Relative Water Use Research Articles

Nitrogen Fertilisation and Seed Rate Regulation Improved Photosynthesis, Grain Yield and Water Use Efficiency of Winter Wheat (Triticum aestivum L.) Under Ridge–Furrow Cropping

ABSTRACTRidge–furrow cropping patterns, nitrogen fertilisation and seed rate regulation are popular management strategies for improving crop yields in the semi‐arid areas of Northwest China, but their interactive effects on grain yield and water use efficiency remain poorly understood. In 2020–2021 and 2021–2022, a two‐season field experiment was conducted on winter wheat. There were two cropping patterns (C), ridge–furrow cropping with film mulch (RC) and traditional cropping without mulch (TC), two nitrogen fertilisation rates (N), 0 and 200 kg N ha−1 (N0 and N1) and three seed rates (S), 240, 360 and 480 plants m−2 (S1, S2 and S3). The study was conducted in a split–split design with three replications (randomised blocks) and a total of 24 experimental plots. It was found that the interactive effects of C × N, C × S and N × S were significant on soil temperature (ST), leaf area index (LAI), relative chlorophyll content (SPAD), photosynthetic parameters, grain yield (GY) and water use efficiency (WUE) (p < 0.05), while C × N × S was significant only for LAI, aboveground biomass (AGB), GY and WUE (p < 0.05). Compared with TC and N0, RC and N1 significantly increased SPAD value (2.4% and 15.8%), net photosynthetic rate (Pn) (19.8% and 32.8%), net photosynthetic rate (Pn), transpiration rate (Tr) (7.0% and 15.7%) and the effective PSII quantum production (ΦPSII) (10.7% and 5.0%). The highest GY (6773 kg ha−1 over 2020–2021 and 8036 kg ha−1 over 2021–2022) and WUE (20.03 kg ha−1 mm−1 over 2020–2021, and 21.77 kg ha−1 mm−1 over 2021–2022) of winter wheat were observed under RC + N1 + S2. The findings showed that the RC cropping pattern with fertilisation and seed rate regulation (360 plants m−2) of winter wheat, which is appropriate for ensuring the long‐term sustainability of agricultural production in the semi‐arid regions of Northwest China, enhanced plant growth, photosynthetic traits, yield and water use efficiency. The study might give useful information for enhancing the productivity and water use efficiency of winter wheat in this and other similar climate locations.

Yields, growth and water use under chemical topping in relations to row configuration and plant density in drip-irrigated cotton

BackgroundWater deficit is an important problem in agricultural production in arid regions. With the advent of wholly mechanized technology for cotton planting in Xinjiang, it is important to determine which planting mode could achieve high yield, fiber quality and water use efficiency (WUE). This study aimed to explore if chemical topping affected cotton yield, quality and water use in relation to row configuration and plant densities.ResultsExperiments were carried out in Xinjiang China, in 2020 and 2021 with two topping method, manual topping and chemical topping, two plant densities, low and high, and two row configurations, i.e., 76 cm equal rows and 10+66 cm narrow-wide rows, which were commonly applied in matching harvest machine. Chemical topping increased seed cotton yield, but did not affect cotton fiber quality comparing to traditional manual topping. Under equal row spacing, the WUE in higher density was 62.4% higher than in the lower one. However, under narrow-wide row spacing, the WUE in lower density was 53.3% higher than in higher one (farmers’ practice). For machine-harvest cotton in Xinjiang, the optimal row configuration and plant density for chemical topping was narrow-wide rows with 15 plants m-2 or equal rows with 18 plants m-2.ConclusionThe plant density recommended in narrow-wide rows was less than farmers’ practice and the density in equal rows was moderate with local practice. Our results provide new knowledge on optimizing agronomic managements of machine-harvested cotton for both high yield and water efficient.

