Higher Soil Moisture Levels Research Articles

In-Vivo and In-Vitro Investigation of Germination Rate of Buried Sclerotia, and Variability in Carpogenic Germination Among Sclerotinia sclerotiorum Isolates

The sclerotia of Sclerotinia sclerotiorum serve as a primary inoculum source for initiating infections. This study aimed to evaluate the effects of environmental factors on sclerotial germination under field conditions by establishing sclerotia depots to monitor apothecia appearance over four consecutive years. Additionally, the effects of soil moisture content (25%, 50%, 75%, and 95%), air temperature (10 °C/10 °C, 14 °C/10 °C, and 18 °C/10 °C), and light conditions (white and UV light) on sclerotial germination and apothecial formation were investigated under controlled conditions with a 17 h day/7 h night regime. Furthermore, variability in carpogenic germination among S. sclerotiorum isolates was examined. From 2021 to 2024, significant differences were observed in both the sclerotia germination rate and timing of germination within the season. High soil moisture, particularly prolonged wetness, and soil temperatures between 10 and 14 °C were key factors for apothecial formation under field conditions. Under controlled conditions, higher soil moisture levels (75% and 95%) accelerated sclerotial germination, with sclerotia incubated at 14 °C/10 °C germinating earlier after 38 days than those at 10 °C/10 °C or 18 °C/10 °C. Additionally, the type of light significantly affected apothecial formation, which was observed only in treatments exposed to a combination of white and UV light. Furthermore, significant variations were also found in the duration until sclerotia of different S. sclerotiorum isolates produced the first stipe and the first apothecium, indicating that the genetic characteristics of each isolate affect carpogenic germination.

Landslide Monitoring and Warning System Based on Wireless Sensor Network

Landslides are common in Indonesia, often caused by factors like heavy rainfall and high soil moisture levels. The Batubrak mini hydro power plant intake area in Lampung province of Indonesia has experienced landslides, prompting the need for an early warning system. This study presents the development of a cost-effective and efficient real-time landslide monitoring and warning system. The system incorporates sensors to measure accelerometer and vibration parameters, enabling real-time data display through a wireless sensor network and SCADA software. Early warnings are issued when triggers are activated. Three sensor nodes were deployed in the intake area for testing, demonstrating their ability to detect, collect, process, and transmit accelerometer and vibration data to the gateway node.

Enhancing stand establishment and yield formation of cotton with multiple drip irrigation during emergence in saline fields of Southern Xinjiang

ContextFlooding irrigation prior to sowing during the winter or spring seasons has been widely employed to mitigate soil salinity and generate adequate soil moisture for cotton seedling emergence in saline fields. In an effort to conserve water, a technique known as "dry sowing and wet emergence" has been utilized in arid regions of Northern Xinjiang, China, where the soil is not irrigated before sowing, and a single drip irrigation is applied to facilitate cotton emergence immediately after sowing. However, the successful implementation of this technique has not been achieved due to high soil salinity in Southern Xinjiang, China. In light of these challenges, we hypothesize that modifying the traditional "dry sowing and wet emergence" technique from a one-time irrigation to multiple irrigations during the seedling stage could improve the microenvironment of the root-zone soil, thereby mitigating salinity stress and promoting seedling emergence and stand establishment. MethodWe conducted a two-year field experiment employing a randomized block experimental design to assess the impacts of various irrigation methods during the seedling stage on soil microenvironment, seedling emergence, stand establishment, plant physiological response to salinity stress, and yield formation of cotton. The experiment encompassed three treatments, including pre-sowing flood irrigation (flood irrigation), the traditional single drip irrigation for dry sowing and wet emergence (single drip irrigation), and the modified dry sowing and wet emergence with three rounds of drip irrigation (multiple drip irrigation). ResultsMultiple drip irrigation resulted in consistently higher soil temperatures during the period of 5–30 days after sowing (DAS), lower soil salinity from 15 to 30 DAS, and also maintained relatively higher soil moisture levels than single drip irrigation between 20 and 30 DAS. In contrast to flood irrigation, multiple drip irrigation led to an increase in soil temperature from 5 to 30 DAS and a reduction in soil salinity levels during the period of 15–30 DAS. Conversely, single drip irrigation led to a decrease in soil salinity during 5–10 DAS, but a substantial increase in soil salinity and decrease in soil moisture from 20 to 30 DAS. Multiple drip irrigations used only 40 % of the irrigation amount needed for flood irrigation but achieved comparable seedling emergence and stand establishment rates. Compared to single drip irrigation, multiple drip irrigations decreased Na+ and malondialdehyde (MDA) content in the leaves by 21.7 % and 15.6 %, and increased photosynthetic (Pn) rate and stand establishment rate by 22.0 % and 36.3 %, respectively. Moreover, multiple drip irrigation produced seedcotton yields equal to those of flood irrigation, with an increase of 24.2 % compared to single drip irrigation. ConclusionsThe results demonstrate that multiple drip irrigations enhance seedcotton yield through improving stand establishment compared to single drip irrigation. This improvement is attributed to reduced salinity stress, as evidenced by the decreased soil salinity, Na+ content, and MDA content in the leaves when using multiple drip irrigation during seedling emergence. Therefore, multiple drip irrigation is a promising technique for promoting cotton seedling emergence and stand establishment in saline fields of Southern Xinjiang and other cotton-growing areas with similar ecological conditions.

