Aboveground Water Research Articles

Developing a Hyperspectral Remote Sensing-Based Algorithm to Diagnose Potato Moisture for Water-Saving Irrigation

Appropriate water supply is crucial for high-yield and high-quality potato tuber production. However, potatoes are mainly planted in arid and semi-arid regions in China, where the precipitation usually cannot meet the water demand throughout the growth period. In view of the actual situation of water shortage in these areas, to monitor the water status of potato plants timely and accurately and thus precisely control the irrigation are of significance for water-saving management of potatoes. Hyperspectral remote sensing has unique advantages in diagnosing crop water stress. In this paper, the canopy spectral reflectance and plant water content were measured under five irrigation treatments. The spectral parameters that respond to plant water content were selected, and a hyperspectral water diagnosis model for leaf water content (LWC) and aboveground water content (AGWC) of potato plants was established. It was found that potato tuber yield was the highest during the entire growth period under sufficient irrigation, and the plant water content showed a downward trend as the degree of drought intensified. The peak hyperspectral reflectance of potato plant canopies appeared in the red wavelength, where the reflectance varied significantly under different water treatments and decreased with decreasing irrigation. Six models with sensitive bands, first-order derivatives, and moisture spectral indices were established to monitor water content of potato plants. The R2 values of partial least squares regression (PLSR), support vector machine (SVM), and BP neural network (BP) models are 0.8418, 0.9020, and 0.8926, respectively, between LWC and hyperspectral data; and 0.8003, 0.8167, and 0.8671, respectively, between the AGWC and hyperspectral data. These six models can all predict the water content of potato plants, but SVM is the best model for predicting LWC of potato plants. These results are of great significance for guiding precision irrigation of potato plants at different growth stages.

Nitrogen facilitation was maintained in sown Mediterranean forage mixtures despite drought stress conditions with concurrent general benefits upon plant aboveground water status and yield

There is an urge to optimise the sustainability and resilience of grasslands, especially in light of the extreme weather risks posed by climate change. Plant sown diversity could contribute to mitigating these risks by improving resource use efficiency as well as reducing reliance on fertilisation. We established a field experiment to determine forage swards’ performance in terms of water use, nitrogen (N) use, and dry matter (DM) yield in a semi-arid Mediterranean area which faced a severe drought period. Most variables were tested over three growing seasons, whilst DM yield had an extra year of sampling in which two levels of N fertilisation were tested. Following the Generalised Diversity-Interactions modelling approach, we manipulated the composition and evenness of forage swards including a grass (Festuca arundinacea), a legume (Medicago sativa), and a non-legume forb (Cichorium intybus). Communities were grown as monocultures or mixtures of three species according to a simplex design, which allowed us to estimate separately the two components of the diversity effect: the individual species effects and that due to species interactions. Models were tested both with sown proportions (Pi0) and realised proportions (PiR). The Pi0 models indicated a major beneficial effect of mixtures in contrast to the average monoculture performance for all studied variables. In contrast, PiR models revealed that some of the effects in Pi0 models are indeed explained by the growing proportion of M. sativa over time. However, beneficial interaction effects are still found in PiR models, especially concerning N2 fixation (with δ15N as proxy), which was maintained regardless of the drought stress level experienced by the swards. All things considered, mixed swards merit attention as a valuable nature-based solution that can optimise N management (by boosting N2 input through fixation) as well as water use. This would result in well-nurtured swards with a better ability to cope with drought stress and maintain productivity.

Расчет времени охлаждения надземного водовода с теплоизоляцией в условиях отрицательных температур

Objective: transport infrastructure facilities include a variety of water supply systems. In the event of an emergency, after stopping the movement of water in the pipeline, it is cooled first, and then there is a risk of freezing and destruction of water pipelines. This work is devoted to the calculation of the cooling time of water in the above-ground water conduit with thermal insulation from the specified temperature value in the initial state to the freezing temperature. Methods: when building a mathematical model of the water cooling process, an approach is used based on averaging the equations of hydrodynamics by the volume of water in the pipeline and averaging the equations of thermal conductivity in the wall of the pipeline and in the layer of the heat insulator by the polar angle. To obtain a quasi-stationary form of equations, a comparative analysis of the rates of thermal processes in different layers of the water conduit is used. Results: a new mathematical model for cooling the water pipeline is formulated — a model of average temperatures. The applicability of the quasi-stationary form of the equations of the model is justified and its analytical solution is found. Explicit formulas are obtained for cooling time of water conduit as a function of its parameters. Cooling time was calculated in a wide range of parameters. The results of model calculations are compared with calculations according to traditional semi-empirical formulas. Practical importance: the formulas obtained in the work can be used to estimate the cooling time of water in an above-ground water pipeline with heat insulation to the freezing temperature in the case when the ambient temperature drops to negative values.

