Indicator Of Water Use Efficiency Research Articles

Isotope-Based Techniques to Investigate Factors Influencing Water Use Efficiency in Pinus koraiensis Leaves during Plant Growth.

Plant water use efficiency (WUE) is a comprehensive physiological indicator of plant growth and ability to adapt to drought. However, research on the mechanisms controlling WUE during plant growth and development remains weak. Here, we studied Pinus koraiensis as a typical evergreen conifer species in Northeast China. After collecting 80 tree samples with varying diameters at breast height (DBH), we measured δ13C and δ18O as an indicator of WUE, leaf morphology (volume, dry weight, and total epidermal area), ecological stoichiometry (carbon, nitrogen, and phosphorus content), and abiotic factors (light environment, soil pH, soil water content, and soil nutrient content). Correlational analysis of these variables revealed distinct differences between smaller/younger and larger/older plants: (1) In plants with DBH less than 52 cm, δ13C was positively related to DBH, and δ18O was negatively related to DBH. Plants with DBH greater than 52 cm showed no relationship between δ13C and DBH, and δ18O was positively related to DBH. (2) In plants with DBH less than 52 cm, there was a negative correlation between δ13C and δ18O and between δ13C and leaf phosphorus content (LP), but a positive correlation between δ13C and DBH, leaf mass per area (LMA), and leaf density (LD). The slopes of DBH-δ13C, δ18O-δ13C, leaf nitrogen content (LN)-δ13C, and LMA-δ13C correlations were greater in smaller plants than large plants. (3) Structural equation modelling showed that in smaller plants, DBH had a direct positive effect on δ13C content and a direct negative effect on δ18O, and there was a direct positive effect of light environment on δ18O. In larger plants, there was a direct negative effect of light environment on δ13C and a direct positive effect of DBH on light environment, as well as a negative effect of soil nitrogen content on leaf nitrogen. In smaller plants, DBH was the most important factor influencing δ13C, followed by δ18O and soil moisture, with light and soil pH showing minimal influence. In larger plants, light environment influenced δ13C the most, followed by soil nitrogen content and soil moisture content, with leaf nitrogen and DBH contributing little. The results suggest that water use efficiency strategies of P. koraiensis vary according to growth stage, and the effects of abiotic factors and functional traits vary at different growth stages.

High-throughput phenotyping reveals multiple drought responses of wild and cultivated Phaseolinae beans.

Although drought resistance of a plant may be achieved through morphological, structural, physiological, cellular, and molecular adaptations, most studies remain limited to quantifying the effect of drought on biomass. Using a highthroughput phenotypic imaging system, we evaluated the drought resistance of 151 bean accessions (Phaseolinae; Fabaceae) in an explorative approach, by quantifying five different traits simultaneously: biomass, water use efficiency (WUE), relative water content (RWC), chlorophyll content (NDVI), and root/shoot ratio. Since crop wild relatives are important resources for breeding programs, we analyzed both wild and cultivated accessions, most of which have never been evaluated for drought resistance before. We demonstrate that the five traits are affected very differently by drought in the studied accessions, with significant correlations existing only between the biomass and WUE indicators (r=0.39), and between the RWC and NDVI indicators (r=0.40). When grouping accessions by subgenus or by species, large intraspecific and withinsubgenus variation was found. For this reason, we performed a cluster analysis, which grouped the accessions into five distinct clusters with similar response profiles. We also correlated the drought resistance for each accession to local climate variables at their original collection sites. The biomass, WUE, and RWC indicators were significantly correlated to annual precipitation (r=0.40, r=0.20, r=0.22, respectively), confirming that accessions from arid environments are generally more drought resistant. Our results demonstrate that the drought resistance of Phaseolinae beans is a multifaceted characteristic and cannot be simply quantified through biomass. Furthermore, the broader knowledge of the drought resistance of the accessions studied here may prove an invaluable resource for future crop production.

