Scholarly Works, School of Plant and Environmental Sciences

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Spatial and temporal dynamics of Collembola (Isotomiella minor) and plant pathogenic fungi (Rhizoctonia solani) interactions
Jernigan, Ashley B.; Kao-Kniffin, Jenny; Pethybridge, Sarah; Wickings, Kyle (Elsevier, 2024-09)
The mechanistic and spatial dynamics of microarthropod-plant pathogen interactions remain understudied, despite the importance of these interactions in plant disease control. We conducted three complementary laboratory experiments using the plant-pathogenic fungus, Rhizoctonia solani, and the Collembola Isotomiella minor. The dominant mechanism (consumption vs. dispersal) of these interactions was investigated over 5 days in a controlled environment. The dominant mechanism observed was consumption, with I. minor decreasing R. solani growth by up to 58 %. There was no evidence of pathogen dispersal, however, there was potential for R. solani dispersal by I. minor as there were viable pathogen structures on the cuticle and in the frass. I. minor effects on R. solani mycelial growth rate were then determined using race tubes over 14 days. I. minor decreased R. solani mycelial growth rate by up to 23 %. Soil environment effects were explored over 5 days in a controlled environment using mineral substrate to mimic a 3-dimensional soil environment, both with and without organic matter (alfalfa) additions. In the soil without organic matter, the high I. minor abundances decreased R. solani growth compared to the low and no I. minor abundances by 23 % and 22 % respectively. In the soil with organic matter, I. minor did not affect R. solani growth. These findings suggest that organic matter in soils may be diminishing collembolan control of plant pathogens in field settings.
Microarthropods improve oat nutritional quality and mediate fertilizer effects on soil biological activity
Jernigan, Ashley B.; Kao-Kniffin, Jenny; Pethybridge, Sarah; Wickings, Kyle (Wiley, 2024-05-27)
Soil biological processes are important drivers of crop productivity in agroecosystems. Soil microarthropods play key roles in nutrient cycling and plant nutrient acquisition, though little is known about how these effects manifest in crop production under different organic fertilizer amendments. We explored the interactive effects of microarthropods and fertilizers on crop productivity in two greenhouse experiments: experiment one involved a single Collembola species, and experiment two involved diverse microarthropod communities. Oats were grown as a model crop in both experiments under one of three initial fauna abundance levels (none, low, and high). In both experiments, four organic fertilization treatments were compared: alfalfa green manure, Kreher's Poultry Litter Compost, Chilean nitrate, and a nonamended control. Oat growth and development were evaluated weekly. During each experiment, 48 pots were selected randomly for destructive harvest at two separate times to mimic forage and grain harvest stages. At each harvest, multiple soil metrics (microarthropods, microbial biomass, microbial enzymes, and soil carbon and nitrogen) and plant metrics (biomass, reproduction, and tissue carbon and nitrogen content) were evaluated. Our findings indicated that microarthropods, both single species and diverse communities, stimulated nitrogen cycling and enhanced crop nutrient status. As microarthropod abundance and diversity increased, microarthropods exerted more effects on soil microbial activity. The effects of the microarthropods enhance the breakdown of fertilizers, ultimately making fertilizer choice less important for soil processes and plant nutrient availability. Our findings suggest that microarthropods drove oat production yields primarily through their effects on soil biological processes.
