Largest Water Use Research Articles

Larger water use efficiency associated with greater dependence on deep water sources in hot-dry valleys with reservoirs

Identifying the carbon–water relationship of plants helps to understand their adaptive water use strategies. The relationship between WUE and the water source remains uncertain in the hot-dry valleys with reservoirs. The leaf δ13C and soil and xylem water isotopes (δ2H and δ18O) were determined to identify the WUE and water source contributions, respectively, in Leucaena leucocephala (Lam.) de Wit communities. We propose a source contributing score (SCS), calculated as a value for the contribution of water from different soil layers (a higher SCS value indicates plants use deeper water sources). The positive relationship between leaf δ13C and SCS (R2 = 0.16, P = 0.022) and the negative relationship between leaf δ13C and topsoil contribution (R2 = 0.21, P = 0.009) confirmed the close association of larger WUE with less reliance on shallow soil water. The redundancy analysis suggested a stronger connection between leaf δ13C and d-excess than leaf δ13C and topsoil moisture content, which emphasized the key role of soil moisture d-excess. Variation partitioning analysis (VPA) suggested soil properties and microclimate explain more than 89.8 % of the variations in tree water use. VPA also suggested different roles of microclimate and soil properties in explaining tree water use strategies. Findings broadened the understanding of the relationship between WUE and water sources and emphasized the key role of soil moisture d-excess in hot-dry valleys with reservoirs.

Projecting China’s future water footprints and water scarcity under socioeconomic and climate change pathways using an integrated simulation approach

Future changes in climate and socioeconomic systems will exacerbate water scarcity. Previous studies on China’s water footprint and scarcity often consider only climate change or socioeconomic factors in isolation. Here, we address these issues by coupling an integrated assessment model, the Global Change Analysis Model, with a global hydrological model to project China’s future water footprints and water scarcity, considering both climate change and socioeconomic factors. We simulated China’s water footprints under 52 scenarios, which include four global climate models (GCMs) and 13 combinations of Shared Socioeconomic Pathway (SSP)–Representative Concentration Pathway (RCPs) scenarios. We then projected the intensity of water stress (WSI), defined as a ratio of water footprint to renewable water volume, based on the simulations of the SSP2-RCP6.0 scenario. Our results align well with statistical data on water footprint variations between 2005 and 2020. China’s water footprints are likely to peak around 2030 and then decrease. We find through a scenario matrix analysis that emission-mitigation measures will significantly impact the water footprint, particularly in the electricity sector, which will become the largest water use sector in the future. This means that the low carbon energy option on China’s path to carbon neutrality may aggravate water scarcity. Water stress in China is projected to be greatest in 2025–2035, and all northern basins will experience water scarcity. Projections based on all GCMs consistently show a decline in WSI in China after 2050.

Water use and soil water balance of Mediterranean tree crops assessed with the SIMDualKc model in orchards of southern Portugal

Orchards consist of complex agricultural systems, with a variety of characteristics (planting density, tree height, training system, canopy cover, irrigation method, interrow management) influencing crop evapotranspiration (ETc). Thus, irrigation water management requires finding crop coefficients (Kc) that represent the characteristics of local orchards, evidencing the need for site specific data. The main objective of this study was to derive the Kc of almond, olive, citrus, and pomegranate orchards in Alentejo, southern Portugal, wherein they became dominant over the last decade. Monitoring was carried out in nine orchards, which management decisions were performed by the farmers. The ETc was estimated from the soil water balance computed for each orchard using the FAO56 dual-Kc approach with the SIMDualKc model. The model successfully simulated the soil water contents measured in the various fields along two growing seasons, with root mean square error values lower than 0.005 m3 m−3 and modeling efficiencies from 0.363 to 0.782. The estimated basal crop coefficients (Kcb) for the initial, mid- and end-seasons were respectively 0.22, 0.58, and 0.50 for almond; 0.32–0.33, 0.35–0.36, and 0.33–0.34 for olive; 0.40, 0.40–41, and 0.40–0.41 for citrus; and 0.24, 0.60, and 0.52 for pomegranate. Small variations in olive and citrus Kcb values were found to be related to differences in the fraction of the ground covered by trees’ canopies and tree height. The single Kc values, which included the component relative to soil evaporation, were also estimated. Furthermore, evaluation of the soil water balance in the nine case studies showed salinity effects in one almond orchard, mild irrigation water deficits in olive systems, and large non-consumptive water use in citrus and pomegranate orchards. These results evidence the need for better management of orchards irrigation water in the region, and the current study provides for reliable information on the Kc of tree crops to support improving the management of local orchard systems and the preservation of soil and water resources. Aimed at these resources and the sustainability of their use, simulated alternative irrigation schedules were performed, which identified possible water savings of 20 mm in case of olives, up to 855 mm for citrus.

