Increased Water Use Research Articles

Water Management to Cope with the Effects of Climate Change Best practices in Water Management at Wageningen University & Research

Wageningen University & Research studies the causes of heavy rainfall and droughts and is looking for solutions to these phenomena [1]. For example, green spaces in the urban environment ensure that water can be drained into the ground. Storage of water is also important, because not only the number of heavy rains is increasing, also there are longer periods of drought. On WUR Campus, these principles of coping with flooding and drought are applied. There is a sizeable area of green space which serves as a groundwater discharge area. The large ponds on campus are used to collect and store excess surface water. During droughts the ponds retain water on campus. In two campus buildings, rain is harvested for flushing toilets and watering inner gardens. The rainwater is harvested from rooftops and stored in underground water tanks. A natural garden was laid out in 1998, and four years ago a natural wetland garden was added to the campus.The effects of climate change, such as droughts and rising sea water levels affect freshwater supplies, which makes efficient use of water increasingly important. WUR aims to reduce consumption of tap water every year, by increasing water use efficiency and switching to sources other than tap water.

Salicylic Acid and Pyraclostrobin Can Mitigate Salinity Stress and Improve Anti-Oxidative Enzyme Activities, Photosynthesis, and Soybean Production under Saline–Alkali Regions

Soybean is a widespread crop in semi-arid regions of China, where soil salinity often increases and has a significant harmful impact on production, which will be a huge challenge in the coming years. Salicylic acid (SA) and pyraclostrobin are strobilurin-based bactericides (PBF). Under rainfall-harvesting conditions in covered ridges, the exogenous application of SA and PBF can improve the growth performance of soybeans, thereby reducing the adverse effects of soil salinity. The objectives of this research are to evaluate the potential effects of SA and PBF on soybean growth in two different regions, Harbin and Daqing. A two-year study was performed with the following four treatments: HCK: Harbin location with control; SA1+PBF1: salicylic acid (5 mL L−1) with pyraclostrobin (3 mL L−1); SA2+PBF2: salicylic acid (10 mL L−1) with pyraclostrobin (6 mL L−1); DCK: Daqing location with control. The results showed that in the Harbin region, SA2+PBF2 treatment reduced the evapotranspiration (ET) rate, increased soil water storage (SWS) during branching and flowering stages, and achieved a maximum photosynthesis rate. Moreover, this improvement is due to the reduction of MDA and oxidative damage in soybean at various growth stages. At different growth stages, the treatment of Harbin soybean with SA2+PBF2 significantly increased the activity of CAT, POD, SOD, and SP, while the content of MDA, H2O2, and O2− also decreased significantly. In the treatment of SA2+PBF2 in Harbin, the scavenging ability of free H2O2 and O2− was higher, and the activity of antioxidant enzymes was better. This was due to a worse level of lipid-peroxidation which successfully protected the photosynthesis mechanism and considerably increased water use efficiency (WUE) (46.3%) and grain yield (57.5%). Therefore, using plastic mulch with SA2+PBF2 treatment can be an effective water-saving management strategy, improving anti-oxidant enzyme activities, photosynthesis, and soybean production.

Role of ACC deaminase-producing rhizobacteria in alleviation of water stress in watermelon

