Toxicity of Diazinon 60 EC for embryos and larvae of tench, <Emphasis Type="Italic">Tinca tinca</Emphasis> (L.)

The effects of Diazinon 60 EC (organophosphate insecticide, active substance diazinon) on mortality, growth rate, early ontogenetic rate, and occurrence of malformations was studied in embryos and larvae of tench, Tinca tinca (L.). The exposure of fish to 0, 10, 100, 1,000, and 3,000 μg dm⁻³ of Diazinon 60 EC was initiated 24 h after fertilization of eggs and concluded 32 days later. At the highest concentration tested (3,000 μg dm⁻³), total mortality was observed within the first 15 days of exposure. A concentration of 1,000 μg dm⁻³ caused high incidence of malformations, decrease in growth rate and ontogenetic development slowed down. A concentration of 100 μg dm⁻³ mildly decreased growth rate, but at 10 μg dm⁻³ no changes compared to the control were observed. Thus, Diazion 60 EC at the concentration of 10 μg dm⁻³ is not dangerous for the embryos and larvae of tench.     

Effects of different dietary fatty acids profiles on the growth performance and body composition of juvenile tench (<Emphasis Type="Italic">Tinca tinca</Emphasis> (L.))

Juvenile tench (initial weight of about 57 g) were fed feed supplemented with fish oil (group FO), linseed oil (group LO), peanut oil (group PO), or rapeseed oil (group RO) containing 47% protein and 12% fat for 55 days. The inclusion of the tested oils was 50 g kg⁻¹ (42% total crude lipids in diets). No significant differences were noted in the fish growth performance. The proximate composition of the whole fish bodies and the viscera (water, protein, fat, ash) was similar in all the dietary treatments (P > 0.05). Differences were noted only with regard to the ash content of the fillets (P < 0.05). The analysis of the fatty acids profiles of tench (whole fish) indicated there were significant differences in the total content of monoenoic and polyenoic (PUFA) acids. Significant differences were also noted with regard to n-3 PUFA and n-6 PUFA. Consequently, the ratio of n-3/n-6 acids ranged from 1.6 (group PO) to 2.08 (group LO; P < 0.05). The feed applied was not confirmed to have had an impact on the fatty acids profile of the tench fillets. There was a statistically significant intergroup difference in the content of saturated fatty acids (SFA) in tench viscera. In the fish fed vegetable oils supplemented diets, the level of SFA was lower (P < 0.05).     

Fed-batch production of a bioflocculant from <Emphasis Type="Italic">Corynebacterium glutamicum</Emphasis>

The constant-rate fed-batch production of the polygalacturonic acid bioflocculant REA-11 was studied. A controlled sucrose-feeding strategy resulted in a slight improvement in biomass and a 7% reduction in flocculating activity compared with the batch process. When fed with a 3 g l⁻¹ urea solution, the flocculating activity was enhanced to 720 U ml⁻¹ in 36 h. High cell density (2.12 g l⁻¹) and flocculating activity (820 U ml⁻¹) were obtained in a 10-l fermentor by feeding with a sucrose-urea solution, with values of nearly two times and 50% higher than those of the batch process, respectively. Moreover, the residual sucrose declined to 2.4 g l⁻¹, and residual urea decreased to 0.03 g l⁻¹. Even higher flocculating activity of 920 U ml⁻¹ and biomass of 3.26 g l⁻¹ were obtained by feeding with a sucrose-urea solution in a pilot scale fermentation process, indicating the potential industrial utility of this constant-rate feeding strategy in bioflocculant production by Corynebacterium glutamicum.     

Insecticide-tolerant and plant growth promoting <Emphasis Type="Italic">Bradyrhizobium</Emphasis> sp. (<Emphasis Type="Italic">vigna</Emphasis>) improves the growth and yield of greengram [<Emphasis Type="Italic">Vigna radiata</Emphasis> (L.) Wilczek] in insecticide-stressed soils