Urban water health: A conceptual framework and assessment system

The quantitative evaluation of urban water health (UWH) is a crucial decision-making process in water management. Healthy water not only encompasses excellent water quality and a diverse ecology but also has other characteristics, such as the amount of water resources, supply-use-drainage problems, flooding, water cycle, and so on. This study proposes a theoretical framework and an indicator system for UWH that integrates ecosystem health and water cycle health. Subsequently, considering the time scale and regional characteristics, an objective evaluation model that combined the real coding accelerated genetic algorithm (RAGA) method and the projection pursuit (PP) method was applied to calculate indicator weights and thresholds for the urban water health index (UWHI). UWHI standard thresholds were calculated as (0.04, 0.87], (0.87, 1.80], (1.80, 2.73], (2.73, 3.50], and (3.50, 4.01] corresponding to the categories of Sick, Unhealthy, Subhealthy, Healthy, and Excellent, respectively. Using Chongqing as a case study, the results showed that the UWHI increased from 1.796 to 2.668 in 2011–2020, and the health level improved from Unhealthy to Subhealthy, approaching Healthy. For each subsystem, the results indicated that the health status of the water cycle was superior to that of the water ecosystem. Finally, a detailed analysis of the changes in the indicators identified important factors affecting water health. The results of this study revealed that the main weaknesses in Chongqing were severe soil erosion, large domestic water use, high water consumption rates, and unsatisfactory water functional areas and indicated key priorities on the path to future water management.

3D characterization of crop water use and the rooting system in field agronomic research

Most field crop phenotyping research has focused on the above-ground parts of crops, ignoring a “hidden half”: the rooting system and its activity. Here we propose and test a new approach to produce 3D characterizations of crop water use and root activity in large field genotype (G) by environment (E) by management (M) experimentation, using electromagnetic induction (EMI) instrument coupled with a quasi-2D inversion algorithm, and crop canopy sensing technologies. A root activity factor (R) was calculated as a function of crop water use, soil water availability, and an indicator of crop demand. We ask i) can this approach provide accurate 3D characterizations of sorghum water use and root activity?, and (ii) does the approach capture complex GxExM dynamics?. This study was conducted based on an on-farm field experiment consisting of the factorial combination of six commercial sorghum genotypes (G), three times of sowing, two levels of irrigation (E), four plant densities (M), and three replications. Two EMI surveys ten days apart were collected using a DUALEM-21S sensor. An artificial neural network (ANN) model was developed to predict 3D soil moisture (θv) using depth-specific true soil electrical conductivity (σ, mS m−1) estimated by the inversion algorithm. Crop water use between surveys was described as the difference of θv. A multispectral index derived from satellite imagery was used as a proxy for crop demand i.e., size of the crop canopy. Principal components analysis, linear mixed models, and recursive partitioning tree techniques and crop-eco-physiological principles were used to untangle complex GxExM interactions. Results indicate that 3D crop water use could be predicted with high accuracy (LCCC = 0.81) and low prediction error (RMSE = 0.03 cm3 cm−3). The calculated water use and the value of R were significantly affected by depth, crop growth stage, irrigation treatment, plant density, and their interactions. At flowering, roots were most active at 0–1.3 m under irrigation, and deeper (0.5–1.5 m) under dryland treatment. The highest water use was for three genotypes (i.e., C, E and F) grown under irrigation and high plant densities (i.e., 9 and 12 pl m-2). The smallest water use was observed under dryland treatment, particularly for two genotypes (i.e., B and C) and high plant densities. For the crops at vegetative stages, the values of water use and R were highest in the top 0.5 m of soil depth. Larger water use was observed under dryland treatment and high plant densities, while the effects of genotypes were small (not significant). We conclude that the approach provides a rapid, accurate and cost-efficient option to phenotype crop root activity i.e., water use, in large field experimentation. We also argue that the improved understanding of the crop water use dynamics can help inform optimum combinations of genotypes and management options i.e., crop designs, across contrasting environments, and help untangle complex GxExM interactions.

