Narrative
Synthetic A Improved is a broad-based maize variety bred primarily from Northern/Flint Flour types, selected for attractive decorative ears and good agronomic performance under Iowa growing conditions. Between 1988 and 1992, more than 20 fully or partially inbred lines (many from the Ornamental Corn Improvement Project’s inbred-line development program) were combined to generate Synthetic A, which was then subjected to two cycles of recurrent full-sib selection, with balanced half-sib intermating at the end of each cycle. By 1999, it was clear that Synthetic A exhibited poor anthocynanin expression in the aleurone layer, likely as a result of including white inbred parents that suppress pigment development. Beginning in 2000, a new synthetic, to be called Synthetic A Improved, was begun by taking Synthetic A and combining it with Quapaw Red PI 213757, Sac Blue PI 213768, and ‘Indian Art 185’, in a balanced (and reciprocal) fashion, such that the new population would be half Synthetic A, one-sixth PI 213757, one-sixth PI 213768, and one-sixth ‘Indian Art 185’. Six F1 interpopulation hybrids were intermated in a balanced fashion in 2001, and recombined in 2002, producing Synthetic A Improved. The new synthetic was subjected to two full cycles of recurrent full-sib selection, with balanced half-sib intermating at the end of each cycle. In 2013, a recombined population was generated to begin a third cycle of selection, but work was then suspended. A balanced sample of 105 ears from the 2013 harvest was grown out in 2024 for balanced half-sib mating. In 2024, 129 control-pollinated ears were produced; 122 of them serve as the base population for this accession, with seven off-type ears culled. Synthetic A Improved is a non-proprietary, decorative maize variety adapted to Iowa with considerable diversity in kernel color and ca. 25% colored husks that is designed to be grown at relatively low densities (ca. 15,000 plants per acre) with harvest by hand. Kernels include both flinty and floury endosperm (with a low frequency of slightly dented types), so healthy, but non-marketable ears can be ground to make corn meal. All breeding and selection work was conducted in Ames, Iowa. The lone exception to cultivation in Ames was a 1992-93 winter nursery conducted in Chile to multiply the seed stock that functioned as cycle zero of the original Synthetic A (but no breeding or selection occurred there). All evaluations were done based on a complex selection index that accounted for productivity (in terms of marketable decorative ears per plant), color expression (both kernel and husk), resistance to insect pests and diseases, husks covering the tips of ears with good retention after hand harvest, and stalk and root lodging. Evaluations were typically conducted on 10-plant, full-sib rows, with a final selection pressure, based on index scores, in the range of 30-40% retention. Recombination was generally conducted with ca. 100 plants serving as pollen parents (pollen samples bulked across multiple parents) and ca. 100 plants serving as females, with very little or no overlap (to maximize effective population size).