Effect of Water Regime, Nitrogen Level, and Biostimulant Application on the Water and Nitrogen Use Efficiency of Wild Rocket [Diplotaxis tenuifolia (L.) DC

The use of biostimulants in agriculture is an emerging technique that can contribute to improved production and resource use efficiency. This research was carried out in southern Italy to evaluate the biostimulating effects of seaweed extract (SW) and azoxystrobin (AZ) on wild rocket subjected to two water regimes (WRs) and three nitrogen levels (NLs), and grown in pots under unheated greenhouse conditions. The following treatments were compared: (i) two WRs: restoration of 100% (WR100) and 50% (WR50) of crop evapotranspiration; (ii) three NLs: 0 (N0), 75 (N75), or 150 (N150) kg ha−1 of N; and (iii) three biostimulants (BSs): an untreated control (C), and the application of AZ or SW. This paper reports the effects on N uptake (Nup), N use efficiency (NUE), and water use efficiency (WUE). The following indicators of NUE were assessed: apparent recovery efficiency (RE), internal utilization efficiency (IE), partial productivity factor (PFPn) of N supplied, agronomic efficiency (AE), and physiological efficiency (PE). The following indicators of WUE were assessed: photosynthetic WUE (p_WUE), yield WUE (Y_WUE), biomass WUE (B_WUE), and irrigation yield WUE (IY_WUE). The indicators of NUE were affected differently by treatments. RE was 20% higher with SW. IE was higher with AZ. PFPn increased by 10.4 and 8.1% with AZ and SW, respectively. AE increased by 10.9 and 19.9% after applying AZ and SW, respectively. PE rose by 6.7 and 9.3% after applying AZ and SW. AZ and SW improved p_WUE, mainly under water deficit (interaction of WR × BS). With AZ application, Y_WUE, B_WUE, and IY_WUE were higher by 17.8, 13.8, and 19.3%, respectively, while the application of SW resulted in a smaller increase (9.5–7.7 and 9.9%). SW and AZ were shown to be effective through the moderate improvement of wild rocket’s nitrogen and water use efficiency. The two biostimulants were more effective at improving p_WUE in water deficit conditions, proving to be particularly useful for farmers operating with water scarcity. Therefore, they can provide valuable support to farmers by improving the sustainability of resource use.

Contributions of climatic and social factors to two water use efficiency indicators in the Yellow River

AbstractTracing the spatiotemporal tendency and driving forces of water use efficiency (WUE) is of great significance for understanding the carbon‐water balance, especially in large river basins. The lack of differential comparisons regarding the tendencies and driving forces of WUE indicators between the upper and lower reaches of rivers often affects the collaborative allocation and utilization of water resources at the basin scale, especially social factors such as population and economy distributions. Using remote sensing data and hierarchical decomposition methods, we identified the spatiotemporal distribution of the WUE of ecosystems (WUEe) and the WUE of canopies (WUEc) in the Yellow River Basin from 2003 to 2017 as well as the contribution rates of climatic and social factors to WUEe and WUEc. Our results show that WUEe had a different distribution pattern than WUEc. An increase in WUEe was accompanied by a decrease in WUEc, and these changes varied among the upper, middle and lower reaches. WUEc was most negatively correlated with pressure (| r | = 0.65), while WUEe was most positively correlated with the precipitation rate (| r | = 0.68). The contribution rates of climatic factors to both WUEc and WUEe in the upper reaches were higher than 95%. The middle reaches were mainly driven by climatic factors, with contribution rates higher than 90%. In the lower reaches, the contribution rates of social factors to WUEe were higher than 30%. These differentiated contributions indicated the importance of considering social factors in the lower reaches than in the upper reaches when managing WUEe under the dominance of climatic factors on WUEc.

Agronomic performance, nitrogen acquisition and water-use efficiency of the perennial grain crop Thinopyrum intermedium in a monoculture and intercropped with alfalfa in Scandinavia