Enhancing Small Millet Farming Resilience through Conservation Agriculture in Rainfed Regions

The Centre of Excellence in Millets, located in Athiyandal, Tamil Nadu, conducted an extensive study from kharif 2020 to 2022, focusing on the impact of conservation agriculture practices on small millet crops in rainfed areas. The experiment, designed in a split-plot layout, included three main plot treatments: No tillage, Minimal tillage, and Mulching, with six sub-plot treatments comprising various millet varieties. Results indicated that a single ploughing significantly reduced weed populations, while mulching played a crucial role in curbing weed growth and conserving water. This led to substantial increases in grain yield and straw yield, ranging from 24.3% to 36.1% over the control, alongside an improvement in relative water use efficiency (RWUE) from 5.16 to 7.03 kg/ha/mm. Among the various millets cultivated with the mulching treatment (S3) emerged as the most favorable option in terms of grain yield. Finger millet, Kodomillet, and Foxtail millet exhibited the highest yields under this treatment, with 3010 kg/ha, 2234 kg/ha, and 2003 kg/ha, respectively. Additionally, Little millet, Barnyard millet, and Proso millet also demonstrated improved yields under Mulching, recording 1015 kg/ha, 1004 kg/ha, and 910 kg/ha, respectively. These results conclude that small millet cultivation in rainfed areas with mulching practices effectively enhances grain production, reduces weed growth, and ensures optimal water conservation, thereby providing sustainable alternatives to herbicide usage.

Energy-water-food security nexus in mung bean production in Iran: An LCA approach

Mung bean is a very important crop in Iran in both socio-economic and nutritional terms. However, although discussions on food and food security increasingly include sustainability issues, there are no precedents in academic literature that analyze in depth the nexus between energy, water use and food security in relation to this crop in Iran from an agri-food system approach. Therefore, our main objective is to assess the energy-water-food security (EWFs) nexus and the environmental impact of mung bean production in Iran from a “cradle to fork” approach using different nutritional units (1 kg of beans, 1 kg of proteins, and 1000 kcal) and load allocation criteria. In addition, an economic analysis of the farms is carried out. The results show that the on-farm production of mung beans is the phase where the largest environmental impacts are concentrated (between 40 % and 96 % of them, including those related to water and energy use), while cooking accounts for more than 50 % of the carbon footprint. The non-renewable cumulative energy demand (NR CED) and total water footprint (TWF) per kilogram of beans (“cradle to fork”) is estimated at 27.4 MJ and 1.55 m3 and the farm Net Margin (NM) is estimated at 3,677 USD per ha. The paper discusses whether mung bean is a low-impact option for protein production, especially when compared to animal products and the importance of using different functional units and load allocation criteria to address the issue of EWFs and sustainability. In this regard, further research is needed to improve the environmental efficiency of bean production, which is critical for promoting sustainable diets in line with food security goals.

Identification of functional traits responsible for environmental vulnerability of Cedrus deodara in temperate forests of Western Himalaya

Climate change is impacting forest tree species adversely and making the ecological system vulnerable. The present study attempts to assess the internal vulnerability of Cedrus deodara occurring in nine sub-types of temperate forests in Western Himalaya, India via a plant functional trait-based approach. Internal vulnerability was assessed based on sensitivity and adaptive capacity through proposing an index using IPCC framework. Sensitivity was determined based on various traits (indicators) of light harvesting, carbon assimilation, nutrient content, and water budget, whereas adaptability was defined based on light harvesting efficiency, water use efficiency, resource use efficiency, and nutrient limitation. Sensitivity was maximum in Dry Deodar Forest (0.51) and Low-Level Blue Pine Forest (0.51) and minimum in Western Mixed Coniferous Forest (o.38), however adaptability was maximum in Kharsu Oak Forest (0.65) and Moist Deodar Forest-II (0.65) with minimum adaptability for Ban Oak Forest (0.53). In Ban Oak Forest, Low-Level Blue Pine Forest and Moist Deodar Forest-II high stomatal conductance compensates the low chlorophyll achieving homeostasis state for photosynthesis. Negative minimum temperature (-6.95 to −2.04 °C) in winters followed by high monsoon rainfall (417.74 to 1256.13 mm) causes high sensitivity amongst the C. deodara population in Low Level Blue Pine Forest, Dry Deodar Forest and Moist Deodar Forest-II; and adaptability was majorly affected by water availability i.e., excessive monsoon rainfall in Ban Oak Forest (1962.45 mm) and least rainfall in Neoza Pine Forest (349.50 mm). Overall, the vulnerability was high in Low Level Blue Pine Forest (0.46), Ban Oak Forest (0.45) and Dry Deodar Forest (0.45). Present study identified key traits for species vulnerability therefore management intervention should orient towards those silvicultural operations which may reduce relative water use of the species and may also facilitate for improved photosynthesis i.e., through water provision and density management of the C. deodara dominated forests in Himalayan region. The study concludes that a unified approach for managing species of the forest may be disadvantageous and detrimental to forest conservation. Rather site-specific management approach, which led to incremental response to the identified traits may support the conservation of species.

