A comparative study of apple and pear tree water consumption measured with two weighing lysimeters

A five-year experiment (2002–2006) was conducted to determine apple (cv ‘Golden Smoothee’) and pear (cv ‘Conference’) crop coefficients (Kc) using two large weighing lysimeters. Daily reference evapotranspiration (ETo) and crop evapotranspiration (ETc) were evaluated. Midday canopy light interception of both crops planted in hedgerows, 4 × 1.6 m, was determined on a weekly basis from bud-break until leaf fall from year 2002 (fourth after planting) to year 2006 of both plantations. Relationships between canopy light interception and calculated Kc (ETc/ETo) were evaluated from bud-break until harvest. There were differences in Kc values between apple and pear trees. When daily Kc values from bud-break until harvest were adjusted to hyperbolic functions each year, adjusted curves for pear trees were very similar regardless of year (maximum Kc around 1.0). In apple trees, the maximum values of Kc increased over time, from 0.49 in 2002 to 1.04 in 2006. Midday light interception in both apple and pear trees increased during the 5 years of experiment from 29.0 to 45.6% in apples and from 27.5 to 41.6% in pears in midsummer. Although there was a significant positive correlation between midday canopy light interception and Kc in apple and pear trees, in different times within a specific year, these relationships were different between crops. While the apple data fitted into the same equation regardless of the year, different equations were needed to fit the pear data in different years. This discrepancy may have been related to differences in the canopy properties between apple and pear trees. Pear canopies had higher porosity than apple canopies and thus improved light penetration. Apple trees were more vigorous and produced taller and denser canopies. Pear Kc values were greatly influenced by the evaporative demands of different years and consequently differences in midday canopy light interception did not adequately reflect the differences in Kc across the two species.

[1]  R. Bendel,et al.  Comparative gas exchange characteristics of potted, glasshouse-grown almond, apple, fig, grape, olive, peach and Asian pear , 1992 .

[2]  J. Ayars,et al.  MODELING YOUNG PEACH TREE EVAPOTRANSPIRATION , 2002 .

[3]  J. Ayars,et al.  Crop coefficients for mature peach trees are well correlated with midday canopy light interception. , 2000 .

[4]  J. Ayars,et al.  IMPROVING A MODEL FOR PREDICTING PEACH TREE EVAPOTRANSPIRATION , 2004 .

[5]  D. W. Grimes,et al.  Water use of mature Thompson Seedless grapevines in California , 2003, Irrigation Science.

[6]  D. Turner,et al.  Water use of plum trees (Prunus salicina) trained to four canopy arrangements. , 1990 .

[7]  J. Girona,et al.  Effect of late Spring defruiting on net CO2 exchange and leaf area development in apple tree canopies , 2006 .

[8]  W. O. Pruitt,et al.  Crop water requirements , 1997 .

[9]  Luis S. Pereira,et al.  Estimating crop coefficients from fraction of ground cover and height , 2009, Irrigation Science.

[10]  R. Snyder,et al.  Measurement of light interception by navel orange orchard canopies : Case study of lindsay, california , 2006 .

[11]  Claudio O. Stöckle,et al.  A simple approach to modeling radiation interception by fruit-tree orchards , 2007 .

[12]  J. E. Ayars,et al.  Grapevine water use and the crop coefficient are linear functions of the shaded area measured beneath the canopy , 2005 .

[13]  Elias Fereres,et al.  Drip irrigation saves money in young almond orchards , 1982 .

[14]  Amnon Erez,et al.  Studies of canopy structure and water use of apple trees on three rootstocks , 2002 .

[15]  G. Campbell.  Extinction coefficients for radiation in plant canopies calculated using an ellipsoidal inclination angle distribution , 1986 .

[16]  J. E. Jackson.  Biology of Apples and Pears: Flowers and fruits , 2003 .

[17]  C. J. Phene,et al.  Water use by drip-irrigated late-season peaches , 2003, Irrigation Science.

[18]  Terence L. Robinson,et al.  Comparison of Four Methods for Estimating Total Light Interception by Apple Trees of Varying Forms , 1995 .

[19]  T. Trout,et al.  Use of Crop Canopy Size to Estimate Crop Coefficient for Vegetable Crops , 2006 .

[20]  L. S. Pereira,et al.  Crop evapotranspiration : guidelines for computing crop water requirements , 1998 .

[21]  J. Girona,et al.  Factors involved in alleviating water stress by partial crop removal in pear trees. , 2008, Tree physiology.