The perennial forage grass Thinopyrum intermedium (Host) Barkworth & Dewey, commonly known as intermediate wheatgrass (IWG) or by the commercial name Kernza™, is being developed as a perennial grain crop, i.e. being bred for its improved agronomic performance and food qualities. Intercropping legumes and grasses is a strategy for improving resource use and sustainability in cropping systems. Here, we show for the first time the agronomic performance of IWG as a perennial cereal grown as a monocrop and as an intercrop (alternate row, 0.5:0.5) with Medicago sativa L. (alfalfa/lucerne) in southern Sweden. The seeds of cycle 3 IWG were accessed from The Land Institute (TLI) of Salinas, Kansas, USA, and used to establish a local seed production plot (in 2014) for the establishment of the perennial systems (in 2016) utilised in this study. Both the monocrop and intercrop were sown with 25 cm row spacing with alternate rows of IWG and alfalfa in the intercrop (i.e. replacement design) with unknown sowing density. Intercropping provided sustained IWG grain production under the dry conditions of 2018, but also in the following year. This was evidently associated with a higher nitrogen accumulation in intercropped practice. Thus, intercropping seems to have stabilised the IWG grain production in the dry conditions of 2018, when the grain production in the intercrop was similar to that of the monocrop in the same year. This result was further supported by the lower discrimination against 13C (as an indicator of water use efficiency) in the intercrop components compared to the sole crop in 2018. The lower discrimination indicates high water use efficiency in the intercropped IWG in comparison to the IWG in monoculture, and we conclude that intercropping perennial cereal grain crops with legumes provides better growing conditions in terms of nitrogen acquisition, and water status, to cope with more extreme drought spells expected from climate change.

Water Footprint of Table Grape Production Systems: A Review of South African and Global Studies

Being a water-scarce country, South Africa (SA) faces several water challenges, including drought and other effects of climate change. Therefore, there is a need to improve water-use efficiency (WUE) by accurately quantifying the water use and WUE of table grape vineyards. The objective of this review is to (i) provide an overview of water footprint (WF) studies conducted on table grape production systems in SA and globally; (ii) identify limitations in current WF assessments of table grape production systems; and (iii) establish a range of WF values for table grape production systems as an indicator of WUE and for use in decision-making regarding sustainable freshwater use. The review has demonstrated that only a limited number of detailed WF studies have been undertaken on table grapes in SA and globally. Region-specific lookup tables for quantifying blue, green and grey water use in table grape production systems are available for three table grape production regions of SA and could be used for future WF assessments. Most global studies conducted on grape WF and WUE were desktop studies and did not include actual field records from production units, nor did they distinguish between different grape types (table, raisin and wine grapes). WF values must be interpreted in context, specifically regarding the water used versus yield, quality and income, as well as the region, climatic conditions, soil characteristics, irrigation and cultivation practices. For future WF and WUE assessments, a more detailed breakdown of water use is recommended, both during the production process and postharvest.

Fifteen-year Variations of Water Use Efficiency over a Wheat-Maize Rotation Cropland in the North China Plain

Based on fifteen-year observations, we explored the interannual variations of five water use efficiency (WUE) indicators (i.e., standard ecosystem WUE (EWUE), plant-canopy WUE (PWUE), inherent WUE (IWUE), underlying WUE (uWUE) and stomatal slope (G1)) over a typical winter wheat-summer maize rotation cropland in the North China Plain. The results showed that none of WUE indicators had a significant interannual trend. PWUE showed the lowest interannual variability and could be regarded as stationary for these two crops. G1 was stationary for wheat which was under an essentially constant soil water condition, whereas exhibited a strong fluctuation for maize experiencing more variable soil water content (SWC) than wheat. IWUE and uWUE were non-stationary for both crops. SWC and leaf area index (LAI) dominated EWUE for maize and wheat, respectively. PWUE was dominated by the shortwave solar radiation (Rg) in maize seasons and not significantly affected by any meteorological or biophysical factors in wheat seasons. For IWUE and uWUE, air temperature (Ta) and LAI were the most important drivers in maize and wheat seasons, respectively. Atmospheric CO2 concentration (Ca) and vapor pressure deficit (VPD) were not revealed as important controllers. These findings reflected that the meteorological and biophysical regulatory mechanisms of WUE indicators at the ecosystem level were quite different from that at the leaf level. But G1 was an exception due to that for both maize and wheat, G1 was only significantly affected by SWC. Moreover, we found that none of the remote sensing (RS)-based global products performed satisfactorily on capturing interannual variations of EWUE for both crops. These results cautioned that using these global RS-based products to explore the interannual variations of EWUE for the cropland ecosystem may lead to substantial bias.

