Articles
EVALUATING THE ACCOUNTABILITY OF TRUNK SIZE AND CANOPY VOLUME MODELS FOR DETERMINING APPLE TREE PRODUCTION POTENTIAL ACROSS DIVERSE MANAGEMENT REGIMES
Article number
707_30
Pages
237 – 243
Language
English
Abstract
Trunk cross-sectional area (TCA) is the most common surrogate measurement for determining tree size and, indirectly, the capacity of that tree to produce fruit.
When used in a Honeycrisp cultivar crop density and apple (Malus domestica) fruit quality experiment there was a lack of consistency across sites in fruit size and yield for similar crop densities, based on TCA (fruit/cm²). This reduced confidence in the goal of defining the optimum density and made industry wide recommendations difficult.
The Honeycrisp experiment consisted of three commercial sites which had plantings of identical age, rootstock and nursery source, but differed in tree spacing, training, pruning and management.
To better account for the inconsistencies between sites, methods of calculating crop density per cubic volume of tree canopy were examined (fruit/m3). The contour method for approximating canopy volume was developed and tested.
The established, but underutilized, simple cone along with the elliptical cone method for approximating canopy volumes were also tested.
The simple cone (V = (⅓)
r² h) and elliptical cone (V = (1/12) a b h) methods require three measurements of the trees canopy and assume the contour of the trees profile to be straight.
The contour method (V = ((¼) a b h) / (m(x) + m(y) + 1)) requires five measurements of a trees canopy.
The canopy volume is calculated by first equating the trees unique contour and then by integrating along the contour lines of one of the axis.
Using the Log10 scale the crop density was plotted against average fruit size across all sites cumulatively for the four methods, TCA, simple cone, elliptical cone, and contour method; the variation accounted for using simple linear regression was 58.9, 78.8, 80.1 and 83.9 percent respectively.
When used in a Honeycrisp cultivar crop density and apple (Malus domestica) fruit quality experiment there was a lack of consistency across sites in fruit size and yield for similar crop densities, based on TCA (fruit/cm²). This reduced confidence in the goal of defining the optimum density and made industry wide recommendations difficult.
The Honeycrisp experiment consisted of three commercial sites which had plantings of identical age, rootstock and nursery source, but differed in tree spacing, training, pruning and management.
To better account for the inconsistencies between sites, methods of calculating crop density per cubic volume of tree canopy were examined (fruit/m3). The contour method for approximating canopy volume was developed and tested.
The established, but underutilized, simple cone along with the elliptical cone method for approximating canopy volumes were also tested.
The simple cone (V = (⅓)
r² h) and elliptical cone (V = (1/12) a b h) methods require three measurements of the trees canopy and assume the contour of the trees profile to be straight.The contour method (V = ((¼)
a b h) / (m(x) + m(y) + 1)) requires five measurements of a trees canopy.The canopy volume is calculated by first equating the trees unique contour and then by integrating along the contour lines of one of the axis.
Using the Log10 scale the crop density was plotted against average fruit size across all sites cumulatively for the four methods, TCA, simple cone, elliptical cone, and contour method; the variation accounted for using simple linear regression was 58.9, 78.8, 80.1 and 83.9 percent respectively.
Authors
H. Wright, D. Nichols, C. Embree
Keywords
canopy volume, TCA, ‘Honeycrisp’, orchard productivity
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