Owing to the increased global warming, drought severity has increased in many regions, threatening food security, especially in arid and semi-arid areas. Therefore, it is imperative to mitigate the impact of drought on plants in water-stressed areas. The utilization of plant-growth-promoting rhizobacteria (PGPRs) serves as an environmentally friendly approach to enhance the resilience of plants exposed to abiotic stress, specifically drought. This research focuses on examining the effects of 35 PGPR isolates, possessing significant ACC (1-aminocyclopropane-1-carboxylic acid) deaminase activity, which were obtained from diverse plant-rhizosphere soil samples encompassing approximately 17,000 km2 of semi-arid regions. The investigation was conducted on watermelon plants experiencing varying degrees of water stress (30% and 60% water stress). An increase in water stress exerted a detrimental effect on agro-morphological parameters, such as biomass (root + shoot), leaf number, and leaf area of non-inoculated plants. PGPRs stimulated plant growth and increased water use efficiency, especially under severe water-stress (60% water stress) conditions compared to non inoculated plants (control). Furthermore, some PGPRs such as B7, B22, B26 and B28 supported carotenoid synthesis, which plays an important role in photosynthesis, whereas some alleviated the effect of water stress in watermelon plants by stimulating the antioxidant defense system. The outcomes of principal component, where the data were collectively assessed, demonstrated the superior efficacy of certain PGPRs. Specifically, under water-stress conditions, PGPR isolates B31, B32, and B35 exhibited significant growth-promoting effects on watermelon. Additionally, isolates B13 and B15 demonstrated the activation of antioxidant defense mechanisms, including proline, catalase, and peroxidase. PGPRs showed considerable results on the agro-morphological, physiological, and biochemical properties of watermelon under 60% water-stress conditions compared with those under 30% water stress. In conclusion, PGPRs promoted growth and alleviated severe water stress in watermelon plants compared to their control. The results of this study elucidate PGPR-triggered response mechanisms in water-stressed watermelon plants.

Gradient-based LASER Land Leveling Increases the Water Use Efficiency, Growth, and Yield of Cotton Crop under Changing Climate

Increasing water shortage has compelled farmers to develop plans for efficient use of water resources. The improvement in water use efficiency at the field level is very important and can redress water scarcity. LASER land leveling is increasing quickly in the world to increase water use efficiency. However, in developing countries, the practice of LASER leveling is to level land or field with zero (0 %) gradient due to unawareness of gradient-based land leveling while a small gradient (e.g., 0.1 %) is usually kept during land leveling in developed countries of the world. But farmers of developing countries are not well, therefore, an experiment was conducted in farmers’ fields covering an area of 3 acres in south Punjab of Pakistan to assess the LASER leveling with a 0 % and 0.05 % grade and general farmer’s practice of leveling. Land leveling with LASER using a 0.05 % gradient considerably decreased the amount of irrigation water and/or enhanced water use efficiency by increasing crop yield followed by LASER leveling with a 0 % gradient. Similarly, with a 0.05 % gradient, bolls per plant and final cotton yield increased considerably followed by a 0 % gradient while minimum bolls per plant and cotton yield were obtained from the farmer’s practice of leveling. LASER land leveling with a 0.05 % gradient resulted in higher net benefit due to increased yield and a considerable decrease in irrigation amount that significantly improved use efficiency. The outcomes suggest that benefits from land leveling with LASER keeping a 0.05 % gradient are significantly higher when compared with 0 % gradient and/or farmers’ practice of leveling.

Influences of calcium silicate fertilization to physiological and bio-active responses of maize under drought and well-watered conditions

A pot experiment was conducted to investigate the effects of silicon (Si) on morpho-physiological and bio-chemical traits of maize under different irrigation regimes. Experimental treatments comprised of irrigations [60% and 100% of field capacity (FC)], treatments (0, 50, 100, 150, 200 mg kg−1 CaO4Si) and growing stages (GS) [7th (first) and 14th (second) days of water restriction]. 150 mg kg−1 Si increased the growth of maize by inducing transpiration rate (67.56%), water use efficiency (138.36%) and seedling length (19.83%) at first GS whilst enhanced carotenoids (10.95%), total phenolic compounds (45.04%) and decreased proline (7.87%) at the second GS of 60% treatment. In addition, 200 mg kg−1 Si elevated photosynthesis rate (40.54%), total antioxidant activity (12.69%) and decreased proline (52.77%) at the first GS while increased total anthocyanin content (14.99%) during the second GS of 60% application. Silicon had positive impacts on maize under full irrigation conditions too such that 150 mg kg−1 Si reduced transpiration rate (48.43%) and induced total antioxidant activity (39.95%) at first GS while 200 mg kg−1 Si increased water use efficiency by 144.30% at the second GS. In conclusion Si increased drought resistance due to increasing application doses, and on contrary of the literature, Si positively affected many characters at well-watered environment.

