Browsing by Subject "soybean"
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Item 2014 Progress Report on Grass Seed Production Research(2014) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2015 Progress Report on Grass Seed Production Research(2015) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2016 Progress Report on Grass Seed Production Research(2016) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2018 Progress Report on Grass Seed Production Research(2018) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2019 Progress Report on Grass Seed Production Research(2019) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2020 Progress Report on Grass Seed Production Research(2021) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2020 Progress Report on Grass Seed Production Research(2020) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass and legume seed production conducted by the University of Minnesota.Item 2021 Progress Report on Grass Seed Production Research(2022) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota.Item 2022 Progress Report on Grass Seed Production Research(2023-03) Ehlke, Nancy; Vellekson, Donn; Grafstrom, DaveSummary of research on grass seed production conducted by the University of Minnesota in 2022.Item Assessing the Host-Sanctioning Abilities of Soybean (Glycine max) Cultivars(2025-01-21) Adelmann, NicholasItem Community Characterization and Development of a Sampling Plan for Stink Bugs (Hemiptera: Pentatomidae) in Soybean in the North Central Region of the U.S.(2018-09) Pezzini, DanielaStink bugs are an emerging threat for soybean production in the North Central Region of the U.S., which accounts for 80% of the country’s total soybean production. However, there is a lack of literature on stink bug community composition and management recommendations for the region. Therefore, my research aimed to fill the gap of region-specific literature and management recommendations for stink bugs by using data from 9 states of the North Central Region of the U.S. My first chapter characterized the species composition, abundance and temporal dynamics of stink bugs in the region. We demonstrated that the stink bug community is dominated by Euschistus spp. and Chinavia hilaris, and the invasive Halyomorpha halys was among the most abundant species in the eastern part of the region. Economically damaging infestations of stink bugs occurred in soybean fields in southern areas, and higher densities occurred at later soybean growth stages. Further aspects of stink bug management are addressed in my second chapter, where I assessed spatial patterns and developed fixed-precision sequential sampling plans for stink bugs in the North Central soybean. Results showed that stink bugs were aggregated, but extent of aggregation varied by species, life stage and location. We showed that 40 sample units (i.e., sets of 25 sweeps) would be needed for reliable stink bug estimation under the conditions experienced across the region. However, sample size recommendations could vary significantly by state depending on densities of stink bugs typically encountered. Also, we demonstrated that current sampling recommendations of 6 to 10 sample units may provide unreliable density estimation in some states. Overall, this is the first study to 1) characterize the stink bug community composition in soybean across the region and 2) develop cost-effective, research-based scouting recommendations for these pests. Results obtained from this thesis will provide important insights for the implementation of IPM for stink bugs in soybean in the North Central Region of the U.S.Item Complete Data and Analysis for: Fungicide Effectiveness on Soybean Rust in the Southeastern United States 2004-2014: A Meta-Analysis(2016-08-02) ArchMiller, Althea A; Delaney, Mary A; Delaney, Dennis P; Wilson, Alan E; Sikora, Edward J; althea.archmiller@gmail.com; ArchMiller, Althea ASoybean rust is a concern to soybean growers and management of soybean rust primarily depends on disease scouting and the timely use of fungicides. The goal of this study was to evaluate the efficacy of fungicide-use through a quantitative meta-analysis of data compiled from published and unpublished soybean fungicide trials across the southern United States from 2004 to 2014. The data included in this repository includes the complete dataset as a comma-separated-value file and all Program R code necessary to replicate the data processing, analysis, and graphing.Item Determining the role of plant-parasitic nematodes in the crop rotation yield effect, and the influence of crop rotation and nematicide application on the nematode community(2015-05) Grabau, ZaneIn the Midwestern United States, corn-soybean rotation is an essential agricultural practice to increase crop yield, often known as the rotation effect. Plant-parasitic nematodes, particularly soybean cyst