**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** PRIOR TO ADOPTION OF HYBRIDS IN THE 1930'S, US CORN WAS COMPRISED OF FARMER-SELECTED AND FARMER-MAINTAINED POPULATIONS OF DIVERSE HEIRLOOM VARIETIES. MANY HEIRLOOMS HAD SPECIFIC CULINARY VALUE (E.G., MILLING, BAKING, FERMENTATION), AND NICHE MARKETS FOR THESE VARIETIES STILL EXIST AND ARE EXPANDING TODAY. TODAY'S 'FIELD CORN' IS HIGH YIELDING BUT LACKS BOTH THE GENETIC AND PHENOTYPIC DIVERSITY OF HEIRLOOM VARIETIES. OVER 1000 US HEIRLOOM VARIETIES ARE MAINTAINED IN THE USDA NATIONAL PLANT GERMPLASM SYSTEM, BUT THEY ARE RARELY USED IN MODERN BREEDING. THIS MAY BE BECAUSE NO COMPREHENSIVE ANALYSIS OF THE DIVERSITY AND RELATIONSHIPS OF US HEIRLOOM VARIETIES EXISTS, AND BECAUSE HEIRLOOMS LACK MODERN AGRONOMIC CHARACTERISTICS (E.G., UNIFORMITY AND HIGH YIELD POTENTIAL UNDER HIGH INPUT CONDITIONS). A BETTER UNDERSTANDING OF HEIRLOOM DIVERSITY, ALONG WITH BREEDING FOR IMPROVED PRODUCTION WOULD GO A LONG WAY TOWARDS MAKING HEIRLOOM CORN VARIETIES AVAILABLE AND PROFITABLE FOR SMALL SCALE AMERICAN FARMERS.THIS PROJECT HAS THREE MAJOR GOALS: (1) DESCRIBE 1000 US HEIRLOOM VARIETIES AT A GENETIC RELATIONSHIP LEVEL AND FOR A LARGE NUMBER OF PLANT, EAR, AND KERNEL CHARACTERISTICS THAT WILL INDICATE THEIR LEVEL OF PRODUCTIVITY AND POTENTIAL USAGE; (2) IDENTIFY THE GENES THAT CONTROL HOW WELL THESE 1000 HEIRLOOM VARIETIES MAY GROW IN FIELD CONDITIONS ACROSS THE US, AND THE GENES THAT CONTROL VARIOUS EAR AND KERNEL TRAITS; AND (3) EVALUATE THE YIELD POTENTIAL OF A SET OF PROMISING HEIRLOOM VARIETIES. ULTIMATELY, THIS RESEARCH PROJECT WILL LEAD TO AN UNDERSTANDING OF LOCAL/REGIONAL ADAPTATION OF US HEIRLOOM VARIETIES AND IMPROVED TASTE, AROMA, AND NUTRITION.