Effects of Hemlock Woolly Adelgid Control Using Imidacloprid on Leaf-Level Physiology of Eastern Hemlock

Widespread mortality of eastern hemlock (Tsuga canadensis [L.] Carr.) has been occurring due to the introduction of hemlock woolly adelgid (Adelges tsugae Annand) (HWA), threatening millions of hectares of hemlock-dominated forests in the eastern United States. HWA feeds at the base of needles and removes stored carbohydrates, which can impact leaf-level physiology, contributing to the decline of the tree. However, these physiological mechanisms in HWA-infested hemlocks are still not clearly understood. We investigated hemlock leaf physiology year-round at three forested sites with various degrees of infestation. At each site, half the trees were treated with imidacloprid (Merit® 2 F, Bayer, Kansas City, MO, USA) while the rest were left untreated. Imidacloprid is widely used to control HWA but can itself have phytotoxic effects. After one growing season, there was an increase in photosynthetic rates (7.5%, p = 0.0163) and stomatal conductance (7.1%, p = 0.0163) across sites in the trees treated with imidacloprid. After two years, the imidacloprid treatment also increased bud break from 22.5% to 88.7% at Fishburn (the most severely impacted site) and from 22.7% to 58.9% at Mountain Lake (the least impacted site), and slightly increased chlorophyll fluorescence for treated trees at Fishburn. Chemical treatment also slightly increased water use efficiency at Mountain Lake. These results suggest that HWA is causing tree mortality largely through a reduction in leaf area caused by decreasing bud break and also by a slight, but significant, reduction in leaf-level photosynthesis and stomatal conductance.

Adapting to Climate-Change-Induced Drought Stress to Improve Water Management in Southeast Vietnam

In Southeast Vietnam, droughts have become more frequent, causing significant damage and impacting the region’s socio-economic development. Water shortages frequently affect the industrial and agricultural sectors in the area. This study aims to calculate the water balance and the resilience of existing water resource allocations in the La Nga-Luy River basin based on two scenarios: (1) business-as-usual and (2) following a sustainable development approach. The MIKE NAM and MIKE HYDRO BASIN models were used for rainfall–runoff (R-R) and water balance modeling, respectively, and the Keetch–Byram Drought Index (KBDI) was used to estimate the magnitude of the droughts. The results identified areas within the Nga-Luy River basin where abnormally dry and moderate drought conditions are common, as well as subbasins, i.e., in the southeast and northeast, where severe and extreme droughts often prevail. It was also shown that the water demand for the irrigation of the winter–spring and summer–autumn crop life cycles could be fully met under abnormally dry conditions. This possibility decreases to 85–100% during moderate droughts, however. In contrast, 65% and 45–50% of the water demand for irrigation is met for the winter–spring and summer–autumn crop life cycles, respectively, during severe and extreme droughts. Furthermore, this study demonstrates that the water demand for irrigation could still be met 100% and 75–80% of the time during moderate, and extreme or severe droughts, respectively, through increased water use efficiency. This study could help managers to rationally regulate water in order to meet the agricultural sector’s needs in the region and reduce the damage and costs caused by droughts.

Assessing the efficacy of water management and wheat straw addition in mitigating methane emissions from rice paddy fields

AbstractTo improve the quality of soil, agriculture typically uses organic additions like wheat straw (WS). Water management (WM) methods such as alternative wetness and dryness irrigation (AWDI) in paddy rice farming can increase water use efficiency and reduce greenhouse gas (GHG) emissions. In this study, a randomized complete block design (RCBD) pot greenhouse experiment was conducted to assess the effects of WM (CFI (continued flooding irrigation) and AWDI), WS (15.0 and 30.0 ton ha−1), and their interaction (WS*WM) on CH4 emissions and rice yield in a paddy calcareous soil cultivated with rice. The largest CH4 emission occurred 30 and 70 days following rice planting. Single applications of WS at 15.0 and 30.0 ton ha−1 significantly increased CH4 emissions by 19.60% and 68.70% (P < 0.01), respectively, compared to the Control. Compared to CFI, the AWDI reduced CH4 emissions by 31.20% (P < 0.01). The correlations between AWDI and CH4 emissions in days after rice planting were significantly negative at the 0.01 level based on Pearson correlation. Adding WS in the AWDI significantly decreased CH4 emissions by 27.70 and 25.64% in 15.0 and 30.0 ton ha−1 added WS (P < 0.05), respectively, compared to sole WS. Both rates of WS resulted in a considerable increase in biomass and rice grain compared to the Control, while the AWDI had no significant effect on biomass and grain yield. Our data showed significant interaction between AWDI and WS on biomass. Our study shows that the AWDI saved 18.50% water compared to the CFI.