Analysis of Agricultural Water Use Efficiency Based on Analytic Hierarchy Process and Fuzzy Comprehensive Evaluation in Xinjiang, China

Improving agricultural water use efficiency (WUE) and reducing the proportion of agricultural water consumption are of great significance for coping with the water crisis in the world, particularly in northwest China. However, considering the lack of WUE indicators for the selection and an evaluation of system construction in Xinjiang, the implementation of the strictest water resources management system in this province has been seriously restricted. In order to evaluate the agricultural water utilization situation of 14 administrative regions in Xinjiang, a synthetical evaluation model is proposed combining the analytic hierarchy process method and the fuzzy evaluation method. Firstly, an evaluation system composed of the target layer (i.e., water use efficiency), the criterion layer (i.e., water use situation, engineering measure, planting structure) and the index layer (e.g., utilization coefficient of irrigation water, weighting irrigation quota, grain production per cubic meter of irrigation water, etc.) is constructed. Secondly, a classification standard of evaluation indicators is put forward and a fuzzy evaluation model is introduced into calculate agricultural WUE. Finally, key evaluation indicators that lead to these administrative regions with very low WUE are identified, and discussions on improving agricultural WUE in Kashgar are made. The evaluation results of this study are beneficial for providing support for reforming agricultural water use and promoting sustainable agricultural development in Xinjiang.

WATER RESOURCES OF THE RUSSIAN‐KAZAKHSTAN TRANSBOUNDARY REGION AND THEIR USE

Aim.The study is aimed at examining the regional specifics of using water resources in the Russian‐Kazakhstan transboundary region, taking the current hydroclimatic situation into account.Methods. Statistical data on the availability and use of water resources in the regions of the Russian Federation and the Republic of Kazakhstan served as the initial data for the study. A comparative assessment of water supply was carried out applying traditional procedures widely used in Russia and abroad. The following indicators of water use efficiency were used: volumes of circulating and re‐sequential water supply (million m3), water losses during transportation (million m3) and water intensity of the gross regional product (GRP).Results. It was found that, over the past 20 years, a significant transformation of the water consumption structure has taken place in the studied regions. In the Russian regions, the most serious transformation of the consumption structure occurred in the agricultural sector. A comparative assessment of water supply suggests that most regions within the Russian‐Kazakhstan transboundary territory are characterized by relatively high levels of water availability.Main conclusions. The results indicate a significant impact of socio‐economic transformations in the Russian‐Kazakhstan region on the structure of water consumption, water supply, as well as indicators of water resource efficiency. The current water management problem consists in guaranteed provision of the population and economy with fresh water under the conditions of the spatio‐temporal variability of the river flow. Thus, the integrated management of water resources within the Russian‐Kazakhstan transboundary region should be based on improving the effi‐ ciency of water use in all sectors of the water economy, taking modern hydroclimatic changes into account.

Comprehensive evaluation of water-use efficiency in China’s Huai river basin using a cloud–compound fuzzy matter element–entropy combined model

We are facing the water shortage crisis. To realise sustainable development, we should improve water-use efficiency (WUE). In this study, a cloud–compound fuzzy matter element–entropy combined model was constructed to evaluate WUE. The Huai river basin (HRB) was selected as the study area. The cloud model was used to select some indices and build the comprehensive evaluation index system (CEIS), which included the overall, agricultural, industrial, domestic and environmental categories. The compound fuzzy matter element model was used to calculate the comprehensive indicators of WUE of the HRB and its regions. The weight of each index in the CEIS was determined using the entropy model. The results showed that WUE of the HRB had an upward trend on the whole because of the enhanced emphasis on water resources by the international and national governments. However, the regional difference was obvious. The WUE of Henan province was higher than that of Jiangsu province. The imbalance of regional WUE is an international problem. By analysing the difference among regions, research can provide a reference for the decision making of the water resources management department.