Simulation of cooling of aboveground water pipeline with heat insulation

Aboveground water pipelines are often more preferred in the organization of water supply systems in permafrost and low ambient temperatures conditions. If the water movement in such pipeline stops, there is a risk of cooling and subsequent freezing of the liquid. The purpose of this work is to study the dynamics of the cooling process of an aboveground water pipeline with heat insulation and to calculate the cooling time of water to the freezing temperature. To build a mathematical model of the cooling process, the method of averaging the equations of hydrodynamics and thermal conductivity is used. The model equations do not contain any assumptions about the nature of the water movement in the pipeline during the cooling process. The possibility of using the equations of the model in a quasi-stationary form is justified. The range of task parameter values at which this approximation applies is determined. The possibilities of applying different boundary conditions on the surface of the water pipeline are also considered. In the quasi-stationary approximation, a dependence on the time of the average water temperature in the pipeline was found. An explicit formula is also obtained for calculating the cooling time of water to the freezing temperature. The criteria for the applicability of the obtained formulas have been established. For a wide range of parameters, water cooling time is calculated from the specified initial temperature to the freezing temperature. Ranges of values of parameters at which increase of thickness of heat insulator layer and increase of initial water temperature lead to significant increase of water cooling time in pipeline are determined.

Rootstock effects on leaf function and isotope composition in apple occurred on both scion grafted and ungrafted rootstocks under hydroponic conditions.

Rootstocks are used in modern apple production to increase productivity, abiotic and biotic stress tolerance, and fruit quality. While dwarfing for apple rootstocks has been well characterized, the physiological mechanisms controlling dwarfing have not. Previous research has reported rootstock effects on scion water relations. Root architecture and variability in soil moisture across rooting depths can also contribute to these differences among rootstocks in the field. To exclude these effects on rootstock behavior, scions were grafted onto four different rootstocks with varying effects on scion vigor (B.9, M.9, G.41 and G.890). Non-grafted rootstocks were also grown to examine whether the effects of rootstock occurred independently from scion grafting. Plants were grown in a greenhouse under near steady-state hydroponic conditions. Carbon (δ13C), oxygen (δ18O) and nitrogen (δ15N) isotope composition were evaluated and relationships with carbon assimilation, water relations, and shoot growth were tested. Rootstocks affected scion shoot growth, aligning with known levels of vigor for these four rootstocks, and were consistent between the two scion cultivars. Furthermore, changes in water relations influenced by rootstock genotype significantly affected leaf, stem, and root δ13C, δ18O, and δ15N. Lower δ13C and δ18O were inconsistently associated with rootstock genotypes with higher vigor in leaves, stems, and roots. G.41 had lower δ15N in roots, stems, and leaves in both grafted and ungrafted trees. The effects of rootstock on aboveground water relations were also similar for leaves of ungrafted rootstocks. This study provides further evidence that dwarfing for apple rootstocks is linked with physiological limitations to water delivery to the developing scion.

Анализ процессов теплообмена на поверхности надземного трубопровода с теплоизоляцией

Purpose: Transport infrastructure facilities include a variety of water supply systems. In the conditions of negative ambient temperatures, there is a risk of freezing and destruction of water pipelines. In mathematical modeling of the operation of aboveground pipelines, the correct description of the heat exchange process between the outer wall of the pipeline and the surrounding atmosphere is of great importance. The boundary condition corresponding to this process traditionally includes a heat transfer coefficient depending on a number of unpredictable parameters (wind speed and direction, atmospheric pressure, air humidity). The purpose of this work is to carry out a comparative analysis of the role of free and forced convective heat exchange and to justify the possibility of setting a boundary condition that depends only on the outside air temperature. Methods: To solve this problem, the work uses numerical analysis of similarity criteria for the heat exchange process under conditions typical for the operation of an above-ground pipeline with thermal insulation. The justification of the boundary condition on the external surface of the pipeline is based on the law of energy conservation. Results: The values of the parameters of the problem are determined, in which free or forced convective heat exchange prevails. It has been shown that forced convection prevails in conditions typical for the operation of above-ground water pipelines. Under these conditions, the difference between the temperature of the external surface of the insulated pipeline and the surrounding atmosphere is small. It has been shown that in this case, it is advisable to use the equality of atmospheric air temperatures and pipeline surface temperatures as a boundary condition. Practical significance: Understanding the mechanisms of heat exchange makes it possible to create an adequate model of the operation of pipelines in conditions of negative temperatures. Setting a more accurate and simple boundary condition on the surface of the pipeline simplifies the task of mathematical modeling. The results obtained in this article can be used in mathematical modeling of any pipelines with thermal insulation.