GIS-Based Assessment of Irrigation Water Quality Index in Selected Farm Areas, South-Western, Nigeria

Water is the most essential nutrient for plant survival and its quality is vital to soil health and crop yields. This study evaluated, categorized and mapped water quality application condition in selected farm settlements, Ekiti North Senatorial District, Nigeria, using Irrigation Water Quality Index (IWQI). Twelve water samples from surface and groundwater sources across the farm settlements were collected and analyzed with replicates in the laboratory, following standard procedures. IWQI revealed that 61% of the water samples fall within ‘‘severe restriction" category covering the northeast and northwest parts while 39 % falls into the ‘‘high restriction" category for cropping covering the southern part respectively. The outcomes of the study allows for guided water use in relation to soil factor and provide good quality water database in the face of inadequate rainfall occasioned by climate change for optimum water utilization and crop production.

Categorizing relative water use perception bias using household surveys and monthly water bills

We introduce the concept of relative water use perception bias to highlight the role of human relationships, social cues, and the built environment in household water consumption. Although previous studies have explored actual water use, it is also important to understand how people perceive their relative behaviors because humans are social animals and act in relation to each other. We combine household survey responses and water utility bills in a large sample of households to quantify the degree of over- and under-estimation bias in perceived relative household water use. We then use multi-level nested regression models to investigate four categories of potential influence: sociodemographic characteristics, perceived social norms, neighborhood characteristics, and water bill information. Results show that most households tended to view themselves as ‘better than average’ water users when they actually used more water compared to neighbors. Respondents in high-income households and those who are more concerned about water shortages were more likely to underestimate their relative water use (using comparatively more than they thought). However, in more suburbanized neighborhood environments, households were more likely to overestimate their relative water use (using comparatively less than they thought). We call the inaccuracy in assessing water usage compared to their neighbors' relative water use perception bias. We propose that a better understanding of this bias can aid the design of policy initiatives like neighborhood planning, better water bill design, targeted messaging, and social signaling. By bringing a relational lens to bear on water conservation studies, understanding relative water use perception bias sheds new light on the complex drivers of household water consumption.

Functional traits and drought strategy predict leaf thermal tolerance.

Heat stress imposes an important physiological constraint on native plant species-one that will only worsen with human-caused climate change. Indeed, rising temperatures have already contributed to large-scale plant mortality events across the globe. These impacts may be especially severe in cities, where the urban heat island effect amplifies climate warming. Understanding how plant species will respond physiologically to rising temperatures and how these responses differ among plant functional groups is critical for predicting future biodiversity scenarios and making informed land management decisions. In this study, we evaluated the effects of elevated temperatures on a functionally and taxonomically diverse group of woody native plant species in a restored urban nature preserve in southern California using measurements of chlorophyll fluorescence as an indicator of leaf thermotolerance. Our aim was to determine if species' traits and drought strategies could serve as useful predictors of thermotolerance. We found that leaf thermotolerance differed among species with contrasting drought strategies, and several leaf-level functional traits were significant predictors of thermotolerance thresholds. Drought deciduous species with high specific leaf area, high rates of transpiration and low water use efficiency were the most susceptible to heat damage, while evergreen species with sclerophyllous leaves, high relative water content and high water use efficiency maintained photosynthetic function at higher temperatures. While these native shrubs and trees are physiologically equipped to withstand relatively high temperatures in this Mediterranean-type climate, hotter conditions imposed by climate change and urbanization may exceed the tolerance thresholds of many species. We show that leaf functional traits and plant drought strategies may serve as useful indicators of species' vulnerabilities to climate change, and this information can be used to guide restoration and conservation in a warmer world.