Water use efficiency of corn among the irrigation districts across the Duero river basin (Spain): Estimation of local crop coefficients by satellite images

Irrigation in the Duero river basin accounts for 75% of total water resources. Nevertheless, irrigation in this area is paramount to maintain agricultural production. Within this context, this paper is aimed at assessing the water use efficiency (WUE), for the major crop (corn), among four irrigation districts (IDs) from 2014 to 2017. Since the WUE indicators base upon crop water requirements, these were calculated by estimating the reference evapotranspiration and the local crop coefficients Kc. First, they were estimated by satellite images and then, compared with the recommendation from the Regional Irrigation Advisory Service. Finally, the gross irrigation requirements were compared with the irrigation supply.WUE indicators varied among IDs depending upon the hydrologic year, the water available for irrigation (superficial and subsurface water), and the corn sowing date. Usually, the IDs performed deficit irrigation in the dry years, and either full irrigation or over irrigation in the wet years. The rainfall only fulfilled less than 10% of corn requirements. Small differences in Kc were observed within municipalities (in each ID) and/or among IDs. The pattern of the Kc fitted curves varied among IDs and was affected by sowing dates.Although, the local Kc values were close to the general coefficients recommended by the Irrigation Advisory Service, they affected the determination of gross irrigation requirements which were significant different among IDs. Moreover, it was observed that the FAO recommendation for the duration of the corn growth stages fitted better the estimated Kc than the one from the Advisory Center.The gross irrigation requirements were similar among IDs and years, varying between 6476 and 7646 m3/ha. The local Kc estimation could help irrigation managers to adapt the irrigation supply to the actual corn needs.

SPATIO-TEMPORAL VARIATIONS OF SOIL WATER USE IN THE GROWING SEASON IN NORTHEAST CHINA USING MODIS DATA

Abstract. Water use efficiency is known as an important indicator of carbon and water cycle and reflects the transformation capacity of vegetation water and nutrients into biomass. In this study, we presented a new indicator of water use efficiency, soil water use level (SWUL), derived from satellite remote sensing based gross primary production and the Visible and Shortwave Infrared Drought Index (VSDI). SWUL based on MODIS data was calculated for the growing season of 2014 in Northeast China, and the spatial pattern and the variation trend were analyzed. Results showed that the highest SWUL was observed in forestland with the value of 36.65. In cropland and grassland, the average SWUL were 26.18 and 29.29, respectively. SWUL showed an increased trend in the first half period of the growing season and peaked around the 200th day. After the 220th day, SWUL presented a decreasing trend. Compared to the soil water use efficiency (SWUE), SWUL might depict the water use status at finer spatial resolution. The new indicator SWUL can help promote understanding the water use efficiency for regions of higher spatial heterogeneity.

Water use efficiency of a rice paddy field in Liaohe Delta, Northeast China

Water use efficiency (WUE) of rice paddy fields is very important because of the increasing demand for crop production and increasing scarcity of water for irrigation. The seasonal dynamics of WUE and their environmental controls were determined in a rice paddy field in Liaohe Delta, Northeast China, based on 2-year period (2013–2014) eddy-covariance flux and meteorological measurements. The annual and growing-season ecosystem water use efficiency (eWUE) of the paddy field were 1.00gCkg−1 H2O and 1.35gCkg−1 H2O (two-year average), respectively. The seasonal variation of eWUE showed an asymmetric single-peak curve. The leaf area index (LAI) was the dominant regulator of evapotranspiration-based WUE; however, the VPD was the most important controlling factor of transpiration-based WUE. The significant positive control of LAI on evapotranspiration-based WUE was likely caused by its strong regulation of the ratio of transpiration (TR) to evapotranspiration (ET). The residual WUE (calculated from the WUE subtracted from the modeled WUE using the relationship between the WUE and LAI) was negatively correlated with net radiation (Rn). The WUE was generally higher under cloudy conditions than under clear conditions. Based on a comparison of the four WUE indicators, the separation of ET to TR and soil evaporation (ES), as well as the incorporation of the nonlinear effect of vapor pressure deficit (VPD) on WUE, would both greatly improve the performances of WUE indicators in rice paddy fields.

A new indicator of ecosystem water use efficiency based on surface soil moisture retrieved from remote sensing

Ecosystem water use efficiency is an important indicator of carbon and water cycle coupling. This study presents a new measure of water use efficiency, soil water use efficiency (SWUE), based on gross primary production and surface soil moisture derived from remote sensing products (ECV-SM). Variation in SWUE among biomes, climate conditions, and latitudes from 2000 to 2014 was comprehensively assessed. Average global SWUE over this 15-year period was approximately 3.47 gC/kgH2O. SWUE was relatively high for ecosystems near the equator and decreased gradually with increasing latitude. At the biome level, high SWUE was measured in evergreen broadleaf forests, and lower values were found in shrublands. Compared with two other commonly used indicators of water use efficiency, EWUE (ratio of gross primary production to evapotranspiration) and RUE (ratio of gross primary production to precipitation), average SWUE from 2000 to 2014 was significantly higher and had the largest range of values. In addition, spatial distributions of these three indicators varied greatly. The new indicator SWUE will help promote understanding of soil water use in various ecosystems.