Multi-Year Soil Response to Conservation Management in the Virginia Coastal Plain
Nicholakos, Sophie A.; Frame, W. Hunter; Reiter, Mark S.; Stewart, Ryan D. (Elsevier, 2025-01)
In the coastal plain region of the United States, conservation agriculture practices are being implemented to improve soil health, minimize environmental impacts, and improve farm profitability. Common practices include cover cropping and conservation tillage using strip tillage, minimal tillage, or no tillage. However, the soil response to specific combinations of conservation tillage and cover crop rotations remains poorly quantified. The objective of this research was to evaluate changes in soil properties from different combinations of conservation management. Four tillage systems – conventional, strip, minimal, and no tillage – and three winter cover rotations – fallow, winter cash crop, and high-biomass cover crop – were tested in a split-plot design. Bulk density, depth to a root-restrictive layer, soil carbon concentration, soil carbon stock, field-saturated hydraulic conductivity, and yield were measured over a seven-year period. Bulk density and field-saturated hydraulic conductivity showed greater temporal variation in the strip tillage and conventional tillage practices. Depth to root-restrictive layer was consistently highest in the strip and minimal tillage treatments, which both included implements designed to alleviate subsoil compaction. Treatments that combined conservation tillage with a winter cover (i.e., cash crops or high-biomass cover crops) had greater increases in soil carbon concentrations and carbon stock. Summer cash crop yield was significantly increased following the high-biomass cover crop treatment in 2 out of the 7 years. Altogether, soil carbon showed a more consistent response to conservation management than the other soil properties, which tended to show greater variability based on the time since disturbance (e.g., tillage). Conservation management practices therefore need to be consistently applied for multiple years in order to improve soil properties such as bulk density and saturated hydraulic conductivity.
Modeling water infiltration into soil under fractional wettability conditions
Di Prima, Simone; Stewart, Ryan D.; Abou Najm, Majdi R.; Yilmaz, Deniz; Comegna, Alessandro; Lassabatere, Laurent (Elsevier, 2025-02-01)
The heterogeneous distribution of water-repellent materials at the soil surface causes a phenomenon known as fractional wettability. This condition frequently triggers destabilization of the wetting front during water infiltration, resulting in the formation of fingered bypass flow. However, few analytical tools exist to understand and model this behavior. Moreover, existing infiltration models fail to fit certain infiltration curves that exist in experimental data. For these reasons, we introduce a novel infiltration model to simulate water infiltration under fractional wettable conditions. We conceptualize the soil surface as a composite of two distinct portions: a water-repellent fraction, where hydrophobic effects impede water infiltration, and a wettable fraction, where capillarity and gravity are the dominant forces controlling the process. The new model was validated using a dataset comprising infiltration data from 60 field measurements. Additionally, validation was performed using 660 analytically generated infiltration curves from six synthetic soils with varying textures. This innovative approach enabled us to account for the combined influence of these two fractions and to enhance the interpretation of infiltration curves with mixed shapes, which other common methods are unable to reproduce.
Physiological responses of pepper (Capsicum annum) to combined ozone and pathogen stress
Modelski, Collin; Potnis, Neha; Sanz-Saez, Alvaro; Leisner, Courtney P. (Wiley, 2024-06-24)
Tropospheric ozone [O3] is a secondary air pollutant formed from the photochemical oxidation of volatile organic compounds in the presence of nitrogen oxides, and it is one of the most damaging air pollutants to crops. O3 entry into the plant generates reactive oxygen species leading to cellular damage and oxidative stress, leading to decreased primary production and yield. Increased O3 exposure has also been shown to have secondary impacts on plants by altering the incidence and response to plant pathogens. We used the Capsicum annum (pepper)-Xanthomonas perforans pathosystem to investigate the impact of elevated O3 (eO3) on plants with and without exposure to Xanthomonas, using a disease-susceptible and disease-resistant pepper cultivar. Gas exchange measurements revealed decreases in diurnal photosynthetic rate (A′) and stomatal conductance ((Formula presented.)), and maximum rate of electron transport (Jmax) in the disease-resistant cultivar, but no decrease in the disease-susceptible cultivar in eO3, regardless of Xanthomonas presence. Maximum rates of carboxylation (Vc,max), midday A and gs rates at the middle canopy, and decreases in aboveground biomass were negatively affected by eO3 in both cultivars. We also observed a decrease in stomatal sluggishness as measured through the Ball–Berry–Woodrow model in all treatments in the disease-resistant cultivar. We hypothesize that the mechanism conferring disease resistance to Xanthomonas in pepper also renders the plant less tolerant to eO3 stress through changes in stomatal responsiveness. Findings from this study help expand our understanding of the trade-off of disease resistance with abiotic stresses imposed by future climate change.
