Water Use Efficiency Values Research Articles

Variation Characteristics of Ecosystem Water Use Efficiency and Its Response to Human Activity and Climate Change in Inner Mongolia

Water use efficiency (WUE) reflects the balance between carbon assimilation and water consumption in terrestrial ecosystems. Considering the fragile conditions of global water resources, the evaluation of regional WUE variation characteristics and response mechanisms is critical for promoting sustainable ecological development and water resource utilization. Based on gross primary productivity (GPP) and evapotranspiration (ET) datasets, combined with vegetation and meteorological data, this study examined the spatiotemporal variations, annual variation contribution rate, and driving mechanism of WUE in Inner Mongolia from 2001 to 2020. The main results are as follows: (1) The interannual and spatial variations of GPP, ET, and WUE all exhibited increasing trends, with WUE increasing in approximately 70% of the region and significantly increasing in 22.35% of pixels exhibiting a significant increase. Areas with the most significant increases were located in the Horqin sandy land and Mu Us sandy land. (2) The highest WUE values were observed in the summer season, followed by autumn and winter, and the lowest in spring. (3) Among all vegetation types, the typical steppe ecosystems contributed most to the interannual variability (IAV) of GPP, ET, and WUE, with values of 169.89%, 141.09%, and 193.42%, respectively. While the coniferous forest contributed least or negatively to GPP, ET, and WUE IAV, with values of −36.28%, 28.20%, and −32.86%, respectively. (4) The primary driver of WUE variation was found to be GPP, which contributed 59.36%, mainly in the central and western regions. The remaining 40.64% was attributable to ET, concentrated in the northeast region. (5) Human activities significantly affected WUE, with a contribution (about 53.52%) larger than that of climate change (nearly 46.48%). Increased precipitation improves vegetation WUE and is the most important climate factor influencing WUE variations. These findings will aid the formulation of vegetation protection and water resource management strategies in water-stressed areas.

Differential Post-Fire Recovery of Tree and Shrub Growth and Water-Use Efficiency in a Mediterranean Coastal Dune System

Assessing post-fire recovery is essential to forecast how ecosystems will respond to future warmer conditions and higher fire severity. Such assessments must consider site conditions and the post-fire recovery of trees and shrubs. We used tree-ring data and intrinsic water-use efficiency (WUEi) to quantify the post-fire responses of a tree (Pinus pinea) and a shrub (Juniperus phoenicea) in Mediterranean coastal dunes located in the Doñana protected area, SW Spain. We compared pines and junipers growing in an inter-dune slack with those growing in a nearby dune ridge. We quantified crown damage and bark char in pines impacted by a wildfire. Pines with lower crown damage after the fire showed a higher growth rate one year later. Growth decreased afterwards in the case of fast-growing pines from the slack site, whereas slow-growing dune pines showed increasing growth rates one to three years after the fire. The fire did not change the pines’ WUEi, whereas the junipers located in dunes presented the highest WUEi values. Severe crown damage (damage > 60%) impairs long-term growth recovery in P. pinea. Open and heterogeneous landscapes can reduce the wildfire risk in the study Mediterranean area, where slack vs. dune and tree vs. shrub differences should be considered in post-fire management plans.

Phenological and physiological advantages of invasive annuals are strengthened by nitrogen enrichment