The spatial and temporal variation of water use efficiency in the Huai River Basin using a comprehensive indicator

A comprehensive indicator of water use efficiency (WUE) to promote coordinated development between socio-economic and environmental systems was developed. A comprehensive consideration of the social, economic and environmental benefits of water was made in the evaluation index system of WUE and the projection pursuit model combined with chaotic particle swarm optimization was adopted to calculate the comprehensive indicator of WUE. The Huai River Basin (HRB) was selected as a case study area. The temporal change of WUE showed that the annual WUE of the HRB from 2007 to 2013 increased obviously because of the enhanced emphasis on environmental protection by the government. The spatial results showed that the spatial WUE of each province in 2013 was significantly higher than in 2007. In 2013, Anhui with the lowest WUE was selected as representative to reveal the problems of water use in the HRB. The main reasons were that the government paid more attention to the high water consumption industries and ignored the small-scale water users, and wastewater treatment was still weak in the HRB. The research can provide the foundation for improving WUE and solving the problem of water shortages.

Soil Water Regime Affecting Correlation of Carbon Isotope Discrimination with Yield and Water‐Use Efficiency of Winter Wheat

Improving crop water‐use efficiency (WUE) is critical in securing food production under arid and semiarid regions, but a quick and accurate method for quantifying crop WUE is lacking. A field study on winter wheat (Triticum aestivum L.) was conducted under six irrigation regimes in two growing seasons (2011–2012 and 2012–2013) to determine the sampling time and the condition of soil moisture on the relationship of C isotope discrimination (Δ13C; measured by flag leaves, other leaves, and kernel) with grain yield and WUE at different levels (leaf level as WUEL, biomass level as WUEb and grain‐yield level as WUEg). The results showed that the accumulated average soil water condition affected the leaf and kernel Δ13C. The kernel Δ13C and flag leaf Δ13C after heading were significantly related to the final biomass and grain production (P < 0.05), but their relationship to WUEg and WUEb was variable as a result of the effects of seasonal weather conditions on harvest index (HI) and soil evaporation. Kernel Δ13C or flag leaf Δ13C can be used to assess the yield of winter wheat but may not be able to predict the WUEg and WUEb. The WUEL was related to the soil water condition at the time when the measurements occurred. The WUEL might be a useful indicator of WUE at yield level when soil water condition at measuring of WUEL could represent the average soil water condition of the whole growing season of the crop.

Vigour-yield-quality relationships in long-term deficit irrigated winegrapes grown under semiarid conditions

Regulated deficit irrigation (RDI) and partial root-zone drying irrigation (PRD) are two of the most-promising agronomic practices designed to increase water use efficiency (WUE) and berry and wine quality in field-grown wine grapes in Mediterranean semiarid regions. However, many growers have not yet taken advantage of the new irrigation techniques now available, which would enable them to efficiently manage irrigation in wine grapes with the aims of improving quality and making this crop more competitive and profitable. This study focused on finding significant relationships between several WUE indicators (from the leaf to the plant level) and relevant vine vigour, yield and berry quality traits in order to improve deficit irrigation management in wine grapes under semiarid conditions. Sustained deficit irrigation (SDI), RDI and PRD techniques were compared for 7 years (2006–2012), in field-grown Monastrell grapevines grafted onto 1103P in SE Spain. Five treatments were applied: SDI irrigated at 60–40 % ETc (crop evapotranspiration) for the whole season (308–211 mm year−1); a moderate RDI strategy (110–191 mm year−1) under conventional drip irrigation (RDI-1) and under PRD (PRD-1); and a more-severe RDI strategy (90–144 mm year−1) under conventional drip irrigation (RDI-2) and under PRD (PRD-2). The SDI enhanced root system development and vine vigour, improved technological berry quality but lowered WUE and berry polyphenolic content, compared to deficit irrigation (DI). In contrast, PRD and RDI resulted in lower root growth, vine vigour and leaf-plant canopy water use, but improved cluster microclimate and increased WUE and berry polyphenolic content. Among the DI treatments, the PRD-1 strategy was the one which most improved the long-term vine performance. The most-restrictive DI strategies (PRD-2 and RDI-2) did not give a substantial improvement in WUEyield (kg m−3) or berry quality. Significant interactive effects of irrigation volume (high vs. low) and irrigation placement (PRD vs. RDI) indicate distinct PRD effects on long-term yield, WUE and berry quality, depending on the volume of water applied in the wet root zone and the soil total water availability. Significant vigour-quality relationships were established. We identified a range of optimum physiological and agronomical thresholds in order to develop long-term, efficient deficit irrigation strategies in Monastrell vineyards under semiarid conditions.