Complex Drivers of Riparian Soil Oxygen Variability Revealed Using Self‐Organizing Maps

AbstractOxygen (O2) regulates soil reduction‐oxidation processes and therefore modulates biogeochemical cycles. The difficulties associated with accurately characterizing soil O2 variability have prompted the use of soil moisture as a proxy for O2, as O2 diffusion into soil water is much slower than in soil air. The use of soil moisture alone as a proxy measurement for O2 could result in inaccurate O2 estimations. For example, O2 may remain high during cool months when soil respiration rates are low. We analyzed high‐frequency sensor data (e.g., soil moisture, CO2, gas‐phase soil pore O2) with a machine learning technique, the Self‐Organizing Map, to pinpoint suites of soil conditions associated with contrasting O2 regimes. At two riparian sites in northern Vermont, we found that O2 levels varied seasonally, and with soil moisture. For example, 47% of low O2 levels were associated with wet and cool soil conditions, whereas 32% were associated with dry and warm conditions. Contrastingly, the majority (62%) of high O2 conditions occurred under dry and warm conditions. High soil moisture levels did not always lead to low O2, as 38% of high O2 values occurred under wet and cool conditions. Our results highlight challenges with predicting soil O2 solely based on water content, as variable combinations of soil and hydrologic conditions can complicate the relationship between water content and O2. This indicates that process‐based ecosystem and denitrification models that rely solely on soil moisture to estimate O2 may need to incorporate other site and climate‐specific drivers to accurately predict soil O2.

Leaf, Root, and Crown Tissue Physiology of Annual Bluegrass after Cold Acclimation at Varying Soil Moisture Levels and Ice Encasement

Annual bluegrass (Poa annua) is a turfgrass species prone to winterkill-induced damage such as from ice encasement stress. This research aimed to determine whether different levels of soil volumetric water content (SWC) influence cold acclimation and recovery from ice encasement. Annual bluegrass was exposed to 8%, 12%, and 20% SWC treatments during cold acclimation in growth chambers. After cold acclimation, plants were subjected to ice encasement by misting at –3 °C until a 2.5-cm ice layer was formed. On 0 (no ice encasement exposure), 40, and 80 days of treatment, plants were analyzed for recovery (percent green canopy cover over time), and leaf, crown, and root tissues were harvested for lipid peroxidation and total nonstructural carbohydrates (TNC) including storage carbohydrates and water-soluble carbohydrates (WSC). Low SWC during cold acclimation enhanced recovery from cold temperatures and ice encasement. Root carbohydrates were influenced by SWC regimes during cold acclimation since day 0 plant roots exposed to the 8% SWC treatment had 143.9% higher TNC and 137.6% higher WSC compared with day 0 plants exposed to 12% and 20% SWC. Root levels of carbohydrates and lipid peroxidation were least influenced by cold and ice encasement among the organs evaluated. Prolonged freezing conditions and ice encasement reduced leaf and crown tissue carbohydrates and increased lipid peroxidation compared with day 0 plants not exposed to freezing temperatures and ice encasement. After 40 days of ice encasement, plants exposed to the 8% SWC treatment recovered faster than plants cold acclimated at higher soil moisture levels. Average percent canopy cover after 36 days of recovery in the greenhouse was 71.9% higher for 8% SWC treated plants than in 12% and 20% SWC treated plants. Turfgrass managers may benefit from annual bluegrass putting green management strategies to reduce fall soil moisture. Given that soil moisture did not significantly influence carbohydrate or lipid peroxidation results, except for in roots, additional research is needed to understand the mechanism associated with these findings.