Abstract Anthropogenic nitrogen (N) deposition exerts profound influence on the composition and function of native ecosystems, commonly resulting in reduced plant richness and increases in nonnative plant invasion. Identifying differences in plant N responses and functional traits could help to explain the ongoing invasion and biological impoverishment of ecosystems subject to N deposition. We compared the growth, emergence phenology and functional traits of 30 native and invasive annual plant species under high and low N availability, with the goal of evaluating if invasives exhibit functionally dissimilar responses to N compared with the native species they displace. Invasives grew larger than natives, especially under increased N availability. Overall, invasives and natives did not differ in emergence phenology. However, these groups of species differed in relationships between growth and days to emergence, and N addition further strengthened these differences; invasives consistently grew larger than natives that emerged around the same time, whereas natives showed a strong negative effect of delayed emergence on plant growth. Relative N responses for measures of plant growth and allocation did not differ between native and invasive species, but invasives exhibited greater plasticity in physiological traits. This included significantly lower leaf N content, higher CN ratios and greater water‐use efficiency (WUE) in plants grown under high N. Invasives also showed functionally different patterns of growth and water use. Across species, invasives showed a positive relationship between shoot growth and WUE. Native species showed a trade‐off between root allocation and WUE, whereas invasives displayed high values for WUE even despite reduced root: shoot ratios under high N. Our results highlight the ability of invasives to rapidly accrue biomass, disproportionately benefit from early emergence and N addition and use water efficiently despite rapid growth. Natives, on the other hand, pay a higher cost for delayed emergence and may experience trade‐offs between growth and water use. The more pronounced functional differences between natives and invasives observed under high N likely play an important role in driving invasion and reduced species diversity under N enrichment. These differences could be used to inform successful management strategies for N‐impacted and water‐limited ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Productivity and profitability of modern irrigation methods through the application of on-farm drip irrigation on some crops in the Northern Nile Delta of Egypt

Irrigation method has a great effect on water consumption, productivity and profitability of certain crops. Egypt is suffering from water scarcity, it is of great importance to apply modern irrigation techniques to achieve highest productivity with optimum water consumption. This research aims at evaluating the compare drip and surface irrigation systems in old lands of medium salinity in the Nile Delta, determining the best irrigation method to achieve the highest water productivity and optimum water consumption. A field experiment is performed in summer and winter seasons of 2020/2021. Soil and water characteristics are determined through representative sampling. The results show the differences in total cost of producing different summer and winter crops under tested irrigation systems. Surface irrigation system total cost was increased, while drip irrigation system total cost was decreased under all treatments with 29% to 54% based on the crop type. Also, drip irrigation gave more efficient water uses and water saving under different summer and winter crops. Hence, Drip irrigation system increased the value of water use efficiency, while surface irrigation system gave high value of productivity compared with drip irrigation system, due to higher salinity, additional leaching water used to control soil salinity.

The Effect of Deficit Irrigation on Yield and Quality of Second Crop Sesame (Sesamum indicum L.)

This study was carried out in Bursa, Turkey which has a sub-humid climate, in order to examine the water-yield relationships and responses of yield and quality components under deficit irrigation of second crop sesame plant (Sesamum indicum L.) irrigated with drip irrigation method. Experimental treatments were application of 100% (S1), 75% (S2), 50% (S3), 25% (S4) and 0% (S5) of soil water depleted at effective rooting depth at 7-day intervals. The experiment was applied in 3 replicates according to the completely randomized blocks experimental design. According to the study results, the total amounts of irrigation water applied were between 127.0-354.7 mm. Crop evapotranspiration values varied between 246.0-449.5 mm. Seed yield, oil content and protein content were obtained as between 76.3-189.2 kg da-1, 56.3-62.6% and 18.6-20.4%, respectively. In the study, the seasonal yield response factor (ky) was determined as 1.28. Water use efficiency (WUE) of the sesame plant was found between 0.31-0.43 kg m-3. Irrigation water use efficiency (IWUE) varied between 0.50-0.57 kg m-3. As a result, irrigation treatment S1 can be suggested as an irrigation schedule in order to reach the highest seed yield (189.2 kg da-1) in the second crop sesame plant. When water resources are limited, taking into account the WUE and IWUE values, the S2 treatment (25% water deficit) can be preferred as an irrigation program in terms of water saving.