Review on blueberry drought tolerance from the perspective of cultivar improvement
Ru, Sushan; Sanz-Saez, Alvaro; Leisner, Courtney P.; Rehman, Tanzeel; Busby, Savannah (Frontiers, 2024-05-14)
Blueberry (Vaccinium spp.) is an increasingly popular fruit around the world for their attractive taste, appearance, and most importantly their many health benefits. Global blueberry production was valued at $2.31 billion with the United States alone producing $1.02 billion of cultivated blueberries in 2021. The sustainability of blueberry production is increasingly threatened by more frequent and extreme drought events caused by climate change. Blueberry is especially prone to adverse effects from drought events due to their superficial root system and lack of root hairs, which limit blueberry’s ability to intake water and nutrients from the soil especially under drought stress conditions. The goal of this paper is to review previous studies on blueberry drought tolerance focusing on physiological, biochemical, and molecular drought tolerance mechanisms, as well as genetic variability present in cultivated blueberries. We also discuss limitations of previous studies and potential directions for future efforts to develop drought-tolerant blueberry cultivars. Our review showed that the following areas are lacking in blueberry drought tolerance research: studies of root and fruit traits related to drought tolerance, large-scale cultivar screening, efforts to understand the genetic architecture of drought tolerance, tools for molecular-assisted drought tolerance improvement, and high-throughput phenotyping capability for efficient cultivar screening. Future research should be devoted to following areas: (1) drought tolerance evaluation to include a broader range of traits, such as root architecture and fruit-related performance under drought stress, to establish stronger association between physiological and molecular signals with drought tolerance mechanisms; (2) large-scale drought tolerance screening across diverse blueberry germplasm to uncover various drought tolerance mechanisms and valuable genetic resources; (3) high-throughput phenotyping tools for drought-related traits to enhance the efficiency and affordability of drought phenotyping; (4) identification of genetic architecture of drought tolerance using various mapping technologies and transcriptome analysis; (5) tools for molecular-assisted breeding for drought tolerance, such as marker-assisted selection and genomic selection, and (6) investigation of the interactions between drought and other stresses such as heat to develop stress resilient genotypes.
The physiological and molecular responses of potato tuberization to projected future elevated temperatures
Guillemette, Abigail M.; Casanova, Guillian Hernandez; Hamilton, John P.; Pokorna, Eva; Dobrev, Petre; Motyka, Vaclav; Rashotte, Aaron M.; Leisner, Courtney P. (Oxford University Press, 2024-12-17)
Potato (Solanum tuberosum L.) is one of the most important food crops globally and is especially vulnerable to heat stress. However, substantial knowledge gaps remain in our understanding of the developmental mechanisms associated with tuber responses to heat stress. This study used whole-plant physiology, transcriptomics, and phytohormone profiling to elucidate how heat stress affects potato tuber development. When plants were grown in projected future elevated temperature conditions, abscisic acid (ABA) levels decreased in leaf and tuber tissues, whereas rates of leaf carbon assimilation and stomatal conductance were not significantly affected compared to those plants grown in historical temperature conditions. While plants grown in projected future elevated temperature conditions initiated more tubers per plant on average, there was a 66% decrease in mature tubers at final harvest compared to those plants grown in historical temperature conditions. We hypothesize that reduced tuber yields at elevated temperatures are not due to reduced tuber initiation, but due to impaired tuber filling. Transcriptomic analysis detected significant changes in the expression of genes related to ABA response, heat stress and starch biosynthesis. The tuberization repressor genes SELF PRUNING 5G (StSP5G) and CONSTANS-LIKE1 (StCOL1) were differentially expressed in tubers grown in elevated temperatures. Two additional known tuberization genes, IDENTITY OF TUBER 1 (StIT1) and TIMING OF CAB EXPRESSION 1 (StTOC1), displayed distinct expression patterns under elevated temperatures compared to historical temperature conditions but were not differentially expressed. This work highlights potential gene targets and key developmental stages associated with tuberization to develop potatoes with greater heat tolerance.