Water Management for Sustainable Irrigation in Rice (Oryza sativa L.) Production: A Review

In the face of the negative impacts of climate change and the accelerated growth of the global population, precision irrigation is important to conserve water resources, improve rice productivity and promote overall efficient rice cultivation, as rice is a rather water-intensive crop than other crops. For several decades, various water conserving technologies have been studied in order to significantly increase water use efficiency (WUE). The objective of this paper is to review the main technologies and approaches for assessing the water requirements of rice crop in order to contribute to water saving in irrigated rice production, after clarifying the performance indicators of the irrigated systems. Several scientific articles from previous studies were consulted and analyzed. These studies showed that irrigation water conservation includes a wide range of practices, staring from the crop irrigation water requirements assessment to the implementation of the water saving practices on the field. In addition, irrigation water conservation technologies could be categorized into three groups, namely water-conserving irrigation systems, water-saving irrigation methods, and water-conserving agronomic practices. The influence of the individual and combined irrigation water use efficiency tools was highlighted. This paper will enable researchers to acquire knowledge on water-saving methods for estimating the rice crop water requirements and thus allow them to effectively contribute to improve the performance of irrigated rice cultivation systems using various water conservation technologies.

A Step toward Water Use Sustainability: Implementing a Business Model Canvas for Irrigation Advisory Services

Some major future global challenges are linked to more efficient use of water for irrigation to respond to the growing water scarcity coupled with the increasing food demand. Although irrigation advisory services (IASs) are considered effective instruments to increase water use efficiency in agriculture, their diffusion remains limited. This is due to several constraints mainly linked to their low accessibility and high costs. To overcome the bottlenecks associated with IASs’ adoption, this paper proposes a business model (BM) as a tool for scaling up IASs within a business perspective, with the aim of encouraging the diffusion of this technology while enhancing the associated environmental and social benefits. Drawn from the experience of the OPERA project, we structured the business model taking advantage of the opinion of relevant stakeholders and IASs’ potential users to identify specific limitations and understand their needs. It turned out that farmers are willing to adopt IASs but require that the service is easily accessible, with high-quality information that are delivered at an affordable cost. Indeed, here a BM with an innovative way to produce and deliver value is proposed. The value proposition is built upon key features namely, integration, customization, accessibility, and sustainability that reflect users’ needs and preferences. Our BM also provides a detailed revenues strategy that guarantees the financial sustainability of IASs. To design and represent our BM, the “Business Model Canvas ©” has been adopted. We concluded that an innovative and well-structured BM has the potential to leave the IASs profitable and capable to ensure environmental and social sustainability.

Spatiotemporal characteristics of water use change and its driving factors in China’s urban agglomerations

Under the background of water scarcity, water use change is a vital indicator for coordinated development of socioeconomic and eco-environmental system, especially in China’s urban agglomerations which are “markers” that identify water use change across the country. Therefore, this study adopts detailed data for irrigation, industrial, and domestic subsectors at the prefecture-level city scale to reveal the spatiotemporal characteristics of water use changes across and within China’s urban agglomerations during 2000–2020. Meanwhile, the contributions of nine socioeconomic drivers are quantitatively dissected by Logarithmic Mean Divisia Index (LMDI). The results show that, total water use in China’s urban agglomerations experienced a trend of rising first and then declining, but it remained about 360 billion m3 over the whole period. Total and sectoral water use changes across and within China’s 19 urban agglomerations showed significant differences. The activity and structure effects increased water use by 160 billion m3 and 10 billion m3 for China’s urban agglomerations over the whole period, while the intensity effects decreased water use by 170 billion m3. Most urban agglomerations and prefecture-level cities had the same dominant driving factors as the overall situation of China’s urban agglomerations, belonging to the intensity-driven and activity-driven type. The results could serve as scientific supports to propose targeted water management policies and development pathways for China’s urban agglomerations.