Evaluation of Water Productivity under Furrow Irrigation for Onion (Allium cepa L.) Crop

Irrigation water management practices are the main strategies to improve water productivity. This research work was focused to study the performance of alternate and paired row furrow irrigation systems at three levels of irrigation (100%, 75%, and 50% of crop evapotranspiration) using different water productivity indicators for onion crops. The experiment had six treatments and replicated three times to evaluate the analysis of variance in SAS software. Water productivity indicators like crop water use efficiency, field water use efficiency, and field water expense efficiency were determined through bulb yield and water which were used by the crop. The crop yield was expressed as the total yield of onion bulbs, and crop water use was expressed as crop evapotranspiration (ETc), gross depth of irrigation, and water expense. The estimated maximum values of crop water use efficiency, field water use efficiency, and field water expense efficiency were 11.941, 16.152, and 9.361 kg m−3, respectively, for paired row furrow irrigation with 50% ETc. The performance of the paired row furrow irrigation system in crop yield and water use was better as compared to the alternate furrow irrigation system at all levels of irrigation.

Ecophysiological Responses of Tall Wheatgrass Germplasm to Drought and Salinity.

Tall wheatgrass (Thinopyrum ponticum (Podp.) Barkworth and D.R. Dewey) is an important, highly salt-tolerant C3 forage grass. The objective of this work was to learn about the ecophysiological responses of accessions from different environmental origins under drought and salinity conditions, to provide information for selecting superior germplasm under combined stress in tall wheatgrass. Four accessions (P3, P4, P5, P9) were irrigated using combinations of three salinity levels (0, 0.1, 0.3 M NaCl) and three drought levels (100%, 50%, 30% water capacity) over 90 days in a greenhouse. The control treatment showed the highest total biomass, but water-use efficiency (WUE), δ13C, proline, N concentration, leaf length, and tiller density were higher under moderate drought or/and salinity stress than under control conditions. In tall wheatgrass, K+ functions as an osmoregulator under drought, attenuated by salinity, and Na+ and Cl− function as osmoregulators under salinity and drought, while proline is an osmoprotector under both stresses. P3 and P9, from environments with mild/moderate stress, prioritized reproductive development, with high evapotranspiration and the lowest WUE and δ13C values. P4 and P5, from more stressful environments, prioritized vegetative development through tillering, showing the lowest evapotranspiration, the highest δ13C values, and different mechanisms for limiting transpiration. The δ13C value, leaf biomass, tiller density, and leaf length had high broad-sense heritability (H2), while the Na+/K+ ratio had medium H2. In conclusion, the combined use of the δ13C value, Na+/K+ ratio, and canopy structural variables can help identify accessions that are well-adapted to drought and salinity, also considering the desirable plant characteristics. Tall wheatgrass stress tolerance could be used to expand forage production under a changing climate.

Spatial-temporal variation of vegetation water use efficiency and its relationship with climate factors over the Qinghai-Tibet Plateau, China

Water use efficiency (WUE) is an effective index to study the coupling of land carbon and water cycle. The Qinghai-Tibet Plateau is the most important ecological security barrier in China. Understanding the characteristics and mechanism of WUE is important for the carbon cycle and water resources rational utilization in the plateau. Based on MODIS data of gross primary productivity (GPP) and evapotranspiration (ET), we analyzed the spatial-temporal variations of WUE over the Qinghai-Tibet Plateau and the effects of climate factors. The results showed that WUE in the Qinghai-Tibet Plateau had an upward trend under the combined action of GPP and ET during 2001-2020. The southeast and northeast of the Plateau had the highest WUE value, while the central part had the lowest WUE value. WUE of grassland, marsh and alpine vegetation showed an increasing trend, while that of shrub land, broadleaved forest and coniferous forest showed a decreasing trend. There was a significant positive correlation between WUE and annual air temperature, and the sensitivity increased with the increases of air temperature. The relationship between WUE and annual precipitation was non-linear. When precipitation was less than 700 mm, the sensitivity of WUE to precipitation decreased with the increases of precipitation. When precipitation was more than 700 mm, the sensitivity of precipitation increased with the increases of precipitation. However, WUE was negatively correlated with precipitation in more than 75% of regions, and was affected by precipitation in a larger area. In the future, warm and humid climate would lead to a decrease in WUE.

