Decreasing Water Availability Research Articles

The response of the Dajiuhu Peatland ecosystem to hydrological variations: Implications for carbon sequestration and peatlands conservation

Peatlands, one of the largest biosphere carbon reservoirs, are facing climate change induced water-table drawdown and carbon loss. To provide insights into peatland protection and carbon–water cycle under the background of global change, the detailed relationship between peatland ecology and water table depth (WTD) should be considered. In this study, we focused on carbon flux and synthesized datasets on WTD, carbon dynamics, vegetation and microbiologic activities in the Dajiuhu Peatland to better understand the ecological response to the hydrological variations. Based on modern monitoring, the daily CH4 emission decreased and CO2 emission increased with the fall of the WTD. When the WTD was deeper than 30 cm, daily carbon sequestration reduced until it approached 0 according to nonlinear models. By comparisons with previous spatial soil TOC, vegetation and microbiologic surveys, we proposed that approximately 30 cm is a critical WTD level (turning point or zone) affecting the structure and function of peatland ecosystems. Prolonged and severe droughts might trigger an ecological shift of peatland because increase in oxygen availability and decrease in water availability are not able to meet the physiological needs of living organisms, which further decreases CH4 emission due to limited methanogenesis and enhanced methanotrophy and weakens carbon sequestration through enhanced litter decomposition. This was also confirmed by palaeo-ecological records. In particular, precipitation-induced declines of WTD (WTD > 30 cm) during 9,500–9,200 cal yr BP, 6,000–4,000 cal yr BP and 3,600–3,200 cal yr BP caused a series of ecological changes, including the decreases in wet-preferred Sphagnum and herbs, enhanced aerobic bacteria activities and ecosystem respiration, and changed soil carbon sequestration. Drought during 6,000–4,000 cal yr BP induced low carbon sequestration. However, rapid vegetation succession and peat accumulation caused by the abrupt hydrological variations during 9,500–9,200 cal yr BP and 3,600–3,200 cal yr BP might have resulted in temporary increases in carbon sequestration. Our results demonstrate that WTD is crucial to the regulation of peatland ecological functions. This finding offers references for peatland carbon–water cycles and management.

Diplodia tip blight pathogen's virulence empowered through host switch.

Increased drought combined with emerging pathogens poses an increased threat to forest health. This is attributable to the unpredictable behaviour of forest pathosystems, which can favour fungal pathogens over the host under persistent drought stress conditions. Diplodia sapinea (≡ Sphaeropsis sapinea) is one of the most severe pathogens in Scots pine (Pinus sylvestris) causing Diplodia tip blight (conifer blight) under certain environmental conditions. Recently, the fungus has also been isolated from non-conifer hosts, indicating that it has a broader host range than previously known. In this study we compared the impact of different levels of water availability on necrosis length caused by D. sapinea strains isolated as endophytes (eight strains isolated from asymptomatic Scots pine) and pathogens (five strains isolated from symptomatic Scots pine) and five strains isolated from symptomatic non-pine hosts. For all strains the decreased water availability increased the necrosis length in Scots pine shoots. The isolates from non-pine hosts caused the most severe reactions under all water availabilities. The results of the study indicate the likelihood that effects of climatic changes such as drought will drive D. sapinea damage in Scots pine-dominated forests and increase mortality rates in affected trees. Further, the higher necrosis in the Scots pines caused by strains that had performed a host switch are concerning with regard to future scenarios thus increasing infection pressure on Scots pine from unknown sources.

Impact of Climate Change on Water Resources and Crop Production in Western Nepal: Implications and Adaptation Strategies