Priming Bean Seedlings to Boost Natural Plant Defenses Against Common Bacterial Wilt: Leaf Architecture, Leaf area, Foliage Water Content, and Plant Biomass Results (Part 3)

This greenhouse study evaluated the effects of two chemicals for priming kidney bean seedlings against bacterial wilt disease (Curtobacterium flaccumfaciens pv. Flaccumfaciens) (CFF). The premise of this study was that the oxidant properties of chlorine dioxide would mimic the signaling properties of radical oxygen species thereby initiating a cascade of molecular plant defenses. The factorial study included two levels for the foliar chlorine dioxide treatment, two levels for the bacterial wilt inoculation treatment, and two optional treatments. The biomass variables included oven dry total plant biomass, oven dry fruit biomass, and oven dry leaf biomass. Also, foliage and total plant water content data was collected, as well as total leaf area. Specific leaf area (SLA) was estimated from the leaf area and biomass data. The primers had equivalent leaf area, plant and fruit biomass as the water control for the CFF wilt inoculated plants. The EB 400 mg/l primer reduced SLA for the CFF inoculated plants. Both EB formulations increased aboveground water content in the CFF wilt inoculated plants. Multivariate tables revealed several significant correlations among leaf architecture, plant tissue water content, and biomass growth parameters for the EB primers and the water control treatment for the two CFF wilt treatments. Re-allocation of plant resources from plant growth to plant defenses due to chemical primers were estimated and discussed to determine the tradeoffs between plant yield and enhanced plant defenses. The three articles in this study show that chlorine dioxide primers can initiate a series of ROS and salicylic acid signals. This interplay of ROS signals and salicylic acid signals generated by the chlorine dioxide primers activates a long-term SAR response that protects plants against future pathogen attacks. In addition, interaction of the ROS and salicylic acid signals activates a suite of defense mechanisms that provide universal, multifaceted plant immunity that can be sustained across a crop season.

Estimation of Aboveground Vegetation Water Storage in Natural Forests in Jiuzhaigou National Nature Reserve of China Using Machine Learning and the Combination of Landsat 8 and Sentinel-2 Data

Aboveground vegetation water storage (AVWS) is a fundamental ecological parameter of terrestrial ecosystems which participates in plant metabolism, nutrient and sugar transport, and maintains the integrity of the hydraulic system of the plant. The Jiuzhaigou National Nature Reserve (JNNR) is located in the Eastern Tibet Plateau and it is very sensitive to climate change. However, a regional estimate of the AVWS based on observations is still lacking in the JNNR and improving the model accuracy in such mountainous areas is challenging. Therefore, in this study, we combined the Landsat 8 and Sentinel-2 data to estimate AVWS using multivariate adaptive regression splines (MARS), random forest (RF) and extreme gradient boosting (XGBoost) with the linkage of 54 field observations in the JNNR. The results showed that AVWS varied among different forest types. The coniferous forests had the highest AVWS (212.29 ± 84.43 Mg ha−1), followed by mixed forests (166.29 ± 72.73 Mg ha−1) and broadleaf forests (142.60 ± 46.36 Mg ha−1). The average AVWS was 171.2 Mg ha−1. Regardless of the modelling approaches, both Sentinel-2 and Landsat 8 successfully estimated AVWS separately. Prediction accuracy of AVWS was improved by combining Landsat 8 and Sentinel-2 images. Among the three machine learning approaches, the XGBoost model performed best with a model efficiency of 0.57 and root mean square error of 48 Mg ha−1. Predicted AVWS using XGBoost showed a strong spatial pattern of across the study area. The total AVWS was 5.24 × 106 Mg with 67.2% coming from conifer forests. The results highlight the potential of improving the accuracy of AVWS estimation by integrating different optical images and using machine learning approaches in mountainous areas.