Trading a little water for substantial carbon gains during the first years of a Eucalyptus globulus plantation

The establishment and expansion of commercial plantations for timber production and carbon sequestration raises concerns because of their large water use. Eucalyptus globulus (blue gum) is one of the most planted species globally, as it grows rapidly and is adaptable to a range of climatic conditions. The dearth of experimental observations on water use and growth in blue gum plantations in their early years after establishment makes it difficult to develop management practices. This study quantified the trade-offs between water use and carbon assimilation in a blue gum plantation in the first 4 years after establishment. The study site is located in southwest Victoria, Australia, where energy, water and CO2 fluxes were continuously measured above the tree canopy for 4 years after the trees were planted. During the first year after establishment, understory vegetation and ecosystem respiration had a major impact on the net ecosystem exchange (NEE), with the plantation being a net carbon source. Subsequently, the trees started dominating the contributions to NEE, and after approximately 2 years the plantation became a consistent carbon sink. These shifts in NEE were accompanied by smaller increases in annual evapotranspiration rates, which was 70% of the annual precipitation in the first year and 74% in the 3rd year of measurements. As a result, yearly averages of water use efficiency increased from 2.86 gCkg−1H2O in 2018 to 4.3 gCkg−1H2O in 2020, following tree development. This shows a remarkable increase in productivity at the expense of a small amount of water.

Lightweight and Compact Radiometers for Soil Moisture Measurement: A review

Fresh water is considered to be one of the most precious natural resources in many countries. Given that soil moisture plays a salient role in vegetation growth, the continuous and timely measurement of soil moisture content is critical to manage water shortages, especially in the agriculture sector <xref ref-type="bibr" rid="ref1">[1]</xref>, <xref ref-type="bibr" rid="ref2">[2]</xref>, which is the largest water use sector in Australia. A 10&#x0025; water savings in the Australian agriculture sector would be equivalent to a reduction of more than 30&#x0025; of the combined water consumption from Australian capital cities <xref ref-type="bibr" rid="ref3">[3]</xref>. Further, soil moisture influences the process of rainfall being partitioned into runoff and infiltration, and saturated soil could turn heavy rain into floods. Therefore, soil moisture information is essential for accurate climate forecasting as well as improving flood and drought prediction <xref ref-type="bibr" rid="ref3">[3]</xref>&#x2013;<xref ref-type="bibr" rid="ref4"/><xref ref-type="bibr" rid="ref5">[5]</xref>.

From Torrents to Trickles: Irrigation's Future in Africa and Asia

Irrigation has been a key component of agricultural intensification and transformation in Asia and has the potential to take on the same role in Sub-Saharan Africa. Irrigation has contributed to increased food production, lower food prices, higher rural employment, and overall agricultural and economic growth. At the same time, irrigation—through its large consumptive water use—has accelerated water depletion, degradation, and pollution; moreover, it has benefitted richer farmers more than poorer farmers. This article reviews the contributions and challenges of irrigation and identifies a series of measures to increase the sustainability and equity of irrigation going forward.

