Transitional Organic Dual-Purpose Wheat Systems Research for the Southern Great Plains
Abstract
The Southern Great Plains (SGP) region of the U.S. is widely known for its dryland dual-purpose winter wheat cropping systems—integrated systems that provides both livestock grazing and grain production. Few of these systems are organic, however, representing missed opportunities. Transitioning dual-purpose wheat systems of the U.S. SGP region to organic management has not been investigated, despite the potential for the region to contribute to meeting the growing demand of organic wheat and beef. This lack of research has left a void in knowledge on how to manage the systems organically and a lack of data on organic system performance. Therefore, the research presented in this dissertation aims to develop and test a management system for organic dual-purpose wheat and discern relationships between plant phenotypic factors and grain protein concentration (GPC) in wheat, which is a critical factor in marketing of organic wheat. The experiments described in this dissertation include: 1) a study that compared agronomic performance of a transitional organic dual-purpose wheat system to a conventional system; 2) a study that compared forage productivity, forage nutritive values, and cattle gains in transitional organic and conventional dual-purpose wheat systems; and 3) a study that assessed plant phenotypic factors associated with GPC in wheat. The first two studies were conducted on a large-scale (41-ha) over three years (from 2018 to 2021) near Vernon, TX. The third study was conducted in 2018/2019 at Uvalde and Chillicothe, TX, involving evaluation of 20 wheat genotypes at each location. Results of the first study illustrated that grain yield during the first year of organic transition was substantially lower than conventional, but the systems can have comparable yield by the end of transition, leading into organic certification. Grain protein concentration of the transitional organic wheat was below the 120 g kg-1 threshold for a food market organic price premium, however, indicating that strategies must be implemented to address this issue. Findings of the second study indicated that forage productivity, forage nutritive values, and cattle gains during the dual-purpose grazing period were comparable in the transitional organic and conventional systems throughout the three-year period. Results of the third study illustrated various ways that wheat GPC can be enhanced through breeding and/or crop management. Selection for higher grain number and lower 1000-kernal weight can enhance GPC. Increased time to physiological maturity and a longer grain filling period can likewise lead to greater GPC. Overall, organic dual-purpose wheat systems in the SGP can be a viable enterprise, though additional research is needed to address some challenges identified herein.
Citation
Hinson, Philip O (2021). Transitional Organic Dual-Purpose Wheat Systems Research for the Southern Great Plains. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /196457.