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The permafrost active layer is a key supplier of soil organic carbon and mineral nutrients to Arctic rivers. In the active layer, sites of soil-water exchange are locations for organic carbon and nutrient mobilization. Previously these sites were considered as connected during summer months and isolated during winter months. Whether soil pore waters in active layer soils are connected during shoulder seasons is poorly understood. In this study, exceptionally heavy silicon isotope compositions in soil pore waters show that during late winter, there is no connection between isolated pockets of soil pore water in soils with a shallow active layer. However, lighter silicon isotope compositions in soil pore waters reveal that soils are biogeochemically connected for longer than previously considered in soils with a deeper active layer. We show that an additional 21% of the 0–1 m soil organic carbon stock is exposed to soil - water exchange. This marks a hot moment during a dormant season, and an engine for organic carbon transport from active layer soils. Our findings mark the starting point to locate earlier pathways for biogeochemical connectivity, which need to be urgently monitored to quantify the seasonal flux of organic carbon released from permafrost soils.

Episodic nitrous oxide (N2O) emissions from Vertisols used for furrow-irrigated cotton production mainly occur in response to early season irrigation events. This study evaluated the impact of N fertiliser placement and timing strategies on N2O emissions from Vertisols under cotton production in northeast Australia. We compared N2O emissions in two experiments during the 2015–16 summer. Each experiment consisted of two site-years of data from different commercial cotton paddocks. Experimental comparisons were: (1) all N fertiliser applied pre-plant vs split-N application and (2) applying pre-plant N fertiliser into the irrigated vs non-irrigated side of the plant bed. Where all N fertiliser was applied pre-plant, 46–96% of total N2O emissions occurred in response to the first irrigation. Where N application was split, 33–34% of total N2O emissions followed the in-crop N applications, 2–7 times more than from the same irrigations where no in-crop N was applied (all pre-plant). Splitting N application between pre-sowing and in-season applications gave no difference in cumulative N2O at one site but increased total N2O loss at the other (99 vs 63 g N2O–N/ha). Changing the placement of the pre-sowing N fertiliser band from the non-irrigated to the irrigated side of the hill changed the source location of N2O emissions but the not the cumulative N2O loss. Varying the timing and placement of pre-plant N application affected the spatial and temporal intensity of soil N2O emissions, but generally not the overall total loss of N2O.

To determine whether the proprioceptive ability of advanced and expert snowsport participants increased with time on-snow, and whether gender, age, snowsport discipline and/or previous ankle injury were factors in proprioceptive ability at the start of the winter snow season (T1, n=80) compared to mid- season (T2, n=39).Observational study METHOD: Participants completed a questionnaire at T1, and proprioception was measured at T1 and T2 by the Active Movement Extent Discrimination Apparatus (AMEDA), which tests lower limb proprioception.At T1 there was no significant difference between the proprioception scores of the two cohorts of advanced and expert snowsport participants, between females and males, younger and older age groups, nor between alpine skiers and snowboarders. At T2, after a minimum of 5 weeks on-snow, the whole group had improved their proprioception by 0.04 (p.0001) as measured by the AMEDA. Groups undertaking different snowsport disciplines achieved different gains across the season, with minimal change of 0.02 in skiers (p=.056), while snowboarders and mixed ski/snowboard participants gained 0.05 (p=.034) and 0.06 (p=.005) (ηAmongst an established group of snowsports participants, lower limb proprioception is a consistent skill that is equally well developed in all cohorts. Several weeks of regular snowsport exposure improves this proprioceptive acuity amongst snowboarders, and those who mix snowboarding with skiing. Exposure to a prolonged period of snowsport improves proprioception, with benefits to neuromuscular control mechanisms.