Application of γ-aminobutyric acid (GABA) improves fruit quality and rootstock drought tolerance in apple

GABA (γ-aminobutyric acid) plays a multifaceted role in plant growth, fruit quality, and tolerance to abiotic stresses. However, its physiological roles and mechanisms in the fruit quality and response to long-term drought stress in apple remain unelucidated. To investigate the effect of GABA on apple fruit quality and drought tolerance, we sprayed exogenous GABA on apple cultivar “Cripps Pink” and irrigated rootstock M.9-T337 with GABA, respectively. Results showed that exogenous GABA could effectively improve the fruit quality of “Cripps Pink”, including increased sugar-to-acid ratio, flesh firmness, pericarp malleability, and GABA content, as well as reduced fruit acidity. In addition, pretreatment of M.9-T337 plants with GABA improved their tolerance to both long- and short-term drought stress. Specifically, 1 mM exogenous GABA increased the net photosynthetic rate, relative leaf water content, root-to-shoot ratio, and water use efficiency under long-term drought stress, and delayed the increased of the relative electrolyte leakage under short-term drought stress. RNA-seq analysis identified 1271 differentially expressed genes (DEGs) between nontreated and GABA-pretreated plants under short-term drought stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these DEGs revealed that GABA may enhance plant drought resistance by upregulating the expression of genes related to “Biosynthesis of secondary metabolites”, “MAPK signaling pathway”, “Glutathione metabolism”, and “Carbon fixation in photosynthetic organisms”. In conclusion, these results revealed that exogenous GABA can improve fruit quality and enhance drought tolerance in apple.

Analyzing Embodied Energy and Embodied Water of Construction Materials for an Environmentally Sustainable Built Environment

Buildings consume over 40% of global energy in their construction and operations contributing to over 39% of global carbon emission each year. This huge environmental footprint presents an excellent opportunity to reduce energy use and help deliver an environmentally sustainable built environment. Most of the energy is consumed by buildings as embodied energy (EE) and operational energy (OE). EE is used directly and indirectly during buildings’ initial construction, maintenance and replacement, and demolition phases through construction products and services. OE is used in the processes of heating, cooling, water heating, lighting, and operating building equipment. Most environmental optimization research has been centered on energy and carbon emission overlooking another critical sustainability aspect, water use. Each building also consumes a significant amount of freshwater as embodied water (EW) or virtual water in its initial construction, maintenance and replacement, and demolition phases. Since each primary and secondary energy source depletes water in its extraction, refinement or production, there is also a water expense associated with EE and OE use that must also be included in total EW use. The total EW, therefore, includes both non-energy and energy related water use. Research suggests that there are tradeoffs between EE and EW that may complicate design decisions such as material selection for environmental sustainability. In other words, a material selected for its lower EE may have higher EW and selecting such a material may not help reach environmental sustainability goals since water scarcity is becoming a grave problem. In this paper, we created an input-output-based hybrid (IOH) model for calculating and comparing EE and EW of building materials frequently used in building construction. The main goal is to examine and highlight any tradeoffs that may exist when selecting one material over another. The results reveal that there is a weak correlation between EE and total EW that is the sum of energy and non-energy water use, which means that a design decision made solely based on EE may conflict with EW. The share of energy related water use in total EW of construction materials also varies significantly (2.5%-31.2%), indicating that reducing energy use alone may not be sufficient to reduce freshwater use; additional efforts may be needed to decrease the use of materials and processes that are water intensive. The results of this study are significant to achieving the goal of creating a truly sustainable built environment.