Combining Planting Patterns with Mulching Bolsters the Soil Water Content, Growth, Yield, and Water Use Efficiency of Spring Wheat under Limited Water Supply in Arid Regions

Innovations in water-saving cultivation strategies are urgently needed to achieve high yield and elevated water use efficiency (WUE) simultaneously in arid regions with limited water resources. Here, we conducted a two-year field study to compare the impacts of eight combinations of planting patterns (PPs) and mulching on the soil water content (SWC) in the top 60 cm soil layer, the growth, the yield, and the WUE of wheat under two irrigation rates (1.00 and 0.50 ET). These combinations included three conventional flat planting (CF) patterns, including CF without mulch (CFNM), with plastic film (CFPM), and with wheat straw mulch (CFSM); three raised-bed planting (RB) patterns, including RB without mulch (RBNM), with plastic film (RBPM), and wheat straw (RBSM) mulch; and two ridge–furrow planting (RF) patterns, including RF without mulch (RFNM) and with plastic film mulch (RFPM). The results showed that the tested treatments affected the SWC at different depths under both irrigation rates. Compared with the two non-mulched treatments under 0.50 ET, the SWC of the three PPs with plastic film and the two PPs with wheat straw mulching were significantly higher before irrigation by 14.4–22.0% and 6.9–17.2% at 0–20 cm soil depth, 16.4–29.0% and 6.6–14.9% at 20–40 cm soil depth, and 3.3–34.8% and 3.4–14.5% at 40–60 cm soil depth, respectively. All measured wheat parameters, except harvest index, were significantly affected by the interaction between irrigation rate and PPs. The highest values for plant dry weight (PDW), yield components, grain yield (GY), and WUE under 1.00 ET were obtained in the two PPs with wheat straw mulch, while the three PPs with plastic film showed the highest values of these parameters under 0.50 ET. The yield response factor (Ky) based on PDW was acceptable for all PPs mulched with plastic film and wheat straw as well as for RFNM, while Ky based on GY was acceptable only for the PPs mulched with plastic film and for RFNM, as the Ky values of these PPs were less than 1 under 0.50 ET. The SWC at different depths exhibited quadratic and nonsignificant relationships with all parameters under 1.00 ET, while these relationships were linear and strong under 0.50 ET, with a few exceptions. Overall, we conclude that combining any PPs with plastic film mulching could be used as a feasible and effective strategy for obtaining high wheat yield and WUE in the irrigated and arid agroecosystem.

Determining effects of foliar boron applications on yield and fruit quality of apricot trees for reducing water stress

Aims: The research was carried out to determine the effects of different boron doses on yield, yield components and quality on 5-6 years old apricot trees of Mogador variety, which were exposed to water stress in the Amik Plain in 2019. Methods and Results: The factorial experimental design was conducted on apricot trees of Mogador variety, using four doses of foliar boron (ppm) (0-B0, 150-B150, 225-B225 and 300-B300 ppm) and four irrigation levels (100%-I100, 75%-I75, 50%-I50 and 25%-I25 of available water holding capacity) in four replications. Each replication consisted of two apricot trees. The quantity of irrigation water applied in the experiment ranged from 179 to 742 mm, while the evapotranspiration varied between 295 and 832 mm during the irrigation season. Irrigation water use efficiency (IWUE) and water use efficiency (WUE) varied between 3.51-5.18 kg m-3 and 2.89-4.17 kg m-3, respectively. Boron doses did not cause significant differences in WUE and IWUE values. Each unit increase in crop water use caused an average yield increase of 16.8 kg ha-1. Relative to the full irrigation (I100), fruit weight decreased by 13 and 3% in I25 and I50, respectively, but increased by 2% in I75. Relative to the control group (B0), fruit weight increased by 2, 4, and 2% with B150, B225, and B300, respectively. Average fruit size varied between 47.40 (I75) and 42.99 mm (I25); total soluble solids (TSS) between 16.13 (I100) and 12.65 (I25); and pH between 3.16 (I100) and 3.30 (I50). The increased boron dose did not cause a significant difference in fruit size and width. The leaf boron content increased up to the B225 dose and tended to decrease at the B300 dose.Conclusions: Boron element provides an increase in yield in deficit irrigation conditions, the yield increase is higher in fully irrigated apricot trees. In full irrigation treatment (I100), the B225 treatment was more effective on the yield.Significance and Impact of the Study: The boron element is an important element that causes an increase in photosynthesis by light adsorption. There is not a lot of research investigating the effects of nutrient elements to relieve the negative effect of water stress in orchards. This research is important in terms of revealing the effects of the element boron in water stress conditions.