In many parts of the world including the Great Lakes region of North America, Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is a major foliar disease of sugar beet (Beta vulgaris). Management of CLS involves an integrated approach which includes the application of fungicides. To guide fungicide application timings, disease prediction models are widely used by sugar beet growers in North America. While these models have generally worked well, they have not included information about pathogen presence. Thus, incorporating spore production and dispersal could make them more effective. The current study used sentinel beets to assess the presence of C. beticola spores in the environment early in the 2017 and 2018 growing seasons. Weather variables including air temperature, relative humidity, rainfall, leaf wetness, wind speed, and solar radiation were collected. These data were used to identify environmental variables that correlated with spore levels during a time when CLS is not generally observed in commercial fields. C. beticola spores were detected during mid-April both years, which is much earlier than previously reported. A correlation was found between spore data and all the weather variables examined during at least one of the two years, except for air temperature. In both years, spore presence was significantly correlated with rainfall (P < 0.0001) as well as relative humidity (P < 0.0090). Rainfall was particularly intriguing, with an adjusted R2 of 0.3135 in 2017 and 0.1652 in 2018. Efforts are ongoing to investigate information on spore presence to improve prediction models and CLS management.

Tropical cyclones (TCs) are major meteorological hazards for coastal communities around the world. Among the most active TC development basins are the North Atlantic (NATL) and the eastern North Pacific (ENP), both of which bring impacts to the USA and other countries of North America. This research assesses the climatology of occurrence dates of nth (e.g., 1st and 2nd,) TCs and hurricanes in both basins, as well as occurrence dates of accumulated cyclone energy thresholds. We use statistical methods to develop a base climatology of occurrence dates and assess their trends over time, as well as correlate early season nth TC and hurricane occurrence dates with overall seasonal activity. We find that the climatologies of NATL and ENP occurrence dates exhibit similarities but unique differences that relate to the TC climatologies of their basins. In addition, we find that NATL nth TC occurrence dates generally have been trending earlier with time, while no trends were identified for the ENP or for hurricanes in either basin. Lastly, we find that early season TCs possess the ability to postulate overall seasonal activity in both basins, the strongest correlations in each basin coming from the 3rd and 4th TCs in the NATL and the 5th and 6th TCs in the ENP. Results of this study have utility in improving seasonal TC forecasts for the NATL and ENP made by 1 September and 1 August, respectively, as well as providing a baseline for modeling studies.

Early leaf removal around the cluster zone is a common technique applied in cool climate viticulture, to regulate yield components and improve fruit quality. Despite the increasing amount of information on early leaf removal and its impact on total soluble solids, anthocyanins, and polyphenols, less is known regarding aroma compounds. In order to verify the hypothesis that defoliation, applied before or after flowering, could impact the biosynthesis of thiol precursors, we performed a two year (2013 and 2014) experiment on Sauvignon blanc. We provided evidence that differential accumulation of thiol precursors in berries is affected by the timing of defoliation, and this impact was related to modifications in the biosynthetic pathway. Furthermore, the possible interaction between leaf removal treatment and seasonal weather conditions, and its effect on the biosynthesis of volatile precursors are discussed. Our results suggested that in Sauvignon blanc the relative proportion of 4-S-glutathionyl-4-methylpentan-2-one (G-4MSP) and 3-S-glutathionylhexan-1-ol (G-3SH) precursors can be affected by defoliation, and this could be related to the induction of two specific genes encoding glutathione-S-transferases (VvGST3 and VvGST5), while no significant effects on basic fruit chemical parameters, polyphenols, and methoxypyrazines were ascertained under our experimental conditions.