Geminivirus C4/AC4 proteins hijack cellular COAT PROTEIN COMPLEX I for chloroplast targeting and viral infections
Zhao, Wenhao; Ji, Yinghua; Zhou, Yijun; Wang, Xiaofeng (Oxford University Press, 2024-08-20)
Geminiviruses infect numerous crops and cause extensive agricultural losses worldwide. During viral infection, geminiviral C4/AC4 proteins relocate from the plasma membrane to chloroplasts, where they inhibit the production of host defense signaling molecules. However, mechanisms whereby C4/AC4 proteins are transported to chloroplasts are unknown. We report here that tomato (Solanum lycopersicum) COAT PROTEIN COMPLEX I (COPI) components play a critical role in redistributing Tomato yellow leaf curl virus C4 protein to chloroplasts via an interaction between the C4 and β subunit of COPI. Coexpression of both proteins promotes the enrichment of C4 in chloroplasts that is blocked by a COPI inhibitor. Overexpressing or downregulating gene expression of COPI components promotes or inhibits the viral infection, respectively, suggesting a proviral role of COPI components. COPI components play similar roles in C4/AC4 transport and infections of two other geminiviruses: Beet curly top virus and East African cassava mosaic virus. Our results reveal an unconventional role of COPI components in protein trafficking to chloroplasts during geminivirus infection and suggest a broad-spectrum antiviral strategy in controlling geminivirus infections in plants.
ICPPB & Biocontrol 2024: Abstract book
(Virginia Tech, 2024-07)
The 15th International Conference on Plant Pathogenic Bacteria and the 5th International Symposium of Biological Control of Bacterial Plant Diseases was held as a combined conference at Virginia Tech in Blacksburg, VA, USA from July 7-12, 2024.
Site Preparation and Planting Strategies to Improve Native Forb Establishment in Pasturelands
Bellangue, David; Barney, Jacob; Flessner, Michael; Kubesch, Jonathan; O’Rourke, Megan; Tracy, Benjamin; Reid, John Leighton (MDPI, 2024-11-14)
Increasing the diversity of native forbs in pasturelands can benefit insect pollinator populations, which have been declining widely. Establishing native forbs into existing pasturelands can be challenging, however, and information about effective planting strategies in these systems is lacking. In this study, we evaluated several planting strategies to improve native forb establishment. Two field experiments were conducted in Virginia, USA in 2021 and 2022. Experiment 1 evaluated how six herbicide treatments and tillage affected establishment success when forbs were planted in summer or fall. Experiment 2 investigated how different seeding rates from 2.2 to 56 kg/ha and pre-seeding cold stratification affected forb establishment. In experiment 1, treatments using Roundup/glyphosate and tillage resulted in the most forb establishment. Planting in summer improved establishment with Roundup/glyphosate application. In experiment 2, native forb plant establishment was positively associated with seeding rate (p < 0.001), with a rate of 56 kg/ha resulting in almost 3x more forbs compared to the lowest seeding rate. Cold stratification also increased target plant establishment (p < 0.01), but these effects were inconsistent among species. Our results suggest that effective native forb establishment can be achieved through intensive site preparation with Roundup/glyphosate or tillage to suppress vegetation and planting at rates no higher than 11 kg/ha.
Why Is Reducing the Dead Zone in the Gulf of Mexico Such a Complex Goal? Understanding the Structure That Drives Hypoxic Zone Formation via System Dynamics
Mier-Valderrama, Luis; Ledezma, Jorge; Gibson, Karl; Anoruo, Ambrose; Turner, Benjamin (MDPI, 2024-08-26)
The Northern Gulf of Mexico hosts a severe dead zone, an oxygen-depleted area spanning 1,618,000 hectares, threatening over 40% of the U.S. fishing industry and causing annual losses of USD 82 million. Using a System Dynamics (SD) approach, this study examined the Mississippi–Atchafalaya River Basin (MARB), a major contributor to hypoxia in the Gulf. A dynamic model, developed with Vensim software version 10.2.1 andexisting data, represented the physical, biological, and chemical processes leading to eutrophication and simulated dead zone formation over time. Various policies were assessed, considering natural system variability. The findings showed that focusing solely on nitrogen control reduced the dead zone but required greater intensity or managing other inputs to meet environmental goals. Runoff control policies delayed nutrient discharge but did not significantly alter long-term outcomes. Extreme condition tests highlighted the critical role of runoff dynamics, dependent on nitrogen load relative to flow volume from upstream. The model suggests interventions should not just reduce eutrophication inputs but enhance factors slowing down the process, allowing natural denitrification to override anthropogenic nitrification.