This study was designed to identify rhizobial strains specific to greengram expressing higher tolerance against insecticides, fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide-stress. Of the 50 bradyrhizobial isolates, the Bradyrhizobium sp. strain MRM6 showed tolerance up to 1,600 μg mL⁻¹ against each of fipronil and pyriproxyfen. The tolerant Bradyrhizobium sp. (vigna) produced plant growth promoting substances in substantial amounts, both in the presence and absence of insecticides. The strain MRM6 was further used to investigate its impact on greengram grown in soils treated with 200 (the recommended dose), 400 and 600 μg kg⁻¹ soil of fipronil and 1,300 (the recommended dose), 2,600 and 3,900 μg kg⁻¹ soil of pyriproxyfen. Fipronil at 600 μg kg⁻¹ soils and pyriproxyfen at 3,900 μg kg⁻¹ soils had greatest toxic effects and decreased plant biomass, symbiotic efficiency, nutrient uptake and seed yield of greengram plants. The Bradyrhizobium sp. (vigna) inoculant when used with fipronil and pyriproxyfen significantly increased the measured parameters compared to the plants grown in soils treated solely with the same concentration of each insecticide. This study inferred that the Bradyrhizobium sp. (vigna) strain MRM6 may be exploited as bio-inoculant to increase the productivity of greengram exposed to insecticide-stressed soils.     

Growth and carrageenan quality of <Emphasis Type="Italic">Kappaphycus striatum</Emphasis> var. <Emphasis Type="Italic">sacol</Emphasis> grown at different stocking densities,duration of culture and depth

Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly (P < 0.01) affected the growth rate, carrageenan content and molecular weight of K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower stocking density (500 g m⁻¹line⁻¹) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise, decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period produced the highest molecular weight at both stocking densities (500 g m⁻¹line⁻¹ = 1,079.5 ± 31.8 kDa, 1,000 g m⁻¹line⁻¹ = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m⁻¹line⁻¹, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content and molecular weight.     

Tolazoline antagonises ketamine–xylazine anaesthesia in an endangered Black buck (<Emphasis Type="Italic">Antilope cervicapra</Emphasis>)

Seventy-seven anaesthetic events were carried out in 22 captive adult Black bucks (Antilope cervicapra) of either sex with a combination of 2 mg kg⁻¹ ketamine hydrochloride with 0.25 mg kg⁻¹ xylazine hydrochloride using a dart delivered from a blowpipe. Randomised anaesthetised animals received an intravenous injection of either yohimbine hydrochloride (0.125 or 0.25 mg kg⁻¹) or tolazoline hydrochloride (1 or 2 mg kg⁻¹) after 30–40 min of anaesthesia to antagonise the anaesthetic effects. Ketamine–xylazine induced smooth, rapid and reliable anaesthesia within 5–7 min of darting with no clinical adverse effects and causalities during or post-anaesthesia. Yohimbine failed to antagonise the anaesthetic effects of ketamine–xylazine in the Black buck. On the other hand, tolazoline was found to be very effective in hastening recovery in dose-dependent manner within 0.5–1.5 min. This study documents the first report of ketamine–xylazine anaesthesia and its antagonism by tolazoline in captive Black buck.     

Bio-hydrogen production from cellulose by sequential co-culture of cellulosic hydrogen bacteria of <Emphasis Type="Italic">Enterococcus gallinarum</Emphasis> G1 and <Emphasis Type="Italic">Ethanoigenens harbinense</Emphasis> B49

Microbial conversion of lignocellulose to hydrogen is a fascinating way to provide a renewable energy source. A mesophilic bacterium strain G1 that had high cellulose degradation and hydrogen production activity (2.38 mmol H₂ g⁻¹ cellulose) was isolated from rumen fluid and identified as the Enterococcus gallinarum. Hydrogen production from cellulose by using sequential co-cultures of a cellulosic-hydrolysis bacterium G1 and Ethanoigenens harbinense B49 was investigated. With an initial Avicel concentration of 5 g l^−l, the sequential co-culture with G1 and strain Ethanoigenens harbinense B49 produced H₂ yield approximately 2.97 mmol H₂ g⁻¹ cellulose for the co-culture system.     

