|Thomas, Andrew - UNIVERSITY OF MO COLUMBIA|
Submitted to: Northern Nut Growers Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 5, 2008
Publication Date: N/A
Technical Abstract: Many landowners in the United States have little access to information on economic returns from agroforestry practices. Despite the existence of agroforestry economic simulators, data bases are lacking to predict returns from nuts produced by eastern black walnut (EBW), Julgans nigra L., a hardwood species with potential for agroforestry in the central United States. The objective of this study was to determine the effects of tree stock type (native versus named genotypes selected for higher nut quality) on the relationship between tree diameter at 3.7 feet above ground (DBH) and nut yields in EBW. Nut yields and DBH measurements were collected from five stands of native stock trees and seven stands of grafted named genotypes of EBW in the central United States for two consecutive years (2002-2003). Relationships between 2-year mean DBH and nut yields were highly significant for both tree stock types. However, the slope for the regression equation for predicting nut yields from DBH for named genotype trees was twice as great as that for native trees. DBH and nut yield relationships were utilized to predict nut production 25 years after planting at 4 site indexes from 6.1 to 15.2 m. These analyses indicated that predicted income was greater when grafted named genotypes were planted because of greater nut yields and higher nut prices, despite higher planting costs.