Four Breeding Methods for Sweet Corn under Organic Production Systems

摘要

Organic growers are interested in supporting organic plant breeding and purchase varieties bred under organic conditions. The goal of this work was to develop improved varieties of sweet corn (Zea mays, L.) for organic farmers. Chapter one gives an overview of the organic movement, plant breeding for organic systems, and sweet corn breeding to provide context for variety development.;In chapter two, recurrent selection was used to increase yield under high planting density (82,493 plants ha-1). Three cycles of selection were evaluated using a split plot design with low (43,040 plants ha-1) and high planting densities. Significant positive linear (coefficient 4.8) and quadratic (coefficient 2.4) trends were found for number of marketable ears per plot.;In chapter three, ten top cross varieties were created. They were evaluated in a randomized complete block design in two years with three locations per year. The top crosses had improved performance compared with the open pollinated parent for traits related to inbreeding (p < 0.05). For quality traits, flavor and tenderness, top cross populations out-performed the commercial hybrid check (p < 0.05).;Chapter four uses a half diallel mating design with ten inbred parents developed under organic conditions and evaluated in four environments with three replications. Griffing's analysis and a Bayesian method were used for analysis. Traits related to eating quality and agronomic performance showed large additive effects. Inbred We16408 performed particularly well for flavor (0.31), tenderness (0.48), and husk length (0.62).;Finally, S4 families were used to create four-parent synthetic varieties and evaluated in a randomized complete block design in four environments with three replications. There were three groups of synthetics, early, late, and mixed. Those from the late group performed best for most traits except flavor (p < 0.05). The early group performed best in terms of flavor (p < 0.05).