Weedy rice (Oryza sativa L.) seed dormancy features and potential usage for management

Weedy rice infestation has been expanding with the increasing proportion of direct-seeded rice (DSR) systems in China. Limited herbicides are effective against weedy rice due to its high similarity with cultivated rice. Hence, it is important to figure out some non-chemical management strategies for weedy rice. One of the methods is to reduce the size of seed bank by inducing weedy rice germination. Petri dish germination experiment found that weedy rice with different seed morphologies showed an absence of primary dormancy. The field phenology study showed that weedy rice differed from cultivated rice in many features including plant height, number of tillers, fresh weight, and days required for earing when sown from 1 June to 1 October, and in the case of late sowings (between 1 August and 1 October), the plants produced no heads despite a high germination rate. Simulated field experiment to induce germination found that when soil moisture content was 22.2% and day/night temperatures were 20/15 °C, respectively, germination was more than 60% up to 10 days after sowing; at higher levels of soil moisture and temperature, germination was faster and germination percentage was higher. These results indicated that weedy rice seed bank size could be reduced by inducing the seed germination with post harvest irrigation as the seedlings would be killed overwinter in lower-middle reaches of the Yangtze River in China.

Soil Moisture and Temperature Effects on Granule Dissolution and Urease Activity of Urea with and without Inhibitors—An Incubation Study

Urea granule dissolution in soil and soil urease activity are essential parameters for the accurate prediction of nitrogen dynamics after urea application, but both are scarcely studied. The response of urease activity to temperature is unclear under the addition of urease or nitrification inhibitors. In this study, we conducted laboratory incubation trials using glass jars with 100 g soil to quantify urea granule dissolution. Urease activity after urease and nitrification inhibitor addition were investigated in plastic bottles (5 g soil) under different temperatures. Inhibitor N-(2-nitrophenyl) phosphoric triamide (2-NPT), and a mixture of dicyandiamide and 1 H-1,2,4-triazol (DCD/HZ) were tested as urease and nitrification inhibitors separately and in combination. The dynamics of urease activity was fitted with Michaelis–Menten kinetics combined with the Van’t Hoff equation. At low soil moisture contents close to air-dry conditions (4–8% w/w water content), soil moisture was the dominant factor, but at higher soil moisture contents (28% and 48% w/w), temperature controlled the dissolution process. Dissolution could take several days or even longer at very dry soil conditions, while it was completed between a few hours and 24 h at high soil moisture levels. Urea with urease inhibitor formulation dissolved significantly slower at a moisture level of 28% (w/w). In the studied soil, urease activity varied between 2.9 and 54.4 mg NH4+-N kg−1 h−1. Across all urea concentrations, the addition of urease inhibitor 2-NPT significantly reduced urease activity. The relationship between urease activity and urea addition rate could be accurately described with Michaelis–Menten kinetics, and urease inhibitor addition reduced the temperature sensitivity of urease activity by 7%, while the nitrification inhibitor increased it by 4%. Parameter estimates and process characterization for urea granule dissolution and urea hydrolysis in this study are meaningful for and helpful in agricultural practice and the model simulation of soil nitrogen dynamics.

Ecoengineering techniques to investigate soil moisture dynamics and localized dry spots distribution on golf courses