Leaf surface traits contributing to wettability, water interception and uptake of above-ground water sources in shrubs of Patagonian arid ecosystems.

The ecohydrological significance of leaf wetting due to atmospheric water in arid and semiarid ecosystems is not well understood. In these environments, the inputs of precipitation or dew formation resulting in leaf wetting have positive effects on plant functioning. However, its impact on plant water relations may depend on the degree of leaf surface wettability. In this study we evaluated leaf wettability and other leaf traits and its effects on foliar water uptake and canopy interception in plant species of a Patagonian steppe. We also studied how leaf traits affecting wettability vary seasonally from growing to dry season. Contact angle of a water droplet with the leaf surface, water adhesion, droplet retention angle, stomatal density, cuticular conductance, canopy interception and maximum foliar water uptake were determined in six dominant shrub species. All species increased leaf wettability during the dry season and most species were considered highly wettable. The leaf surface had very high capacity to store and retain water. We found a negative correlation between foliar water uptake and leaf hydrophilia. Despite the diversity of life forms, including cushion shrubs and tall shrubs, as well as phenological variability, all species converged in similar seasonal changes in leaf traits that favour wettability. Intercepted water by crowns and the extremely high capacity of retention of droplets on leaf surfaces can have a significant impact on eco-hydrological process in water limited ecosystems where most of water sources during the growing and the dry season may be small rainfall events or dew, which do not always increase soil water availability.

Роль гидродинамических и структурно-тектонических факторов в формировании залежей углеводородов в юрских отложениях бухаро-хивинского региона

The article discusses the study of reservoir fluids and the role of the hydrodynamic environment in the formation and preservation of hydrocarbon deposits within the Bukhara-Khiva oil and gas region. Aboveground water are the primary "transporter" scattered hydrocarbons, in certain geological hydrogeological conditions, they can contribute to their accumulation or destruction. In this regard, the study of the nature of the movement of fluids due to geological and tectonic processes is a necessary condition for assessing the prospects of oil and gas potential in the territories.

Evaluating sediment and water sampling methods for the estimation of deep-sea biodiversity using environmental DNA

Despite representing one of the largest biomes on earth, biodiversity of the deep seafloor is still poorly known. Environmental DNA metabarcoding offers prospects for fast inventories and surveys, yet requires standardized sampling approaches and careful choice of environmental substrate. Here, we aimed to optimize the genetic assessment of prokaryote (16S), protistan (18S V4), and metazoan (18S V1–V2, COI) communities, by evaluating sampling strategies for sediment and aboveground water, deployed simultaneously at one deep-sea site. For sediment, while size-class sorting through sieving had no significant effect on total detected alpha diversity and resolved similar taxonomic compositions at the phylum level for all markers studied, it effectively increased the detection of meiofauna phyla. For water, large volumes obtained from an in situ pump (~ 6000 L) detected significantly more metazoan diversity than 7.5 L collected in sampling boxes. However, the pump being limited by larger mesh sizes (> 20 µm), only captured a fraction of microbial diversity, while sampling boxes allowed access to the pico- and nanoplankton. More importantly, communities characterized by aboveground water samples significantly differed from those characterized by sediment, whatever volume used, and both sample types only shared between 3 and 8% of molecular units. Together, these results underline that sediment sieving may be recommended when targeting metazoans, and aboveground water does not represent an alternative to sediment sampling for inventories of benthic diversity.

Prospective policy safeguards to mitigate hydrogeological risk pathways in advance of shale gas development in the Karoo basin, South Africa

Policies surrounding energy development are frequently implemented in response to known or perceived problems. South Africa is in a unique position to develop prospective policies that build on knowledge gained from elsewhere. This paper provides a prospective analysis of hydrogeological risk pathways and vulnerability attributes in advance of anticipated shale gas operations in the Karoo Basin of South Africa. The ‘hazard-pathways-receptors’ approach is applied to define the hydrogeologic system in the context of potential sources of water resource contamination. This case study focuses on two critical hydrogeological risk pathways: regional groundwater flow and discrete structural features. Depending on the targeted area (hydro-litho-structural domain, depth of target, presence of aquitard, intrusion ratio), the capacity of deep natural pathways to enable hydraulic fracturing fluids, chemicals, or produced water to reach shallow groundwater, will be reduced or difficult. Deep artesian water could however be intercepted at different depths and, based on past groundwater exploration in the Karoo, water could flow into horizontal fractures or openings characterising the shallow aquifers: sills-ring complexes, lithological contacts, and transgressive fractures across dolerite dykes. However, above-ground water and wastewater management safeguards are needed to protect shallow groundwater from potential water quality degradation due to a) flowback or produced water b) stray gas and/or c) spills or illicit discharges that could introduce contaminants into groundwater resources. This paper describes a systematic approach to evaluate hydrogeologic risk pathways and informs adaptive management policies to protect South African groundwater resources.

