Open Access Publications
Permanent URI for this collection
Open access publications by faculty, postdocs, and graduate students in the Department of Plant and Soil Sciences.
Browse
Recent Submissions
Item Cropland expansion links climate extremes and diets in Nigeria(Science Advances, 2025-01-10) Khan, Bhoktear; Mehta, Piyush; Wei, Dongyang; Ali, Hanan Abou; Adeluyi, Oluseun; Alabi, Tunrayo; Olayide, Olawale; Uponi, John; Davis, Kyle FrankelClimate change threatens smallholder agriculture and food security in the Global South. While cropland expansion is often used to counter adverse climate effects despite ecological trade-offs, the benefits for diets and nutrition remain unclear. This study quantitatively examines relationships between climate anomalies, forest loss from cropland expansion, and dietary outcomes in Nigeria, Africa’s most populous country. Combining high-resolution data on forest cover and climate variables within random forest and panel regression models, we find that 25 to 31% of annual forest loss is linked to climate variability. Using georeferenced household survey data, we then find that changes in forest cover have a significant positive association with changes in child diet diversity—a key proxy of nutritional adequacy—while cropland expansion does not, suggesting that such forest conversions may be an ineffective climate adaptation strategy for improving nutrition. Our findings highlight the potential of nutrition-sensitive climate adaptation to enhance yields, promote nutritious cropping choices, and protect remaining forests.Item Potassium Sulfate Supplementation with Elevated Electrical Conductivity Was Unproductive for Hydroponic Strawberry at the Original Yamazaki Nutrient Solution Nitrogen Level(HortScience, 2025-01-08) Ries, Jonathan; Meng, Qingwu; Park, YujinThe production of strawberries (Fragaria ×ananassa) in hydroponic systems has been increasing. In hydroponic systems, precise nutrient management is crucial for optimal plant growth and fruit production. Among essential elements, potassium (K) is a key nutrient that affects fruit yield and quality in fruiting crops. The objective of this study was to investigate whether increasing the K concentration in the Yamazaki strawberry nutrient solution could enhance plant growth, fruit yield, and fruit quality in hydroponic strawberries. Bare-root plants of strawberry ‘Monterey’ and ‘San Andreas’ were planted in a deep water culture hydroponic system and grown with initial K concentrations of 117, 194, 271, and 348 mg·L−1 under the same initial nitrogen concentration of 77 mg·L−1. As the K concentration increased from 117 to 348 mg·L−1, the nutrient solution electrical conductivity increased from 1.0 to 1.9 dS·m−1. The experiment was conducted inside an indoor vertical farm at a 23 °C air temperature with an extended photon flux density (400–750 nm) of 350 µmol·m−2·s−1 under an 18-hour photoperiod. Increasing the K concentration from 117 to 348 mg·L−1 had minimal effects on plant growth characteristics of both cultivars, although root dry mass of ‘Monterey’ increased linearly with increasing K. Increasing the K concentration from 117 to 348 mg·L−1 did not affect the total fruit number or total fruit fresh mass of ‘Monterey’, but for ‘San Andreas’, it reduced the total fruit number by 34% and total fruit fresh mass by 45%. Additionally, increasing the K concentration from 117 to 348 mg·L−1 reduced the individual fruit mass, fruit length, and fruit diameter and increased titratable acidity in both cultivars. These results indicate that increasing the K concentration in the Yamazaki strawberry nutrient solution did not benefit plant growth, fruit yield, or fruit quality of the hydroponically grown strawberries ‘Monterey’ or ‘San Andreas’.Item Improving future agricultural sustainability by optimizing crop distributions in China(PNAS Nexus, 2025-01-07) Guan, Qi; Tang, Jing; Davis, Kyle Frankel; Kong, Mengxiang; Feng, Lian; Shi, Kun; Schurgers, GuyImproving agricultural sustainability is a global challenge, particularly for China's high-input and low-efficiency cropping systems with environmental tradeoffs. Although national strategies have been implemented to achieve Sustainable Development Goals in agriculture, the potential contributions of crop switching as a promising solution under varying future climate change are still under-explored. Here, we optimize cropping patterns spatially with the targets of enhancing agriculture production, reducing environmental burdens, and achieving sustainable fertilization across different climate scenarios. Compared with current cropping patterns, the optimal crop distributions under different climate scenarios consistently suggest allocating the planting areas of maize and rapeseed to the other crops (rice, wheat, soybean, peanut, and potato). Such crop switching can consequently increase crop production by 14.1%, with accompanying reductions in environmental impacts (8.2% for leached nitrogen and 24.0% for irrigation water use) across three representative Shared Socio-economic Pathways from 2020 to 2100. The sustainable fertilization rates vary from 148–173 kg N ha−1 in 2030 to 213–253 kg N ha−1 in 2070, significantly smaller than the current rate (305 kg N ha−1). These outcomes highlight large potential