A comparative study of apple and pear tree water consumption measured with two weighing lysimeters |
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Authors: | Joan Girona Jesus del Campo Merce Mata Gerardo Lopez Jordi Marsal |
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Institution: | (1) Irrigation Technology, Institut de Recerca i Tecnologia Agroalimentaries (IRTA), Centre UdL-IRTA, Av Rovira Roure 191, 25198 Lleida, Spain |
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Abstract: | 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. |
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