Ammonium fertilization increases pearl millet yield by promoting early root growth, higher tillering, and water use during grain filling in a low P Sahelian soil

AbstractBackground: Adaptation of pearl millet [Pennisetum glaucum (L.) R. Br.] to low soil phosphorus (P) at early seedling stages and efficient P fertilizer application are crucial for its survival in the West African Sahel. While addition of to P in the microdose technique has been reported to stimulate early growth of pearl millet, there is little information regarding root length (RL) at different timings.Aims: Our study aimed at assessing the effects of added and to P on (1) pearl millet agronomic traits such as root and shoot growth and (2) the water use dynamics during the cropping cycle.Methods: Twenty‐four “RhizoTubes” filled with P‐deficient soil were used to grow pearl millet under three treatments: (T1) placed P addition alone at 0.4 g per seed hole, Pplaced, (T2) Pplaced + , and (T3) Pplaced + . At 2, 3, 4, and 5 weeks after sowing (WAS) we took non‐destructive measurements of RL. Water use (transpiration) was measured from 3.5 to 9 WAS.Results: At early growth, roots in the topsoil of T2 were longer than T3 and T1 roots (at 4 WAS: 129.3 cm for T2, 87.5 cm for T3, and 93.3 cm for T1, p &lt; 0.05). Total RL at 2 WAS correlated positively with seedling height and final grain yield. Fertilization with reduced the time to flowering and increased the number of tillers and grain yield, whereas addition of increased vegetative dry matter at harvest and water use efficiency.Conclusions: Our findings suggest that fertilization with plays a critical root stimulating role at early growth stages, seemingly by increasing lateral root initiation, which carries through to a larger water use during grain filling and higher grain yield.

Burning Water, Overview of the Contribution of Arjen Hoekstra to the Water Energy Nexus

This paper gives an overview of the contribution of water footprint (WF) studies on water for energy relationships. It first explains why water is needed for energy, gives an overview of important water energy studies until 2009, shows the contribution of Hoekstra’s work on WF of energy generation, and indicates how this contribution has supported new research. Finally, it provides knowledge gaps that are relevant for future studies. Energy source categories are: 1. biofuels from sugar, starch and oil crops; 2. cellulosic feedstocks; 3. biofuels from algae; 4. firewood; 5. hydropower and 6. various sources of energy including electricity, heat and transport fuels. Especially category 1, 3, 4, 5 and to a lesser extent 2 have relatively large WFs. This is because the energy source derives from agriculture or forestry, which has a large water use (1,2,4), or has large water use due to evaporation from open water surfaces (3,5). WFs for these categories can be calculated using the WF tool. Category 6 includes fossil fuels and renewables, such as photovoltaics and wind energy and has relatively small WFs. However, information needs to be derived from industry.

Global convergence but regional disparity in the hydrological resilience of ecosystems and watersheds to drought

Drought is a major climate disturbance that can lower vegetation productivity and induce widespread vegetation die-off, which in turn can have a profound effect on the water cycle. Therefore, quantification of vegetation-specific responses to drought is essential to predict the impacts of climate change on ecosystem services. We used two previously-suggested quantitative metrics – dynamic deviation (d) and elasticity (e) based on the Budyko framework –to evaluate site- and watershed-level hydrological resilience of different plant functional types (PFTs) to drought. By using data from 41 FLUXNET sites and 2275 watersheds, we found a global convergence in hydrological resilience to drought across a variety of PFTs. Hydrological resilience of vegetation was related to drought intensity and water use efficiency. A greater hydrological resilience was found in PTFs in drier areas than in wetter areas, while this greater hydrological resilience was related to the coefficient of variation in precipitation. We also found that PFTs with a larger water use efficiency had higher hydrological resilience, particularly in drier regions, indicating adaptation strategies to changes in local climate conditions. Our findings can shed light on how ecosystems and watersheds dominated by different PFTs will respond to future climatic change and inform water resources management.