Optimizing bioenergy and by-product outputs from durian shell pyrolysis

Durian shells (DS) constitute an abundant agricultural waste stream with a large yield in Southeast Asia and higher heating value. This study aimed to quantify the bioenergy and by-product outputs of the DS pyrolysis as a function of heating rate (5, 10, 20, and 40 K/min) combining thermogravimetric, Fourier transform infrared spectrometry, and pyrolysis–gas chromatography/mass spectrometry analyses. The joint optimizations of multiple responses were also performed as a function of a changing biofeedstock, heating rate, and temperature. The DS pyrolysis composed of three stages, with the main decomposition stage occurring between 141.2 and 616.5 °C. The increased heating rate promoted the DS pyrolysis, while the pyrolysis reaction was more complete at the low heating rate. Activation energy of the pyrolysis reaction was estimated to vary between 221.58 and 245.71 kJ/mol. The major gases evolved from the DS pyrolysis included CO2, CO, CH4, H2O, carbonyl compounds, acids, and NH3. The major pyrolytic by-products were aromatic and alicyclic hydrocarbons, phenolic substances, and N-containing compounds. Joint optimizations pointed to 999 °C, 5 K/min, and aboveground water hyacinth biomass, or DS as the most optimal operational conditions. Our findings provide insights into the optimization and scale-up for the industrial pyrolytic applications of DS.

Agro Pastoralist’s Perception and Willingness to Participate in Water Harvesting Practices in South Omo Zone, Southern Ethiopia

This study was conducted to assess agro pastoralist’s perception and willingness to participate in water harvesting practices that could improve their decision to construct and manage water storage technologies at individual household level or community level in the study area. A total of 192 agro pastoralist’s households were assessed and 92.7% of them were willing to participate in rainwater harvesting practices and the rest 7.3% were not. Of the willing respondents 27.53%, 54.49% and 17.98% preferred clay lined pond, plastic lined pond and aboveground tank water storage technologies. And also the study specified the binary logistic for the participation decision and multinomial logistic for the choice decision model to identify factors that affect participation decision on water harvesting technologies and preference of water storage technologies. Accordingly, estimation of the binary logistic model showed that labor availability, distance to water source, perception towards water harvesting practice, age of respondent and credit services significantly affect the willingness of agro pastoralists to participate in water harvesting technologies. Whereas labour availability, ownership of plot, plot distance and area of particular plot affect the choice decision of agro pastoralists on rain water storage options among alternatives in the study area. It can be concluded that policy makers must give attention on factors affecting perception/participation decision of agro pastoralist’s in water harvesting works and their preference among water storage options, and on gender issues in the planning/implementation of water harvesting activities.

Heating houses by using vacuum-tube solar collectors and a small aboveground water tank: a cost-effective solution for maritime climates

ABSTRACT This work presents a simple dynamical solar-thermal modelling and cost-optimized solution for heating houses in maritime climates by using many vacuum-tube solar collectors together with one small well-insulated aboveground water tank and the underfloor hot-water heating system. This was performed for a single house in the cold-maritime climate of Bariloche (13,000 kWh/y), which could be fully satisfied by using ten collectors on 70°-inclined roof and 4.6 m3 tank, costing €12,900. This cost is noticeably lower than for previous large projects in cold-continental climates, what is supported by four key factors: (1) solar resource and heating demand in maritime climates are more distributed than in continental climates; (2) small aboveground tanks can get noticeably higher efficiencies and lower costs that huge underground tanks; (3) vacuum-tube collectors get higher performances than flat collectors during winters; (4) high winter solar yield is achieved by installing collectors on high tilt angles (or half on low-inclined roofs and half on walls). These four factors will be discussed by solar-thermal and cost analyses, by comparing the system performance for climatic conditions of Bariloche and Okotoks.