Convergence in water use efficiency within plant functional types across contrasting climates

Water use efficiency (WUE) provides a direct measure of the inextricable link between plant carbon uptake and water loss, and it can be used to study how ecosystem function varies with climate. We analysed WUE data from the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS), leveraging the high spatial resolution of ECOSTRESS to study the distribution of WUE values both within and among regions with different plant functional types. Our results indicate that despite wide local variability of WUE estimates, WUE tended to converge to common global optima (peaked distributions with variance <0.5 g C per kg H2O, kurtosis >3.0) for five of nine plant functional types (grassland, permanent wetland, savannah, deciduous broadleaf and deciduous needleleaf forest), and this convergence occurred in functional types that spanned distinct geographic regions and climates.

Influence of plants on the salinity of constructed wetlands effluents.

Reuse of constructed wetlands effluents for fertigation is a promising practice in regions that suffer from water scarcity. Thus this study aimed to evaluate the influence of Vetiver (Chrysopogon zizanioides) and Tifton 85 (Cynodon sp.) grasses cultivation on salinity of the saturated solution of the Horizontal Subsurface Flow Constructed Wetlands (HSSF-CW) porous medium. The grasses were cultivated in HSSF-CW mesocosm and submitted to different levels of salinity for six months. The crop's evapotranspiration, biomass productivity, the electrical conductivity variation (ΔEC) in the solution under treatment and the water use efficiency (WUE) of these grasses were evaluated. The cultivation of Vetiver and Tifton 85 in HSSF-CW provided an increase in the electrical conductivity of the solution mainly for the lowest levels of affluent salinity. The ΔEC in HSSF-CW grown with Vetiver and Tifton 85 grasses were 90.20 and 27.13 mS cm-1, respectively. Meteorological variables maximize the effect of the vegetative development in ΔEC of the solution. The WUE values of Vetiver and Tifton 85 grasses were 1.77 and 4.18 g kg-1, respectively. Thus plants with high water use efficiency such as Tifton 85 is indicated for HSSF-CW in which the effluents are used in the fertigation of agricultural crops.

Remote Sensing of Ecosystem Water Use Efficiency in Different Ecozones of the North China Plain

Water use efficiency (WUE), as an environmental factor of metabolism in different ecosystem functional areas, is a key indicator of the ecosystem carbon-water cycle. WUE is defined as the ratio of carbon absorbed by ecosystems to water evaporated. Exploring the spatiotemporal variation in carbon and water cycles in different ecological zones of the North China Plain and their driving factors is important for the ecological management and sustainable development of the different ecological zones in the North China Plain. Based on remote sensing data products, this paper studies the spatiotemporal variations of WUE and their driving factors in different ecological functional areas of the North China Plain from 2001 to 2017. This study found that: (1) The spatial distribution of WUE and gross primary production (GPP) in the North China Plain is similar, with the multiyear average of WUE at 0.74 g C m−2 y−1. The variation trend of WUE is mainly affected by the variation trend of GPP (44.38% of the area of the North China Plain). (2) The change trend of WUE mainly showed a mild decrease and a mild increase, accounting for 73.22% of the area of the North China Plain; the area with medium-low fluctuation of WUE accounted for the largest proportion, accounting for 59.90% of the area of the North China Plain. In addition, the multiyear average values of WUE in the ecological functional area are Qin Ling Mountains deciduous forests &gt; Central China loess plateau mixed forests &gt; Mongolian-Manchurian grassland &gt; Ordos Plateau steppe &gt; Changjiang Plain evergreen forests &gt; Huang He Plain mixed forests &gt; Bohai Sea saline meadow, in the order from high to low. (3) The influence of precipitation on WUE was higher than that of temperature. The area of WUE that increased with the increase of precipitation accounted for 23.74% of the area of the North China Plain and was mainly distributed in the Qin Ling Mountains deciduous forests, Changjiang Plain evergreen forests, and Huang He Plain mixed forests’ ecological functional areas. The results of the study can provide a reference and theoretical basis for the conservation and management of carbon and water cycles in the functional areas of North China’s ecosystems.