Response of the Edamame Germplasm to Early-Season Diseases in the United States
Li, Xiaoying; Zaia, Rafael; Liu, Kathryn; Xu, Xueming; Silva, Marcos Da; Rojas, Alejandro; Welbaum, Gregory E.; Zhang, Bo; Rideout, Steven (MDPI, 2024-07-29)
Edamame (Glycine max (L.) Merr.) is a specialty soybean newly grown in the United States that has become the second most widely consumed soy food (25,000–30,000 tons annually). Poor crop establishment caused by soilborne diseases is a major problem limiting edamame production in the U.S. This study investigated 24 edamame cultivars/lines to determine their response to three soilborne pathogens causing seed rot and seedling damping off, including Rhizoctonia solani, Sclerotium rolfsii, Pythium irregulare, and Xanthomonas campestris pv. glycines, a seedborne pathogen that caused severe outbreaks of bacterial leaf pustules in mid-Atlantic regions in 2021. The hypothesis was that resistant variations existed among the genotypes, which could be used for production and future breeding efforts. The results reveal that all genotypes were affected, but partially resistant varieties could be clearly recognized by a significantly lower disease index (p < 0.05), and no genotype was resistant to all four diseases. Newly developed breeding lines showed overall higher disease resistance than commercial cultivars, particularly to R. solani and P. irregulare. This study found genetic variability in edamame, which can be helpful in breeding for resistance or tolerance to early-season diseases. The result will promote domestic edamame production and further strengthen and diversify agricultural economies in the U.S.
Uptake and Economic Value of Macro- and Micronutrient Minerals in Wheat Residue
Adams, Curtis B.; Rogers, Christopher W.; Marshall, Juliet M.; Hatzenbuehler, Patrick; Walsh, Olga S.; Thurgood, Garrett; Dari, Biswanath; Loomis, Grant; Tarkalson, David D. (MDPI, 2024-08-15)
Wheat (Triticum aestivum, L.) producers have the choice to retain or remove residue from the cropping system following grain harvest. In the U.S. Pacific Northwest and other regions, wheat residue is often sold to increase operational profitability, especially from higher-yielding systems. But there are several benefits to retaining residue, including recycling of mineral nutrients contained therein, though this is understudied. Therefore, the primary objectives of this research were to collect and analyze a large and diverse dataset on wheat residue nutrient uptake (N, P, K, Ca, Mg, S, Fe, Zn, Mn, Cu), develop tools to estimate nutrient amounts in residue, and make economic estimates of the fertilizer replacement value of those nutrients. This was accomplished by conducting replicated variety trials on five classes of wheat across many Pacific Northwest sites over two years, then collecting and analyzing data on wheat residue biomass, residue nutrient concentrations, and grain yield. The results showed that wheat residue contained a significant amount of nutrients, but was particularly concentrated in K. Production environment had the most substantial effect on residue mineral uptake amounts, due to site differences in yield and soil nutrient availability. To enable simple estimation of residue nutrient uptake across a broad range of wheat production levels, two estimation tools are presented herein. Economic analysis showed the substantial monetary value of residual nutrients. For example, in a high-yielding wheat crop (9 Mg ha⁻¹), the average fertilizer replacement value of just residue N, P, K, and S was similar to the entire fertilizer budget to grow the crop (~$211 vs. $205 ha⁻¹), not considering micronutrients in the residue or any nutrients removed through grain harvest. In making residue management decisions, wheat producers should consider the tradeoff between the immediate economic gains of residue sale and the multifaceted benefits of residue retention, including savings on future nutrient costs.
