Browsing by Subject "Phenotyping"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Evaluation of Terrestrial Laser Scanning and Ground Penetrating Radar for Field-Based High-Throughput Phenotyping in Wheat Breeding(2014-08-05) Thompson, Sean MTargeted adaptive physiological trait introgression, a method by which breeders seek to introduce specific characteristics into breeding germplasm in a specific and targeted manner, is one of the primary methods breeders are using to develop cultivars optimized for performance and yield under heat and drought conditions. In traditional breeding platforms, this is carried out in a stepwise fashion, with the crossing of parental lines and the phenotype-driven selection of offspring. As with other adaptive physiological traits, rapid field-based high-throughput phenotyping of early season aboveground biomass and ideal root architecture is limited by our inability to accurately and nondestructively characterize these important traits. Terrestrial laser scanning (TLS) and ground penetrating radar (GPR) have the potential to fill this gap by non-invasively estimating biomass and mapping three-dimensional above- and below-ground vegetation. The research objective was to evaluate the use of TLS to estimate aboveground wheat (Triticum aestivum L.) biomass. Linear regressions comparing mean canopy height and total plot forage yield for each experimental plot across four replications was poorly correlated (R^2 0.08). Mean plot normalized difference vegetation index measurements were evaluated against total plot forage biomass with limited correlation (R^2 0.036). The mean value of the TLS elevation points had the highest correlation with both plot (R^20.09458) and sub plot (R^2 0.37984) forage yield as compared to traditional platforms. GPR is a remote sensing technology that has been successfully used in the evaluation of coarse tree root biomass. Incorporating GPR into current crop phenotyping methodologies could potentially provide a long awaited solution to the current inability to efficiently phenotype roots under realistic field conditions. Here, the utility of using GPR to estimate root biomass of wheat was evaluated. GPR ability to predict root presence and absence was tested and GPR was able to differentiate root mass from soil significantly (? = 0.95, t = 1.96022). Linear regression between Log10 of the mean GPR amplitude return at the 0-3 ns range was compared with agronomic breeding traits. Overall increased amplitude was observed in plots scoring higher with regard to overall yield and yield components.Item Phenotyping Drought Tolerance in Cotton (Gossypium hirsutum, L.)(2014-04-30) Terhune, Austin CatesCotton plant breeders need well-defined phenotypic parameters by which they can select drought tolerant lines as well as correlate phenotypes to allelic polymorphisms in the cotton genome. Soil-moisture availability is usually the most limiting factor for cotton crop productivity, especially in Texas. Characteristics of roots logically play an important role in determining the response of plants to limited soil moisture. The objectives of this study were to develop and refine techniques that could be used by plant breeders to phenotype plants? drought tolerance. Approaches include using a Trimble GreenSeeker?, to identify individual and progeny rows with enhanced photosynthetic capabilities in the presence of drought, leaf canopy temperatures under drought conditions, and measurement of root parameters in growth tubes in a greenhouse. Results from these experiments were related to yield performance in field trials at three locations in 2013. Several conclusions can be drawn from this study. First, Normalized Difference Vegetative Index and leaf temperature are rapid and reliable tools to evaluate plant health. The utility of these tools hinges upon timing of data collection, but they clearly demonstrated the propensity to differentiate phenotypic differences. Secondly, evaluation of root systems in growing tubes in a greenhouse is probably an ineffective method of characterizing drought tolerance potential since the growing conditions are radically different from what a plant would encounter in a field environment. Examining roots with this system would likely yield significant differences among plant species, but within upland cotton, it would be difficult to determine differences among genotypes. Ultimately the best determinant of drought tolerance is performance testing in droughty conditions because it encompasses most of the contributing factors that induce drought stress and measures the cotton plant?s inherent ability to recover and compensate in response to rainfall through the course of a growing season.