Evaluation of the toxicity of <Emphasis Type="Italic">Arthrospira</Emphasis> (<Emphasis Type="Italic">Spirulina</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis> extract

In this study, the methanol extract of Arthrospira (Spirulina) platensis was examined for acute and subchronic toxicities. The extract did not produce any sign of toxicity within 7 days after feeding it at a single high dose of 6 g kg⁻¹ body weight to female and male Swiss mice. For the subchronic toxicity test, the extract at doses of 6, 12, and 24 mg kg⁻¹ body weight was orally administered to six male and six female Wistar rats daily for 12 weeks. Throughout the study period, we did not observe any abnormalities on behavior, food and water intakes, and health status among the treated animals. The hematology and clinical chemistry parameters of treated groups did not significantly differ from those of the controls in both sexes. Postmortem examination of the test groups also showed no abnormalities in both gross and histological findings. These results thus suggest that the methanol extract of A. platensis did not cause acute or subchronic toxicity in our experimental animals.     

In vitro propagation of four threatened <Emphasis Type="Italic">Paphiopedilum</Emphasis> species (Orchidaceae)

The effects of seed maturity, media type, carbon source, and organic nutrient additives on seed germination, protocorm development, and plant growth of Paphiopedilum villosum var. densissimum Z. J. Liu et S. C. Chen were investigated. Micropropagation frequency was enhanced through the use of 200-day-old seed, Knudson C (KC) medium, and the presence of both glucose and coconut milk in the medium. The effects of various plant growth regulators on the frequency of shoot organogenesis in four Paphiopedilum species were also investigated. Explants of P. villosum var. densissimum and P. insigne (Lindl.) Stein incubated in the presence of 5 mg l⁻¹ 6-benzyladenine (BA) with 0.5 mg l⁻¹ α-naphthalene acetic acid (NAA) and 0.2 mg l⁻¹ BA with 0.1 mg l⁻¹ NAA, respectively, showed a twofold increase in the frequency of shoot organogenesis. For explants of P. bellatulum (Rchb. f.) Stein and P. armeniacum S. C. Chen et F. Y. Liu, the combination of 5.5 mg l⁻¹ BA with 0.5 mg l⁻¹ NAA and 4 mg l⁻¹ BA with 0.1 mg l⁻¹ NAA, respectively, resulted in the highest frequencies of shoot organogenesis.     

Direct gene transfer study and transgenic plant regeneration after electroporation into mesophyll protoplasts of <Emphasis Type="Italic">Pelargonium</Emphasis> <Emphasis Type="Italic">×</Emphasis> <Emphasis Type="Italic">hortorum</Emphasis>, ‘Panaché Sud’

Direct genetic transformation of mesophyll protoplasts was studied in Pelargonium × hortorum. Calcein and green-fluorescent protein (GFP) gene were used to set up the process. Electroporation (three electric pulses from a 33-μF capacitor in a 250-V cm⁻¹ electric field) was more efficient than PEG 6000 for membrane permeation, protoplast survival and cell division. Transient expression of GFP was detected in 33–36% of electroporated protoplasts after 2 days and further in colonies. A protoplast suspension conductivity of >1,500 μS cm⁻¹ allowed high colony formation and plant regeneration. Stable transformation was obtained using the plasmid FAJ3000 containing uidA and nptII genes. When selection (50 mg l⁻¹ kanamycin) was achieved 6 weeks after electroporation, regenerated shoots were able to grow and root on 100 mg l⁻¹ kanamycin. The maximum transformation efficiency was 4.5%, based on the number of colonies producing kanamycin-resistant rooted plants or 0.7% based on the number of cultured protoplasts. Polymerase chain reaction (PCR) analysis on in vitro micropropagated plants showed that 18 clones out of 20 contained the nptII gene, while the uidA gene was absent. These results were confirmed after PCR analyses of five glasshouse-acclimatized clones.     

