Identification of Unique Reproductive Characteristics in Six Pawpaw Populations for Germplasm Enhancement

Abstract

The North American pawpaw [Asiminatriloba (L.) Dunal] is a tree fruit native to the eastern and midwestern areas of the United States. The fruit has a rich, unique flavor and pawpaw has great potential as a new fruit crop. Kentucky State University (KSU) in Frankfort is the site for the USDA National Clonal Germplasm Repository (NCGR) for Asimina species, containing over 1700 accessions from 17 different states. The objective of this study was to evaluate the diversity in reproductive characteristics for pawpaw accessions in the KSU-USDA repository orchard from six geographic regions (Ind.-site 1, Ind.-site 2, Ky., Md., N.Y., and W.Va.). Data were collected in 2002, 2003, and 2004 for trunk cross-sectional area, total number of flowers, length of flowering, flowering peak, fruit set, total number of clusters, total number of fruit, number of fruit per cluster, average fruit weight, yield, yield efficiency, length of harvest, harvest peak, and growing degree days required for ripening. Significant differences in characteristics were found within and among populations for the various regions. Accessions from Kentucky and West Virginia had the latest flowering peaks. Trees from Maryland had the highest fruit weight in 2002, whereas the West Virginia population produced the largest fruit in 2004. The New York accessions consistently had the latest harvest peak and required the fewest growing degree days for ripening. Correlations were also found between several vegetative and reproductive characteristics. This study suggests that a significant level of reproductive diversity exists within KSU's repository collection that could be used in future breeding strategies for cultivar improvement.