The study is aimed at the effect of wetting agents on golf course fairways from ‘PLS’ creeping bentgrass (Agrostis stolonifera). The study was conducted to determine the occurrence of localized dry spots (LDS) on the turfgrass, dynamic of soil moisture change and to find the most effective wetting agent. This study was conducted in climatic conditions of Central region of Russia, in golf club Skolkovo (Moscow region). The research is aimed at studying the demand on wetting agents in golf industry, that will help to estimate of their effectiveness and practicability. There were used methods: Advanced method of the definition of dry spots on turf; Advanced method of the definition of sand soil moisture. According to three data collections of visual turf conditions and soil moisture during growing season the worst result has shown B2 plot (product Liven, rate 20 l/ha). It had the most percent of damaged turf by localized dry spots. Later its conditions became better than B1 (Revolution, rate 20 l/ha), D9 and A1 (Liven, 20 l/ha), C4 (Dispatch, 5 l/ha) plots. G9 (untreated control) and C2 (Revolution, 10 l/ha) plots kept high level of soil moisture. Low level of soil moisture had C4 (Dispatch, 5 l/ha) and F8 (Revolution, 10 l/ha) plots. Mild and snowless winter has been contributed to slight deterioration of visual turf conditions. The highest percent of damages by dry spots had B2 plot (Liven, 20 l/ha), but the product showed a positive result. The most effective wetting agent turned out to be Revolution with application rate 10 l/ha.

Vitality of Rubus arcticus L. in medium and southern taiga

Vitality strategies for 11 coenopopulations of arctic bramble (Rubus arcticus L.) were defined in conditions of medium and southern taiga on the edge of the species range. In studied conditions optimal habitats for R. arcticus growth, while maintaining high vitality index, are open meadows and coniferous-small-leaved forests with high level of soil moisture: Epilobium-gramineous wet meadow formed on a runway and surrounded by spruce-birch forest with pine and aspen-birch herbaceous forest with spruce. The study showed that the pedicel length, width of the central lobe of the 3rd leaf from the metamere base, and number of living leaves are the most sensitive features which react to the state of environment. R. arcticus shows 3 ontogenetic tactics near the border of its range: divergent, convergent and stabilizing tactic. Most of morphological features studied prove divergent character of ontogenetic tactic, which determines the increase in features’ variability in close-to-stress conditions. Near its southern border arctic bramble uses defensive strategies for survival allowing its successful vegetative reproduction. According to the results of the study and species’ ecological peculiarities and in order to achieve effective monitoring and prognosis of the species’ state, it is important that we apply complex estimation of variability of physiological-biological and morphological parameters of R. arcticus.

Grapes drip irrigation regimes and their efciency

The influence of drip irrigation regimes on the yield of Rkatsiteli grapes, the efciency of irrigation water use, the formation of costs of natural, fnancial and energy resources in the South of Ukraine has been studied. The results of the study confrmed that the yield of grapes is not proportional to the consumption of irrigation water, but depends on the level of moisture in the local soil volume in the most important phases of development. It was found out that plants unimpeded water consumption during the entire growing season requires maximum (within 1134 m3/ha)irrigation water consumption and resources to ensure a high level of irrigation soil moisture, while plant yields increased by only 45–47 % compared to non-irrigated control. The regime of soil moisture during the frst half of the growing season did not have a signifcant effect on the number of fruit shoots that are indicators of their fertility. The most signifcant influence of moisture availability thresholds of the active layer of soil was manifested in the process of berry harvest formation. The total effect of the interaction of factors such as high soil moisture, more fruit shoots, their high fruiting and high average weight of the bunch provided the highest yield of grapes, which amounted to 11.3– 11.7 t/ha, or 47.4 % more than with a control area. In the conditions of the economical irrigation regime, at the level of 100–70 % of HB during the whole period of vegetation of plants, the average yield of berries was 10.7 t/ha, which exceeds by 37.1 % similar indicators of the control area. A detailed analysis of the results of the experiment shows that the irrigation regime differently affects the effciency of the main resource-irrigation water, the cost of which for the formation of 1 ton of berries with unimpeded moisture (100–80 % HB), during the growing season, is 476 m3/t. The most economically used irrigation water in the economical irrigation mode at the level of 100–70 % HB reduces the specifc water consumption to 266 m3/t. In the area of this variant, the yield of berries was 10.5 t/ha, ie decreased by 8.6 %, while the specifc water consumption decreased by 38.3 %, compared with similar indicators of the area with unimpeded inflow of moisture. Key words: grapes, Rkatsiteli, drip irrigation, berry yield, irrigation regime, moisture defciency, irrigation water.