Virtual water trade: Economic development and independence through optimal allocation

The uneven temporal and spatial distribution of water has led to water crises in many countries. The virtual water trade constitutes a means of dealing with such crises. The virtual water trade uncovers the hidden flow of water in traded commodities between countries. This work proposes a multi-objective optimization model that maximizes the revenue and minimizes the direct and indirect water uses of producing strategic agricultural and industrial goods. Several water prices and levels of subsidies are accounted for in the optimization. A country’s agricultural and industrial independence is used to constraint the optimization problem, which achieves food security and economic benefit. The proposed optimization model is applied to identify the portfolio of suitable agricultural products in Iran. Results show that wheat features the largest portion of water use in the agricultural sector, while potatoes and tomatoes are more lucrative due to their relative high price and low water use of about 400 m3 per ton of produce. Moreover, it is found that raising the water price reduces industrial imports because producing industrial goods is cost-effective in offsetting the reduction of net-revenue from agricultural production.

Water Allocation, Return Flows, and Economic Value in Water-Scarce Environments: Results from a Coupled Natural-Human System Model

In many parts of the world including the western United States, the allocation of water is governed by complex water laws that dictate who receives water, how much they receive, and when. Because these rules are generally based on the seniority of water rights, they are not necessarily focused on maximizing economic value across the entire economy. The maximization of value from water use economy-wide is a complex optimization problem that must explicitly consider each user’s water demand, willingness to pay (WTP) function, and the feedbacks among users in a coupled natural-human system model. In this study, we distill these complexities into a simple MATLAB® model developed to represent a two-user economy with water-dependent sectors representative of agriculture and industry. We feed the model with realistic values of relative water use, relative willingness to pay, and return flows to explore the relationships among these factors in water-limited systems. We find that the total economic value generated from water-dependent users depends primarily on the total water available in the system. However, for a given volume of water available, economic value is not necessarily maximized when all the water is appropriated to the user with the highest WTP. Rather, total economic value depends on the amount of water available, the relative WTP between the two users, and on the return flows generated from each sector’s water use. While our simple two-user model is a significant abstraction of the complexities inherent in natural systems, our study provides important insights into the coupled natural-human system dynamics of water allocation and use in water-limited environments.

The Effects of Osmosis and Thermo-Priming on Salinity Stress Tolerance in Vigna radiata L.

A plant’s response to osmotic stress is a complex phenomenon that causes many abnormal symptoms due to limitations in growth and development or even the loss of yield. The current research aimed to analyze the agronomical, physiological, and biochemical mechanisms accompanying the acquisition of salt resistance in the Vigna radiata L. variety ‘Ramzan’ using seed osmo- and thermopriming in the presence of PEG-4000 and 4 °C under induced salinity stresses of 100 and 150 mM NaCl. Seeds were collected from CCRI, Nowshera, and sowing was undertaken in triplicate at the Department of Botany, Peshawar University, during the 2018–2019 growing season. Rhizospheric soil pH (6.0), E.C (2.41 ds/m), field capacity, and moisture content level were estimated in the present study. We observed from the estimated results that the agronomic characteristics, i.e., shoot fresh weight and shoot dry weight in T9 (4oC + 150 mM NaCl), root fresh weight and root dry weight in T4 (PEG + 100 mM NaCl), shoot moisture content in T5 (PEG + 100 mM NaCl), and root moisture content in T6 (PEG + 150 mM NaCl) were the highest, followed by the lowest in T1 (both shoot and root fresh weights) and T2 (shoot and root dry weights). Similarly, the shoot moisture content was the maximum in T5 and the minimum in T6, and root moisture was the highest in T6. We observed from the estimated results that agronomical parameters including dry masses (T4, T6, T4), leaf area index, germination index, leaf area, total biomass, seed vigor index under treatment T9, and relative water content and water use efficiency during T5 and T6 were the highest. Plant physiological traits such as proline, SOD enhanced by T1, carotenoids in treatment T2, and chlorophyll and protein levels were the highest under treatment T4, whereas sugar and POD were highest under treatments T7 and T8. The principal component analysis enclosed 63.75% of the total variation among all biological components. These estimated results confirmed the positive resistance by Vigna radiata during osmopriming (PEG) and thermopriming (4 °C) on most of the features with great tolerance under a low-saline treatment such as T4 (PEG), T5 (PEG + 100 mM NaCl), T7 (4 °C), and T8 (4 °C + 100 mM NaCl), while it was susceptible in the case of T6 (PEG + 150 mM NaCl) and T9 (4 °C + 150 mM NaCl) to high salt application. We found that the constraining impact of several priming techniques improved low salinity, which was regarded as economically inexpensive and initiated numerous metabolic processes in plants, hence decreasing germination time. The current study will have major applications for combatting the salinity problem induced by climate change in Pakistan.