benefits of crop switching and fertilizer management for improving China's future agricultural sustainability.Item Searching for consistent postemergence weed control in progressively inconsistent weather(Weed Science, 2024-11-18) Landau, Christopher; Bradley, Kevin; Burns, Erin; Dobbels, Anthony; Essman, Alyssa; Flessner, Michael; Gage, Karla; Hager, Aaron; Jhala, Amit; Johnson, Paul O.; Johnson, William; Lancaster, Sarah; Lingenfelter, Dwight; Loux, Mark; Miller, Eric; Owen, Micheal; Sarangi, Debalin; Sikkema, Peter; Sprague, Christy; VanGessel, Mark; Werle, Rodrigo; Young, Bryan; Williams, Martin, IIFoliar applied postemergence herbicides are a critical component of corn and soybean weed management programs in North America. Rainfall and air temperature around the time of application may affect the efficacy of herbicides applied postemergence in corn or soybean production fields. However, previous research utilized a limited number of site-years and may not capture the range of rainfall and air temperatures that these herbicides are exposed to throughout North America. The objective of this research was to model the probability of achieving successful weed control (≥85%) with commonly applied postemergence herbicides across a broad range of environments. A large database of over 10,000 individual herbicide evaluation field trials conducted throughout North America was used in this study. The database was filtered to include only trials with a single postemergence application of fomesafen, glyphosate, mesotrione, or fomesafen + glyphosate. Waterhemp (Amaranthus tuburculatus (Moq.) J. D. Sauer), morningglory species (Ipomoea spp.), and giant foxtail (Setaria faberi Herrm.) were the weeds of focus. Separate random forest models were created for each weed species by herbicide combination. The probability of successful weed control deteriorated when the average air temperature within the first ten d after application was <19 or >25 C for most of the herbicide by weed species models. Additionally, dryer conditions prior to postemergence herbicide application reduced the probability of successful control for several of the herbicide by weed species models. As air temperatures increase and rainfall becomes more variable, weed control with many of the commonly used postemergence herbicides is likely to become less reliable.Item Weed Communities of Snap Bean Fields in the United States(Weed Science, 2024-11-15) Pavlovic, Pavle; Colquhoun, Jed B.; Korres, Nicholas E.; Liu, Rui; Lowry, Carolyn J.; Peachey, Ed; Scott, Barbara; Sosnoskie, Lynn M.; VanGessel, Mark J.; Williams, Martin M., IIWeeds are one of the greatest challenges to snap bean production. Anecdotal observation posits certain species frequently escape the weed management system by the time of crop harvest, hereafter called residual weeds. The objectives of this work were to 1) quantify the residual weed community in snap bean (Phaseolus vulgaris L.) grown for processing across the major growing regions in the U.S., and 2) investigate linkages between the density of residual weeds and their contributions to weed canopy cover. In surveys of 358 fields across the Northwest (NW), Midwest (MW), and Northeast (NE), residual weeds were observed in 95% of the fields. While a total of 109 species or species-group were identified, one to three species dominated the residual weed community of individual fields in most cases. It was not uncommon to have >10 weeds m-2 with a weed canopy covering >5% of the field’s surface area. Some of the most abundant and problematic species or species-group escaping control included amaranth species (such as smooth pigweed (Amaranthus hybridus L.), Palmer amaranth (Amaranthus palmeri S. Watson), redroot pigweed (Amaranthus retroflexus L.), and waterhemp [Amaranthus tuberculatus (Moq.) J. D. Sauer]), common lambsquarters (Chenopodium album L.), large crabgrass [Digitaria sanguinalis (L.) Scop.], and ivyleaf morningglory (Ipomoea hederacea Jacq.). Emerging threats include hophornbeam copperleaf (Acalypha ostryifolia Riddell) in the MW and sharppoint fluvellin [Kickxia elatine (L.) Dumort.] in the NW. Beyond crop losses due to weed interference, the weed canopy at harvest poses a risk to contaminating snap bean products with foreign material. Random forest modeling predicts the residual weed canopy is dominated by common lambsquarters, large crabgrass, carpetweed (Mollugo verticillata L.), I. hederacea, amaranth species, and A. ostryifolia. This is the first quantitative report on the weed community escaping control in U.S. snap bean production.Item Weather and glufosinate efficacy; a retrospective analysis looking forward to the changing climate(Weed Science, 2025-01-08) Landau, Christopher; Bradley, Kevin; Burns, Erin; DeWerff, Ryan; Dobbels, Anthony; Essman, Alyssa; Flessner, Michael; Gage, Karla; Hager, Aaron; Jhala, Amit; Johnson, Paul O.; Johnson, William; Lancaster, Sarah; Lingenfelter, Dwight; Loux, Mark; Miller, Eric; Owen, Micheal; Sarangi, Debalin; Sikkema, Peter; Sprague, Christy; VanGessel, Mark; Werle, Rodrigo; Young, Bryan; Williams II, MartinFoliar-applied postemergence applications of glufosinate are often applied to glufosinate-resistant crops to provide nonselective weed control without significant crop injury. Rainfall, air