Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2013
Publication Date: 4/11/2014
Citation: Ledbetter, C.A., Sisterson, M.S. 2014. Membership within the Nonpareil Marketing Group: Examination of an unclassified accession. Acta Horticulturae. 1028:397-400.
Interpretive Summary: Kernels from California almond cultivars are divided into five marketing groups based on kernel shape and appearance. These marketing groups assist in the promotion and sale of California almonds, which now represent more than 80% of the annual world harvest. Objective methods have been recently developed to define kernel shape and appearance boundaries within the important Nonpareil Marketing Group, but methodology is still lacking in determining the fit of newly-developed or unclassified almond accessions into this important marketing group. A technique has now been established to determine whether membership of an unclassified almond accession is warranted in the Nonpareil Marketing Group. The procedure simultaneously compares 16 kernel shape and appearance characters of the unclassified accession with those of cultivars in the Nonpareil Marketing Group. The means of categorization is important for almond breeders and commercial nurseries that market newly-bred almonds, some of which might resemble kernels in the Nonpareil Marketing Group. Since market prices for Nonpareil Marketing Group almonds are typically 30% more than all other California almonds, the categorization technique provides an objective way for breeders and nurseries to compare kernels of newly-bred almonds with kernels from the premium marketing group.
Technical Abstract: California almonds are categorized into marketing groups based on kernel shape and appearance to facilitate promotion and sale. Market prices for Nonpareil Marketing Group (NMG) kernels are 30% higher than for almonds in other marketing groups. Accordingly, there is economic incentive for breeders to offer a new cultivar capable of kernel sales in the NMG. The ‘Nonpareil’ almond cultivar accounts for a majority of kernel tonnage produced in the NMG along with cultivars ‘Jeffries,’ ‘Kapareil’ and ‘Milow.’ No objective standards exist to determine whether any new or unclassified cultivar should also be included in the NMG. Hence, research objectives were twofold: 1) to determine the phenotypic kernel variability of unclassified almond accession 23-122; and 2) to compare kernel misclassification of 23-122 with the four NMG cultivars. Kernel shape and appearance variability was characterized over three harvest seasons along with cultivars from different marketing groups (‘Carmel’ - California Marketing Group, ‘Padre’ – Mission Marketing Group). Discriminant analyses were used to examine kernel misclassifications. ‘Carmel’ and ‘Padre’ kernels were distinguished with misclassifications less than 1%. Misclassifications among cultivars within the NMG were much higher, varying between 8.0% - 21.9%. A leave-one-out cross-validation procedure was used to compare kernel misclassifications between 23-122 and each NMG cultivar. Misclassification of accession 23-122 taken as NMG kernels was only 1.4%, significantly less than any NMG cultivar, and demonstrating an inappropriate fit in the NMG. These methods provide an objective classification where newly developed or unclassified almond kernels can be compared objectively to the NMG.