Silvopastures: Benefits, Past Efforts, Challenges, and Future Prospects in the United States
Poudel, Sanjok; Pent, Gabriel J.; Fike, John H. (MDPI, 2024-06-26)
The global human population is projected to reach 9.7 billion by 2050, increasing the demand for food and fiber, but also raising concerns about the environmental impact of agricultural production scaled to meet their needs. Silvopastures—integrated tree–forage–livestock systems—have emerged as a viable practice to meet the required productivity and environmental stewardship outcomes. This review consolidates the extensive research on silvopasture practices in the United States and highlights the benefits of these systems. A comprehensive literature search across databases such as ScienceDirect and Google Scholar revealed 152 publications on silvopastures in the United States since 2000, indicating growing interest. These studies have primarily focused on the impacts of silvopastures on livestock welfare and productivity, forage production and composition, soil health and nutrient dynamics, and socio-economic factors. Geographical distribution analysis indicated that the research is more focused in the Southeastern United States, with Florida, Virginia, Alabama, Missouri, and Arkansas being the top five contributing states. The review also offers insights into the tree and forage species used across these states and discusses the challenges to silvopasture adoption among producers and land managers while exploring future prospects. This review may be used as a resource for understanding the multifaceted dimensions of silvopasture adoption, providing insights for researchers, policymakers, and practitioners alike.
Implementing Digital Multispectral 3D Scanning Technology for Rapid Assessment of Hemp (Cannabis sativa L.) Weed Competitive Traits
Singh, Gursewak; Slonecki, Tyler; Wadl, Philip; Flessner, Michael; Sosnoskie, Lynn; Hatterman-Valenti, Harlene; Gage, Karla; Cutulle, Matthew (MDPI, 2024-06-28)
The economic significance of hemp (Cannabis sativa L.) as a source of grain, fiber, and flower is rising steadily. However, due to the lack of registered herbicides effective in hemp cultivation, growers have limited weed management options. Plant height, biomass, and canopy architecture may affect crop–weed competition. Greenhouse experiments conducted at the joint Clemson University Coastal Research and Education Center and USDA-ARS research facility at Charleston, SC, USA used 27 hemp varieties, grown under controlled temperature and light conditions. Weekly plant scans using a digital multispectral phenotyping system, integrated with machine learning algorithms of the PlantEye F500 instrument, (Phenospex, Heerlen, Netherlands) captured high-resolution 3D models and spectral data of the plants. Manual and scanner-based measurements were validated and analyzed using statistical methods to assess plant growth and morphology. This study included validation tests showing a significant correlation (p < 0.001) between digital and manual measurements (R² = 0.89 for biomass, R² = 0.94 for height), indicating high precision. The use of 3D multispectral scanning significantly reduces the time-intensive nature of manual measurements, allowing for a more efficient assessment of morphological traits. These findings suggest that digital phenotyping can enhance integrated weed management strategies and improve hemp crop productivity by facilitating the selection of competitive hemp varieties.
Hemp Seed Yield Responses to Nitrogen Fertility Rates
Podder, Swarup; Shafian, Sanaz; Thomason, Wade E.; Wilson, T. Bain; Fike, John H. (MDPI, 2024-04-11)
Industrial hemp (Cannabis sativa L.) holds promise as a crop for more sustainable supply chains given its potential as a source of high-strength fibers, adsorbents, and nutrient-dense feedstuffs. Developing nutrient management guidelines for hemp will be an important part of optimizing the crop’s sustainability attributes. This study measured hemp seed yield in response to N fertilization rate (0, 60, 120, 180, and 240 kg N ha⁻¹). Treatments were tested with four hemp cultivars (‘Joey’ and ‘Grandi’ in 2020, 2021, and 2022 and ‘NWG 2463’ and ‘NWG 4113’ in 2023) in Virginia. Nitrogen input influenced (p ≤ 0.0177) seed yield in all four experimental years, although the pattern of response varied substantially. In 2020, following delayed seeding, hemp showed a weak quadratic (p = 0.0113) response to N inputs, with peak yield (1640 kg ha⁻¹) occurring with 120 kg N ha⁻¹. In 2021, hemp displayed a strong linear (p < 0.0001) response to N inputs, with the highest seed yield (2510 kg ha⁻¹) at 240 kg N ha⁻¹. In 2022, a season characterized by low precipitation and high weed pressure, a weak, linear (p = 0.0111) response to the N rate was observed. The greatest seed yield (380 kg ha⁻¹) was again observed with 240 kg N ha⁻¹. In 2023, weed pressure remained an issue, but the response to N was strong and linear (p < 0.0001), with the greatest seed yield (831 kg ha⁻¹) again measured at 240 kg N ha⁻¹. These findings indicate hemp can be quite responsive to N inputs but that the magnitude of response is sensitive to other factors such as available soil moisture, weed pressure, and growing period.