Assessing Variations in Water Use Efficiency and Linkages with Land-Use Changes Using Three Different Data Sources: A Case Study of the Yellow River, China

The dependence of water use efficiency (WUE) on changes in land cover types is crucial for understanding of long-term water availability and assessment of water-saving strategies. Investigating the impact of land cover types on ecosystem WUE has important implications when revealing water dynamics and land management. However, the determination of WUE and its dominant factors have always been subject to high data dependency and large calculation consumption within large basins. This paper proposes a framework for processing actual evapotranspiration (AET) and WUE calculation by coupling the Maximum Entropy Production (MEP) method with the Google Earth Engine (GEE). By employing the proposed framework and three data sources available in the GEE platform, results for actual ET and WUE from 2001 to 2020 were obtained in the Yellow River Basin (YRB). The results show that the proposed framework provides an acceptable estimation of actual ET via validation with Eddy Covariance flux sites in the YRB. The calculated WUE values varied greatly in different sub-basins within the YRB, indicating a cumulative growth rate of about 56% during the past 20 years. The dominant factor that led to these changes was the transition from Grasslands into other land-use types. Our results suggest that the use of the GEE platform coupled with the MEP method offers new possibilities for advancing understanding of water exchange and water resource management.

Effect of Different Sowing Methods on Water Use Efficiency and Grain Yield of Wheat in the Loess Plateau, China

Research has revealed that summer fallow sowing improves the water use efficiency (WUE) and grain yield of winter wheat. However, wheat yields differ yearly with crop management. A field experiment over 8 years was established in the Loess Plateau to determine the role of precipitation and soil water storage in wheat yield formation under conservation tillage. The average WUE values were 7.8, 11.0, and 12.6 t·ha−1, while the average evapotranspiration (ET) values were 334.7, 365.5, and 410 mm when the yields were 3.0, 3.0–4.5, and over 4.5 t·ha−1, respectively. Compared to drill sowing (DS), high water consumption during early growth increased the spike number, grain number, and yield. In years of intermediate or low yields, wide-space sowing (WS) and furrow sowing (FS) improved the ET, WUE, spike number, grain number, and yield of wheat compared to (DS) drill sowing. When the wheat yield was 3.0–4.5 t·ha−1, higher soil water intake during jointing, anthesis, and anthesis–maturity increased the tiller number, 1000-grain weight, and yield, related to the use of suitable tillers. Synchronous increases in grain number per spike and 1000-grain weight were observed with increased soil water content at jointing, maturity, and anthesis, as well as consumption of soil water in the latter part during the growing season.

Carbon isotope discrimination and water use efficiency in interspecific Prunus hybrids subjected to drought stress

In C3 plants, carbon isotope composition (δ13C) is influenced by isotopic effects during diffusion from the atmosphere to the chloroplasts and carboxylation reactions. This work aimed to demonstrate if δ13C of leaf soluble carbohydrates (δ13Cleaves) and of dry matter from new-growth shoots (δ13Cshoots) of Prunus plants subjected to a period of water deficit was related to water use efficiency (WUE). For this purpose, three interspecific Prunus hybrids rootstocks (6–5, 7-7 and G × N) were gradually subjected to drought and then rewatered. Soil water content (SWC) decreased from 26.1 to 9.4% after 70 days of water shortage, when plants reached values of predawn leaf water potential (LWP) ranging from −3.12 to −4.00 MPa. Gas exchange, particularly net photosynthetic and transpiration rates, differed among the three hybrids, leading to different values of WUE. After 70 days of drought, a significant δ13C increase of 5.86, 4.28 and 4.99‰ was observed in 6–5, 7-7 and G × N, respectively. Significant correlations between δ13C and other parameters (substomatal CO2/atmospheric CO2 ratio, stomatal conductance and stem water potential) were found in all hybrids. The rewatering phase caused a recovery of the physiological status of the plants. The isotope composition of δ13Cshoots was correlated with the average WUE measured during the whole experiment. δ13Cleaves and δ13Cshoots were positively related (r = 0.87; p < 0.001). The isotopic signature was a reliable screening tool to identify Prunus genotypes tolerant to drought stress. The results suggest the possibility of using δ13C as an integrated indicator of level of drought stress in plants subjected to prolonged stress conditions.