Growth dynamics and the proximate biochemical composition and fatty acid profile of the heterotrophically grown diatom <Emphasis Type="Italic">Cyclotella cryptica</Emphasis>

To investigate the nutritional value of the diatom Cyclotella cryptica as an alternative feed for aquaculture, its heterotrophic growth characteristics were studied. First, the proximate biochemical composition and fatty acid profiles were studied under a controlled heterotrophic growth condition. The approximate total ash, carbohydrate, lipid, and protein content were 245 mg g⁻¹ (dry weight), 360 mg g⁻¹, 165 mg g⁻¹ and 260 mg g⁻¹, respectively. Polyunsaturated fatty acids accounted for 24.5, 31.3, 45.1 and 17.3% of the total lipids in the phospholipid, sterol, free fatty acid and triglyceride classes. Secondly, the effect of aeration and agitation rates on the specific growth rate of C. cryptica under heterotrophic conditions was studied. The maximum specific growth rate was not significantly affected (P > 0.05) by the rate of agitation within the range of 100 to 160 rpm, but it was significantly affected (P > 0.05) by the rate of aeration. Optimal growth occurred when the aeration rate was within the range of 0.44 to 1.07 v/v/min. Viability measurements throughout the growth period showed that the C. cryptica cells remained viable in spite of the varied cultivation conditions. Hydrodynamic forces are an important parameter within biological systems, and optimisation is crucial for the successful scale-up of microalgal cultivation systems. Whilst the investigation was preliminary in nature, the information gained in this study will be useful for the continual development of an alternative and cost-effective feed for bivalve spat rations.     

Preparation of galactans from <Emphasis Type="Italic">Gracilaria debilis</Emphasis> and <Emphasis Type="Italic">Gracilaria salicornia</Emphasis> (Gracilariales,Rhodophyta) of Indian waters

Superior quality non-methylated and low-sulphated galactans were extracted from two Indian agarophytes namely Gracilaria debilis and G. salicornia growing naturally along the west coast of India, using an eco-friendly method developed in our laboratory. The galactans were characterised by FT-IR, ¹³C NMR, GC-MS, ICP, GPC and rheological measurements. G. debilis produced exclusively non-methylated galactan exhibiting the greatest gel strength of 650±25 g cm⁻² and lowest sulphate of 0.21±0.06%. On the contrary, G. salicornia polysaccharide was composed of non-methylated galactose (major) and mannose (minor), having gel strength of 510±25 g cm⁻² and sulphate of 0.45±0.06%. Very low heavy metal contents were determined in both the galactan samples, which may thus be potentially useful in food and biological applications.     

Introduction of <Emphasis Type="Italic">OsglyII</Emphasis> gene into <Emphasis Type="Italic">Oryza sativa</Emphasis> for increasing salinity tolerance

Mature seed-derived embryogenic calli of indica rice (Oryza sativa L. cv. PAU201) were induced on semisolid Murashige and Skoog medium supplemented with 2.5 mg dm⁻³ 2,4-dichlorophenoxyacetic acid + 0.5 mg dm⁻³ kinetin + 560 mg dm⁻³ proline + 30 g dm⁻³ sucrose + 8 g dm⁻³ agar. Using OsglyII gene, out of 3180 calli bombarded, 32 plants were regenerated on medium containing hygromycin (30 mg dm⁻³). Histochemical GUS assay of the hygromycin selected calli revealed GUS expression in 50 % calli. Among the regenerants, 46.87 % were GUS positive. PCR analysis confirmed the presence of the transgene of 1 kb in 60 % of independent plants. Further, these plants have been grown to maturity in glasshouse. In vitro screening for salt tolerance showed increase in fresh mass of OsglyII putative transgenic calli (185.4 mg) as compared to control calli (84.2 mg) on 90 mM NaCl after 15 d. When exposed to 150 mM NaCl, OsglyII putative transgenic plantlets showed normal growth while the non-transgenic control plantlets turned yellow and finally did not survive.     

Alginate production and <Emphasis Type="Italic">alg8</Emphasis> gene expression by <Emphasis Type="Italic">Azotobacter vinelandii</Emphasis> in continuous cultures