Irrigation-led farming system intensification and efficient use of ground and surface water resources are currently being championed as a crucial ingredient for achieving food security and reducing poverty in Nepal. The potential scope and sustainability of irrigation interventions under current and future climates however remains poorly understood. Potential adaptation options in Western Nepal were analyzed using bias-corrected Regional Climate Model (RCM) data and the Soil and Water Assessment Tool (SWAT) model. The RCM climate change scenario suggested that average annual rainfall will increase by about 4% with occurrence of increased number and intensity of rainfall events in the winter. RCM outputs also suggested that average annual maximum temperature could decrease by 1.4 °C, and average annual minimum temperature may increase by 0.3 °C from 2021 to 2050. Similarly, average monthly streamflow volume could increase by about 65% from March–April, although it could decrease by about 10% in June. Our results highlight the tight hydrological coupling of surface and groundwater. Farmers making use of surface water for irrigation in upstream subbasins may inadvertently cause a decrease in average water availability in downstream subbasins at approximately 14%, which may result in increased need to abstract groundwater to compensate for deficits. Well-designed irrigated crop rotations that fully utilize both surface and groundwater conversely may increase groundwater levels by an average of 45 mm from 2022 to 2050, suggesting that in particular subbasins the cultivation of two crops a year may not cause long-term groundwater depletion. Modeled crop yield for the winter and spring seasons were however lower under future climate change scenarios, even with sufficient irrigation application. Lower yields were associated with shortened growing periods and high temperature stress. Irrigation intensification appears to be feasible if both surface and groundwater resources are appropriately targeted and rationally used. Conjunctive irrigation planning is required for equitable and year-round irrigation supply as neither the streamflow nor groundwater can provide full and year-round irrigation for intensified cropping systems without causing the degradation of natural resources.

Soil-plant interactions modulated water availability of Swiss forests during the 2015 and 2018 droughts.

Central Europe has been experiencing unprecedented droughts during the last decades, stressing the decrease in tree water availability. However, the assessment of physiological drought stress is challenging, and feedback between soil and vegetation is often omitted because of scarce belowground data. Here we aimed to model Swiss forests' water availability during the 2015 and 2018 droughts by implementing the mechanistic soil‐vegetation‐atmosphere‐transport (SVAT) model LWF‐Brook90 taking advantage of regionalized depth‐resolved soil information. We calibrated the model against soil matric potential data measured from 2014 to 2018 at 44 sites along a Swiss climatic and edaphic drought gradient. Swiss forest soils' storage capacity of plant‐available water ranged from 53 mm to 341 mm, with a median of 137 ± 42 mm down to the mean potential rooting depth of 1.2 m. Topsoil was the primary water source. However, trees switched to deeper soil water sources during drought. This effect was less pronounced for coniferous trees with a shallower rooting system than for deciduous trees, which resulted in a higher reduction of actual transpiration (transpiration deficit) in coniferous trees. Across Switzerland, forest trees reduced the transpiration by 23% (compared to potential transpiration) in 2015 and 2018, maintaining annual actual transpiration comparable to other years. Together with lower evaporative fluxes, the Swiss forests did not amplify the blue water deficit. The 2018 drought, characterized by a higher and more persistent transpiration deficit than in 2015, triggered widespread early wilting across Swiss forests that was better predicted by the SVAT‐derived mean soil matric potential in the rooting zone than by climatic predictors. Such feedback‐driven quantification of ecosystem water fluxes in the soil–plant‐atmosphere continuum will be crucial to predicting physiological drought stress under future climate extremes.

Branch xylem vascular adjustments in European beech in response to decreasing water availability across a precipitation gradient.

Crucial for the climate adaptation of trees is a xylem anatomical structure capable of adjusting to changing water regimes. Although species comparisons across climate zones have demonstrated anatomical change in response to altered water availability and tree height, less is known about the adaptability of tree vascular systems to increasing water deficits at the intraspecific level. Information on the between-population and within-population variability of xylem traits helps assessing a species' ability to cope with climate change. We investigated the variability of wood anatomical and related hydraulic traits in terminal branches of European beech (Fagus sylvatica L.) trees across a precipitation gradient (520-890mmyear-1) and examined the influence of climatic water balance (CWB), soil water capacity (AWC), neighborhood competition (CI), tree height and branch age on these traits. Furthermore, the relationship between xylem anatomical traits and embolism resistance (P50) was tested. Within-population trait variation was larger than between-population variation. Vessel diameter, lumen-to-sapwood area ratio and potential conductivity of terminal branches decreased with decreasing CWB, but these traits were not affected by AWC, whereas vessel density increased with an AWC decrease. In contrast, none of the studied anatomical traits were influenced by variation in tree height (21-34m) or CI. Branch age was highly variable (2-22years) despite equal diameter and position in the flow path, suggesting different growth trajectories in the past. Vessel diameter decreased, and vessel density increased, with increasing branch age, reflecting negative annual radial growth trends. Although vessel diameter was not related to P50, vessel grouping index and lumen-to-sapwood area ratio showed a weak, though highly significant, positive relationship to P50. We conclude that the xylem anatomy of terminal tree-top branches in European beech is modified in response to increasing climatic aridity and/or decreasing soil water availability, independent of a tree height effect.

