Modeling Survival of Young Olive Trees (Olea europaea L. cv. Arbequina) in Saline and Waterlogging Field Conditions

Abstract

As the pressure to use marginal or low-quality lands for crop production increases, it becomes increasingly necessary to determine the influence of stress factors such as salinity or waterlogging on crop growth and yield. This paper models the survival of olive trees (Olea europaea L. cv. Arbequina) under salinity and waterlogging field conditions. The effects of soil salinity [electrical conductivity of the saturation extract (ECe)] and waterlogging [relative ground elevation (RGE) and water table depth (WTD)] on the survival of 338 young olive trees were analyzed by logistic regression. The logit and probit models based on ECe, RGE, and WTD and their interactions were fitted to the data. Also, a nonlinear regression with 100% probability of olive survival (P) below a first ECe limit, 0% P above a second ECe limit, and a linear decrease in between (threshold-slope regression model) was fitted to the ECe data. The ECe and RGE were the two factors significantly affecting olive survival. The ECe was 7.7 dS m−1 for P = 50% (estimated median lethal ECe) and 3.7 dS m−1 for P = 95%. The threshold-slope model ECe estimates were 5.0 dS m−1 (upper threshold for unrestricted survival or P = 100%) and 10.3 dS m−1 (lower limit for the nonsurvival or P = 0%). Young olive trees were moderately tolerant to soil salinity, and their P under saline conditions was satisfactorily explained by both the logistic and the threshold-slope regression models.