temperature, solar radiation, and relative humidity near the time of application have been reported to affect glufosinate efficacy. However, previous research may have not captured the full range of weather variability to which glufosinate may be exposed to prior to or following application. Additionally, climate models suggest more extreme weather will become the norm, further expanding this weather range glufosinate can be exposed to. The objective of this research was to quantify the probability of successful weed control (efficacy ≥85%) with glufosinate applied to some key weed species across a broad range of weather conditions. A database of >10,000 North American herbicide evaluation trials was used in this study. The database was filtered to include treatments with a single POST application of glufosinate applied to waterhemp (Amaranthus tuburculatus (Moq.) J. D. Sauer), morningglory species (Ipomoea spp.), and/or giant foxtail (Setaria faberi Herm.) <15cm in height. These species were chosen because they are well represented in the database and listed as common and troublesome weed species in both corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] (Van Wychen 2020, 2022). Individual random forest models were created. Low rainfall (≤20 mm) over the five days prior to glufosinate application was detrimental to the probability of successful control of A. tuburculatus and S. faberi. Lower relative humidity (≤70%) and solar radiation (≤23 MJ m-1 day-1) the day of application reduced the probability of successful weed control in most cases. Additionally, the probability of successful control decreased for all species when average air temperature over the first five days after application was ≤25C. As climate continues to change and become more variable, the risk of unacceptable control of several common species with glufosinate is likely to increase.Item Drawdown of soil phosphorus by crop removal: A meta-analysis of 56 fields with interrupted fertilization(Agricultural & Environmental Letters, 2025-01-03) Gatiboni, Luke; Shober, Amy L.; Fiorellino, Nicole; Osmond, Deanna; Mosesso, Lauren R.Phosphorus (P) is an essential nutrient applied as fertilizer in agricultural fields. However, excessive fertilization leads to P build up in soils, increasing its potential to cause environmental pollution. The objective of this study was to evaluate the average P drawdown rate of 56 sites with drawdown management presented in 14 publications. Soil test P (STP) results were converted to Mehlich-3 equivalent and resampling analysis was used to compare the annual drawdown rate in fields grouped by four initial STP classes. The STP was reduced by 4.3%–8.2% per year, depending on the initial STP class. It took from 8.4 to 15.9 years to reduce the STP by half. The resulting equations from this meta-analysis can be used by landowners to estimate the time needed for STP drawdown by cropping without additional P to achieve the desired STP concentration. Core Ideas - Cropping without phosphorus (P) fertilization is one of the few options to reduce soil test P (STP). - A meta-analysis of the annual P drawdown rate was performed using 56 sites presented in 14 publications. - Fields were grouped into four initial STP classes based on Mehlich-3 STP equivalent. - The STP was reduced from 4.3% to 8.2% per year in fields with high and low initial STP. - The time needed to reduce the STP by half varied from 8.4 to 15.9 years depending on the initial STP. Graphical Abstract available at: https://doi.org/10.1002/ael2.70007 Abbreviations ICP inductively coupled plasma optical emission spectroscopy IPNI International Plant Nutrition Institute STP soil test phosphorus STPi initial soil test phosphorusItem Evaluation of soil properties and bulk δ15N to assess decadal changes in floodplain denitrification following restoration(Restoration Ecology, 2024-10-29) Galella, Joseph G.; Rahman, Md. Moklesur; Yaculak, Alexis M.; Peipoch, Marc; Kan, Jinjun; Sena, Matthew; Joshi, Bisesh; Kaushal, Sujay S.; Inamdar, ShreeramStream and floodplain restoration is a popular billion-dollar industry in the United States, with many restorations being conducted to satisfy water pollution regulations and nutrient reduction goals. The long-term efficacy of these restorations is, however, not well studied, and key soil metrics that can be used for performance assessments have not been developed. We evaluated a chronosequence of 12 restoration sites spanning an age range of 0–22 years to assess changes in denitrification rates and associated soil parameters. Restored versus unrestored reaches were compared for denitrification rate and functional gene nosZ, bulk soil δ15N, soil organic carbon (SOC), soil organic matter (SOM), bulk density, and soil moisture. Denitrification, SOM, SOC, and soil moisture were all found to increase with site age at restored sites, with the largest increase for the 10–22 age category. Bulk density decreased with time, with a significant decrease in restored floodplain soils. Bulk soil δ15N was highest immediately after restoration, decreased with restoration age, and was not positively correlated with denitrification. This may reduce its potential as a proxy for denitrification. Overall, this study reveals that selected soil metrics (SOC, SOM, soil