Near‐surface water fluxes and their controls in a sloping heterogeneously layered volcanic soil beneath a supra‐wet tropical montane cloud forest (NW Costa Rica)

AbstractTropical montane cloud forests (TMCF) receive additional (‘occult’) inputs of water from fog and wind‐driven rain. Together with the concomitant reduction in evaporative losses, this typically leads to high soil moisture levels (often approaching saturation) that are likely to promote rapid subsurface flow via macropores. Although TMCF make up an estimated 6.6% of all remaining montane tropical forest and occur mostly in steep headwater areas that are protected in the expectation of reduced downstream flooding, TMCF hillslope hydrological functioning has rarely been studied. To better understand the hydrological response of a supra‐wet TMCF (net precipitation up to 6535 mm y−1) on heterogeneously layered volcanic ash soils (Andosols), we examined temporal and spatial soil moisture dynamics and their contribution to shallow subsurface runoff and stormflow for a year (1 July 2003–30 June 2004) in a small headwater catchment on the Atlantic (windward) slope near Monteverde, NW Costa Rica. Particular attention was paid to the partitioning of water fluxes into lateral subsurface flow and vertical percolation. The presence of a gravelly layer (C‐horizon) at ~25 cm depth of very high hydraulic conductivity (geometric mean: 502 mm h−1) intercalated between two layers of much lower conductivity (7.5 and 15.7 mm h−1 above and below, respectively), controlled both surface infiltration and delayed vertical water movement deeper into the soil profile. Soil water fluxes during rainfall were dominated by rapid lateral flow in the gravelly layer, particularly at high soil moisture levels. In turn, this lateral subsurface flow controlled the magnitude and timing of stormflow from the catchment. Stormflow amount increased rapidly once topsoil moisture content exceeded a threshold value of ~0.58 cm3 cm−3. Responses were not affected appreciably by rainfall intensity because soil hydraulic conductivities across the profile largely exceeded prevailing rainfall intensities.

Restoration objectives create surface carbon cycle trade‐offs in coastal habitats

Coastal habitats are important and imperiled. To mitigate climate change impacts, carbon (C) sequestration has joined established restoration objectives, including habitat diversity, public access, and native vegetation. Changing topography, maintaining trails, and removing invasive plants may influence coastal C production and retention in different ways depending on how each activity influences the stabilization of organic matter in surface sediments. We quantified variation in litter and surface soil dynamics within and between coastal parks that varied in age from prerestoration to nearly 20 years old in Manatee County, Florida. Older parks had deeper soil organic horizons with higher levels of soil moisture and respiration, indicating that restoration sequesters soil C despite increases in microbial efficiency. However, variation within parks indicated that detrital C dynamics change depending on local management objectives. Relative to unmanaged locations, restored wetlands, including mangroves, salt marshes, and freshwater ponds, had soil organic horizons nearly 20 cm deeper, with high litter stabilization rates despite less litter mass and shorter projected soil sample C mineralization. In contrast, public access features like trails and kayak launches were associated with increased surface CO2 efflux and marginally reduced soil organic horizon depth. Removing invasives had little impact on detrital carbon pools and fluxes. Incorporating detrital C dynamics improved a multivariate model for variation in C pool sizes across sites. Overall, our results suggest that management objectives influence the C production and retention capacity of restored coastal habitats with restored uplands and public access points storing less C than relatively inaccessible wetlands.

Application of a Structured Water Generator for Crop Irrigation: Structured Water, Drought Tolerance, and Alteration of Plant Defense Mechanisms to Abiotic Stressors

A greenhouse study was conducted to enhance drought tolerance in velvet bean plants (Mucuns pruriens) using structured irrigation water. The study combined magnetized seed treatments with watering plants with structured water treatments. A closed-loop, water system was custom-built to generate the structured irrigation water. The custom water generator utilized two energy fields (magnetic and ultra-violet radiation) to generate the structured water. The objectives of the study were to: 1) determine the effects of a magnetized seed treatment on velvet bean plants, 2) determine the effects of magnetized water treatments on velvet bean plants, 3) determine the effects of water treated with a hydroxylated water generator on velvet bean plants, 4) determine the effects of three soil moisture levels on velvet bean plants. The plant responses included: 1) foliage gas exchange rates 2) soil moisture, 3) cumulative water volume for each plant, 4) plant water use efficiency, and 5) oven-dry foliage biomass. The foliage gas exchange responses showed that the magnetized seed and structured water treatments disassociated the relationships between photosynthesis, stomatal conductance, transpiration and internal carbon dioxide rates from soil moisture and leaf temperature. The optimal, combined magnetized seed and structured water treatments increased water savings from 32 to 52% over the unstructured water treatments, under the low soil moisture level. The maximum plant water use efficiency was 2.81, which occurred with a structured water treatment under the high soil moisture level. There was a 6.8 % decrease in oven-dry foliage biomass for the optimal magnetized seed and structured water treatment when compared with the control treatment. However, the tradeoff in reduced biomass was compensated with a 41% savings in water usage, 25% reduction in Pn, 34% reduction in stomatal conductance, and a 7% reduction in internal carbon dioxide under the low soil moisture level for the optimal magnetized seed and structured water treatment. The combined seed and water treatments fundamentally alter drought adaptation plant responses to water stress conditions which resulted in a significant reduction in irrigation water usage. The interactions between magnetized seed treatments and structured water treatments on plant stress physiology need to be further investigated to confirm these water conservation findings. Structured water generators should be evaluated for physicochemical water properties and stability of water in soil and plant matrices.