Silicon Improves Heat and Drought Stress Tolerance Associated with Antioxidant Enzyme Activity and Root Viability in Creeping Bentgrass (Agrostis stolonifera L.)
Zhang, Xunzhong; Goatley, Mike; Wang, Kehua; Goddard, Ben; Harvey, Rose; Brown, Isabel; Kosiarski, Kelly (MDPI, 2024-05-30)
Creeping bentgrass (Agrostis stolonifera L.) is an important cool-season turfgrass species widely used for golf course putting greens; however, it experiences summer stress and quality decline in the U.S. transition zone and other regions with similar climates. Silicon (Si) may improve the abiotic stress of creeping bentgrass, but the mechanism of its impact on plant drought and heat tolerance is not well understood, and a few studies have reported on the effects of Si on creeping bentgrass drought and heat tolerance. The objectives of this study were to determine the effects of Ortho-silicic acid (Ortho-Si) on antioxidant metabolism and root growth characteristics and viability in creeping bentgrass under drought and heat-stress conditions. The three treatments, including control, Ortho-Si at 0.16 mL m⁻² and 0.32 mL m⁻², were applied biweekly to creeping bentgrass. Foliar application of the Ortho-Si exhibited beneficial effects on turf quality, physiological fitness, and root growth in creeping bentgrass. The Ortho-Si application at 0.16 mL m⁻² and 0.32 mL m⁻² improved turf quality ratings by 9.5% and 11.1%, respectively, photochemical efficiency (PE) by 6.9% and 8.5%, respectively, chlorophyll content by 27.1% and 29.9%, and carotenoids content by 25.5% and 27.2%, respectively, when compared to the control at the end of the trial. The Ortho-Si treatments enhanced antioxidant enzyme activity; the highest amount, in particular, increased superoxide dismutase (SOD) activity by 32.8%, catalase (CAT) by 12.8%, and ascorbate peroxidase (APX) activity by 37.4%, as compared to the control. The Ortho-Si application reduced leaf hydrogen peroxide (H₂O₂) concentration relative to the control. In addition, exogenous Ortho-Si improved leaf Si concentration. The Ortho-Si application at 0.32 mL m⁻² increased root biomass by 52.7% and viability by 89.3% relative to the control. Overall, Ortho-Si at 0.32 mL m⁻² had greater beneficial effects than the low rate (0.16 mL m⁻²). Exogenous Si may improve drought and heat tolerance by protecting photosynthetic function, enhancing the activities of leaf antioxidant enzymes, and stimulating root growth, viability, and Si uptake. The results of this study suggest that foliar application of Ortho-Si at 0.32 mL m⁻² may be considered to be an effective approach to improve turf quality and physiological fitness of creeping bentgrass during the summer months in the U.S. transition zone and other regions with similar climates.