moisture, and bulk density) could serve as a valuable proxy for denitrification and could help assess the denitrification effectiveness of floodplain restorations at the decadal time scales. Ideally, the soil metrics should be combined with other short-term assessment measures, such as those for stream and groundwaters, for a robust performance assessment of restored floodplains. Implications for Practice - Soil characteristics have not been routinely used for assessing the long-term effectiveness of stream and floodplain restorations, and guidance is needed for their use. - Soil organic matter, moisture, and bulk density improved over time for restored floodplains and could be used as reliable proxies for denitrification nitrogen removal. - Site-specific differences in restoration design and construction (e.g. soil amendments such as woody debris/chips) could significantly affect the response of soil metrics. - Since soil characteristics change slowly over decadal time scales, restoration assessments should also include quicker, short-term performance measures such as those associated with surface and groundwater quality.Item Soil bacterial communities in urban deciduous forests are filtered by site identity, soil chemistry, and shrub presence(Scientific Reports, 2024-12-30) Wu, Derek Griffin; D’Amico, Vincent; Trammell, Tara Lynn EckardUrban forest soils are complex environments subjected to various stressors that alter chemical and microbial properties. To understand soil chemistry and bacterial community patterns in urban forest soils with respect to site identity and multiflora rose (Rosa multiflora) invasion, soils were collected from beneath R. multiflora, native spice bush (Lindera benzoin), and uncovered ground in three forests in Newark, Delaware. High-throughput sequencing was used to analyze bacterial communities with corresponding soil chemical properties. Soil chemistry and operational taxonomic unit (OTU) communities were explained by site rather than by shrub cover type. Unlike other invasive plant studies, R. multiflora had minimal effects on either soil chemistry or bacterial communities. Phylum level bacterial communities were more uniform under shrub cover versus no cover, indicative of a generalized plant effect shaping soil microbiomes. Correlations between bacterial phyla and soil chemistry varied, with some phyla positively or negatively correlating with the same property at different sites. Filters for bacterial communities differ across forest scales, where sites and sampling location primarily correlate with OTU communities yet shrub presence mediates phylum level organization. Forest soil studies should consider location-based differences in bacterial communities and their correlations with soil chemistry before generalizing outcomes for whole macrosystems.Item Graft incompatibility between pepper and tomato elicits an immune response and triggers localized cell death(Horticulture Research, 2024-09-11) Thomas, Hannah Rae; Gevorgyan, Alice; Hermanson, Alexandra; Yanders, Samantha; Erndwein, Lindsay; Norman-Ariztía, Matthew; Sparks, Erin E.; Frank, Margaret H.Graft compatibility is the capacity of two plants to form cohesive vascular connections. Tomato and pepper are incompatible graft partners; however, the underlying cause of graft rejection between these two species remains unknown. We diagnosed graft incompatibility between tomato and diverse pepper varieties based on weakened biophysical stability, decreased growth, and persistent cell death using viability stains. Transcriptomic analysis of the junction was performed using RNA sequencing, and molecular signatures for incompatible graft response were characterized based on meta-transcriptomic comparisons with other biotic processes. We show that tomato is broadly incompatible with diverse pepper cultivars. These incompatible graft partners activate prolonged transcriptional changes that are highly enriched for defense processes. Amongst these processes was broad nucleotide-binding and leucine-rich repeat receptors (NLR) upregulation and genetic signatures indicative of an immune response. Using transcriptomic datasets for a variety of biotic stress treatments, we identified a significant overlap in the genetic profile of incompatible grafting and plant parasitism. In addition, we found over 1000 genes that are uniquely upregulated in incompatible grafts. Based on NLR overactivity, DNA damage, and prolonged cell death, we hypothesize that tomato and pepper graft incompatibility is characterized by an immune response that triggers cell death which interferes with junction formation.Item Increasing the Nighttime Lighting Duration Can Hasten Flowering of Long-day Plants(HortScience, 2024-11-20) Meng, Qingwu; Kramer, Thomas J.Low-intensity (≈2 μmol·m−2·s−1) photoperiodic lighting is often delivered at night to promote flowering of long-day greenhouse ornamentals when natural daylengths are short. An intermediate far-red (FR) fraction [percentage of FR light in red (R) + FR light] is necessary for the most rapid flowering in some crops, including snapdragon (Antirrhinum majus) and petunia (Petunia ×hybrida), compared with a low FR fraction. Specialty light-emitting diodes (LEDs) that include R+FR light with an intermediate FR fraction are effective at