Embodied water analysis of higher education buildings using an input-output-based hybrid method

From the production of raw materials to the construction of a building, construction activities consume large quantities of water as embodied water . In fact, over 16% of global water use occurs in construction activities. Total embodied water of a building includes water directly used in construction activities, water indirectly consumed in the production and delivery of construction materials, and water used by the energy sources powering the construction activities as embodied energy . However, the number of comprehensive studies on embodied water of buildings is lacking. In this study, an input-output-based hybrid model is developed to determine and analyze not only direct and indirect embodied water intensities, but also the energy related embodied water intensities of construction materials and higher education buildings. The results indicate that, similar to embodied energy, using an aggregated input-output-based hybrid analysis may return misleading embodied water values as compared to a disaggregated analysis because embodied water intensities vary for each material. The results also show that the amount of energy related embodied water could be significant (7%–12% of total embodied water at the building level), highlighting the significance of energy related water use when evaluating total embodied water. Results further underscore the significance of applying a more energy-water nexus perspective when evaluating the environmental and resource consumption impacts of buildings.

Association of jasmonic acid priming with multiple defense mechanisms in wheat plants under high salt stress.

Salinity is a global conundrum that negatively affects various biometrics of agricultural crops. Jasmonic acid (JA) is a phytohormone that reinforces multilayered defense strategies against abiotic stress, including salinity. This study investigated the effect of JA (60 μM) on two wheat cultivars, namely ZM9 and YM25, exposed to NaCl (14.50 dSm−1) during two consecutive growing seasons. Morphologically, plants primed with JA enhanced the vegetative growth and yield components. The improvement of growth by JA priming is associated with increased photosynthetic pigments, stomatal conductance, intercellular CO2, maximal photosystem II efficiency, and transpiration rate of the stressed plants. Furthermore, wheat cultivars primed with JA showed a reduction in the swelling of the chloroplast, recovery of the disintegrated thylakoids grana, and increased plastoglobuli numbers compared to saline-treated plants. JA prevented dehydration of leaves by increasing relative water content and water use efficiency via reducing water and osmotic potential using proline as an osmoticum. There was a reduction in sodium (Na+) and increased potassium (K+) contents, indicating a significant role of JA priming in ionic homeostasis, which was associated with induction of the transporters, viz., SOS1, NHX2, and HVP1. Exogenously applied JA mitigated the inhibitory effect of salt stress in plants by increasing the endogenous levels of cytokinins and indole acetic acid, and reducing the abscisic acid (ABA) contents. In addition, the oxidative stress caused by increasing hydrogen peroxide in salt-stressed plants was restrained by JA, which was associated with increased α-tocopherol, phenolics, and flavonoids levels and triggered the activities of superoxide dismutase and ascorbate peroxidase activity. This increase in phenolics and flavonoids could be explained by the induction of phenylalanine ammonia-lyase activity. The results suggest that JA plays a key role at the morphological, biochemical, and genetic levels of stressed and non-stressed wheat plants which is reflected in yield attributes. Hierarchical cluster analysis and principal component analyses showed that salt sensitivity was associated with the increments of Na+, hydrogen peroxide, and ABA contents. The regulatory role of JA under salinity stress was interlinked with increased JA level which consequentially improved ion transporting, osmoregulation, and antioxidant defense.