Background Annual vaccination is the most effective strategy for preventing influenza. We assessed trends and demographic and access-to-care characteristics associated with place of vaccination in recent years. Methods Data from the 2014-2018 National Internet Flu Survey were analyzed to assess trends in place of early-season influenza vaccination during the 2014-15 through 2018-19 seasons. Multivariable logistic regression was conducted to identify factors independently associated with vaccination settings in the 2018-19 season. Results Among vaccinated adults, the proportion vaccinated in medical (range: 49%-53%) versus nonmedical settings (range: 47%-51%) during the 2014-15 through 2018-19 seasons were similar. Among adults aged ≥18 years vaccinated early in the 2018-19 influenza season, a doctor's office was the most common place (34.4%), followed by pharmacies or stores (32.3%), and workplaces (15.0%). Characteristics significantly associated with an increased likelihood of receipt of vaccination in nonmedical settings among adults included household income ≥$50,000, having no doctor visits since July 1, 2018, or having a doctor visit but not receiving an influenza vaccination recommendation from the medical professional. Conclusions Place of early-season influenza vaccination among adults who reported receiving influenza vaccination was stable over 5 recent seasons. Both medical and nonmedical settings were important places for influenza vaccination. Increasing access to vaccination services in medical and nonmedical settings should be considered as an important strategy for improving vaccination coverage.

Irrigation is essential for hop production in the Pacific Northwestern United States, the primary growing region in the U.S. Irrigation water supplies can be inadequate in drought years and may bec...

We present a hurricane risk assessment model that simulates North Atlantic Ocean tropical cyclone (TC) tracks and intensity, conditioned on the early season large-scale climate state. The model, Cluster-Based Climate-Conditioned Hurricane Intensity and Track Simulator (C3-HITS), extends a previous version of HITS. HITS is a nonparametric, spatial semi-Markov, stochastic model that generates TC tracks by conditionally simulating segments of randomly varying lengths from the TC tracks contained in NOAA’s Best Track Data, version 2, dataset. The distance to neighboring tracks, track direction, TC wind speed, and age are used as conditioning variables. C3-HITS adds conditioning on two early season, large-scale climate covariates to condition the track simulation: the Niño-3.4 index, representing the eastern equatorial Pacific Ocean sea surface temperature (SST) departure from climatology, and main development region, representing tropical North Atlantic SST departure from climatology in the North Atlantic TC main development region. A track clustering procedure is used to identify track families, and a Poisson regression model is used to model the probabilistic number of storms formed in each cluster, conditional on the two climate covariates. The HITS algorithm is then applied to evolve these tracks forward in time. The output of this two-step, climate-conditioned simulator is compared with an unconditional HITS application to illustrate its prognostic efficacy in simulating tracks during the subsequent season. As in the HITS model, each track retains information on velocity and other attributes that can be used for predictive coastal risk modeling for the upcoming TC season.

This study assessed early-season effects of spontaneous wildfires on soil fertility and weed diversity in two managed plantations – cashew and teak – in Ilorin, Nigeria. Soil pH and nutrients in the topsoils and subsoils of burned and unburned plantations plots after a spontaneous wildfire were analysed. Species diversity and similarity were determined based on the composition and abundances of weed flora two months post-fire. The fire effects on soil nutrients and weed composition in the plantations were evaluated using the canonical correspondence analysis. Burns incidence significantly improved the organic carbon, organic matter, and Ca contents while reducing total N and Mg in both plantations. Twenty-eight weed species were distributed in 9 angiosperm families. Fire differently affected weed composition, abundance and diversity in the plantations. Burning improved soil organic carbon and organic matter contents and restricted Tephrosia bracteolata, Desmodium tortuosum, Daniellia oliveri, Senna obtusifolia and Zornia latifolia to the burned cashew plantation. The occurrence of Euphorbia heterophylla, Eriosema psoraleoides and Crotalaria retusa in the burned teak plantation was associated with a direct fire effect on soil Na and Ca contents. Burning influenced soil nutrients in the studied plantations, but weed diversity increased in the teak plantation and was reduced in the cashew plantation.