The seasonal response of vegetation water use efficiency to temperature and precipitation in the Loess Plateau, China

Water use efficiency (WUE), which integrates ecosystem carbon and water cycles, is an important index for evaluating ecosystem sensitivity to climate change. Based on MODIS remote sensing data and meteorological data, this paper quantitatively studied the variation in seasonal vegetation WUE in the Loess Plateau over the period 2001–2019. Temperature and precipitation threshold effects on seasonal WUE of different vegetation types were also discovered using regression and partial correlation analysis methods. The results showed that seasonal WUE decreased with time in each season studied, with the rate of decrease of WUE in summer being the most significant of the three seasons studied. The following was the order of change in vegetation WUE values over time in different seasons: summer > autumn > spring. WUE of different vegetation types showed seasonal differences as well as varying responses to temperature and precipitation. The WUE of shrubland and grassland both tended to decrease over the study period from spring to autumn, with grassland WUE decreasing the most. When compared to grassland and shrubland, the negative relationship between forest WUE and the temperature was highest in spring and summer. The proportion of the area of vegetation where WUE was negatively correlated with temperature and precipitation in the three seasons, was largest in summer. In the relationship between seasonal WUE and either temperature or precipitation, there was a threshold effect. In spring, summer, and autumn, the optimum precipitation thresholds were 50–80 mm, 280–370 mm, and 65–125 mm, respectively, and the corresponding optimum temperature thresholds were > 14 °C, 15–19 °C, and 6–13 °C, respectively.

Assessment of fodder corn grown under surface and subsurface drip irrigation in Mendoza, Argentina

Drip irrigation –surface (DI) and subsurface (SDI)– is one of the best irrigation systems to increase both irrigation and water use efficiency. The objective of this research is to assess and compare the response of fodder corn to SDI treatments at two depths with DI in Mendoza. A full factorial experimental design was used on random plots and measurements were replicated through time. Tests were run in two consecutive cycles. Germination percentage (GP), yield, water use efficiency (WUE) and water productivity (WP) were assessed. High yields ranging from 70,214 to 105,771 kg ha-1 of green matter and from 10,020 to 22,476 kg ha-1 of dry matter (DM) were obtained in both cycles, respectively. DM production from the first sowing was significantly higher in both cycles under SDI treatment than under DI. No significant differences in WP or WUE were found. GP and soil moisture (SM) did not show differences between treatments, but significant differences were found in SM (p=&lt;0.0001) between the first soil layer and the other two layers. Highlights Germination percentage was not affected by the depth of the drip irrigation lines. No significant differences were found in green matter yields between treatments in both crop cycles. High crop water use was achieved. WUE values were 12 percent (and up to 41 percent) higher.