nematode (SCN, Heterodera glycines) in soybean and Pratylenchus in corn, may contribute to the rotation effect and the nematode community is a sensitive indicator of changes in soil ecology. A long-term research site in Waseca, Minnesota was established in 1982 to study corn-soybean rotation. At the site, various corn-soybean crop sequences can be compared each year including corn and soybean in 1 to 5 years of monoculture, annual rotation of each crop, and continuous monoculture of each crop. Granular nematicides (terbufos or aldicarb) have been applied to half of each plot since 2010 to minimize nematode populations across crop sequences. If successful, the rotation yield effect could be compared with unaltered nematode populations and with minimal nematode populations to determine the role of nematodes in the rotation effect. For this thesis, crop yield and plant-parasitic nematode populations were measured from 2010-14 while the nematode community was assessed from 2013-14 at the long-term rotation research site. Specifically, the objectives of this research were to: (i) investigate the impact of crop sequences and nematicide application on plant-parasitic nematode populations and crop yield (Chapter 2), (ii) determine the role of plant-parasitic nematode populations in the corn-soybean rotation effect using nematicide application (Chapter 2), and (iii) study the impact of crop sequences and nematicide application on soil ecology based on the nematode community (Chapter 3). Research related to these objectives is reviewed in Chapter 1. SCN egg population densities significantly increased in soybean and decreased in corn—particularly in the initial 3 years of monoculture-- so populations were significantly greater in soybean than corn monoculture for most sequences (P ≤ 0.05, Fischer’s LSD). After two to three years of corn monoculture, SCN populations were below 200 eggs/100 cm3 soil, the proposed damage threshold guideline for SCN, in most seasons. Pratylenchus populations significantly decreased in soybean monoculture and increased in corn monoculture—particularly in the initial 3 years of monoculture-- leading to significantly greater Pratylenchus populations under corn than soybean monoculture for most sequences (P ≤ 0.05, Fischer’s LSD). Helicotylenchus population densities were similar among many crop sequences, but significantly greater in extended corn monoculture and smaller in extended soybean monoculture than most sequences (P ≤ 0.05, Fischer’s LSD). Xiphinema was present at the site, but population densities were small at an average of 8 nematodes/100 cm3 soil across plots and seasons. Corn yields decreased significantly in monoculture, particularly in the initial 3 years in monoculture (P ≤ 0.05, Fischer’s LSD). Soybean yields also decreased significantly in monoculture, often decreasing throughout the length of monoculture tested when comparing crop sequence treatments within single years (P ≤ 0.05, Fischer’s LSD). Aldicarb nematicide consistently significantly decreased Pratylenchus, Helicotylenchus, and Xiphinema populations but was inconsistent against SCN (P ≤ 0.05, ANOVA). Aldicarb nematicide consistently increased corn yield and decreased Pratylenchus and Helicotylenchus populations (P ≤ 0.05, ANOVA), suggesting these nematodes, particularly Pratylenchus, may have decreased corn yield. Aldicarb nematicide also significantly increased soybean yield in 2012 and 2013, but decreased SCN populations did not consistently correspond with increased soybean yield (P ≤ 0.05, ANOVA). While nematicide reduced nematode populations, there was still significant variation across crop sequences in most seasons (P ≤ 0.05, ANOVA), so nematicide application was not a successful method for determining the role of nematodes in the rotation effect in most seasons. However, the strong influence of crop sequences on SCN and Pratylenchus populations suggest nematodes have a role in the rotation effect. Nematicide application also impacted non-target nematodes and thus soil ecology with significantly decreased fungivore and bacterivore populations, diversity, and maturity; but significantly increased enrichment (P ≤ 0.05, ANOVA). The nematode community and soil ecology was significantly different in corn compared to soybean cropping systems and changed most during initial years of crop monoculture (P ≤ 0.05, Fischer’s LSD). Cropping systems in corn supported significantly greater fungivore populations, fungal decomposition pathways, more diversity, and a more mature ecosystem compared to soybean systems (P ≤ 0.05, Fischer’s LSD). Soybean systems supported significantly greater bacterivore populations and a more disturbed, enriched ecosystem (P ≤ 0.05, Fischer’s LSD). These differences between corn and soybean systems suggest nutrient mineralization by nematodes and other microorganisms may play a role in the benefits of crop rotation