Effect of grafting and cover crop quality on nitrogen uptake from different pools by drip irrigated heirloom tomatoes in an open field trial

Fresh-market tomatoes (Lycopersicon esculentum Mill.) are increasingly produced with subsurface drip irrigation in California, as growers adapt to decreased water availability. Drip irrigation improves water use efficiency, but may reduce the soil volume where conditions are optimal for microbial and root activity. This poses complications for organic growers, whose cropping systems are dependent on microorganisms to convert the nitrogen (N) from organic sources into plant-available N. To investigate grafting as a potential practice to increase access to N, grafted and non-grafted “Brandywine” heirloom tomatoes were grown with drip irrigation in a two-year field trial. The three rootstocks were “Maxifort,” “Fortamino,” and “DRO138TX.” Prior to each growing season, a legume cover crop mix was grown and labeled with 15N ammonium sulfate to track tomato N uptake from cover crop residues. There were no significant differences in yield, N uptake and N partitioning in the plants due to rootstock treatments. Leaf analyses suggested that the tomato plants were not N deficient in either year. However, there was a significant difference in total N uptake from cover crop residues between years. This was caused by large differences in N concentration in the cover crop. Plants responded to a lower N availability by producing less vine biomass, while producing the same fruit yield. A budget revealed that the tomato plants accessed a considerable amount of N from the soil below 60 cm of the profile to cover their demand.

Dietary changes could compensate for potential yield reductions upon global river flow protection

Non-technical summaryGlobally, freshwater systems are degrading due to excessive water withdrawals. We estimate that if rivers’ environmental flow requirements were protected, the associated decrease in irrigation water availability would reduce global yields by ~5%. As one option to increase food supply within limited water resources, we show that dietary changes toward less livestock products could compensate for this effect. If all currently grown edible feed was directly consumed by humans, we estimate that global food supply would even increase by 19%. We thus provide evidence that dietary changes are an important strategy to harmonize river flow protection with sustained food supply.Technical summaryTo protect global freshwater ecosystems and restore their integrity, freshwater withdrawals could be restricted to maintain rivers' environmental flow requirements (EFRs). However, without further measures, reduced irrigation water availability would decrease crop yields and put additional pressure on global food provision. By comparing the quantitative effects of both global EFR protection and dietary changes on regional and global food supply in a spatially explicit modeling framework, we show that dietary changes toward less livestock products could effectively contribute to solving this trade-off. Results indicate that protection of EFRs would almost halve current global irrigation water withdrawals and reduce global crop yields by 5%. Limiting animal protein share to 25, 12.5 and 0% of total protein supply and shifting released crop feed to direct human consumption could however increase global food supply by 4, 11 and 19%, respectively. The effects are geographically decoupled: water-scarce regions such as the Middle East, or South and Central Asia would be most affected by EFR protection, whereas dietary changes are most effective in North America and Europe. This underpins the disproportionally high responsibilities of countries with resource-intensive diets and the need for regionally adapted and diverse strategies to transform the global food system toward sustainability.Social media summaryCombining dietary changes and global river flow protection could contribute to a more sustainable food system.

Semi-dry carbonation of recycled concrete paste

Demolished concrete is a large carbon sink which has not been utilized yet. Carbonation of hydrated cement paste from old concrete can effectively store CO2, and in addition, the resulting carbonated cement paste can be used as a pozzolanic material in new composite cements. This concept reduces the CO2 footprint of cement and promotes circularity and recycling. This work investigates a semi-dry gas-solid process for the carbonation of recycled cement paste. Decreasing gas humidity and hence the content of water adsorbed on the solid cement grains limits the transport of reactants from the dissolving hydrates and the overall reaction kinetics. It also leads to co-precipitation of the carbonation products, i.e., calcium carbonate and the alumina-silica gel, into a single dense matrix within the original grains. A decreasing water availability increases also the complexity and heterogeneity of the microstructure formed, since calcium carbonate precipitates as different polymorphs, including an amorphous form, and because the final phase assemblage comprises intermediate phases such as decalcified C-(A)-S-H, remains of the original hydrates in addition to the final carbonation products.

