions. In addition, stomatal conductivity (gs) measurements were performed on rainfed (K1) and control (K2) treatments every two hours on 4 different days during the period to monitor changes in stomatal conductivity during the day. Tretatments are K1: non-irrigated (rainfed), K2: soil water deficit in a 90 cm soil depth was refilled to field capacity for every 7 days, K3: application of the 66% of water given at K2, K4: application of the 33% of water given at K2. In this study (01/06/2018-30/09/2018), irrigation water requirement was ranged from 0 to 911 mm, evapotranspiration (ETa) varied from 132 to 894 mm. In the study, the seasonal averages of pre-irrigation stomatal conductivity data were found to be 179.6, 275.6, 250.2 and 242.4 mmol m-2 s-1 for K1, K2, K3 and K4, respectively The seasonal averages of post-irrigation stomatal conductivity were found to be 330.7, 293.3, and 245.1 mmol m-2 s-1 for K2,K3 and K4,respectivelyd. According to the data obtained in this study, the difference between the stomatal conductivity values were statistically significant. Seasonal average of plant sap flow measurements were calculated as 0.035, 0.080, 0.069 and 0.054 ml cm-1 min-1 for K1, K2, K3, K4, respectively. It was observed that there was a positive linear relationship (R2= 0.603), (R2= 0.555) between sapflow and pre and post irrigation stomatal conductance values. As a result of the study; It can be said that stoma conductivity (gs) and plant sap flow rate measurement values can be used to determine water stress in olive trees. Keywords: Olive, Sapflow, Stomatal conductance, Water stress, leaf porometer