Incentive‐Stacking to Increase Water Use Efficiency

Key TakeawaysIn 2012, the Metropolitan Water District of Southern California combined its commercial and residential water conservation rebate programs into SoCal Water$mart, still in use today.Member agencies and their retail agency customers can add funding to Metropolitan's base‐level incentives for what are referred to as “stacked incentives.”Metropolitan has processes in place to allow for co‐funding flexibility, ensure rebate accuracy, and maintain agency and consumer satisfaction.

Climate change: challenges and limitations in agriculture

Climate has always been changing, but the current changes and climate models indicate a significant and rapid increase of temperatures, atmospheric CO2 concentration, shifts in precipitation patterns and consequently a higher frequency, duration and intensity of climate extremes (frost, heat and drought periods, heavy precipitation, hail, storms, floods, storm surges, etc.). Thus, agriculture on the whole but also agro-ecosystems are very susceptible and highly vulnerable to the effects of these changes. The scenarios for climate development in Austria also follow the global trends. Increasing temperatures in combination with more frequent heat waves, water shortage and drought events will be the most serious constraints on growth and quality of many crop plants. However, such changes do not result only in the negative effects. Higher average temperatures accelerate the development of many plants. The increasing CO2 concentration in the atmosphere to a certain extent may stimulate plant growth (fertilization effect) combined with an increased water use efficiency. The cultivation period is longer and the winters milder and wetter, which may allow new cultivation time and forms as well as new species. For agriculture, several adaptive strategies are possible, which include but are not limited to plant breeding, choice of plant species and variety as well as soil and cultivation management. However, the extent to which negative and positive climate impacts will strongly influence the agriculture in the given area is still largely unknown, but will be of crucial importance for the prediction of future crop yields.

Modulation of Antioxidant Defense Mechanisms and Morpho-Physiological Attributes of Wheat through Exogenous Application of Silicon and Melatonin under Water Deficit Conditions

Although the individual influences of silicon (Si) and melatonin (MT) have been widely studied under various abiotic stresses, little is known about their interaction under drought stress. In this study, an experiment in pots was carried out to investigate the potential of an individual or combined foliar application of silicon (Si) and melatonin (ML) (control (ck), water spray, 4.0 mM Si, 200 µM ML, and 4.0 mM Si + 200 µM ML) on wheat grown at two different water-holding capacity levels (80% well-water condition and 40% drought stress) in order to check of grain yield and some important physiological characteristics. Under drought stress conditions, grain yield and yield attributes, water content and photosynthetic efficiency of wheat crops were significantly decreased. Application of Si+ ML significantly improved leaf pigments (Chl a, Chl b and Chll a + b), leaf relative water content (RWC), proline, total soluble sugars, and total soluble protein. As well as, the activities of important antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX) were effectively boosted through the combined application of Si + ML. This improvement was correlated with an obvious decrease in the levels of MDA, H2O2, and electrolyte leakage and increased water use efficiency. Conclusively, the combination of Si + ML significantly enhanced the 20.21% yield and various morpho-physiological attributes of drought-stressed wheat plants and can be recommended as a promising treatment to enhance wheat productivity in drought-affected regions. Additionally, the results of this study may open up a whole new area of research opportunities at the transcriptional level to further understand the mechanisms underlying how Si + ML integrates and interacts with plants under drought stress.