Climate Change Impact on Farmers’ Perception and Adaptation Response under Rainfed Agriculture in Southern India

Rainfed agriculture covers 80 percent of the World’s cropland and produces about 60 percent of the World’s food grains. In India, 55 percent of gross sown area accounts 40 percent of food production. In Tamil Nadu, nearly 48 per cent of gross sown area is under rainfed cultivation which is highly vulnerable to climate change and therefore it requires appropriate climate adaptation strategies. The present study covering 180 sample households to examine the farmers perception on climate change and various adaptation responses practiced in rainfed agriculture in Tamil Nadu, Southern India. The farmers were requested to choose one or more response among the three options namely, change in rainfall pattern, change in temperature and decrease in ground water availability. The results of the analysis indicated that rainfall and ground water availability are major concerns due to climate change were perceive by 84 and 58 percent of farmers. The adaptation responses to climate change are examined and the farmers were requested to indicate the various adaptation strategies viz., changing the cropping pattern, drilling new bore wells, deepening existing wells, introducing water saving irrigation methods and reducing the number of irrigations etc. The change in rainfall and temperature perceived by farmers were followed the reduction in number of irrigations, change in cropping pattern, advancement or delaying of cropping seasons and growing rain-fed crops are the major adaptation strategies to reduce the impact of climate change.

Does the Age of Pinus sylvestris Mother Trees Influence Reproductive Capacity and Offspring Seedling Survival?

We assess how the age of Pinus sylvestris mother trees influences seed size, seed viability, germination capacity and later offspring seedling survival under greenhouse conditions. Thirty trees ranging from 30 to 219 years old were selected in the north facing slopes in the Sierra de Guadarrama, where we could find the oldest Pinus sylvestris trees in central Spain. Forty cones per tree were harvested to study cone and seed characteristics (size and weight), seed viability and germination capacity related to the mother tree age. In addition, 25 germinated seeds per tree were grown in a greenhouse to assess offspring seedling survival during a death trial, where watering was stopped. Significant differences between trees in cone and seed morphological traits were observed. The age of the mother tree had a significant effect on cone size, seed size, and seed weight, but there was no effect on seed germination capacity and seed viability. Seedling survival was mainly affected by the decrease in water availability. However, a significant effect of the tree age was found once soil moisture had reached 0%. Our results show the ability of overmature Pinus sylvestris trees to maintain a relatively high reproductive capacity that assures its persistence.

Analysis of drought conditions and their impacts in a headwater stream in the Central European lower mountain ranges

Headwaters represent a significant fraction of the global stream length and are important for streamflow quality and quantity. Since climate change is predicted to affect runoff generation processes fundamentally, it is essential to understand potential consequences for the water availability in headwater catchments. The Lehstenbach catchment, located in the Fichtel Mountains (Germany), represents many headwater catchments in the lower mountain ranges in Central Europe. This study’s primary objective is to predict and analyze potential shifts in the catchment’s water balance, estimate periods of hydrological drought conditions, and their characteristics. For this purpose, we used an integrated process-based hydrological model to represent surface/groundwater interactions and runoff generation mechanisms for the Lehstenbach catchment until 2100, using a Regional Climate Model Ensemble. The simulations indicate decreased water availability in summer and autumn, mainly due to increased evapotranspiration rates. The Minimum Environmental Flow (MEF), a quantitative measure of aquatic species’ exposition to abnormally low streamflow conditions, implies an increase of low flow conditions towards 2100. A first estimate indicates a possible increase of hydrological drought duration and intensity in the future. These findings suggest severe impacts on ecosystem health and services, such as decreasing water availability, leading to consequences like forest and wetland degradation and declining biodiversity. These findings can be used to implement suitable mitigation strategies to reduce climate change effects on the headwater ecosystems, such as water shortage for irrigation and drinking water supply and loss of flora and fauna.