Alginates are polysaccharides that are used as thickening agents, stabilizers, and emulsifiers in various industries. These biopolymers are produced by fermentation with a limited understanding of the processes occurring at the cellular level. The objective of this study was to evaluate the effects of agitation rate and inlet sucrose concentrations (ISC) on alginate production and the expression of the genes encoding for alginate-lyases (algL) and the catalytic subunit of the alginate polymerase complex (alg8) in chemostat cultures of Azotobacter vinelandii ATCC 9046. Increased alginate production (2.4 g l⁻¹) and a higher specific alginate production rate (0.1 g g⁻¹ h⁻¹) were obtained at an ISC of 15 g l⁻¹. Carbon recovery of about 100% was obtained at an ISC of 10 g l⁻¹, whereas it was close to 50% at higher ISCs, suggesting that cells growing at lower sucrose feed rates utilize the carbon source more efficiently. In each of the steady states evaluated, an increase in algL gene expression was not related to a decrease in alginate molecular weight, whereas an increase in the molecular weight of alginate was linked to higher alg8 gene expression, demonstrating a relationship between the alg8 gene and alginate polymerization in A. vinelandii for the first time. The results obtained provide a possible explanation for changes observed in the molecular weight of alginate synthesized and this knowledge can be used to build a recombinant strain able to overexpress alg8 in order to produce alginates with higher molecular weights.     

Influence of gelling agent and cytokinins on the control of hyperhydricity in <Emphasis Type="Italic">Aloe polyphylla</Emphasis>

Shoot regeneration and occurrence of hyperhydricity in Aloe polyphylla were greatly affected by the type of gelling agent. The use of gelrite resulted in a significantly lower multiplication and almost four times higher hyperhydricity (65%) compared to agar-solidified medium. Gelrite was further selected to evaluate if hyperhydricity can be overcome by altering the physical properties of the gel, as represented by increasing gelrite concentrations. Four concentrations of gelrite (0, 2.4, 6 and 16 g l⁻¹) were tested in combination with zeatin, N⁶-benzyladenine (BA) or thidiazuron (TDZ). Almost all explants grown in liquid media in the presence of cytokinins became hyperhydric and lost their ability to regenerate. The greatest shoot formation was obtained on media with 2.4 g l⁻¹ gelrite and 5 μM zeatin or BA, however hyperhydricity was very high. Satisfactory reduction in hyperhydricity was achieved only at 16 g l⁻¹ gelrite, under which conditions the multiplication also decreased. The use of TDZ resulted in very low shoot regeneration and high hyperhydricity irrespective of the gelrite concentration.     

Cultivation of <Emphasis Type="Italic">Rubrivivax gelatinosus</Emphasis> in fish industry effluent for depollution and biomass production

One application of biotechnology that contributes to sustainable development is the utilization of industrial byproducts as substrates for the production of substances of interest by microorganism. In this work, liquid effluent from tilapia fish processing was used as a substrate for the growth of Rubrivivax gelatinosus with the aim of studying the bacterial photo heterotrophic metabolism. Cultivation conditions included 32 ± 2°C, 1,400 ± 200 lux and 7 days. In the initial days, the best cell mass production (0.273 g l⁻¹ with 72 h), specific growth rate (0.188 h⁻¹ with 48 h) and chemical oxygen demand (COD) decrease (43% with 72 h) were reached. Typical bacterial oxycarotenoids were identified after 3 days of cultivation, averaging 3.03 mg g⁻¹ biomass. Bacterial growth in the effluent during the period of study resulted in pH increase to 7.9, total nitrogen, oils and greases and COD decreases of 22.46, 47.71 and 52%, respectively, and dry cell mass production of 0.18 g l⁻¹. The bacterial growth in the wastewater provided biomass and oxycarotenoids and the removal of pollutant load.     

Enhanced <Emphasis Type="SmallCaps">d</Emphasis>-ribose biosynthesis in batch culture of a transketolase-deficient <Emphasis Type="Italic">Bacillus subtilis</Emphasis> strain by citrate

In this study, the effects of citrate addition on d-ribose production were investigated in batch culture of a transketolase-deficient strain, Bacillus subtilis EC2, in shake flasks and bioreactors. Batch cultures in shake flasks and a 5-l reactor indicated that supplementation with 0.2–0.5 g l⁻¹ of citrate enhanced d-ribose production. When B. subtilis EC2 was cultivated in a 15-l reactor in a complex medium, the d-ribose concentration was 70.9 g l⁻¹ with a ribose yield of 0.497 mol mol⁻¹. When this strain was grown in the same medium supplemented with 0.3 g l⁻¹ of citrate, 83.4 g l⁻¹ of d-ribose were obtained, and the ribose yield was increased to 0.587 mol mol⁻¹. Addition of citrate reduced the activities of pyruvate kinase and phosphofructokinase, while it increased those of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Metabolic flux distribution in the stationary phase indicated that citrate addition resulted in increased fluxes in the pentose phosphate pathway and TCA cycle, and decreased fluxes in the glycolysis and acetate pathways.     