floral promotion but cost-prohibitive, whereas common warm-white (WW) LEDs with a low FR fraction can delay flowering. Because the duration to saturate flowering is longer than currently used (e.g., 4 to 8 hours) for some long-day plants, we conducted a replicated greenhouse experiment to determine how the WW or R+FR LED lighting duration influenced flowering. We grew snapdragon ‘Liberty Classic Yellow’, petunia ‘Easy Wave Burgundy Star’, and petunia ‘Wave Purple Improved’ under truncated 8-h natural short days with or without WW or R+FR (1:1) LEDs operating for 0, 4, 8, 12, or 16 hours in the middle of each night throughout the experiment. Snapdragon flowered 13 to 16 days earlier (21% to 28% earlier) under R+FR LEDs than under WW LEDs regardless of the lighting duration. Increasing the lighting duration from 0 to 16 hours decreased flowering time by up to 16 days and decreased plant height and leaf number at flowering under R+FR LEDs but not under WW LEDs. For petunia ‘Easy Wave Burgundy Star’, although WW LEDs delayed flowering by 6 to 13 days but promoted lateral branching compared with R+FR LEDs, the gap in flowering time narrowed as the lighting duration increased from 4 to 16 hours. Increasing the lighting duration improved the efficacy of WW LEDs but not R+FR LEDs. Flowering of petunia ‘Wave Purple Improved’ was unaffected as the lighting duration increased from 4 to 16 hours regardless of the lamp type and was delayed by 6 to 10 days under WW LEDs than under R+FR LEDs. For both petunia cultivars, flowering time was similar under 16-hour WW LEDs and 4-hour R+FR LEDs. In conclusion, increasing the nighttime lighting duration increased the efficacy of WW LEDs at promoting flowering of petunia and increased the efficacy of R+FR LED lamps at promoting flowering of snapdragon. Delivering WW LEDs all night long can minimize flowering delay in petunia compared with R+FR LEDs. In contrast, an intermediate FR fraction was indispensable to promote flowering of snapdragon, for which WW LEDs were ineffective.Item Soybean Bradyrhizobium spp. Spontaneously Produce Abundant and Diverse Temperate Phages in Culture(Viruses, 2024-11-07) Richards, Vanessa A.; Ferrell, Barbra D.; Polson, Shawn W.; Wommack, K. Eric; Fuhrmann, Jeffry J.Soybean bradyrhizobia (Bradyrhizobium spp.) are symbiotic root-nodulating bacteria that fix atmospheric nitrogen for the host plant. The University of Delaware Bradyrhizobium Culture Collection (UDBCC; 353 accessions) was created to study the diversity and ecology of soybean bradyrhizobia. Some UDBCC accessions produce temperate (lysogenic) bacteriophages spontaneously under routine culture conditions without chemical or other apparent inducing agents. Spontaneous phage production may promote horizontal gene transfer and shape bacterial genomes and associated phenotypes. A diverse subset (n = 98) of the UDBCC was examined for spontaneously produced virus-like particles (VLPs) using epifluorescent microscopy, with a majority (69%) producing detectable VLPs (>1 × 107 mL−1) in laboratory culture. Phages from the higher-producing accessions (>2.0 × 108 VLP mL−1; n = 44) were examined using transmission electron microscopy. Diverse morphologies were observed, including various tail types and lengths, capsid sizes and shapes, and the presence of collars or baseplates. In many instances, putative extracellular vesicles of a size similar to virions were also observed. Three of the four species examined (B. japonicum, B. elkanii, and B. diazoefficiens) produced apparently tailless phages. All species except B. ottawaense also produced siphovirus-like phages, while all but B. diazoefficiens additionally produced podovirus-like phages. Myovirus-like phages were restricted to B. japonicum and B. elkanii. At least three strains were polylysogens, producing up to three distinct morphotypes. These observations suggest spontaneously produced phages may play a significant role in the ecology and evolution of soybean bradyrhizobia.Item Methane fluxes in tidal marshes of the conterminous United States(Global Change Biology, 2024-09-05) Arias‐Ortiz, Ariane; Wolfe, Jaxine; Bridgham, Scott D.; Knox, Sara; McNicol, Gavin; Needelman, Brian A.; Shahan, Julie; Stuart‐Haëntjens, Ellen J.; Windham‐Myers, Lisamarie; Oikawa, Patty Y.; Baldocchi, Dennis D.; Caplan, Joshua S.; Capooci, Margaret; Czapla, Kenneth M.; Derby, R. Kyle; Diefenderfer, Heida L.; Forbrich, Inke; Groseclose, Gina; Keller, Jason K.; Kelley, Cheryl; Keshta, Amr E.; Kleiner, Helena S.; Krauss, Ken W.; Lane, Robert R.; Mack, Sarah; Moseman‐Valtierra, Serena; Mozdzer, Thomas J.; Mueller, Peter; Neubauer, Scott C.; Noyce, Genevieve; Schäfer, Karina V. R.; Sanders‐DeMott, Rebecca; Schutte, Charles A.; Vargas, Rodrigo; Weston, Nathaniel B.; Wilson, Benjamin; Megonigal, J. Patrick; Holmquist, James R.Methane (CH4) is a potent greenhouse gas (GHG) with atmospheric concentrations that have nearly tripled since pre-industrial times. Wetlands account for a large share of global CH4 emissions, yet the magnitude and factors controlling CH4 fluxes in tidal wetlands remain uncertain. We synthesized CH4 flux data from 100 chamber and 9 eddy covariance (EC) sites across tidal marshes in the conterminous United States to assess controlling factors and improve predictions of CH4 emissions. This