Climate change, climatic disasters, and adaptation techniques: learnings from the lowlands of Nepal

Nepal is experiencing inevitable consequences of changing climate. Rural communities are badly suffering from these implications. Meanwhile, the rural communities are trying to acclimatize through small–scale adaptation efforts. This study aims to analyze changes in temperature and rainfall trends, identify major climatic disasters, and document current adaptation measures being adopted by rural communities. For this study, we randomly selected 220 households from a total of 4,282 Households, and seven key informants for the questionnaire survey within the study area. Meteorological data from the nearest station were used to analyze changes in temperature and rainfall trends. The study revealed that both mean annual maximum and minimum temperature increased by 0.063 °C/year and 0.072° C/year respectively, between 1991 and 2020. Similarly, mean annual rainfall increased by 12.329 mm/year. Floods, droughts, landslides, hailstorms, and forest fires were major climate disasters experienced by the locals. The adverse impact perceived were loss of crop yield, decrease in water availability, an increase of mosquitoes, and a decline in sightings of the birds and waterfowls in the area. Embankment construction along rivers, changing cropping patterns and cultivation time, forest protection, and maintaining home gardens were major adaptation measures being practiced by the locals. We believe the findings of this study will be helpful for policymakers to develop strategies and programs for communities that will promote resilience against climate– induced disasters at a local level in the lowlands of Nepal.

Effects of Climate Change on Hydrology in the Most Relevant Mining Basin in the Eastern Legal Amazon

The Itacaiúnas River basin, an important watershed for the mining sector in Brazil, has had 51% of its native forest area deforested in the last forty years. It is in the arc of deforestation of the Amazon. It has protected areas essential to local biodiversity maintenance, in addition to owning ore reserves. Here, we present the first study to assess the mean annual, seasonal, and spatialized hydrological processes, providing results on a detailed scale in the basin, including mining sites. We used five future projections of mean monthly temperature and daily precipitation as input to the MGB hydrological model to simulate how hydrological processes, such as evapotranspiration, water availability, and high flows, may change in the next 30 years. The future decrease in precipitation (−8%) and increase in temperature (10%) may strengthen the monsoon seasonal cycle and lengthen the dry month for evapotranspiration. Furthermore, some parts of the basin expect an increase in the high flows (8.1%) and a decrease in water availability (−93.6%). These results provide subsidies to develop adaptation strategies to ensure the viability of mining operations and safeguard the surrounding environment and communities.

Regional Water Availability and WASH Indicators as Predictors of Malnutrition in Under-5 Children: Analysis of the National Family Health Survey, India (2015-16).

Water, sanitation and hygiene (WASH) practices determine child nutrition in resource-constrained countries and are influenced by regional water availability. We assessed any relationship between malnutrition and WASH practices among under-5 children in India's areas as per water availability. We did a secondary data analysis of the National Family Health Survey-IV. Stunting, wasting and being underweight were the significant outcomes. Regional water availability, households' source of water, sanitation and disposal of the child stool were the major independent variables. We report the prevalence estimates, bivariate associations and adjusted odds ratio to predict the child's malnutrition per regional water availability after using appropriate sampling weight. Of the 186875 children, 41%, 20% and 36% were stunted, wasted and underweight. Only 26% of children had access to improved drinking water sources, whereas 50.0% were defecating in open. Around 65% of children's stools were disposed of in unhygienic ways. Undernutrition depicted a significant association with independent variables. There were higher chances of stunting with a decrease in regional water availability, unimproved sanitation and unhygienic ways of stool disposal. Wasting was intensified by all these factors, except the safe disposal of stools. WASH indicators exert a protective effect on undernutrition.

Global Agricultural Water Scarcity Assessment Incorporating Blue and Green Water Availability Under Future Climate Change

AbstractClimate change was projected to have negative effects on water availability and consequently a serious constraint to food production in many areas of the world. However, such effects have not been well understood, particularly over rainfed croplands, partly because of the poor representation of green water in associated assessments. In this study, we develop an integrated agricultural water scarcity index (WSIag) that incorporates blue and green water components to examine the agricultural water scarcity in the baseline (1981–2005) and future (2026–2050) periods under the Representative Concentration Pathway (RCP)2.6 and RCP6.0 scenarios. Results show that ∼3.8 million km2 (∼39% of total) croplands experienced water scarcity in the baseline period and it would expand by more than 3% in the future. Under the two scenarios, WSIag projections are similar overall and are higher than that under the baseline in 83%–84% of global total croplands. Differences are found between the scenarios in Amazonia, Southern Africa, and South Asia. The increases in future WSIag are dominated by the decreased water availability in ∼60% of total croplands and ∼24% of which is dominated by the increased crop water requirement. Changes in green water availability have a significant contribution to changes in WSIag in 16% of global croplands, mostly in arid/semiarid regions (e.g., the South edge of the Sahel, Southern Africa, Northeast China, and Central America). This implies the important role of green water management for agriculture in these regions. The integrated assessment can help develop effective strategies for agricultural water management under climate change.