for plant growth.Item Environmental Association Analyses Identify Candidates for Abiotic Stress Tolerance in Glycine soja, the Wild Progenitor of Cultivated Soybeans(2016-09-26) Anderson, J; Kono, Thomas J Y; Stupar, Robert M; Kantar, Michael B; Morrell, Peter L; kant0063@umn.edu; Kantar, Michael BUnderstanding the genetics basis of adaption is a fundamental goal of biological research. The present study explores an ex situ conservation collection, the USDA germplasm collection, genotyped at 32,416 SNPs, to identify population structure and test for associations with bioclimatic and biophysical variables in Glycine soja, the wild progenitor of Glycine max (soybean). Candidate loci were detected that putatively contribute to adaptation to abiotic stresses.Item Evaluating biological control of the soybean gall midge (Resseliella maxima Gagné) in Minnesota(2023-12) Melotto, GloriaThe soybean gall midge, Resseliella maxima Gagné (Diptera: Cecidomyiidae), poses a threat to soybean crops in the Midwest US. However, little is known regarding its natural enemies and the potential for biological control. Therefore, this thesis aims to fill this knowledge gap by focusing on evaluating biological control for R. maxima. To achieve this, we conducted a two-year survey to investigate the parasitoid and predator communities associated with R. maxima infestations in Minnesota. Our findings confirmed parasitism of R. maxima larvae by the wasp Synopeas maximum Awad & Talamas (Hymenoptera: Platygastridae) and examined the spatial-temporal dynamics of parasitism within fields. Additionally, our observations showed that the predator Pterostichus melanarius (Illiger) (Coleoptera: Carabidae) was the most prevalent species in the soybean fields in this study, presented temporal overlap with the pest, and had a high propensity to feed on R. maxima larvae. We concluded that further research should evaluate how parasitism rates by S. maximum could be promoted in production fields and that Pt. melanarius should receive further attention as a potential biological control agent of R. maxima.Item Evaluation of resistance to Rhizoctonia solani in soybean and assessment of fungicide sensitivity in isolates from sugar beet and soybean(2020-06) Sharma, PratibhaSoybean and sugar beet are commonly grown in rotation in the Red River Valley of MN and ND and southern Minnesota. Both crops are highly susceptible to Rhizoctonia solani. Currently there are no Rhizoctonia resistant soybean cultivars available to the growers. Partially resistant commercial sugar beet cultivars are available, but they are susceptible to R. solani during the seedling stage. Disease management for both crops relies partially on the use of fungicides. The primary objectives of this study were (i) to determine the response of different soybean genotypes to R. solani in the field and growth chamber, and (ii) to determine the sensitivity of R. solani isolates from soybean and sugar beet to the fungicides sedaxane, penthiopyrad, fluxapyroxad, azoxystrobin, and pyraclostrobin. Soybean genotypes were evaluated for their response to R. solani at Waseca and Crookston, MN field locations. All genotypes evaluated at Crookston (n=20) in 2018 and 2019 had high losses in inoculated plots in plant population and yield compared to noninoculated control plots. Losses were also severe for all genotypes (n=36) at Waseca in 2018. Some soybean genotypes had relatively low losses in 2017 and 2019, however, their performance was not consistent across the years. MN 1613CN was the only genotype that performed well in 2017 and 2019, but it had high plant population and yield losses in 2018. Significant genotype by isolate interaction was detected when 16 soybean genotypes were evaluated for their response to four isolates of R. solani in the growth chamber. All genotypes were highly susceptible to isolate Rs 16WC3-2, but they differed in susceptibility to some other isolates. The soybean genotypes used in this study were not resistant to R. solani, but those with relatively low losses in plant population should be investigated further along with additional genotypes. The response of soybean genotypes to R. solani is strongly influenced by the isolate and environment, so future studies should continue to be conducted under different environmental conditions using multiple isolates. Sensitivity of R. solani AG 2-2 isolates (n=35) collected from soybean and sugar beet to the SDHI fungicides sedaxane, penthiopyrad, and fluxapyroxad, and to the QoI fungicides pyraclostrobin and azoxystrobin was determined using a mycelial growth inhibition method. The concentration of fungicide required to inhibit the radial growth of mycelium 50% (EC50) compared to the growth on non-amended media was estimated for each isolate. The mean and range of EC50 values for sedaxane, penthiopyrad, fluxapyroxad and pyraclostrobin were 0.1 (0.03 to 