Glassbrook, DJ, Fuller, JT, Wade, JA, and Doyle, TLA. Not all physical performance tests are related to early season match running performance in professional rugby league. J Strength Cond Res 36(7): 1944-1950, 2022-This study aimed to determine which physical tests correlate with early season running performance. Sixteen professional rugby league players performed the 30-15 intermittent fitness test (IFT), 1.2-km time trial, 1 repetition maximum (RM) barbell back squat, isometric midthigh pull (IMTP), countermovement jump (CMJ), barbell squat jump (SJ), and ballistic bench press throw (BBP). Bivariate Pearson's correlations and linear regression were used to compare physical tests with peak match running intensities recorded by a portable Global Positioning System and represented by peak match velocity and acceleration, as well as peak 1-, 4-, 6-, and 8-minute instantaneous acceleration/deceleration periods of play. Significant (p0.05) negative correlations (r = -0.55 to -0.60) were observed between the IFT and relative 1-, 4-, 6-, and 8-minute peaks, and between the relative 1RM back squat and relative 1-, 4-, 6-, and 8-minute peaks. Significant positive correlations (r = 0.52-0.84) were observed between the following physical tests and match performance pairs: IFT and peak acceleration; relative 1RM back squat and peak acceleration; SJ peak power (relative and absolute) and peak acceleration; CMJ peak force (relative and absolute) and peak acceleration; CMJ peak power (relative and absolute) and peak acceleration and 1-, 4-, 6-, and 8-minute peaks; and relative BBP peak power and peak velocity and peak acceleration. The results of this study highlight that not all generic tests of physical qualities are related to peak match running performance and only those with significant correlations are likely to be able to indicate how players may perform during match-play.

Early-season crop identification is of great importance for monitoring crop growth and predicting yield for decision makers and private sectors. As one of the largest producers of winter wheat worldwide, China outputs more than 18 % of the global production of winter wheat. However, there are no distribution maps of winter wheat over a large spatial extent with high spatial resolution. In this study, we applied a phenology-based approach to distinguish winter wheat from other crops by comparing the similarity of the seasonal changes of satellite-based vegetation index over all croplands with a standard seasonal change derived from known winter wheat fields. Especially, this study examined the potential of early-season large-area mapping of winter wheat and developed accurate winter wheat maps with 30 m spatial resolution for 3 years (2016–2018) over 11 provinces, which produce more than 98 % of the winter wheat in China. A comprehensive assessment based on survey samples revealed producer's and user's accuracies higher than 89.30 % and 90.59 %, respectively. The estimated winter wheat area exhibited good correlations with the agricultural statistical area data at the municipal and county levels. In addition, the earliest identifiable time of the geographical location of winter wheat was achieved by the end of March, giving a lead time of approximately 3 months before harvest, and the optimal identifiable time of winter wheat was at the end of April with an overall accuracy of 89.88 %. These results are expected to aid in the timely monitoring of crop growth. The 30 m winter wheat maps in China are available via an open-data repository (DOI: https://doi.org/10.6084/m9.figshare.12003990, Dong et al., 2020a).

This experiment was conducted in the farmer’s field at Khajrauta, Gadhawa-4, Dang, Nepal to evaluate the effect of integrated nutrient management on growth and yield of cauliflower as well as their residual effects on soil properties. The cauliflower variety silvercup-60 was grown under eight different treatments; T1: 50% N through RDF + 50% N through FYM; T2: 50% N through RDF + 50% N through PM; T3: 50% N through RDF + 50% N through VC, T4: 50% N through RDF + 25% N through FYM + 25% N through PM; T5: 50% N through RDF + 25% N through VC + 25% N through PM; T6: 50% N through RDF + 25% N through VC + 25% N through FYM; T7: 50% N through RDF + 25% N through VC +25% N through FYM; T8: 50% N through RDF + 50% N through FYM,VC and poultry manure. The experiment was laid out in RCB design with three replications. The result revealed that the highest plant height (36.40 cm), number of leaves (15), plant spread (31.72 cm), leaf area (526.5 cm2), curd weight (207.3g) and curd yield (12.85 t/ha) were found under 50% N through RDF +50% N through VC. The root length, root diameter and root density were better under all INM treatments as compared to 100% N through RDF. INM treatments showed lesser bulk density, lesser particle density, greater infiltration rate and greater organic matter content than application of 100% N through RDF. Soil total nitrogen was increased in all INM treatments while soil available phosphorus decreases in all treatments except 100% N trough RDF and 50% N through RDF +50% N through PM. Thus, farmers are suggested to apply 50% N through VC along with 50% N through RDF to increase cauliflower yield.