Can Water Rights Trading Scheme Promote Regional Water Conservation in China? Evidence from a Time-Varying DID Analysis

Using the panel data of 30 provinces in China from 1998 to 2017, we adopt a time-varying difference-in-differences (time-varying DID) model to estimate the impact of water rights trading scheme on regional water consumption. The results show that water rights trading can significantly promote water conservation in the pilot regions by 3.1% compared to that in the non-pilot regions, and a series of robustness tests show consistent results. Policy effects are mainly driven by improving water-use efficiency and adjusting water structure; that is, by transferring water resources from the agricultural sector to the other sectors, agricultural water efficiency is improved and water conflict among sectors is alleviated; thus, water saving is achieved. In addition, by constructing two indexes of regional water pressure and tradable water resources, our heterogeneity analysis shows that water rights trading performs better in areas with high water pressure and large tradable water resources. Under the high pressure of large water use and low water endowment, water rights trading will evidently reduce water consumption more so than in the low-pressure regions, and with water rights trading, it is hard to achieve a policy effect in regions without sufficient tradable water resources. This paper provides important policy implications for China for further promoting the water rights trading scheme in the field of resource conservation.

Time series analysis of water use and indirect reuse within a HUC-4 basin (Wabash) over a nine year period

Anthropogenic water use and reuse represent major components of the water cycle. In the context of climate change, water reuse and recycling are considered necessary components for an integrated water management approach. Unplanned, or de facto, indirect water reuse occurs in most of the U.S. river systems, however, there is little real-time documentation of it. Despite the fact that there are national and state agencies that systematically collect data on water withdrawals and wastewater discharges, their databases are organized and managed in a way that makes it challenging to use them for water resource management analysis. The ability to combine reported water data to perform large scale analysis about water use and reuse is severely limited. In this paper, we apply a simple but effective methodology to complete a time series watershed-scale analysis of water use and unplanned indirect reuse for the Wabash River Watershed. Results document the occurrence of indirect water reuse, ranging from 3% to 134%, in a water-rich area of the U.S. The time series analysis shows that reported data effectively describe the water use trends through nine years, from 2009 to 2017, clearly reflecting both anthropogenic and natural events in the watershed, such as the retirement of thermoelectric power plants, and the occurrence of an extreme drought in 2012. We demonstrate the feasibility and significance of using available water datasets to perform large scale water use analysis, describe limitations encountered in the process, and highlight areas for improvement in water data management.

A study on water's green economy for development in agriculture

The concept of a green economy has gained currency in recent years as a paradigm for promoting economic growth and increased well-being while protecting the environment and contributing to poverty alleviation. There is no common definition of green economy, but the term clearly emphasizes the economic dimension of sustainability. Not only do the environmental (stewardship) and economic (growth) dimensions coexist in the green economy, but they are also complementary and mutually reinforcing strategies to achieve development. Water scarcity, pollution, and other water related environmental and ecological problems have been increasing rapidly in many areas of the world. Water demand management or making better use of the water we have as opposed to augmenting supply is increasingly proposed as a way of mitigating water scarcity problems. Although the achievements of irrigation in ensuring food security and improving rural welfare have been impressive, past experience also indicates problems and failures of irrigated agriculture. In addition to large water use and low efficiency, environmental concerns are usually considered the most significant problem of the irrigation sector. Environmental problems include excessive water depletion, water quality reduction, water logging and salinization. In some basins (water resources), excessive diversion of river water for irrigation (and other uses) has brought environmental and ecological disasters to downstream areas, and groundwater pumping at unsustainable rates has contributed to the lowering of groundwater tables and to salt water intrusion in some coastal areas. Many water quality problems have also been created or aggravated by changes in stream flows associated with agriculture’s consumptive uses. Moving water away from agriculture to uses with higher economic value is one of the main measures widely seen as desirable. This apparent misallocation is often attributed to the failure of government to allocate water rationally. This paper focuses on achieving a sustainable balance between irrigation management and sustainable development and water investments.

