© 2007 Heron Publishing—Victoria, Canada
Daily sap flow and maximum daily trunk shrinkage measurements for diagnosing water stress in early maturing peach trees during
the post-harvest period
W. Conejero (1), J. J. Alarcón (1, 2), Y. García-Orellana (3), J. M. Abrisqueta (1, 2) and A. Torrecillas (1, 2, 4)
1. Dpto. Riego. Centro de Edafología y Biología Aplicada del Segura (CSIC). P.O. Box 160, E-30100 Espinardo (Murcia), Spain / 2. Unidad Asociada al CSIC de Horticultura Sostenible en Zonas Áridas (UPCT-CEBAS), Paseo Alfonso XIII s/n, E-30203 Cartagena
(Murcia), Spain / 3. Dpto. Ingeniería Agrícola. Universidad Centro Occidental Lisandro Alvarado (UCLA), Barquisimeto, Venezuela / 4. Corresponding author (atorreci@cebas.csic.es) / Received February 14, 2006; accepted April 12, 2006; published online October 2, 2006
Summary
We compared the sensitivity of two continuously recorded plant-based water stress indicators (sap flow, SF, and maximum daily
trunk shrinkage, MDS) to detect changes in the water status of 4-year-old early maturing peach trees (Prunus persica (L.) Batsch cv. Flordastar grafted on GF-677 peach rootstock) during a cycle of deficit irrigation and recovery. The feasibility
of obtaining SF and MDS reference equations for use in irrigation scheduling during the post-harvest period was also studied
in trees irrigated in excess of crop water requirements. We found that MDS was a more sensitive and reliable detector of changes
in plant water status than SF, making it a more precise tool for irrigation scheduling. Baseline relationships between SF
or MDS and the climatic variables (air temperature, vapor pressure deficit (VPD) and crop reference evapotranspiration (ETo))
were established, despite some scatter in the data. Among the climatic variables, SF correlated more closely with ETo, whereas
MDS correlated more closely with mean daily air temperature (Tm). The fits of the regressions between MDS and ETo, midday air temperature and Tm for individual periods were better than those obtained in the overall regressions, confirming that daily stem diameter variations
must be considered not only in the context of plant water status but also in the context of plant carbon status.
Keywords:
baselines, irrigation scheduling, trunk diameter fluctuations, water relations.