Effect of Restoration on Plant Greenness and Water Use in Relation to Drought in the Riparian Corridor of the Colorado River Delta

ABSTRACTRevitalization of the Colorado River delta riparian corridor and increasing riparian plant greenness and water use may be accomplished by added water and restoration efforts to offset declines measured since 2000 by Landsat. We use the two‐band Enhanced Vegetation Index (EVI2; a proxy for greenness) and evapotranspiration (ET, mm/day) using EVI2 and potential ET(ETo) from Yuma Valley. We assess if restoration with only 7.5% landcover had an impact on the unrestored reach‐level landcover by measuring these two metrics, EVI2 and ET(EVI2) by comparing restored and unrestored areas. A key finding is that over 21‐years EVI2 in the unrestored corridor decreased by 23.6% and ET(EVI2) decreased by 32% (0.87 mm/day). Since 2011, the unrestored reaches lost EVI2 (11%) and −0.73 mm/day ET(EVI2) (28%), but restored sites increased in EVI2 (36%) and 0.58 mm/day ET(EVI2) (20%). Water delivered to restored sites increased EVI2 by 33.6% and 1.29 mm/day ET(EVI2) (58%). EVI2 and ET(EVI2) as a function of the Standardized Precipitation Evapotranspiration Index for drought periods highlight that restored and unrestored sites respond differently. Unrestored reaches are in decline; restored sites show increases in EVI2 and ET(EVI2). Restored sites do not have a significant impact on unrestored adjacent area, but smaller surface flows, a greater reliance on directed agricultural return flows, and deliveries of water to active restoration sites have revitalized habitat and increased ecosystem services in the delta.

The role of water and energy use in expanding the boundaries of irrigated agriculture in the Berrechid plain of Morocco

AbstractDespite the attention given to the water–energy–food nexus, there is little field evidence of how this plays out for irrigators. This article analyses the diversity of irrigation system configurations and their related water and energy use in semi‐arid Morocco, where groundwater‐fed and pressurized drip irrigation, although supposedly thrifty, is energy intensive. The analysis relying on hydraulic calculations and multiple linear regressions was based on interviews, observations and measurements on irrigation systems in 25 farms. The results show that each farmer used between one and three pumps and up to two storage reservoirs to pump groundwater from up to 120 m deep borehole(s) and transfer it along a distance often exceeding 2 km to reach available fertile lands that are rented. Such distances had little effect on the system‐wise energy consumption, varying between 4.62 and 4.88 kWh m−3, although the recycled car engines powering these irrigation systems were largely inefficient, consuming on average 2.5 kWh m−3. State subsidies encourage these water‐intensive and energy‐inefficient farming systems, increasing pressure on groundwater and land. These findings underline the importance of going beyond a strict nexus perspective, as expansion of the ‘groundwater economy’ is accompanied by conflicts over tenure and increasing inequalities in access to water that threaten the sustainability of irrigated agriculture.

Applying Biostimulants to Combat Water Deficit in Crop Plants: Research and Debate