Phenotypic Dissection of Drought Tolerance in Virginia and Carolinas within a Recombinant Inbred Line Population Involving a Spanish and a Virginia-Type Peanut Lines
Kumar, Naveen; Haak, David C.; Dunne, Jeffrey C.; Balota, Maria (MDPI, 2024-06-08)
Peanut (Arachis hypogaea L.) is a rainfed crop grown in both tropical and subtropical agro-climatic regions of the world where drought causes around 20% yield losses per year. In the United States, annual losses caused by drought are around $50 million. The objective of this research was to (1) identify genetic variation for the normalized difference vegetation index (NDVI), canopy temperature depression (CTD), relative chlorophyll content by SPAD reading (SCMR), CO₂ assimilation rate, and wilting among recombinant inbred lines (RILs) derived from two diverse parents N08086olJCT and ICGV 86015, to (2) determine if the physiological traits can be used for expediting selection for drought tolerance, and (3) experimental validation to identify lines with improved yield under water-limited conditions. Initially, 337 lines were phenotyped under rainfed production and a selected subset of 52 RILs were tested under rainout shelters, where drought was imposed for eight weeks during the midseason (July and August). We found that under induced drought, pod yield was negatively correlated with wilting and CTD, i.e., cooler canopy and high yield correlated positively with the NDVI and SPAD. These traits could be used to select genotypes with high yields under drought stress. RILs #73, #56, #60, and #31 performed better in terms of yield under both irrigated and drought conditions compared to check varieties Bailey, a popular high-yielding commercial cultivar, and GP-NC WS 17, a drought-tolerant germplasm.
A Review of Bioactive Compound Effects from Primary Legume Protein Sources in Human and Animal Health
Shea, Zachary; Ogando do Granja, Matheus; Fletcher, Elizabeth B.; Zheng, Yaojie; Bewick, Patrick; Wang, Zhibo; Singer, William M.; Zhang, Bo (MDPI, 2024-05-01)
The global demand for sustainable and nutritious food sources has catalyzed interest in legumes, known for their rich repertoire of health-promoting compounds. This review delves into the diverse array of bioactive peptides, protein subunits, isoflavones, antinutritional factors, and saponins found in the primary legume protein sources—soybeans, peas, chickpeas, and mung beans. The current state of research on these compounds is critically evaluated, with an emphasis on the potential health benefits, ranging from antioxidant and anticancer properties to the management of chronic diseases such as diabetes and hypertension. The extensively studied soybean is highlighted and the relatively unexplored potential of other legumes is also included, pointing to a significant, underutilized resource for developing health-enhancing foods. The review advocates for future interdisciplinary research to further unravel the mechanisms of action of these bioactive compounds and to explore their synergistic effects. The ultimate goal is to leverage the full spectrum of benefits offered by legumes, not only to advance human health but also to contribute to the sustainability of food systems. By providing a comprehensive overview of the nutraceutical potential of legumes, this manuscript sets a foundation for future investigations aimed at optimizing the use of legumes in the global pursuit of health and nutritional security.
Evaluating Different Methods to Establish Biodiverse Swards of Native Grasses and Wildflowers for Pasturelands
Kubesch, Jonathan O. C.; Greiner, Scott P.; Pent, Gabriel J.; Reid, J. Leighton; Tracy, Benjamin F. (MDPI, 2024-05-14)
Many cool-season pastures in the southeastern U.S. are dominated by a competitive cool-season grass, tall fescue (Schedonorus arundinaceus), and lack substantial plant diversity. Planting native warm-season grasses (NWSGs) and wildflowers (WFs) into these pastures could provide summer forage for cattle and more floral resources for pollinators. This paper summarizes field experiments designed to evaluate different spatiotemporal planting arrangements of NWSGs and WFs to improve their establishment success. The study was conducted from April 2021 to October 2023 in central Virginia (USA). Planting treatments included NWSG and WF mixtures planted: (1) together in the same space, (2) spatially separated in space (i.e., side by side), or (3) temporally separated where NWSGs and WFs were planted in difference sequences. Results showed few differences in forage mass, floral production, and botanical composition as well as stand density in 2021 and 2022. In 2023, NWSG abundance was greater where grasses were planted first or mixed with WFs. Similarly, the WF component was favored when they were planted before NWSGs. Overall, planting NWSG and WF mixes separately, either spatially or temporally, favors successful establishment and could offer more flexibility for using selective herbicides to suppress the heavy weed pressure that often accompanies these plantings.

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