effort included creating an open-source database of chamber-based GHG fluxes (https://doi.org/10.25573/serc.14227085). Annual fluxes across chamber and EC sites averaged 26 ± 53 g CH4 m−2 year−1, with a median of 3.9 g CH4 m−2 year−1, and only 25% of sites exceeding 18 g CH4 m−2 year−1. The highest fluxes were observed at fresh-oligohaline sites with daily maximum temperature normals (MATmax) above 25.6°C. These were followed by frequently inundated low and mid-fresh-oligohaline marshes with MATmax ≤25.6°C, and mesohaline sites with MATmax >19°C. Quantile regressions of paired chamber CH4 flux and porewater biogeochemistry revealed that the 90th percentile of fluxes fell below 5 ± 3 nmol m−2 s−1 at sulfate concentrations >4.7 ± 0.6 mM, porewater salinity >21 ± 2 psu, or surface water salinity >15 ± 3 psu. Across sites, salinity was the dominant predictor of annual CH4 fluxes, while within sites, temperature, gross primary productivity (GPP), and tidal height controlled variability at diel and seasonal scales. At the diel scale, GPP preceded temperature in importance for predicting CH4 flux changes, while the opposite was observed at the seasonal scale. Water levels influenced the timing and pathway of diel CH4 fluxes, with pulsed releases of stored CH4 at low to rising tide. This study provides data and methods to improve tidal marsh CH4 emission estimates, support blue carbon assessments, and refine national and global GHG inventories.Item Mitigating Toxic Metal Exposure Through Leafy Greens: A Comprehensive Review Contrasting Cadmium and Lead in Spinach(GeoHealth, 2024-06-17) Seyfferth, Angelia L.; Limmer, Matt A.; Runkle, Benjamin R. K.; Chaney, Rufus L.Metals and metalloids (hereafter, metal(loid)s) in plant-based foods are a source of exposure to humans, but not all metal(loid)-food interactions are the same. Differences exist between metal(loid)s in terms of their behavior in soils and in how they are taken up by plants and stored in the edible plant tissue/food. Thus, there cannot be one consistent solution to reducing toxic metal(loid)s exposure to humans from foods. In addition, how metal(loid)s are absorbed, distributed, metabolized, and excreted by the human body differs based on both the metal(loid), other elements and nutrients in the food, and the nutritional status of the human. Initiatives like the United States Food and Drug Administration's Closer to Zero initiative to reduce the exposure of young children to the toxic elements cadmium, lead, arsenic, and mercury from foods warrant careful consideration of each metal(loid) and plant interaction. This review explores such plant-metal(loid) interactions using the example of spinach and the metals cadmium and lead. This review highlights differences in the magnitude of exposure, bioavailability, and the practicality of mitigation strategies while outlining research gaps and future needs. A focus on feasibility and producer needs, informed via stakeholder interviews, emphasizes the need for better analytical testing facilities and grower and consumer education. More research should focus on minimization of chloride inputs for leafy greens to lessen plant-availability of Cd and the role of oxalate in reducing Cd bioavailability from spinach. These findings are applicable to other leafy greens (e.g., kale, lettuce), but not for other plants or metal(loid)s. Key Points -The toxic elements targeted in the Food and Drug Administration Closer to Zero action plan behave differently in soils and in plant uptake - Mitigation strategies to reduce exposure to toxic elements must consider the drivers of soil mobility and accumulation into edible tissues - Health and nutrition factors that affect metal and metalloid bioavailability upon ingestion should also be considered Plain Language Summary Toxic metals like cadmium and lead in foods can be harmful to our health, especially for babies and young children who are more vulnerable due to their smaller size and rapid development. Leafy greens like spinach can absorb these metals from the soil but in different ways. In addition, how and where they accumulate in edible plant tissues also differs. This review uses spinach as an example to compare and contrast how cadmium and lead differ in how they move through soil and accumulate in plant foods. It also discusses practical pre- and post-harvest techniques to lessen human exposure to these metals that can be adopted by producers and consumers. Finally, it highlights future needs and research directions.Item Controlling exposure to As and Cd from rice via irrigation management(Environmental Geochemistry and Health, 2024-07-29) Limmer, Matt A.; Seyfferth, Angelia L.Irrigation management controls biogeochemical cycles in rice production. Under flooded paddy conditions, arsenic becomes plant-available as iron-reducing conditions ensue, while oxic conditions lead to increased plant availability of Cd in acidic soils. Because Cd enters rice through Mn transporters, we hypothesized that irrigation resulting in intermediate redox could simultaneously limit both As and Cd in rice grain due to As retention in soil and Mn competition for Cd uptake. In a 2 year field study, we used 6 irrigation managements that varied in extent and frequency of inundation, and we observed strong