Akgöl ve Gebekirse Göllerinde (Selçuk, İzmir, Türkiye) Bazı Fiziko-Kimyasal Parametrelerin Mevsimsel Değişimi

Akgöl ve Gebekirse gölleri İzmir ili Selçuk ilçesi sınırları içindedir. Göller, Küçük Menderes Havzası’nda tarımsal sulamada kullanılmaktadır. Küçük Menderes Havzası önemli tarım bölgesi olduğundan, tarımsal sulamada kullanılan suyun kalite parametrelerinin bilinmesi ve izlenmesi sürdürülebilir bir tarım açısından önemlidir. Bu çalışmada, Akgöl ve Gebekirse göllerinin bazı fiziko-kimyasal özellikleri (sıcaklık, pH, toplam çözünmüş madde, iletkenlik, tuzluluk, orto fosfat fosforu, anyonik deterjan, bor, amonyum azotu, nitrit azotu, nitrat azotu) belirlenmiştir. Ortalama değerler Yerüstü Su Kalitesi Yönetmeliği’nde belirtilen kriter değerler ile karşılaştırıldığında, her iki göl sularının orto fosfat fosforu ve nitrit parametreleri açısından ikinci kalite su (az kirlenmiş su) olduğu belirlenmiştir. İletkenlik parametresi bakımından Akgöl’ün ikinci kalite (az kirlenmiş su), Gebekirse Gölü’nün üçüncü kalite (kirlenmiş su) su sınıfında olduğu tespit edilmiştir. Ayrıca Gebekirse Gölü anyonik deterjan parametresi açısından da ikinci kalite (az kirlenmiş su) su sınıfındadır. Sulama suyu kriterlerine göre de, sıcaklık, pH, bor, nitrat ve amonyum ortalama konsantrasyonlarının sınır değerlerin altında olduğu ve her iki göl sularının da bu parametreler açısından birinci sınıf sulama suyu olduğu görülmüştür.

Biochar influences nitrogen and phosphorus use efficiency of tomato and soil nutrients under groundwater and wastewater irrigation

Wastewater irrigation is a common practice in developing countries, while the application of biochar in agricultural lands is gathering momentum worldwide. However, it is not known how biochar and wastewater in concert influence the uptake and concentration of nutrients in plants and soil, respectively. The influence was investigated of biochar on the growth performance of tomato plants grown in pots and the concentration of mineral N and soluble P in soil under wastewater and groundwater irrigation. Two biochars (wood-derived and manure-derived) were applied to soil as 3% and 7% amendments and tomato plants were grown. Both biochar types tended to increase the aboveground and belowground biomass and water use efficiency of plants at the higher application rate under both irrigation treatments (p < 0.05). The N contents in plant tissues were significantly higher for almost all treatments of biochar application rate under both irrigation treatments while under wastewater irrigation, biochar significantly reduced the P contents. The nitrogen use efficiency and phosphorus use efficiency of plants tended to increase (p < 0.05) at higher biochar application rates under both irrigation treatments. Amendment using biochars increased the concentration of mineral N and soluble P at both application rates under groundwater irrigation while under wastewater irrigation, only the P contents were increased in response to both biochar types at both application rates (p < 0.05).