Soil respiration and its responses to biotic and abiotic factors in patchy remnant forests and urban green landscapes of Tianjin, China

Soil respiration (Rs) of forests plays an important role in the global carbon cycle. However, patchy remnant forests and their Rs characteristics are rarely studied. In this study, the diurnal and seasonal dynamics of the Rs of three patchy remnant forests and two urban green landscapes were determined using a portable soil carbon flux automatic analyzer in the urban fringe of Tianjin, China. Then, the effects of abiotic and biotic factors on the Rs of the patchy remnant forests and urban green landscapes were evaluated. Results showed that the patchy remnant forests had higher Rs than the urban green landscapes throughout the year. However, the Rs responses of the patchy remnant forests to soil temperature (ST) were more modest than those of the urban green landscapes, which indicated the higher resistant capacity to global warming of the former than the latter. In contrast to the pair traits of Rs-ST, fit lines of Rs and soil water content (SWC) showed an opposite trend in the growing and dormant periods. In the growing season, the slopes of Rs-SWC were similar between the patchy remnant forests and the urban green landscapes. The higher y-intercept of the patchy remnant forests indicated their larger water use efficiency than the urban green landscapes. In the dormant period, the higher slope of Rs-SWC for the patchy remnant forests suggested they were more sensitive to changes in SWC than the urban green landscapes. Meanwhile, the linear slopes of Rs and fine root biomass (FRB) were lower in the patchy remnant forests than in the urban green landscapes, which demonstrated that the Rs of the patchy remnant forests increased gently with increasing FRB. In addition, Rs was positively correlated with the amounts of bacteria and actinomycetes but negatively correlated with fungi. Results of canonical correlation analysis showed that the first two driving factors on the Rs of the patchy remnant forests were ST and FRB.

Watershed water balance changes as furrow irrigation is converted to sprinkler irrigation in an arid region

Irrigation is the largest water use in the western United States. The Upper Snake Rock Conservation Effects Assessment Project in southern Idaho began in 2005 to quantify the impacts of conservation practices in this irrigated watershed. The objective of this study was to determine the changes in the watershed water balances as farmers converted furrow irrigated fields to sprinkler irrigation from 2006 to 2016. More than 75% of annual watershed inflow was irrigation water diverted into the watershed from the Snake River and distributed through canals to 82,000 ha of cropland, while annual precipitation was only 10% to 23% of the annual inflow. Approximately 30% of the annual watershed inflow flowed back to the Snake River as irrigation return flow. Water balances showed that irrigation exceeded evapotranspiration (ET) in the spring and fall, indicating that irrigation diversions could be reduced early and late in the irrigation season. Annual irrigation project efficiency, defined as ET divided by the amount of diverted irrigation water, varied from 61% to 73%, but project efficiency did not increase as the amount of cropland that was sprinkler irrigated increased from 46% in 2006 to 59% in 2016. The only significant trends indicating that increasing sprinkler irrigation impacted the water balances were increasing irrigation project efficiency in July and increasing irrigation return flow during the irrigation season. Farmers may be applying less irrigation water with sprinkler irrigation compared to furrow irrigation, which could have caused return flow to increase since irrigation diversions did not change with the supply-based water allocation. Irrigation scheduling based on soil moisture measurement or daily ET would help irrigation application match crop water needs on individual fields. For the entire irrigation project, irrigation efficiency could improve if irrigation diversions into the watershed could be adjusted to more closely match ET in the spring and fall, which may require structural changes to the canal system and policy changes for the Snake River reservoir system.

Socioeconomic drivers of water use in China during 2002–2017

Rapid socioeconomic transitions have significantly influenced water use in China. This study aims to evaluate the water use implications of the changes in China’s economic development patterns and urbanization process. We quantify the relative contributions of various socioeconomic factors to water use changes during 2002–2017, based on environmentally extended input-output analysis and structural decomposition analysis. The results show that China’s water use has increased by 58 billion m3 during 2002–2012, and then decreased by 13 billion m3 during 2012–2017. Water use efficiency gains and economic structural improvements effectively offset the increase in water use, which is driven by the rising final demand level and growing population. Slight changes in inter-sectoral transactions of water intensive sectors would lead to significant influences on the effects of production structure changes on water use changes. Thus, close attention should be paid to the changes in production structures of these sectors. In addition, the effects of the urbanization process are mainly reflected by the growing gaps between water uses caused by rural and urban households, as well as increased urbanization-related water use. This is notably driven by intensive investments in construction activities. Water conservation policies in China should specially focus on the optimization of production structure, such as improving the production efficiency of sectors with large consumption-based water use.