effects of irrigation management on porewater chemistry, soil redox potentials, plant As and Cd concentrations, plant nutrient concentrations, and methane emissions. Plant As decreased with drier irrigation management, but in the grain this effect was stronger for organic As than for inorganic As. Grain organic As, but not inorganic As, was strongly and positively correlated with cumulative methane emissions. Conversely, plant Cd increased under more aerobic irrigation management and grain Cd was negatively correlated with porewater Mn. A hazard index approach showed that in the tested soil with low levels of As and Cd (5.4 and 0.072 mg/kg, respectively), irrigation management could not simultaneously decrease grain As and Cd. Many soil properties, such as reducible As, available Cd, soil pH, available S, and soil organic matter should be considered when attempting to optimize irrigation management when the goal is decreasing the risk of As and Cd in rice grain.Item El Niño and positive Indian Ocean Dipole conditions simultaneously reduce the production of multiple cereals across India(Environmental Research Letters, 2024-09-09) Gurazada, Madhulika; McDermid, Sonali; DeFries, Ruth; Davis, Kyle F.; Singh, Jitendra; Singh, DeeptiNatural climate phenomena like El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) influence the Indian monsoon and thereby the region's agricultural systems. Understanding their influence can provide seasonal predictability of agricultural production metrics to inform decision-making and mitigate potential food security challenges. Here, we analyze the effects of ENSO and IOD on four agricultural production metrics (production, harvested area, irrigated area, and yields) for rice, maize, sorghum, pearl millet, and finger millet across India from 1968 to 2015. El Niños and positive-IODs are associated with simultaneous reductions in the production and yields of multiple crops. Impacts vary considerably by crop and geography. Maize and pearl millet experience large declines in both production and yields when compared to other grains in districts located in the northwest and southern peninsular regions. Associated with warmer and drier conditions during El Niño, >70% of all crop districts experience lower production and yields. Impacts of positive-IODs exhibit relatively more spatial variability. La Niña and negative-IODs are associated with simultaneous increases in all production metrics across the crops, particularly benefiting traditional grains. Variations in impacts of ENSO and IOD on different cereals depend on where they are grown and differences in their sensitivity to climate conditions. We compare production metrics for each crop relative to rice in overlapping rainfed districts to isolate the influence of climate conditions. Maize production and yields experience larger reductions relative to rice, while pearl millet production and yields also experience reductions relative to rice during El Niños and positive-IODs. However, sorghum experiences enhanced production and harvested areas, and finger millet experiences enhanced production and yields. These findings suggest that transitioning from maize and rice to these traditional cereals could lower interannual production variability associated with natural climate variations.Item Influence of weed species and density on lima bean yield and other pests(Frontiers in Agronomy, 2024-06-27) Sankula, Sujatha; Everts, Kathryne L.; Whalen, Joanne M.; VanGessel, Mark J.Weeds interfere with lima bean production by reducing crop yield, hindering harvest, and contributing contaminants to harvested beans, yet there are very few trials documenting the impact of weeds on lima bean. This research was designed to evaluate weeds on lima bean yield, quality, as well as Rhizoctonia solani and pod-feeding insects in order to assist in implementing a more integrated approach to pest management. Field studies at four sites evaluated the impact of common cocklebur (Xanthium strumarium L.), jimsonweed (Datura stramonium L.), and ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.] at densities of 0, 7, 10, or 20 plants 10 m-1 row in the presence and absence of Rhizoctonia solani on lima bean (Phaseolus lunatus L.). The planting dates of late June to mid-July represented a typical planting period for the mid-Atlantic region of USA, while one site represented an early planting date in this region (28 May). Differences in response to weed competition for total lima bean yield, marketable yield, yield components, and R. solani discoloration on lima bean occurred at one or more sites. Weed competition from 7 plants 10 m-1 of row or higher, reduced number lima bean pods by as much as 40%. However, weed density had little impact on percentage of flat, plump, or dry pods. Marketable yield was reduced at two sites in response to 7 plants 10-1 row (19% yield loss) and higher weed densities resulted in 29 to 33% yield loss. The presence of lima bean resulted in 40 to 60% reduction of common cocklebur and jimsonweed biomass and burs or seeds compared to weeds grown without crop competition. Weed competition in lima bean was influenced by many factors including weed species and planting date. Weed management is important to not only preserve yield but limit weed seed return