© 2007 Heron Publishing—Victoria, Canada
Evaluation of sap flow and trunk diameter sensors for irrigation scheduling in early maturing peach trees
W. Conejero (1), J. J. Alarcón (1, 2), Y. García-Orellana (3), E. Nicolás (1) and A. Torrecillas (1, 2, 4)
1. Dpto. Riego., Centro de Edafología y Biología Aplicada del Segura (CSIC), P.O. Box 164, 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 January 18, 2007; accepted February 23, 2007; published online September 4, 2007
Summary
Five-year-old early maturing peach trees (Prunus persica (L.) Batsch cv. Flordastar grafted on GF-677 peach rootstock) were subjected to three irrigation treatments from March 18
to November 10, 2006. Control plants (T0 treatment) which received irrigation in excess of their crop water requirements (1089.7
mm) were compared with plants watered according to sap flow (SF; T1 treatment) or maximum daily trunk shrinkage (MDS; T2 treatment)
measurements, so as to maintain SF and MDS signal intensities (control SF/SF in T1 and MDS in T2/control MDS, respectively)
close to unity. When SF or MDS signal intensity on at least two of three consecutive days was at or below unity, irrigation
was reduced by 10%. When the MDS signal intensity on at least two of three consecutive days exceeded unity, irrigation was
increased by 10%. During the experiment, estimated crop evapotranspiration was 704.9 mm, and the cumulative amounts of applied
water in the T1 and T2 treatments were 463.2 and 654.5 mm, respectively. The MDS-signal-intensity-driven irrigation schedule
was more suitable than the SF-signal-intensity-driven irrigation schedule because it was more sensitive and reliable in detecting
changes in plant water status, preventing the development of detectable plant water stress. Moreover, it had no effect on
fruit size. We conclude that peach tree irrigation scheduling can be based on MDS measurements alone. Changes in the irrigation
protocol assayed were proposed to reduce MDS signal intensity deviations above unity, for example, by increasing the irrigation
scheduling frequency or the amount of water applied, or both. Irrigation schedules based on maintaining MDS signal intensities
close to unity could be applied when local crop factor values are unavailable.
Keywords:
stem water potential, trunk diameter fluctuations, water relations.