A Multidataset Assessment of Climatic Drivers and Uncertainties of Recent Trends in Evaporative Demand across the Continental United States

AbstractIncreased atmospheric evaporative demand has important implications for humans and ecosystems in water-scarce lands. While temperature plays a significant role in driving evaporative demand and its trend, other climate variables are also influential and their contributions to recent trends in evaporative demand are unknown. We address this gap with an assessment of recent (1980–2020) trends in annual reference evapotranspiration (ETo) and its drivers across the continental United States based on five gridded datasets. In doing so, we characterize the structural uncertainty of ETo trends and decompose the relative influences of temperature, wind speed, solar radiation, and humidity. Results highlight large and robust changes in ETo across much of the western United States, centered on the Rio Grande region where ETo increased 135–235 mm during 1980–2020. The largest uncertainties in ETo trends are in the central and eastern United States and surrounding the Upper Colorado River. Trend decomposition highlights the strong and widespread influence of temperature, which contributes to 57% of observed ETo trends, on average. ETo increases are mitigated by increases in specific humidity in non-water-limited regions, while small decreases in specific humidity and increases in wind speed and solar radiation magnify ETo increases across the West. Our results show increases in ETo across the West that are already emerging outside the range of variability observed 20–40 years ago. Our results suggest that twenty-first-century land and water managers need to plan for an already increasing influence of evaporative demand on water availability and wildfire risks.Significance StatementIncreased atmospheric thirst due to climate warming has the potential to decrease water availability and increase wildfire risks in water-scarce regions. Here, we identified how much atmospheric thirst has changed across the continental United States over the past 40 years, what climate variables are driving the change, and how consistent these changes are among five data sources. We found that atmospheric thirst is consistently emerging outside the range experienced in the late twentieth century in some western regions with 57% of the change driven by temperature. Importantly, we demonstrate that increased atmospheric thirst has already become a persistent forcing of western landscapes and water supplies toward drought and will be an essential consideration for land and water management planning going forward.

Evaluation of soil wetting patterns in drip irrigation

Increasing agricultural water use efficiency is of prime importance owing to the decrease in availability of fresh water for agriculture. In these circumstances, drip irrigation is considered so far as the most efficient irrigation systems and can be utilized correctly with the knowledge of dimension of the soil wetted volume which is the main factors in determining the spacing of drippers. Therefore, the present study was conducted at the Instructional Farm, Faculty of Agricultural Engineering, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal during 2019–20 to examine the vertical (Z) and horizontal (W) water fronts advance within the soil profile at the dripper in a clay loam soil. Same volume of water (50 litre) was applied at the rate of 2.3 and 4.9 lph at each irrigation. By observing the soil on the tips of the auger, the depth of wetting was determined and noted down for different points on the line of the wetted area. It was found that there is little variation in the theoretical width and depth with the actual width and depth of wetting of the soil in case of 4.9 lph discharge rate. For the given discharge rate, the inaccuracy was less for the wetted depth than the wetted diameter. So, the information obtained from this investigation, about soil wetting pattern of drip irrigation system can be helpful to decide emitter, lateral spacing and system pressure for delivering required amount of water to the plant root zone. Thus, this investigation can be instrumental in design and management of drip system, which is slowly becoming a promising agricultural water management practice to tackle the huge food productivity problem and environmental issues of developing and under-developed countries.

Effect of various crop establishment methods on the crop performance and water use efficiency of rice (Oryza sativa)

