2007 Annual Report 1a.Objectives (from AD-416) The objective of this research is to develop a 3-D dynamic computational model of the pecan nut during development. 1b.Approach (from AD-416) 1) Conduct microscopy to characterize the pecan nut shell and provide measurements for use in a computational model;. 2)mechanically test nut specimens at several stages of development from several pecan cultivars (selected for a range of nut sizes and shapes) to determine transverse and longitudinal compression, fracture toughness and hardness;. 3)input information obtained above into mechanical engineering simulation software to construct three dimensional models duplicating the internal nut structure and;. 4)develop criteria to assess structural integrity. 3.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 project 6202-21000-023-00D, Conservation and Characterization of Genetic Diversity in Carya. The goal of this project is to develop a 3-D dynamic computational model of the pecan nut during development. In previous work under this project, compressive tests were conducted on entire pecans of 'Pawnee' to assess its strength along three axes: Longitudinal, transverse parallel, and transverse perpendicular. Results indicated that 'Pawnee' pecans are much stronger longitudinally than in transverse orientations, with the transverse perpendicular load failure being the lowest. In FY 2007, additional pecan and hickory nut samples, representing wide variation in nut size, shape, and structure, were collected and curated. Mechanical testing of those samples has been slowed by loss of personnel, a problem being addressed by active recruitment. Ongoing work by the project will focus on the relative contributions of nut structure on shell strength throughout nut development. Work under this project, overall, 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. The ADODR of this project and the cooperator are located in close physical proximity, and are in contact with one another on an ongoing basis. The ADODR and the cooperator (or key personnel working under the cooperator) meet and discuss the direction and progress of the project on a regular basis.