N2 fixation ability of different dry bean genotypes

Farid, M. and Navabi, A. 2015. N2 fixation ability of different dry bean genotypes. Can. J. Plant Sci. 95: 1243–1257. Common bean (Phaseolous vulgaris L.) is generally known as a weak N2 fixer compared with other legumes. The availability of genetic variation for N2 fixation potential of common bean supports the idea that symbiotic nitrogen fixation (SNF) in common bean can be improved through breeding. To assess the potential N2 fixation of selected common bean genotypes, 12 bean varieties including three Andean and nine Middle American were screened for SNF ability and related traits in controlled environments and field trials in Ontario, Canada. A non-nodulating mutant, R99, was used as the reference plant to estimate nitrogen derived from the atmosphere (Ndfa) through the natural 15N abundance method. Significant variation was found among the bean genotypes for Ndfa and its related traits. Environmental and genotype by environmental effects significantly influenced Ndfa and its related traits. The three Andean bean genotypes were superior to Middle American genotypes for nodulation ability, while the Middle American genotypes were generally stronger nitrogen fixers in optimum soil moisture conditions. In general, nitrogen fixation was found to be significantly associated with seed yield and carbon isotope discrimination, an indicator of water use efficiency.

Analysis of Difference of Water Use Efficiency in China

Water consumption per ten thousand yuan GDP (WG) is an internationally comparative indicator of water use efficiency (WE), but it cannot further reveal the causes of the differences of WE. The shift-share analysis method is introduced, and the WG-shift-share analysis model (WG-SSM) is built combined with the regression model. According to the model, WE is decomposed and analyzed from the three levels of the country, the region and the industry from 1997 to 2011. The results show that: WG of the country, the region and the industry shows a significant downward trend, but WE is greatly different of inter-region and inter-industry; total shift of each region relative to the national average level is shrinking year by year, and inter-regional differences are mainly due to the competitive effect; the influence of the industrial mix effect is determined by the WE of the primary industry;the allocation effect least impacts on the differences of regional WE, but it can test the interaction between the competitive effect and the industrial mix effect, which can provide objective reference for drafting the water-saving policies and measures.

Water-use efficiency in grapevine cultivars grown under controlled conditions: effects of water stress at the leaf and whole-plant level

Background and Aims: Improving water‐use efficiency (WUE) is desirable for future grapevine growth and grape production, especially in Mediterranean areas where water is predicted to be limiting. Understanding the genetic variability in WUE is important to identify the most appropriate cultivars to be used in semi‐arid areas. Most previous studies have focused at leaf‐level WUE, while information on whole‐plant level is scarce. This study explored the genetic variability of grapevine in whole‐plant WUE (WUEWP) to determine whether several leaf WUE (WUEl) indicators are suitable as proxies of WUEWP. Methods and Results: Three similar experiments were performed to compare WUE in up to eight different grapevine cultivars under irrigation and water‐stress treatments. Although WUEl and WUEWP varied with cultivar and treatment, WUEl was not a reliable parameter to predict WUEWP. Conclusions: Large variability in WUEWP between grapevine cultivars was observed, although this variability was not described by leaf‐level indicators of WUE. Significance of the Study: This study showed that the large variability existing for WUEWP in different cultivars offers an potential method for selecting the more suitable cultivars to grow in water‐scarce viticulture areas, although WUEl is not reliable for estimating WUEWP.