to the soil seedbank and maintain harvest efficiency.Item Unwrapping the Native Plant Black Box: Consumer Perceptions and Segments for Target Marketing Strategies(HortTechnology, 2024-05-23) Rihn, Alicia L.; Torres, Ariana; Behe, Bridget K.; Barton, SueThe increasing demand for sustainable products has helped spur demand for native plants. This study used an online survey of 2066 US consumers, a factor analysis, and Ward’s linkage cluster analysis to identify unique customer segments in the native plant marketplace. The following three clusters were identified: native averse (31.6%), native curious (35.7%), and native enthusiast (32.7%). The native enthusiast cluster agreed strongly with positive statements related to native plant perceptions and attributes. The native averse cluster exhibited the lowest level of agreement with these items and the greatest level of agreement with negative or neutral statements about native plants. The native curious cluster was intermediate between the other clusters but generally agreed with positive attributes. Demographic characteristics impacted cluster membership. The marketing implications are discussed.Item Varietal Tolerance of Cucurbitaceous Crops with S-metolachlor Applied Postemergence(HortTechnology, 2024-06-01) Vollmer, Kurt M.; Lynn M. Sosnoskie; VanGessel, Mark J.; Besançon, Thierry E.Cucurbit crops comprise ∼25% of the vegetable acreage in the mid-Atlantic and Northeastern United States. However, options for postemergence weed control in these crops are limited. Overlapping herbicides is a technique that involves sequential applications of soil-applied residual herbicides to lengthen herbicidal activity before the first herbicide dissipates. Residual herbicides such as S-metolachlor will not control emerged weeds, but weed control efficacy may be extended if these herbicides are applied after crop emergence, but before weed emergence occurs. Currently S-metolachlor is not labeled for broadcast applications over cucurbit crops. Greenhouse studies were conducted to evaluate pumpkin, cucumber, and summer squash variety response to varying S-metolachlor rates. S-metolachlor was applied at 1.42 and 2.85 lb/acre at the two-leaf stage of pumpkin and 0.71, 1.42, 2.85, and 5.7 lb/acre at the two-leaf stage of cucumber and summer squash. Cucumber showed a greater response to S-metolachlor with up to 67% injury observed at 5.70 lb/acre. S-metolachlor applications to pumpkin and summer squash resulted in less than 6% injury, regardless of application rate or crop variety. S-metolachlor applied at 2.85 lb/acre reduced pumpkin and cucumber dry weight 6% and 19%, respectively, but did not reduce squash dry weight. S-metolachlor reduced cucumber dry weight 78% for all varieties. Pumpkin varieties ‘Munchkin’ and ‘Baby Bear’ exhibited a 23% difference in dry weight, but no other differences were observed among other varieties because of S-metolachlor applications. Summer squash varieties ‘Respect’ and ‘Golden Glory’ exhibited a 31% difference in dry weight, but no other differences were observed among other varieties. Results show that pumpkin and summer squash demonstrated good crop safety when S-metolachlor was applied as a broadcast treatment after crop emergence. However, caution should be urged when applying this herbicide to cucumber.Item Role of Bacillus subtilis exopolymeric genes in modulating rhizosphere microbiome assembly(Environmental Microbiome, 2024-05-14) Nishisaka, Caroline Sayuri; Ventura, João Paulo; Bais, Harsh P.; Mendes, RodrigoBackground Bacillus subtilis is well known for promoting plant growth and reducing abiotic and biotic stresses. Mutant gene-defective models can be created to understand important traits associated with rhizosphere fitness. This study aimed to analyze the role of exopolymeric genes in modulating tomato rhizosphere microbiome assembly under a gradient of soil microbiome diversities using the B. subtilis wild-type strain UD1022 and its corresponding mutant strain UD1022eps−TasA, which is defective in exopolysaccharide (EPS) and TasA protein production. Results qPCR revealed that the B. subtilis UD1022eps−TasA− strain has a diminished capacity to colonize tomato roots in soils with diluted microbial diversity. The analysis of bacterial β-diversity revealed significant differences in bacterial and fungal community structures following inoculation with either the wild-type or mutant B. subtilis strains. The Verrucomicrobiota, Patescibacteria, and Nitrospirota phyla were more enriched with the wild-type strain inoculation than with the mutant inoculation. Co-occurrence analysis revealed that when the mutant was inoculated in tomato, the rhizosphere microbial community exhibited a lower level of modularity, fewer nodes, and fewer communities compared to communities inoculated with wild-type B. subtilis. Conclusion This study advances our understanding of the EPS and TasA genes, which are not only important for root colonization but also play a significant role in shaping rhizosphere microbiome assembly. Future research should concentrate on specific microbiome genetic traits and their implications for rhizosphere colonization, coupled with rhizosphere microbiome modulation. These efforts will be crucial for optimizing PGPR-based approaches in agriculture.