The Effect Irrigation Scheduling and Potassium Fertilization on Water Consumption of Potato (Solanum tuberosum L.) Under Modern Irrigation Systems

A field experiment was conducted in Yusufiya sub-district - Mahmudiya township/Baghdad governorate in silty loam texture soil during the spring season of 2020. The experiment included three treatments with three replicates, as the Randomized Complete Block Design (RCBD) was used according to the arrangement of the split design block. The treatments are in the irrigation system, which included surface drip irrigation (T1) and sprinkler irrigation (T2). Secondly, the Irrigation levels including the irrigation using 0.70 Pan Evaporation Fraction PEF (I1), irrigation using 1.00 PEF (I2), and irrigation using 1.30 PEF (I3). Coupled with, Potassium fertilization treatments that include (0.0 kg k ha-1 (K1), 150 kg k ha-1 (K2) and 300 kg k ha-1 (K3)). The results showed that the actual seasonal water consumption reached its peak at irrigation level I1, which reached 390.03 and 256.41 mm for the sprinkler and drip irrigation systems, respectively. However, the actual seasonal water consumption at irrigation level I2 was 373.92 and 255.63, and it was 353.82 and T255.15 mm at irrigation level I3 for the sprinkler and drip irrigation systems, respectively. The lowest values of the crop coefficient at the tuber maturity stage using the sprinkler irrigation system were 0.49, 0.46, and 0.44, and at the vegetative growth stage using the surface drip irrigation system by 0.37, 0.32, and 0.38 for irrigation levels I1, I2, and I3, respectively. Even though the greatest values were in the tuber Initiation and bulking stages, as they reached 0.86, 0.66, and 0.79 using the sprinkler irrigation system, while they reached 0.49, 0.54, and 0.51 using the surface drip irrigation system for I1, I2, and I3 levels, respectively. The highest water productivity for treatment I3K3 was 15.70 and 27.20 kg m-3 of sprinkler and surface drip irrigation systems, respectively. In contrast, the lowest water productivity was 8.73 and 17.72 kg m-3 for treatment I1K1 of sprinkler and surface drip irrigation systems, respectively. Whereas, the highest value of crop water use efficiency was 11.70 and 17.58 kg m-3 for I3K3 treatment of sprinkler and surface drip irrigation systems, respectively. Although, the lowest value of crop water use efficiency was 6.71 and 11.49 kg m-3 for I1K1 treatment of sprinkler and surface drip irrigation systems, respectively. Lastly, the highest yield was 44.87 Mg ha-1 at treatment T1I3K3.

Maize grain yield and water use efficiency in relation to climatic factors and plant population in northern China

Water scarcity has become a limiting factor for increasing crop production. Finding ways to improve water use efficiency (WUE) has become an urgent task for Chinese agriculture. To understand the response of different maize populations to changes in precipitation and the effects of changes in maize populations on WUE, this study conducted maize population experiments using maize hybrids with different plant types (compact and semi compact) and different planting densities at 25 locations across China. It was found that, as precipitation increased across different locations, maize grain yield first increased and then decreased, while WUE decreased significantly. Analyzing the relationship between WUE and the main climatic factors, this study found that WUE was significantly and negatively correlated with precipitation ($$ (daily mean precipitation) and R (accumulated precipitation)) and was positively correlated with temperature (TM (daily mean maximum temperature), TM–m (Tm, daily mean minimum temperature) and GDD (growing degree days)) and solar radiation ($$ (daily mean solar radiation) and Ra (accumulated solar radiation)) over different growth periods. Significant differences in maize grain yield, WUE and precipitation were found at different planting densities. The population densities were ranked as follows according to maize grain yield and WUE based on the multi-site experiment data: 60 000 plants ha–1 (P2)>90 000 plants ha–1 (P3)>30 000 plants ha–1 (P1). Further analysis showed that, as maize population increased, water consumption increased significantly while soil evaporation decreased significantly. Significant differences were found between the WUE of ZD958 (compact type) and that of LD981 (semi-compact type), as well as among the WUE values at different planting densities. In addition, choosing the optimum hybrid and planting density increased WUE by 21.70 and 14.92%, respectively, which showed that the hybrid played a more significant role than the planting density in improving WUE. Therefore, choosing drought-resistant hybrids could be more effective than increasing the planting density to increase maize grain yield and WUE in northern China. Comprehensive consideration of climatic impacts, drought-resistant hybrids (e.g., ZD958) and planting density (e.g., 60 000 plants ha–1) is an effective way to increase maize grain yield and WUE across different regions of China.