Effects of Calcium Levels on Colonial Aggregation and Buoyancy of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis>

Colonial aggregation of Microcystis plays a key role in bloom formation. Limited studies have been reported about effects of environmental factors on the aggregation of Microcystis. Calcium is an important chemical element in water system. In this study, we investigated the effects of a low- (0.015 g l⁻¹) and a high-concentration of calcium (0.100 g l⁻¹) on the aggregation and buoyancy of a colonial strain M. aeruginosa XW01. Results show that compared to the low concentration of calcium, the high-calcium condition results in bigger colonial size, higher level of buoyancy and increased production of extracellular polysaccharides (EPS) of M. aeruginosa XW01. Increased production of EPS induced by the high-calcium concentration should contribute to the colonial aggregation and buoyancy of M. aeruginosa XW01. These results suggest that an increase in calcium concentration may be beneficial for Microcystis blooms occurring in a soft water lake.     

Activity-density of <Emphasis Type="Italic">Pardosa cribata</Emphasis> in Spanish citrus orchards and its predatory capacity on <Emphasis Type="Italic">Ceratitis capitata</Emphasis> and <Emphasis Type="Italic">Myzus persicae</Emphasis>

The wolf spider Pardosa cribata Simon is the most abundant ground-dwelling spider inhabiting citrus orchards in eastern Spain. However, little is known about its activity-density and its predatory role in the citrus agrosystem. Here we report on the activity-density of P. cribata monitored by pitfall traps, and on its capacity to prey on two citrus pests that appear both in the citrus canopy and the ground cover, Ceratitis capitata (Wiedemman) and Myzus persicae (Sulzer), respectively. Pardosa cribata was present in citrus orchards throughout the year, with a peak in spring and a higher peak in summer. Pardosa cribata preyed on adults and third-instar larvae but not on pupae of C. capitata. A type II functional response was obtained for teneral-like adults, with an estimated attack rate (a′) of 0.771 ± 0.213 days⁻¹ and a handling time (T _h) of 0.051 ± 0.013 days. Pardosa cribata also preyed efficiently on M. persicae, giving a type II functional response with an estimated attack rate and handling time of 2.833 ± 0.578 days⁻¹ and 0.031 ± 0.001 days, respectively. The data reported here indicate that this wolf spider could play an important role in regulating both these pests, and therefore might contribute to developing conservation biological control strategies for citrus pests. Handling Editor: Arne Jenssen.     

Water relations advantages for invasive <Emphasis Type="Italic">Rubus</Emphasis> <Emphasis Type="Italic">armeniacus</Emphasis> over two native ruderal congeners

Despite species in the Rubus fruticosus complex (wild blackberry) being among the most invasive plants globally in regions with large annual fluctuations in water availability, little is known about their water relations. We compared water relations of a prominent member of the complex, R. armeniacus (Himalayan blackberry), with species native to the Pacific Northwest of North America (PNW), R. spectabilis (salmonberry) and R. parviflorus (thimbleberry). In eight stands of each species located near Portland, Oregon, USA, we measured mid-day hydraulic resistance (R _plant), and daily time series of stomatal conductance (g _s), leaf water potential (Ψ_lf), and environmental conditions at four time periods spanning the 2007 growing season. Although all species maintained Ψ_lf above −0.5 MPa in spring, R. armeniacus maintained less negative Ψ_lf (≥−1.0 MPa) than the natives in summer, a factor attributable to advantages in both its root and shoot systems. R _plant of R. armeniacus was ≤0.1 MPa mmol⁻¹ m² s for the duration of the study, and approximately 25–50% of R _plant for the native species in summer. R. armeniacus had higher g _s compared to the native species throughout the spring and summer, with approximately twice their rates in summer. Our R _plant and g _s results show that R. armeniacus has access to more water during PNW summers than congeneric natives, allowing it to maintain high water-use, and potentially helping it achieve higher growth and reproductive rates. Water relations may therefore be a critical component of the competitive and invasive success of R. armeniacus and other R. fruticosus species worldwide.