Understanding the relationship between rainfall and flood probabilities through combined intensity-duration-frequency analysis

The aim of this paper is to explore how rainfall mechanisms and catchment characteristics shape the relationship between rainfall and flood probabilities. We propose a new approach of comparing intensity-duration-frequency statistics of maximum annual rainfall with those of maximum annual streamflow in order to infer the catchment behavior for runoff extremes. We calibrate parsimonious intensity-duration-frequency scaling models to data from 314 rain gauges and 428 stream gauges in Austria, and analyze the spatial patterns of the resulting distributions and model parameters. Results indicate that rainfall extremes tend to be more variable in the dry lowland catchments dominated by convective rainfall than in the mountainous catchments where annual rainfall is higher and rainfall mechanisms are mainly orographic. Flood frequency curves are always steeper than the corresponding rainfall frequency curves with the exception of glaciated catchments. Based on the proposed approach of combined intensity-duration-frequency statistics we analyze elasticities as the percent change of flood discharge for a 1% change in extreme rainfall through comparing rainfall and flood quantiles. In wet catchments, the elasticities tend to unity, i.e. rainfall and flood frequency curves have similar steepness, due to persistently high soil moisture levels. In dry catchments, elasticities are much higher, implying steeper frequency curves of floods than those of rainfall, which is interpreted in terms of more skewed distributions of event runoff coefficients. While regional differences in the elasticities can be attributed to both dominating regional rainfall mechanisms and regional catchment characteristics, our results suggest that catchment characteristics are the dominating controls. With increasing return period, elasticities tend towards unity, which is consistent with various runoff generation concepts. Our findings may be useful for process-based flood frequency extrapolation and climate impact studies, and further studies are encouraged to explore the tail behavior of elasticities.

Exploring the Functional Strategies Adopted by Coastal Plants Along an Ecological Gradient Using Morpho-functional Traits

Coastal dunes are characterised by strong interactions between biotic and abiotic factors along a short gradient from the shoreline to the inland region. We carried out an ecological analysis of the vegetation in a protected area of the Italian coast to evaluate the relationships among species abundance, the occurrence of morphoanatomical traits related to leaves, stems, and roots, and soil variables. Three transects were established perpendicular to the shoreline, with 27 plots distributed in the frontal dunes, backdunes, and temporarily wet dune slacks. An analysis based on community-weighted mean values showed that the pioneer communities of the frontal dunes were dominated by ruderals that are well adapted to the harsh ecological conditions of these environments, showing succulent leaves, high limb thickness values, and low values for leaf dry matter content (LDMC). The backdune vegetation was a mosaic of annual herbaceous and perennial shrub communities showing both ruderal and stress-tolerant strategies (clonality, sclerified leaves, high LDMC values, root phenolics) consistent with less extreme ecological conditions. The dune slack areas were dominated by plants showing adaptations to both arid and flooded environments, such as C4 photosynthesis, amphistomatic leaves, and abundant aerenchyma in the roots. The invasive status, C4 photosynthesis, leaf trichomes, and aerenchyma in the roots were significantly correlated with soil humidity, organic matter content, and pH. These results demonstrate the usefulness of anatomical traits (including root system traits) in understanding the functional strategies adopted by plants. Invasive species tended to occupy plots with high levels of soil moisture, suggesting an avoidance strategy for the harsh environmental conditions of coastal sand dunes. Finally, we suggest including information regarding root systems into coastal monitoring programs because they are directly linked to soil parameters useful in coastal dune management and protection.