苗期紫花苜蓿株体对不同地区垂穗披碱草种子萌发生长的化感作用

PDF HTML阅读 XML下载 导出引用 引用提醒 苗期紫花苜蓿株体对不同地区垂穗披碱草种子萌发生长的化感作用 DOI: 10.5846/stxb201809051896 作者: 作者单位: 西藏农牧学院,西藏农牧学院,西藏农牧学院,西藏农牧学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2018YFD0502401-1）；西藏俊富环境恢复有限公司资助（JOFO-RD-2016001，JOFO-RD-2016002）；国家自然科学基金（31560142） Allelopathic effects of alfalfa (Medicago sativa) in the seedling stage on seed germination and growth of Elymus nutans in different areas Author: Affiliation: Tibet Agriculture and Animal Husbandry College,Tibet Agriculture and Animal Husbandry College,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以发芽率、苗长、根长、苗干重、根干重变化为种子萌发和幼苗生长参数，研究苗期紫花苜蓿（Medicago sativa）植株浸提液对不同地区垂穗披碱草（Elymus nutans）种子萌发生长的化感作用。结果表明：地上部浸提液对LS、DX垂穗披碱草种子发芽率具有明显的促进作用，而对GS、KMX、LKZ、LZ地区垂穗披碱草种子发芽率均表现为抑制作用，其中对GS垂穗披碱草种子发芽率的抑制作用最强，在14.5%和5.5%浓度处理时抑制率分别为57.89%、55.26%；苗长方面，浸提液5.5%浓度对垂穗披碱草苗长的抑制率顺序为：LZ > NQ > DX > LS > KMX > QH > GS > LKZ，14.5%处理时抑制率顺序为：LZ > KMX > LKZ > NQ > GS > QH > DX > LS，其中抑制率最高的为LZ垂穗披碱草，在14.5%和5.5%浓度处理时抑制率分别为33.03%、28.97%；根长方面，5.5%处理对垂穗披碱草根长的抑制率顺序为：QH > NQ > LZ > KMX、GS > LKZ > DX、LS，14.5%处理时抑制率顺序为：GS > QH、NQ > LZ > LS > KMX > DX > LKZ，其中在高浓度下抑制率最高的为GS垂穗披碱草，抑制率为57.69%；地上部浸提液对LKZ、LZ垂穗披碱草苗干重均具有促进作用，高浓度浸提液对NQ垂穗披碱草苗干重产生促进作用（RI > 0），而对KMX、DX垂穗披碱草苗干重均表现为抑制作用；根干重方面，浸提液对LS、QH、GS、NQ、LKZ垂穗披碱草根干重均有明显的抑制作用，而对KMX、DX垂穗披碱草根干重产生促进作用，高浓度浸提液对LZ垂穗披碱草的根干重产生促进作用。从根浸提液的作用来看，根浸提液除对LS、DX垂穗披碱草种子发芽率和根干重、GS垂穗披碱草种子发芽率和苗干重及NQ垂穗披碱草根干重具有促进作用外（P > 0.05），对其余地区垂穗披碱草的各项指标均有明显的抑制作用（RI < 0）。所有以上结果表明，紫花苜蓿植株浸提液对垂穗披碱草种子萌发生长的作用具有一定的浓度效应。不同地区垂穗披碱草对紫花苜蓿地上部浸提液的敏感性趋势总体为：GS > QH > LS > KMX > NQ > LKZ > LZ，最不敏感或有促进作用的是DX垂穗披碱草；对根浸提液的敏感性趋势总体为：QH > NQ > LZ > KMX，根浸提液对LS、GS、LKZ、DX垂穗披碱草种子萌发生长具有促进作用。紫花苜蓿植株不同部位浸提液对垂穗披碱草种子萌发生长的化感效应顺序为：地上部 > 根。 Abstract:The allelopathic effects of water extracts from alfalfa (Medicago sativa) in the seedling stage on seed germination and growth of Elymus nutans in different areas were examined in the laboratory based on seed germination rate, seedling length, root length, and dry weight of seedlings and roots. The results showed that the seed germination rate of Elymus nutans in LS (Lhasa) and DX (Damxung County) was significantly promoted by water extracts from the aboveground alfalfa, but that of those in GS (Gansu), KMX (Kangma County), LKZ (Nagarzê County), and LZ (Nyingchi County) was inhibited, and Elymus nutans in GS was the most inhibited, with suppression rates of 57.89% and 55.26% at concentrations of 14.5% and 5.5%, respectively. At the concentration of 5.5%, the seedling length of Elymus nutans in LZ was the most inhibited with the suppression rate of 33.03%, followed successively by those in NQ (Nagqu region), DX, LS, KMX, QH (Qinghai), GS, and LKZ. At the concentration of 14.5%, the seedling length of Elymus nutans in LZ was nearly the most inhibited with the suppression rate of 28.97%, followed successively by those in KMX, LKZ, NQ, GS, QH, DX, and LS. At the concentration of 5.5%, the root length of Elymus nutans in QH had the strongest inhibition, followed by those in the order of NQ > LZ > KMX, GS > LKZ > DX, LS. At the concentration of 14.5%, the root length of Elymus nutans in GS had the strongest inhibition with the suppression rate of 57.69%, followed successively by those in the order of QH, NQ > LZ > LS > KMX > DX > LKZ. The dry weight of seedlings of Elymus nutans in LKX and LZ increased by the aboveground water extracts, whereas that of those in KMX and DX decreased and the dry weight of seedlings of Elymus nutans in NQ was only increased at high concentrations (RI > 0). The dry weight of roots of Elymus nutans in LS, QH, GS, NQ, and LKZ was decreased by the aboveground water extracts, whereas that of those in KMX and DX was increased and the dry weight of roots of Elymus nutans in LZ was only increased at high concentrations. Seed germination rate, seedling length, root length, and dry weight of seedlings and roots of Elymus nutans in most areas were significantly inhibited (RI < 0) by water extracts from the root of alfalfa, except for seed germination and dry weight of roots of Elymus nutans in LS and DX. Seed germination and dry weight of seedlings of that in GS and the dry weight of roots of that in NQ were significantly promoted (P > 0.05). All the above results showed that the sensitivity of Elymus nutans in different areas to the allelopathic effects of the aboveground alfalfa in the seedling stage is in the order of GS > QH > LS > KMX > NQ > LKZ > LZ > DX from the highest to the lowest allelopathic sensitivity. The allelopathic sensitivity to the root of the alfalfa is in the order of QH > NQ > LZ > KMX > LS,from the highest to the lowest. The allelopathic sensitivity of Elymus nutans in different areas to water extracts from the aboveground alfalfa is higher than that from the root of alfalfa. 参考文献 相似文献 引证文献