Climate change has increased the severity of drought episodes by further reducing precipitation in vulnerable zones. Drought induces a substantial decrease in agricultural water, reducing crop yields. Consequently, addressing water consumption can increase farmers’ profits. This work describes lab-to-field research in Zea mays, using two biostimulants: glycine betaine (GB) and L-pyroglutamic acid (PG). The biostimulant optimal dosages were selected using a hydroponic system with 20% polyethylene glycol and nursery experiments under water-deficit irrigation. The established dosages were evaluated in field trials in which irrigation was reduced by 20%. Laboratory biostimulant optimisation showed in stressed treated seedlings (GB 0.1 mM; PG 1 mM) an increased dry weight, relative growth rate and water use efficiency, reducing seedling growth loss between 65 and 85%, respectively. Field trials using a GB-optimised dosage showed an increase in plants’ growth, grain yield and flour Ca content. In addition, grain flour carbohydrate content and protein remained similar to control well-watered plants. Finally, the economic aspects of biostimulant treatments, water consumption, water sources (ground vs. desalinated) and grain biomass were addressed. Overall, GB treatment demonstrated to be a valuable tool to reduce water consumption and improve farmers’ earnings.

Quantifying water stress of safflower (Carthamus tinctorius L.) cultivars by crop water stress index under different irrigation regimes

Infrared thermometry allows evaluating water status of the crop by measuring crop water stress index (CWSI), without the need of physical contact to leaves. In order to quantify water stress by CWSI and finding the best irrigation regime a two-year field experiment was conducted in safflower during 2017 and 2018 growing seasons at Darab, Fars province, Iran. Two safflower cultivars (Goldasht and Local Isfahan) and four irrigation regimes consisted of well-watered [Irrigation based on 100% field capacity (FC)], mild (75% FC), severe (50% FC), and most severe (25% FC) water stress were arranged as split plot according to randomized completely block design with four replicates. The relationship between vapor pressure deficit (VPD) and canopy-air temperature differences (Tc-Ta) was plotted under upper (fully stressed) and lower baselines (non-stressed) equations. In two cultivars, by VPD increment, the distance between upper and lower base lines increased. In Goldasht, the upper baseline (Tc-Ta)ul, was 7.8 °C in 2017 and 8.9 °C in 2018. From April to July when air warmed, Tc-Ta differential was increased up to July and the highest seasonal CWSI (0.72–0.77) were obtained in Local Isfahan under most severe water stress. In 2017, under water stress, the highest relative water content (RWC; 55%), color quality (6–7) and water use efficiency (WUE; 2.69 g m−2 mm−1) was observed in Goldasht under mild water stress which was more than 2018 and Local Isfahan. It might be attributed the more tolerance of Goldasht to water stress and lower air temperature and evaporation in the first year. CWSI with total water consumed (R2 = 0.88∗∗), RWC (R2 = 0.87∗∗), color quality (R2 = 0.75∗) and seed yield (R2 = 0.83∗∗) related, negatively. Overall, a mild water stress (75% FC) with 0.28–0.33 seasonal CWSI had higher RWC, color quality, WUE, with an acceptable yield, which could be the best irrigation regime under water deficit conditions for safflower.

Physiological Responses and Root Profiles of Melastoma malabathricum Grown with Food Waste Compost and Lime as Soil Amendments in Acidic Soil Condition

Soil acidification prevents the elongation of roots, which is one of the major constraints to crop productivity. Proper acidic soil amelioration can improve soil fertility, resulting in an increase in plant physiological processes and the survival of the plants. The interaction of physiological responses and root profiles in Melastoma malabathricum as a result of soil amelioration using food waste compost, liming, and a combination of food waste compost and liming when grown in acidic soil conditions was assessed. The resulting plants exhibited an outstanding leaf area index, relative chlorophyll content, photosynthetic rate and water use efficiency in food waste compost treatment. Similarly, the plants also showed the highest root volume and diameter. The results implied that the application of soil amendment, specifically food waste compost towards acidic soil was able to enhance plant growth through better gas exchange and root morphology. In addition, a positive correlation was observed between root diameter and root volume with the physiological responses, indicating that soil amendments assisted plants in getting the nutrients necessary for gas exchange, hence influencing the plant roots. In conclusion, the use of food waste compost alone was deemed adequate as it showed good effects on plant physiological performances as well as root profiles. Hence, the preliminary results of this study highlight the potential use of food waste compost as a promising solution to support the growth and development of plants, especially those grown under acidic soil conditions.