Early-season crop type mapping could provide important information for crop growth monitoring and yield prediction, but the lack of ground-surveyed training samples is the main challenge for crop type identification. Although reference time series based method (RBM) has been proposed to identify crop types without the use of ground-surveyed training samples, the methods are not suitable for study regions with small field size because the reference time series are mainly generated using data set with low spatial resolution. As the combination of Landsat data and Sentinel-2 data could increase the temporal resolution of 30-m image time series, we improved the RBM by generating reference normalized difference vegetation index (NDVI)/enhanced vegetation index (EVI) time series at 30-m resolution (30-m RBM) using both Landsat and Sentinel-2 data, then tried to estimate the potential of the reference NDVI/EVI time series for crop identification at early season. As a test case, we tried to use the 30-m RBM to identify major crop types in Hengshui, China at early season of 2018, the results showed that when the time series of the entire growing season were used for classification, overall classification accuracies of the 30-m RBM were higher than 95%, which were similar to the accuracies acquired using the ground-surveyed training samples. In addition, cotton, spring maize and summer maize distribution could be accurately generated 8, 6 and 8 weeks before their harvest using the 30-m RBM; but winter wheat can only be accurately identified around the harvest time phase. Finally, NDVI outperformed EVI for crop type classification as NDVI had better separability for distinguishing crops at the green-up time phases. Comparing with the previous RBM, advantage of 30-m RBM is that the method could use the samples of the small fields to generate reference time series and process image time series with missing value for early-season crop classification; while, samples collected from multiple years should be further used so that the reference time series could contain more crop growth conditions.

Tracking concentrations of regional airborne pollen is valuable for a variety of fields including plant and animal ecology as well as human health. However, current methods for directly measuring regional pollen concentrations are labor-intensive, requiring special equipment and manual counting by professionals leading to sparse data availability in select locations. Here, we use publicly available Google Trends data to evaluate whether searches for the term “pollen” can be used to approximate local observed early-season pollen concentrations as reported by the National Allergy Bureau across 25 U.S. regions from 2012–2017, in the context of site-specific characteristics. Our findings reveal that two major factors impact the ability of internet search data to approximate observed pollen: (1) volume/availability of internet search data, which is tied to local population size and media use; and (2) signal intensity of the seasonal peak in searches. Notably, in regions and years where internet search data was abundant, we found strong correlations between local search patterns and observed pollen, thus revealing a potential source of daily pollen data across the U.S. where observational pollen data are not reliably available.

The article shows the results of a comparative assessment of grain productivity and adaptability parameters of early- ripe maize hybrids in the South-West of non-chernozem region (Bryansk region). The aim of this work is to study and evaluate the productive and adaptive potential of early- ripe maize hybrids in the agroclimatic conditions of the non-chernozem region. 22 hybrids of the early- ripe group (FAO 100-200) were taken as the object of research. The tasks of agroecological examining for the period 2016-2019. included an overall assessment of adaptive properties of studied maize genotypes in terms of environmental stability and plasticity, using the “yield” criterion. The features of the production process of maize seeds depending on changes in meteorological conditions of cultivation for the years of examining were studied, which allowed us to assess objectively the level of variation in the grain yield. We calculated the following indicators: index of environmental conditions (Ij), parameters of environmental plasticity - stability (Sd2) and plasticity (bi), stress resistance, yield span (d), ultrastability (Hom), variation coefficient (V). As a result of examining carried out over 4 years, the yield of maize grain varied from 6.02 t / ha of the LG 2195 hybrid of Limagrain Europe selection (France) to 8.69 t/ha of the Ladoga 181 MV hybrid (NGO “Kuban Seed Production”). According to the set of adaptability parameters, hybrids of domestic selection Ladozhsky 181 MV, Ladozhsky 191 MV, Krasnodar 194 AMV and foreign selection - P7954 (Pioneer, France) and Cromwell (KWS, Germany), which have stability, selection value, stress resistance and high productivity of grain in agro-landscape conditions of the Bryansk region were noted.