0.3), 0.15 (0.05 to 0.27), 0.16 (0.08 to 0.3), and 0.24 (0.04 to 1.02) µg a.i./mL, respectively. The mean EC50 values of azoxystrobin for 22 isolates ranged from 0.76 to 2.36 µg a.i./mL. EC50 values for azoxystrobin could not be estimated for 13 isolates due to < 50% inhibition in growth, however, a pronounced decrease in mycelial density was observed as fungicide concentration increased. The SDHI fungicides and pyraclostrobin effectively inhibited the growth of the isolates of R. solani in vitro at low concentrations, but new methods are needed to determine in vitro sensitivity to azoxystrobin. In summary, the different levels of partial resistance to R. solani detected in soybean genotypes suggest a need for improving resistance to R. solani, and fungicide sensitivity results indicate that currently labeled fungicides continue to be useful in managing seedling damping-off and root rot.Item Evaluation of Wild and Cultivated Soybean Genomic Resources for Genotype Variation and Identity(2018-08) Mihelich, NicoleCultivated soybean has low genetic diversity due to a strong domestication bottleneck and selection in modern breeding. This lack of diversity limits the identification of genetic loci responsible for traits of interest to breeders. However, recent advancements in genotyping have resulted in an influx of genomic resources for soybean germplasm around the globe. In this thesis, the high-throughput SoySNP50K Chip genotyping of USDA Soybean Germplasm Collection was used to evaluate wild and cultivated soybean accessions for within-accession variation. Intervals of heterogeneity were found in 4% of the collection, representing 870 accessions (Supplemental Table S1.1). The SoySNP50K dataset was also used to compare genotype identity with a dataset of 106 resequenced soybean genomes. Although 78% unambiguous matches were found, some discrepancies in identity were detected. These analyses can be used to harness unutilized standing variation and maintain consistency across datasets to innovate and streamline international efforts for soybean improvement.Item Evolution of energy storage traits in symbiotic rhizobia(2018-01) Muller, KatherineThe mutually-beneficial symbiosis between legume plants and nitrogen-fixing rhizobia involves an inherent conflict-of-interest over how rhizobia allocate the resources they receive from the host plant. In theory, rhizobia could enhance their future fitness by diverting resources from nitrogen-fixation into storage compounds like polyhydroxybutyrate (PHB). Although the conflict-of-interest between PHB accumulation and nitrogen-fixation has been discussed as a driving factor in the evolution of legume-rhizobia interactions, its role in natural populations is unclear. Therefore, this dissertation fills in key empirical gaps between what we know about the functional role of PHB and hypotheses about how natural selection might act on continuous variation in the amount of PHB that rhizobia acquire during symbiosis. The first chapter assesses the extent of heritable phenotypic variation within natural rhizobia populations interacting with soybean (Glycine max) and partridge pea (Chamaecrista fasciculata) and evaluates implications for fitness in the free-living stage after rhizobia are released from nodules. The results from my first chapter show that 1) natural populations of rhizobia contain heritable, quantitative variation in the amount of PHB they accumulate during symbiosis (a prerequisite for evolution by natural selection) and, 2) natural selection on PHB accumulation may be mediated by how rhizobia allocate PHB over time and among life functions, which could vary independently from traits underlying the amount of PHB acquired during symbiosis. The second chapter assesses phenotypic response to selection based on resident rhizobia populations from long-term agricultural plots varying in host (soybean) or non-host (maize) frequency over years. The mean PHB per cell (measured in nodules) was two times higher in rhizobia populations from plots with 5 or 30 years of continuous maize than from plots where soybean was grown in the previous year. An apparent decrease in mean PHB per cell after the first year of soybean following five years of maize supports the hypothesis that low-PHB rhizobia have higher reproduction in nodules, perhaps due to host sanctions against rhizobia that divert more resources to PHB. A model used to interpret the results suggests that, 1) PHB acquired during symbiosis may contribute to fitness variation for several years after the last host crop, and 2) host sanctions against less-beneficial rhizobia may be stronger in the first soybean crop due to a combination of lower initial rhizobia population size and negative frequency-dependent selection during symbiosis. Collectively, these findings provide empirical support for previously unsubstantiated hypotheses about how conflicts-of-interest