Technical and administrative feasibility of alluvial aquifer storage and recovery on the South Platte River of northeastern Colorado

Abstract Increasing population and climate change are causing water managers to reassess water storage. In this context, alluvial aquifer storage and recovery (ASR), in which excess water is stored in the alluvium near a river, offers a plausible option. To investigate this option, a coupled technical–administrative analysis was conducted to investigate the feasibility of alluvial ASR in the semi-arid US state of Colorado, where water rights are governed by the doctrine of prior appropriation. A hypothetical alluvial ASR facility near Brighton, Colorado with a storage capacity of 118,500 cubic meters (96 ac-ft) was considered. This analysis comprises both technical feasibility, using a groundwater model that explicitly accounts for clogging, and administrative feasibility, using a first-of-its-kind analysis of the legal availability of water including both free river and reusable effluent water. This coupled technical–administrative analysis suggests that alluvial ASR facilities present a viable option to meet rising demand for water storage, preventing water loss due to evaporation, reducing the effect of climate stress on water resources, and avoiding the need to purchase land for above-ground water storage facilities. More generally, this study illustrates the crucial importance of placing hydrologic analysis in the broader context of policy constraints.

Soil water content determination with cosmic-ray neutron sensor: Correcting aboveground hydrogen effects with thermal/fast neutron ratio

Summary The cosmic-ray neutron sensor (CRNS), which estimates field scale soil water content, bridges the gap between point measurement and remote sensing. The accuracy of CRNS measurements, however, is affected by additional hydrogen pools (e.g., vegetation, snow, and rainfall interception). The objectives of this study are to: (i) evaluate the accuracy of CRNS estimates in a farmland system using depth and horizontal weighted point measurements, (ii) introduce a novel method for estimating the amounts of hydrogen from biomass and snow cover in CRNS data, and (iii) propose a simple approach for correcting the influences of aboveground hydrogen pool (expressed as aboveground water equivalent, AWE) on CRNS measurements. A field experiment was conducted in northeast China to compare soil water content results from CRNS to in-situ data with time domain reflectometry (TDR) and neutron probe (NP) in the 0–40 cm soil layers. The biomass water equivalent (BWE) and snow water equivalent (SWE) were observed to have separate linear relationships with the thermal/fast neutron ratio, and the dynamics of BWE and SWE were estimated correctly in the crop seasons and snow-covered seasons, respectively. A simple approach, which considered the AWE, AWE at calibration, and the effective measurement depth of CRNS, was introduced to correct the errors caused by BWE and SWE. After correction, the correlation coefficients between soil water contents determined by CRNS and TDR were 0.79 and 0.77 during the 2014 and 2015 crop seasons, respectively, and CRNS measurements had RMSEs of 0.028, 0.030, and 0.039 m 3 m −3 in the 2014 and 2015 crop seasons and the snow-covered seasons, respectively. The experimental results also indicated that the accuracies of CRNS estimated BWE and SWE were affected by the distributions of aboveground hydrogen pools, which were related to the height of the CRNS device above ground surface.