Soybean [Glycine max (L.) Merr.] yield losses may be attributable to early-season nutrient competition with weeds; however, research investigating macro- and micronutrient accumulation of weeds in ...

Multiple genetically distinct influenza B/Victoria lineage viruses have cocirculated in the United States recently, circulating sporadically during the 2018-19 season and more frequently early during the 2019-20 season (1). The beginning of the 2019-20 influenza season in Louisiana was unusually early and intense, with infections primarily caused by influenza B/Victoria lineage viruses. One large pediatric health care facility in New Orleans (facility A) reported 1,268 laboratory-confirmed influenza B virus infections, including 23 hospitalizations from July 31 to November 21, 2019, a time when influenza activity is typically low. During this period, Louisiana also reported one pediatric death associated with influenza B virus infection. An investigation of the influenza B virus infections in Louisiana, including medical and vaccine record abstraction on 198 patients, primarily from facility A, with sporadic cases from other facilities in the state, found that none of the patients had received 2019-20 seasonal influenza vaccine, in part because influenza activity began before influenza vaccination typically occurs. Among 83 influenza B viruses sequenced from 198 patients in Louisiana, 81 (98%) belonged to the recently emerged B/Victoria V1A.3 genetic subclade. Nationally, to date, B/Victoria viruses are the most commonly reported influenza viruses among persons aged

Background: Influenza virus infections are common and lead to substantial morbidity and mortality worldwide. We characterized the first eight influenza epidemics since the 2009 influenza pandemic by describing the distribution of viruses and epidemics temporally and geographically across the WHO European Region. Methods: We retrospectively analyzed laboratory-confirmed influenza detections in ambulatory patients from sentinel sites. Data were aggregated by reporting entity and season (weeks 40-20) for 2010-2011 to 2017-2018. We explored geographical spread using correlation coefficients. Results: There was variation in the regional influenza epidemics during the study period. Influenza A virus subtypes alternated in dominance, except for 2013-2014 during which both cocirculated, and only one season (2017-2018) was B virus dominant. The median start week for epidemics in the Region was week 50, the time to the peak ranged between four and 13 weeks, and the duration of the epidemic ranged between 19 and 25 weeks. There was evidence of a west-to-east spread across the Region during epidemics in 2010-2011 (r = .365; P = .019), 2012-2013 (r = .484; P = .001), 2014-2015 (r = .423; P = .006), and 2017-2018 (r = .566; P < .001) seasons. Variation in virus distribution and timing existed within reporting entities across seasons and across reporting entities for a given season. Conclusions: Aggregated influenza detection data from sentinel surveillance sites by season between 2010 and 2018 have been presented for the European Region for the first time. Substantial diversity exists between influenza epidemics. These data can inform prevention and control efforts at national, sub-national, and international levels. Aggregated, regional surveillance data from early affected reporting entities may provide an early warning function and be helpful for early season forecasting efforts. WHO Regional Office for Europe was supported for work on influenza by a cooperative agreement from the United States Centers for Disease Control and Prevention (NU511P000876); the funder had no role in the analysis or interpretation of the data. Sí

