Greater projected demand for food, fuel, and fiber will require substantial increases in global agricultural production over the next three decades. Climate change is also forecasted to make weather events more extreme and variable. Efficiency will become more important as demand for food products increases and the availability of fertilizer and land decreases. Technology may be of paramount importance for pushing the boundaries of production while remaining sustainable for generations to come. The first chapter of this dissertation investigated the importance of rate and timing of the plant growth regulator trinexapac-ethyl to malting barley in Virginia. Plant growth regulators can help plants remain upright during strong winds, thereby preserving grain quality and yield. However, this study demonstrated that risks of plant injury also exist. Application should be restricted to fields with greater risk of lodging and made only after the barley crop has broken dormancy and a substantial increase in air temperature is not forecasted in the week following application. Chapter two compared the efficacy of eight vegetation indices calculated from three satellites (Landsat 8, Sentinel 2, and Planet) for estimating cover crop biomass. Cover crops can have beneficial effects on agricultural land as well as groundwater and surface water, but only when adequate biomass is established to reduce erosion and nutrient leaching. Satellite imagery was able to estimate multi-species cover crop biomass more accurately than field-based sensors, although the most accurate vegetation index was dependent upon which satellite was being tested. Chapter three investigated the potential of Arabidopsis thaliana ipk1-, a loss-of-function mutant which exhibits decreased growth at elevated phosphorus concentration, for serving as in indicator of plant available phosphorus. An indicator crop could provide greater spatial resolution compared to soil testing, as well as represent plant available nutrients as opposed to chemically extracted nutrient estimations. Plant response exhibited a quadratic relationship with media P concentration in the range of fertilizer decision making for maize, providing valuable insight for potential yield response in agricultural fields below 'very high' phosphorus concentration. / Doctor of Philosophy / Climate change, increased demand for locally sourced ingredients, and elevated pressure for environmentally responsible practices will make meeting the growing demand for food difficult for farmers to achieve over the next few decades. Similar to many other industries, implementation of advanced technology may be necessary to keep up with agricultural demand. Plant growth regulators are one such technology which when applied to plants can cause them to remain short, decreasing the chance of blowing over during windstorms. However, chapter one of this dissertation concluded that risks of plant injury also exist when applying plant growth regulator on malting barley (for brewing or distilling). Application should be restricted to fields with greater risk of wind damage (e.g. taller barley) and made only after the barley crop begins spring growth and a decrease in air temperature is not forecasted in the week following application. Chapter two compared eight spectral vegetation indices across three satellites with different image resolution for their ability to estimate cover crop biomass. Cover crops protect groundwater and surface water quality, but only when adequate growth is achieved. Satellite imagery was able to estimate multi-species cover crop biomass more accurately than field-based sensors, although the most accurate vegetation index was dependent upon which satellite was being tested. Chapter three investigated the potential of Arabidopsis thaliana ipk1-, a loss-of-function mutant which exhibits decreased growth at elevated phosphorus concentration, as in indicator of plant available phosphorus in soil. An indicator crop could help determine which areas of a field are likely to have increased crop yield if fertilized and which are not. The mutant tested could be useful as an indicator crop given its response to phosphorus concentration, warranting further research with other plant species more appropriate for field use.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/104449 |
| Date | 05 February 2020 |
| Creators | Swoish, Michael Joseph |
| Contributors | Crop and Soil Environmental Sciences, Thomason, Wade E., Campbell, James B. Jr., Reiter, Mark S., Stewart, Ryan D. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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