Canola (Brassica napus L.) water use indicators as affected by sustained deficit irrigation and plant density in central Free State, South Africa

In South Africa canola (Brassica napus L.) is cultivated in rotation with wheat under winter rainfall in the Western Cape Province, primarily for seed to make oil. Expansion of the crop to the other 8 provinces is proposed to reduce shortages of locally produced plant oils. At the same time, canola can serve as a rotational crop for wheat in these summer rainfall provinces. In central Free State, information on evapotranspiration and various water use indicators for canola as influenced by sustained deficit irrigation and plant density is lacking. An experiment with a line source sprinkler irrigation system was therefore conducted, comprising of full irrigation as a control with 4 sustained deficit irrigation levels (mean reduction in irrigation depth per event of 67%, 52%, 34% and 19%) and 5 plant densities (25, 50, 75, 100 and 125 plants‧m−2). Mean seasonal maximum evapotranspiration amounted to 429 mm across plant densities. Plant density did not significantly influence seasonal evapotranspiration. Reducing the irrigation depth per event by more than 20% decreased seasonal evapotranspiration by a mean 3.5 mm per percentage increase in irrigation depth. A maximum biomass water productivity of 22 kg‧ha−1‧mm−1 was measured with full irrigation and a plant density of 75 plants‧m−2. Seed water productivity amounted to a high of 11 kg‧ha−1‧mm−1 with full irrigation and a plant density of 25 plants‧m−2. A percentage reduction in irrigation depth and increase in plant density above 25 plants‧m−2 will reduce seed water productivity by 0.071 and 0.033 kg‧ha−1‧mm−1, respectively. Sustained deficit irrigation increased water use efficiency by a mean 0.5% per percentage reduction in irrigation depth per event.

Time to Onset of Flowering, Water Use, and Yield in Wheat

Crop breeding has been successful in increasing crop grain yield (GY; reproductive biomass) largely through reduced vegetative size, increased reproductive effort (RE = reproductive biomass/total biomass) and increased water-use efficiency (WUE) in grain production. Flowering time is an important life history trait that signifies the switch from vegetative to reproductive growth. The relationship between GY and time from sowing to flowering (Tsf) is unclear. We fit the relationships between GY and RE vs. Tsf to the logistic model using data from 18 spring wheat genotypes grown under simulated rainfed conditions. Tsf accounted for water use before and after flowering, root length density, total leaf area, and the time from flowering to harvest. Early flowering meant decreased water use before flowering and increased water use afterward. Soil water remaining at harvest was positively correlated with yield. Early flowering genotypes have a higher WUE of grain production, but there was no significant difference in the WUE of total biomass production. The relationship between grain yield and Tsf is described as a unimodal curve, as is the relationship between RE and Tsf. Higher yields and a higher RE have been achieved through earlier flowering, and both RE and Tsf reached their optimal values for maximizing GY. Crop breeding is unlikely to achieve further increases in GY through this route in the future. The results suggest that breeding does not improve biomass’s water-use efficiency, but causes changes in biomass allocation strategy, and this could be a new direction for genetically improving grain yield.

Effect of Magnetic Water Treatment on the Growth, Nutritional Status, and Yield of Lettuce Plants with Irrigation Rate

Climate change is causing an increase in dry spells, altering rainfall patterns and soil moisture, and affecting water and nutrient plant uptake, which inevitably affects vegetable production. To mitigate this issue, some technologies that allow the maintenance of the ideal soil moisture for the uptake process are being investigated. Considering this, we hypothesize that the use of water treated with a magnetic field can increase water use efficiency in lettuce crop production. Thus, the present study aimed to evaluate the effect of the irrigation rate of magnetically treated water on biomass accumulation and nutrient uptake by lettuce plants. An experiment was conducted in a randomized block design with a 2 × 5 factorial arrangement of two water sources (conventional water and magnetically treated water) and five irrigation application rates to replace crop evaporation: 25, 50, 75, 100, and 125%, with five replicates. The use of magnetically treated water increased the concentrations of nitrogen and phosphorus in leaves, meaning that it induced higher nitrogen assimilation, leading to increases in agronomical characteristics (leaf number, fresh and dry shoot weight, fresh and dry root weight). The conclusions of this study showcase that magnetically treated water has beneficial effects on lettuce plants, improving their nutritional status and yield. Moreover, the results presented can lead to an increase in water use efficiency, thus optimizing irrigation management.