Curly top is an important widespread disease in semiarid regions that can be caused by several Curtovirus and Becurtovirus species. The strains of beet curly top virus (BCTV) have been some of the most widely reported to be associated with curly top. The viruses causing curly top are phloem limited and transmitted by the beet leafhopper (BLH), Circulifer tenellus Baker (Hemiptera: Cicadellidae). The BLH can also transmit other important pathogens such as phytoplasmas. Both the virus and insect vector have a broad host range of crops and weeds, including the winter annual weed London rocket (Sisymbrium irio L.). Prior prediction of disease would allow growers a window of opportunity to make informed management choices. A prediction model of BLH abundance was developed for southern New Mexico based on fall precipitation, which corresponds with London rocket emergence, and BLH sticky trap catch data for 2001 to 2018. Regression analyses showed positive associations between BLH numbers and October + November rainfall (P < 0.001) for two areas within southern New Mexico. A third area, where good weed management was used, had lower BLH numbers, and the relationship with precipitation was not significant (P = 0.190). Cumulative-season BLH abundance was correlated with BLH abundance in late April (r = 0.43) and late May (r = 0.56), indicating that early season knowledge of BLH abundance is useful for planning later season management. Although models based on October + November precipitation are good predictors of BLH abundance through June, they may not predict year-long BLH abundance because other environmental and biological factors contribute to subsequent BLH success and movement.

Rainfall variability in Northeast Thailand during 2000-2015 was examined with objectives to determine any changes in rainfall pattern with time, and to determine its effects on duration of rice growing period and grain yield using a simulation model. Variation in mean annual rainfall over 16 years in 93 locations in the region ranged from over 1,600 to less than 1,200 mm, and the locations were grouped into 4 based on the annual rainfall. The change in annual rainfall, and early, mid and late season rainfall was analysed for the rainfall groups. There was a significant reduction in the amount of early season rainfall during the 16-year period in all groups. However, there was no significant change for annual, and mid and late season rainfall. Simulation study showed that the start of rice growing period (SGP) was delayed with reduced early rainfall during the 16 year period and the end of rice growing period (EGP) was also delayed while there was no significant change for the length of rice growing period (LGP). Simulation results showed that grain yield of KDML105, leading variety in Thailand, tended to increase during the 16 year period, as delayed planting time was optimum for achieving maximum yield in all rainfall groups. With general delay in rainfall season, occurrence of late season drought was predicted to be reduced and this helped to increase simulated grain yield. However, adaptation to changing rainfall pattern needs to be planned in advance to maximize its effect.

During the 2014 and 2015 seasons, peanut root anatomy studies were conducted under well-watered and under drought conditions using three peanut genotypes which are known to differ in their physiological responses to early- and mid-season drought (ICGV 98,305, ICGV 98,324 and Tifton-8). Cross sections of the newly formed roots revealed that the average vessel diameter and total vessel area in the first-order roots were significantly reduced under drought in ICGV 98,305 and ICGV 98,324, yet not in Tifton-8, which had the smallest vessel diameters and total area in both well-watered and drought treatments. The xylem vessel structure in newly formed roots of ICGV 98,324 was very responsive to changes in soil moisture content. This adaptive capacity of ICGV 98,324 to change xylem structure as soil moisture conditions change may provide plant breeders an important trait which will lead to better water-use efficiencies in both moist and drought conditions.

The timing of abiotic stress elicitors on wood formation largely affects xylem traits that determine xylem efficiency and vulnerability. Nonetheless, seasonal variability of elevated CO2 (eCO2) effects on tree functioning under drought remains largely unknown. To address this knowledge gap, 1-year-old aspen (Populus tremula L.) trees were grown under ambient (±445 ppm) and elevated (±700 ppm) CO2 and exposed to an early (spring/summer 2019) or late (summer/autumn 2018) season drought event. Stomatal conductance and stem shrinkage were monitored in vivo as xylem water potential decreased. Additional trees were harvested for characterization of wood anatomical traits and to determine vulnerability and desorption curves via bench dehydration. The abundance of narrow vessels decreased under eCO2 only during the early season. At this time, xylem vulnerability to embolism formation and hydraulic capacitance during severe drought increased under eCO2. Contrastingly, stomatal closure was delayed during the late season, while hydraulic vulnerability and capacitance remained unaffected under eCO2. Independently of the CO2 treatment, elastic, and inelastic water pools depleted simultaneously after 50% of complete stomatal closure. Our results suggest that the effect of eCO2 on drought physiology and wood traits are small and variable during the growing season and question a sequential capacitive water release from elastic and inelastic pools as drought proceeds.