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Breeding maize under biodynamic-organic conditions for nutritional value and N efficiency/N₂ fixation

W. Goldstein, A.A. Jaradat, C. Hurburgh, L.M. Pollak, M. Goodman
Open Agriculture 2019 v.4 no.1 pp. 322-345
Zea mays, alleles, breeding programs, carotenoids, chlorophyll, corn, cultivars, genetic engineering, grain protein, hybrids, inbreeding, landraces, leaves, methionine, microorganisms, nitrogen, nitrogen fixation, philosophy, plant breeding, pollen, protein value, root growth, seeds, texture, topsoil, vigor, weeds, winter, Chile, Hawaii, Puerto Rico, Wisconsin
An overview is given for an ongoing maize breeding program that improves populations, inbreds, and hybrids in the Midwestern USA. Breeding and selection occurred under biodynamic conditions in Wisconsin, on an organic winter nursery in Puerto Rico, a biodynamic winter nursery in Hawaii, and a conventional winter nursery in Chile. Emphasis is on improving protein quality, carotenoid content, competitiveness with weeds, nitrogen (N) efficiency/N₂ fixation, and cross incompatibility to pollen from genetically engineered (GE) maize. Philosophy is that the plant species is a responding partner in the breeding process. Adaptation and selection emphasizes vigor and yield under N limited conditions. The Ga1 and Tcb1 alleles were utilized to induce cross incompatibility. The program resulted in inbreds and hybrids with increased N efficiency and protein quality coupled with softer grain texture, more chlorophyll in foliage, and densely branched root growth in the topsoil relative to conventionally bred cultivars under N limited conditions. Grain protein quality was improved by utilizing opaque kernels that emerged in populations during the course of the program in surprisingly high frequencies. N efficiency was accentuated by breeding with landraces that may fix N₂ with microbes coupled with selection for response traits under N-limited conditions. When grown next to conventional hybrids, the best hybrids from this program have exhibited 30% more methionine and 16% more protein in grain and more protein/ha.