Nitrogen application rates influence on yield and water productivity of quinoa under saline irrigation water regimes and saline water table

There are areas with high saline water and saline irrigation water in Iran that may be used for quinoa cultivation. In these conditions, proper saline irrigation water regimes and nitrogen application should be determined and used. Therefore, the aim of this experiment is to investigate the effect of different saline irrigation water regimes (100, 75 and 50% of full irrigation, FI) and nitrogen application rates (0, 100, 200 and 300 kg ha−1) on growth and yield of quinoa with water table depth of 0.8 m, salinity of irrigation water and water table of 20 dS m−1. The irrigation of 75% FI and 50% FI decreased the applied water by 19 and 38%, respectively. Further, there was no reducing effect of irrigation water regimes in seed and shoot dry matter yield. Furthermore, groundwater contribution (GWC) increased significantly by 8 and 18% in 75%FI and 50%FI compared with that obtained in full irrigation, and resulted in no extreme water stress under high water table depth (0.8 m). Increasing application of nitrogen fertilizer significantly increased the yield components, ETc and GWC. In addition, reducing irrigation water did not show a significant decrease in water use efficiency (WUE) in high water table depth. However, water productivity increased significantly by decreasing irrigation water. It is concluded that under deficit irrigation, high water table depth could be a valuable source of water supply to meet quinoa water requirements. Moreover, application of nitrogen fertilizer at all levels significantly increased water use efficiency and water productivity.

Seasonal Differences in Ecophysiological Performance between Resprouters and Non-Resprouters across an Aridity Gradient in Northwest Tunisia

Understanding the functioning of shrub species during dry periods is necessary to forecast ecosystem responses to future climates, particularly in Mediterranean environments. We evaluated the seasonal changes in leaf gas exchange, hydraulic traits, carbon and nitrogen isotopes, and non-structural carbohydrates of seeders and resprouting shrub species typical of Aleppo pine forests across an aridity gradient in Tunisia: Djebel Zaghouan (subhumid climate), Djebel Mansour (semiarid transitional climate), and Djebel El Sarj (semi-arid climate). We monitored seven woody species: Pistacia lentiscus, Erica multiflora, Phillyrea latifolia (resprouters), Cistus monspeliensis, Rosmarinus officinalis (seeders), Globularia alypum, and Calicotome villosa (resprouters-seeders). The seasonal variation in leaf water content was usually higher in seeders than in resprouters and was associated with higher resistance to embolism. In contrast, the seasonal variation in non-structural carbohydrates was higher in resprouters, especially at the driest site. Both δ13C and δ15N displayed seasonal enrichment-depletion patterns, with seeders showing an overall higher δ13C in summer than in spring, consistent with a water-saving strategy of increasing water use efficiency. Discriminant analysis suggested that resprouters can sustain a positive carbon balance during drought periods. The differential impact of summer droughts on water status and the ecophysiology of these plant strategies may lead to different ecosystem dynamics depending on whether climate change tips the balance towards a preponderance of stressors (drought) or disturbances (fire) in dry Mediterranean areas.

Effect of Bacillus paralicheniformis on soybean (Glycine max) roots colonization, nutrient uptake and water use efficiency under drought stress

AbstractSpore‐forming, plant growth‐promoting bacteria (PGPR) offer extraordinary opportunities for increasing plant productivity in climate change scenarios. Plant–water relationships, root development and photosynthetic performances are all key aspects of plant physiology determining yield, and the ability of PGPR to influence these in a coordinated manner is crucial for their success. In this study, we dissected the mode of action of a commercial Bacillus paralicheniformis FMCH001 in promoting soybean (Glycine max, seed variety: Sculptor) establishment in well‐watered and drought conditions. We found that FMCH001 colonizes the roots, improved root growth and allowed plants to absorb more nutrients from the soil. FMCH001 inoculation had no effect on abscisic acid in leaf or xylem sap, while significantly improved photosynthesis rate, stomatal conductance and transpiration rate at 28 days after planting when drought stress exposed for 7 days, with depressed leaf water potential and osmotic potential. Moreover, the bacterium increased water use efficiency and the inoculated soybean plants exposed to drought used 22.94% less water as compared to control, despite producing comparable biomass. We propose that the ability of the bacterium to promote root growth and also modulate plant water relations are key mechanisms that allow FMCH001 to promote growth and survival in dicotyledon plants.