Date Available

12-7-2011

Year of Publication

2004

Degree Name

Master of Science (MS)

Document Type

Thesis

College

Agriculture

Department

Plant and Soil Science

First Advisor

Dr. Robert L. Geneve

Second Advisor

Dr. Kirk W. Pomper

Abstract

The North American Pawpaw [Asimina triloba (L.) Dunal] shows great potential as a new fruit crop. Kentucky State University in Frankfort, Ky. is the site for the USDA National Clonal Germplasm Repository (NCGR) for Asimina species. Both the fruit and the trees themselves are of high value to growers and nursery producers. Pawpaw cultivars are currently propagated by grafting or budding onto seedling rootstock; no method currently exists to clonally propagate pawpaw on its own roots. Three methods of layering were attempted in this study to clonally propagate pawpaw: trench layering, pot layering, and mound layering. Both trench layering and pot layering experiments showed the importance of both juvenility and auxin application in adventitious rooting of pawpaw. Although rooting of more mature pawpaw shoots in these experiments did not exceed 30%, these propagation methods were more successful then previous attempts at rooting more mature pawpaw stems. Mound layering was less successful, but an easierto-root genotype of pawpaw in the KSU-USDA NCGR for Asimina spp. was discovered that may show promise for future propagation studies.

Diversity in reproductive characteristics of pawpaw was also assessed in this study. Accessions in the KSU-USDA repository orchard collected from six different geographic regions were selected and 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 by weight, yield efficiency, length of harvest, harvest peak, and growing degree days required for ripening were evaluated. Significant differences were found among the regions in most of the characteristics evaluated. Correlations were also found between several vegetative and reproductive characteristics. This indicates that a significant level of reproductive diversity exists within KSUs repository collection, and between pawpaws collected from different regions of the native range.

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