Evaluation of water status indicators in olive trees under different water regimes

摘要

Physiological responses of olive(Olea europaea L.)trees under different water regimes(irrigated and rainfed)was monitored through the selected indicators(the soil water content,the tree stem water content,the sap flow and the leaf conductance)at the experimental field of the CIHEAM-IAMB from March to August 2012.The difference in response of olive trees under two water regimes was significant in terms of four water status indicators.In addition,the growth of olive tree(leaf area and fruit establishment)was also different.The water status indicators responded differently to both the application of water(by irrigation)and to the moment in which water stress appeared.A sort of “critical point” of soil water content for olive was detected for this field,and it was consistent with the one calculated from the retention curve.The values of water status indicators were found to be clearly correlated within each other,following similar paths and trends for both water regimes until a critical value of the soil water content was reached.Close to this point,all the plant water status indicators showed a clear trend of reduction to minimal values.The differences in the physiological responses of olive trees under irrigated and rainfed conditions can be evaluated by means of integrated observations of water movement in soil-plant –atmosphere continuum.The tree stem water content and/or the sap flow could be effectively used to evaluate the occurrence of water stress in olive,better still with additional data on the soil water content and/or the evaporative demand of the atmosphere.The effectiveness of irrigation strategies to avoid water stress can be confirmed by the use of such indicators.