Effect of Irrigation Strategies on Yield of Drip Irrigated Sunflower Oil and Fatty Acid Composition and its Economic Returns

A field trial was conducted to observe the effects of different irrigation strategies on the yield and the water use, oil content and marginal return of sunflower which was irrigated by means of a drip system during 2010 and 2011 under Cukurova condition of Turkey. The irrigation strategies include three irrigation intervals (A1: 25 mm; A2: 50 mm; A3: 75 mm of cumulative pan evaporation) and six water levels (WL) based upon the percentages of cumulative pan evaporation (WL1= 0.50, WL2= 0.75, WL3= 1.00 and WL4= 1.25). In addition, WL5= PRD50 and WL6= PRD75 treatments were evaluated. They obtained water from alternative laterals 50% and 75% of the WL3 treatment. Additionally, a nonirrigated treatment (NI) was included as control plot in the experiment. In each of the experimental years, the largest and the smallest average yields were acquired from the A2WL4 and NI treatments, respectively. The oil content and fatty acid composition were significantly affected by irrigation strategies. The oil content increased with the increasing amount of irrigation. Among all irrigation intervals, PRD-50 (WL5) treatment provided the largest water use efficiency (WUE) and irrigation water use efficiency (IWUE) values in both growing seasons. In order to attain higher yields and a generated the marginal return, A2WL4 irrigation regime is suggested for sunflower production in the Mediterranean region. A2WL3 water strategy is proposed for an acceptable marginal return in case of water shortage.

Field-grown transgenic wheat expressing the sunflower gene HaHB4 significantly outyields the wild type.

HaHB4 is a sunflower transcription factor belonging to the homeodomain-leucine zipper I family whose ectopic expression in Arabidopsis triggers drought tolerance. The use of PCR to clone the HaHB4 coding sequence for wheat transformation caused unprogrammed mutations producing subtle differences in its activation ability in yeast. Transgenic wheat plants carrying a mutated version of HaHB4 were tested in 37 field experiments. A selected transgenic line yielded 6% more (P<0.001) and had 9.4% larger water use efficiency (P<0.02) than its control across the evaluated environments. Differences in grain yield between cultivars were explained by the 8% improvement in grain number per square meter (P<0.0001), and were more pronounced in stress (16% benefit) than in non-stress conditions (3% benefit), reaching a maximum of 97% in one of the driest environments. Increased grain number per square meter of transgenic plants was accompanied by positive trends in spikelet numbers per spike, tillers per plant, and fertile florets per plant. The gene transcripts associated with abiotic stress showed that HaHB4's action was not dependent on the response triggered either by RD19 or by DREB1a, traditional candidates related to water deficit responses. HaHB4 enabled wheat to show some of the benefits of a species highly adapted to water scarcity, especially in marginal regions characterized by frequent droughts.

Development of an integrated method of concentration and immunodetection of bacteria.

The microbial quality of water is a key aspect to avoid environmental and public health problems. The low pathogen concentration needed to produce a disease outbreak makes it essential to process large water volumes and use sensitive and specific methods such as immunoassays for its detection. In the present work, we describe the development of a device based on microfiltration membranes to integrate the concentration and the immunodetection of waterborne bacteria. A microfiltration membrane treatment protocol was designed to reduce the non-specific binding of antibodies, for which different blocking agents were tested. Thus, the proof of concept of the microbial detection system was also carried out using Escherichia coli as the bacterial pathogen model. E. coli suspensions were filtered through the membranes at 0.5mLs-1, and the E. coli concentration measurements were made by absorbance, at 620nm, of the resultant product of the enzymatic reaction among the horseradish peroxidase (HRP) bonded to the antibody, and the substrate 3,3',5,5'-tetramethylbenzidine (TMB). The results showed that the homemade concentration system together with the developed membrane treatment protocol is able to detect E. coli cells with a limit of detection (LoD) of about 100CFU in 100mL. Graphical abstract Scheme of the integrated method of concentration and immunodetection of bacteria.