Understanding the Opportunities to Mitigate Carryover of Imidazolinone Herbicides in Lowland Rice

(1) Background: The Clearfield™ system (CL) is currently the primary tool for selective weedy-rice management in irrigated rice. However, herbicide persistence in the soil may cause damage to successive crops. Thus, it is necessary to understand agricultural practices that can favor the dissipation of these herbicides. The objective of this study was to analyze the factors that affect the persistence of imidazolinones and to use this information to provide management strategies to mitigate carryover in lowland rice. (2) Methods: A literature review was performed, and the publications were selected using the soil half-life parameter. The data were summarized according to the biotic conditions, soil parameters, and environmental variables. (3) Results: Imidazolinone dissipation in soil occurs primarily through biodegradation. The herbicide biodegradation rate depends on environmental conditions such as temperature and bioavailability of the herbicide in the soil. Herbicide bioavailability is affected by soil conditions, with higher bioavailability in soil with higher pH, less clayey texture, moderate organic matter content, and higher soil moisture levels. Therefore, environmental conditions that favor biological activity, especially high temperatures, reduce the herbicide half-life in the soil. Strategies to mitigate carryover should focus on improving herbicide availability and enhancing biological activity in the soil, especially in the rice off-season, when low temperatures limit herbicide biodegradation. Cover and rotational crops, such as ryegrass and soybean, are recommended, with the potential to mitigate soil residues. (4) Conclusions: The establishment of crops other than rice would automatically enhance degradation rates as soil amendment practices such as pH correction and drainage practices would favor soil availability and biological activity.

Wide-Area Near-Real-Time Monitoring of Tropical Forest Degradation and Deforestation Using Sentinel-1

The use of Sentinel-1 (S1) radar for wide-area, near-real-time (NRT) tropical-forest-change monitoring is discussed, with particular attention to forest degradation and deforestation. Since forest change can relate to processes ranging from high-impact, large-scale conversion to low-impact, selective logging, and can occur in sites having variable topographic and environmental properties such as mountain slopes and wetlands, a single approach is insufficient. The system introduced here combines time-series analysis of small objects identified in S1 data, i.e., segments containing linear features and apparent small-scale disturbances. A physical model is introduced for quantifying the size of small (upper-) canopy gaps. Deforestation detection was evaluated for several forest landscapes in the Amazon and Borneo. Using the default system settings, the false alarm rate (FAR) is very low (less than 1%), and the missed detection rate (MDR) varies between 1.9% ± 1.1% and 18.6% ± 1.0% (90% confidence level). For peatland landscapes, short radar detection delays up to several weeks due to high levels of soil moisture may occur, while, in comparison, for optical systems, detection delays up to 10 months were found due to cloud cover. In peat swamp forests, narrow linear canopy gaps (road and canal systems) could be detected with an overall accuracy of 85.5%, including many gaps barely visible on hi-res SPOT-6/7 images, which were used for validation. Compared to optical data, subtle degradation signals are easier to detect and are not quickly lost over time due to fast re-vegetation. Although it is possible to estimate an effective forest-cover loss, for example, due to selective logging, and results are spatiotemporally consistent with Sentinel-2 and TerraSAR-X reference data, quantitative validation without extensive field data and/or large hi-res radar datasets, such as TerraSAR-X, remains a challenge.

Emissões de CO2 e sua relação com atributos físicos de um latossolo fertirrigado com efluente de esgoto tratado e dois níveis de palha

