2004 Annual Report 4.What were the most significant accomplishments this past year? D. Progress report: This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Texas A&M University. Additional details of research can be found in the report for the parent CRIS 6202-21000-023-00D Conservation and Characterization of Genetic Diversity in Carya. This is a new project. The goal of this project is to develop a 3-D dynamic computational model of the pecan nut during development. Compressive tests were conducted on whole, mature pecans of Pawnee, to assess shell strength along three axes defined as longitudinal, transverse parallel, and transverse perpendicular. The results indicate that Pawnee pecans are much stronger longitudinally than in transverse orientations, with the transverse perpendicular load failure being the lowest. Ring samples were cut and tested in compression, yielding measurements that were incorporated into initial simulation models. Future tests will be conducted with pecan cultivars having different nut shapes, as well as during the course of nut development. Work under this project will better define the structural characteristics of the pecan nut during growth and at maturity, and will facilitate development of new pecan cultivars that go through the harvesting process with less damage, that better maintain quality during storage, and that experience less kernel breakage during the cracking and shelling processes. The work will also facilitate the development of new technology for pecan nut processing to increase the yield of whole, undamaged kernel halves.