With decreasing water availability for agriculture and increasing demand for rice, water use in rice production systems has to be reduced and water productivity increased. In this paper we compared the effects of two varieties on crop performance and water use under different methods of crop establishment, in the field experiments at students’ farm, Khalsa College, Amritsar during kharif season of 2016 and 2017. The field was laid out in split plot design with four replications with two cultivars i.e., PR 126 and PR 121 in main plot treatments and six methods of sowing/transplanting i.e., W-DSR (Wet-Direct Seeded Rice) on flat beds, D-DSR (Dry-Direct seeded Rice) on flat beds, PTR (puddle transplanted rice), RSR (Ridge Sown Rice), RTR (Ridge Transplanted Rice), W-DSR (Wet- Direct Seeded Rice) on ridges, D-DSR (Dry- Direct Seeded Rice) on ridges and RTR (Ridge Transplanted Rice) were kept in sub plot treatments. The experiments were conducted in irrigated lowlands where soil texture was sandy loam. The results revealed that grain yields of rice were 72.63 q/ha and 73.54 q/ha under W-DSR on flat beds, 70.07 q/ha and 71.50 q/ha under D-DSR on flat beds, 69.24 q/ha and 73.84 q/ha under PTR, 70.48 q/ha and 73.76 q/ha under W-DSR on ridges, 74.51 q/ha and 71.64 q/ha under D-DSR on ridges and 69.21 q/ha and 73.13 q/ha under RTR in both years. Yield did not significantly differ between DSR and other crop establishment technologies in both years, but water use efficiency was higher under W-DSR on flat beds as well as on ridges than under PTR and RTR in both years. Flat sowing of rice under W-DSR was economical than other treatments. Accordingly, conventional practice of rice planting is no longer able to sustain the productivity of rice cropping systems.

Development of lab-on-chip biosensor for the detection of toxic heavy metals: A review

Recently, a decrease in water availability and quality has been raised due to rapid industrialization, unsustainable agricultural activities and anthropogenic activities. Heavy metals are considered significant pollutants in the water environment, cause environmental hazards and health effects to humans. For monitoring water contaminants utilized different conventional techniques. Still, they have some drawbacks, such as cost expensive, ecological issues, and processing time, requiring technicians and researchers to operate them effectively. Biosensors have become reasonable devices for screening and identifying environmental contaminants because of their different benefits contrasted with other detecting techniques. This review summarizes the toxic effect of heavy metal and their source, occurrence. A detailed discussion is provided on the heavy metal recognition materials for detecting heavy metals in wastewater. Lab on chip (LOC) is an emerging micro-electrical mechanical system (MEMS) device that intakes liquid and makes it move through the micro-channels, to accomplish fast, cost-effective and profoundly sensitive analysis with significant yield. LOC also provided a discussion on numerous laboratory functions on a single platform. This article attempts to discuss the detection of heavy metals using lab on a chip by suitable recognition materials. Further, the design and fabrication mechanism and their recognition abilities of LOC were also reviewed. The review mainly focuses on the application of LOC biosensors, pros, and cons, and suggests a roadmap towards future development to enhance the practical use in pollutant monitoring.

High Phenotypic Plasticity, but Low Signals of Local Adaptation to Climate in a Large-Scale Transplant Experiment of Picea abies (L.) Karst. in Europe

The most common tool to predict future changes in species range are species distribution models. These models do, however, often underestimate potential future habitat, as they do not account for phenotypic plasticity and local adaptation, although being the most important processes in the response of tree populations to rapid climate change. Here, we quantify the difference in the predictions of future range for Norway spruce, by (i) deriving a classic, occurrence-based species distribution model (OccurrenceSDM), and (ii) analysing the variation in juvenile tree height and translating this to species occurrence (TraitSDM). Making use of 32 site locations of the most comprehensive European trial series that includes 1,100 provenances of Norway spruce originating from its natural and further beyond from its largely extended, artificial distribution, we fit a universal response function to quantify growth as a function of site and provenance climate. Both the OccurrenceSDM and TraitSDM show a substantial retreat towards the northern latitudes and higher elevations (−55 and −43%, respectively, by the 2080s). However, thanks to the species’ particularly high phenotypic plasticity in juvenile height growth, the decline is delayed. The TraitSDM identifies increasing summer heat paired with decreasing water availability as the main climatic variable that restricts growth, while a prolonged frost-free period enables a longer period of active growth and therefore increasing growth potential within the restricted, remaining area. Clear signals of local adaptation to climatic clines spanning the entire range are barely detectable, as they are disguised by a latitudinal cline. This cline strongly reflects population differentiation for the Baltic domain, but fails to capture the high phenotypic variation associated to the geographic heterogeneity in the Central European mountain ranges paired with the species history of postglacial migration. Still the model is used to provide recommendations of optimal provenance choice for future climate conditions. In essence, assisted migration may not decrease the predicted range decline of Norway spruce, but may help to capitalize on potential opportunities for increased growth associated with warmer climates.