Volume 63 Number 2 Article 2
Year 2009 Month 4
Title: Cultivars of Eastern Black Walnut Trees (Juglans nigra L.) Have Greater Nut Yields Than Native Trees at Similar Trunk Cross-Sectional Areas
Authors: D. Brauer, A. Ares and A. Thomas
Abstract:
Orchard production of eastern black walnut (Juglans nigra L.) cultivars may be the best way to stabilize the
supply of nuts.
The objective of this study was to determine if the relationship between trunk cross-sectional area
(TCSA) and nut yield is different between cultivars of black walnut and native trees.
Data were collected from 13
stands of black walnut (six stands of native trees and seven stands of cultivars) growing in open canopy or free-togrow
circumstances in the central United States for two consecutive years (2002-2003). The regression equations
between two-year mean for nut yield per tree and trunk cross-sectional area (TCSA) were highly significant for
data from native trees and cultivars of black walnut; however the slopes and Y-intercepts differed.
For cultivars,
the equation was: two-year mean yield (kg per tree) = 0.0071*(mean TCSA, cm2) + 1.38. For native trees, the
equation was: two-year mean yield (kg per tree) = 0.0049*(mean TCSA, cm2) – 0.11. When various independent
variables were assessed as predictors of two-year means for yield among the 13 stands, the regression equations
generated by backward selection included two variables: 1) the tree stock type, i.e. cultivars versus native trees; 2)
annual mean increase in TCSA. These analyses indicate that cultivars did differ from native trees in the relationship
between TCSA and nut yield per tree.
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