over resource allocation contribute to the evolution of the legume-rhizobia mutualism and develop a more nuanced framework for future research.Item Fast neutron mutagenesis in soybean creates frameshift mutations(2021-12-01) Wyant, Skylar R; Rodriguez, Fernanda M; Carter, Corey K; Parrott, Wayne A; Jackson, Scott A; Stupar, Robert M; Morrell, Peter L; pmorrell@umn.edu; Morrell, Peter L; University of California Department of Ecology and Evolutionary Biology; University of Minnesota Department of Agronomy and Plant Genetics; University of Georgia Department of Crop and Soil SciencesThe mutagenic effects of ionizing radiation have been used for decades to create novel variants in experimental populations. Fast neutron (FN) bombardment as a mutagen has been especially widespread in plants, with extensive reports describing the induction of large structural variants, i.e., deletions, insertions, inversions, and translocations. However, the full spectrum of FN-induced mutations is poorly understood. We contrast small insertions and deletions (indels) observed in 27 soybean lines subject to FN irradiation with the standing indels identified in 107 diverse soybean lines. We use the same populations to contrast the nature and context (bases flanking a nucleotide change) of single nucleotide variants. The rate of accumulation of new single nucleotide changes in FN lines is marginally higher than expected based on spontaneous mutation. In both FN treated lines and in standing variation, C→T transitions and the corresponding reverse complement G→A transitions are the most abundant and occur most frequently in a CpG local context. These data indicate that most SNPs identified in FN lines are likely derived from spontaneous de novo processes that occurred in subsequent generations following mutagenesis, rather than from the FN irradiation mutagen. However, small indels in FN lines differ from standing variants. Short insertions, from 1 – 6 base pairs, are less abundant than in standing variation, and short deletions are more abundant and more prone to induce frameshift mutations that should disrupt the structure and function of encoded proteins. These findings indicate that FN irradiation generates numerous small indels in the genome, increasing the abundance of loss of function mutations that will impact single genes.Item Identification of Quantitative Trait Loci for Resistance to White Mold in Soybeans via Genome-Wide Association and Linkage Mapping(2022-06) Mayta, JuanWhite mold disease in soybeans is one of the most important causes of yield losses in the northern regions of the United States and Canada. Host resistance continues to be the most viable tactic for managing white mold; however, progress is slow due to laborious phenotyping techniques that are difficult to replicate and the polygenic nature of the white mold resistance trait. Breeding for white mold resistance will be significantly facilitated by improved screening methods and the use of molecular markers. In this work, we developed and validated a phenotyping method using spray mycelium and inoculated sorghum in two field environments. Using this methodology, a collection of 230 F5:12 recombinant inbred lines derived from the Minsoy x Noir1 cross and 280 diverse PIs and cultivars were phenotyped for white mold resistance in two field environments. Additionally, both populations were phenotyped in the greenhouse using the cut stem method. Five breeding lines and one PI with resistance levels similar to the current resistant check S19-90 were identified. This material is adapted to the Upper Midwest and could be used as potential donor germplasm to improve resistance to white mold. Linkage mapping analysis was performed on the Minsoy x Noir1 population using a set of 957 SSR and SNP markers. Four markers showed significant associations with white mold resistance on Chromosomes 6, 7, 8, and 12 (LOD>3), explaining 45% of the variability. Marker Satt567 on chromosome 7 is a new white mold resistance QTL, explaining 17% of the variability. Genome-wide association (GWAS) was performed using 1,536 SNP markers. Five QTLs showed significant associations with white mold resistance (FDR, qvalue≤0.1). The identified QTLs correspond to two regions on chromosome 19 and one region on chromosome 14. Of particular interest is marker BARC-039375-07306 on the short arm of chromosome 19; this marker corresponds with a major QTL associated with canopy architecture in soybeans. A second region on chromosome 19 consists of three markers positioned between 47,988,748 and 48,229,536 bp. Among these three markers, BARC-007569-00135 was the most significant and consistent across environments. Phenotypic variation explained by all significant markers was 13%. The QTLs on chromosome 19 were identified in field experiments, whereas the QTL on chromosome 14 resulted from the greenhouse evaluation.