O Efluente de Tratamento de Esgoto (ETE) é um resíduo urbano, que por sua composição química pode ser aproveitado como fonte de macronutrientes, reduzindo o uso de fertilizantes químicos e ter um destino ambientalmente mais adequado. Neste trabalho foi investigado o efeito da aplicação de dois níveis de palha de Brachiaria fertirrigados, com três frações de efluente de esgoto tratado (FETE), na emissão de CO2 (ECO2) e suas relações com os atributos físico-químicos do solo: temperatura, umidade, porosidade total do solo, pH e porosidade livre de água. O experimento foi conduzido ao longo de 23 dias de novembro de 2013, em área de 160 m2 de Latossolo Vermelho eutroférrico, desprovida de vegetação e sem preparo do solo. O delineamento utilizado foi de blocos ao acaso, em esquema fatorial 2 x 3, sendo os tratamentos constituídos da combinação de dois níveis de palha de Brachiaria brizantha (SPA: sem palha e CPA: com palha, 10 Mg ha-1) e 3 frações de irrigação (F1: 11% de ETE, F2: 60% de ETE e F3:100% de ETE). Os resultados evidenciaram que a presença da palha sobre o solo favoreceu as maiores emissões de CO2 e lâminas menores de ETE (F1 e F2) amenizaram o impacto ambiental de ECO2. A presença de palha sobre o solo resultou em manutenção de maiores teores de umidade no solo, o que pode beneficiar o ciclo de culturas diversas. A presença de palha neste curto período de avaliação contribuiu pouco para aumentar a degradação da palha utilizada. As frações intermediárias de ETE conciliam a condição de menores ECO2 combinado com atributos físico-químicos de solo mais apropriados em manter matéria orgânica e umidade no solo.

Exploring seedling-based aspen (Populus tremuloides) restoration near range limits in the Intermountain West, USA

With the effects of climate change expected to intensify over the coming century, land managers will require more proactive and novel approaches to conserve and restore threatened ecosystems. In the US Intermountain West, quaking aspen (Populus tremuloides Michx.) is a foundation species of considerable conservation interest. However, traditional silvicultural practices in the region focus exclusively on its vegetative regeneration potential, limiting restoration efforts to locations where aspen is already established, and precluding approaches such as afforestation and assisted migration. Planting nursery-grown aspen seedlings could overcome these limitations. This approach has become common for forest land reclamation and afforestation projects in the boreal forests of western North America, but has received little attention in the US Intermountain West to date. In this study we explored the potential for seedling-based aspen restoration in an Intermountain West landscape. We planted 7,200 nursery-grown aspen seedlings across 15 unirrigated plots at three high elevation (~2,800 m) sites in southwestern Utah, USA and monitored their growth and survival rates for two growing seasons. Overall seedling survival was only 10% by the end of the study, with 49% of mortality due to apparent drought stress, 38% due to small mammal herbivory, and 3% due to unknown causes. 79% of the surviving seedlings were located in just two plots, where higher levels of soil moisture were present during the driest summer months. A subsequent test of wood mulch to retain moisture in one of the plots increased seedling survival to 62%, compared to 0% in a non-mulched treatment. Together, these findings indicate that seedling-based aspen restoration in these habitats was limited primarily by site conditions. For this approach to become operational, additional study on seedling quality, site selection and site preparation will be necessary.

Effects of Plant Growth Regulators, Soil Moisture Contents, and Carbon/Nitrogen Ratios on Sex Differentiation in Persimmon (Diospyros kaki Thunb.) Flowers

The sex types of persimmon (Diospyros kaki Thunb.) flowers are occasionally alterable. The feminizing agents such as ethrel, 5-azacytidine, a mixture of exogenous zeatin (ZT), abscisic acid (ABA), and indole-3-acetic acid (IAA) were injected into androecious wild persimmon trees. Different concentrations of masculinizing exogenous gibberellin (GA3) were injected into gynoecious ‘Jiro’ cultivar trees. ‘Jiro’ trees were also grown in soils differing in moisture content and carbon/nitrogen (C/N) ratio, to determine their effects on floral development and sex differentiation in persimmons. Injection of ethrel significantly decreased the diameter of pollen grains and the length of pollen tubes, thereby demonstrating a feminizing effect. Injection of GA3 significantly increased the length of arrested stamens in gynoecious trees, demonstrating a masculinizing effect. High soil moisture levels (55% and 45% volumetric moisture contents) significantly increased the length of pistils compared to the control (20% moisture content) in gynoecious trees; a high C/N ratio markedly increased the length of both pistils and arrested stamens. Many of the treatments also significantly changed the expression patterns of crucial genes, the contents of assimilates and stress markers, and the activities of antioxidative enzymes in floral buds. These treatment responses may relate to changes in phenotypes. Although the sex types of persimmon flowers were not completely transformed in our study, the treatments significantly influenced pistil and stamen length. Improved artificial treatments may be used to control sex type in persimmons in the future.