Effects of time and dietary iron on tissue iron concentration as an estimate of relative bioavailability of supplemental iron sources for ruminants

Two experiments were conducted to investigate the effects of time and dietary Fe on tissue Fe concentrations following short-term, high level supplementation for use as a bioassay procedure for supplemental Fe sources for ruminants. In Experiment 1, 28 wethers were allotted randomly to four experimental diets which were fed for 15 or 30 days. The basal maize–soyabean meal–cottonseed hulls diet (193 mg kg⁻¹ Fe) was supplemented with 0, 400, 800 or1200 mg kg⁻¹ added Fe from reagent grade ferrous sulfate (FeSO₄·7H₂O). Iron concentrations in liver, kidney, and spleen increased (P<0.05) as dietary Fe increased; however, muscle, heart, and bone Fe concentrations were unaffected. A logarithmic transformation of liver or kidney Fe concentrations at 30 days regressed on added dietary Fe produced the best fits to a linear model. In Experiment 2, bioavailability of Fe from three feed grade ferrous carbonates known to differ (carbonates A, B, and C) was compared to that from reagent grade ferrous sulfate. The dietary treatments fed for 30 days included the above basal diet (90 mg kg⁻¹ Fe) supplemented with 0, 300, 600 or 900 mg kg⁻¹ added Fe from ferrous sulfate or 600 mg kg⁻¹ Fe from ferrous carbonates A, B, or C. Liver Fe concentrations from sheep fed ferrous sulfate were numerically greater than those of animals fed the carbonate sources or control diet. Kidney Fe concentrations from lambs fed ferrous sulfate at 600 mg kg⁻¹ Fe or carbonate-A were greater (P<0.05) than those fed carbonates B or C. Iron concentrations in spleen were lower (P<0.05) in lambs fed carbonate-B than for those fed 600 mg kg⁻¹ Fe as ferrous sulfate, but were similar to other carbonates. Overall average bioavailability estimates based on multiple regression slope ratios for the three tissues were ferrous sulfate 1.00, carbonate-A 0.55, carbonate-B 0.00, and carbonate-C 0.20. Estimates for carbonates A and C were similar to those based on hemoglobin concentrations reported previously for young swine supplemented at dietary concentrations near the requirement.     

Biodegradation of waste-lubricating petroleum oil in a tropical alfisol as mediated by animal droppings

This study evaluated the applicability of some organic wastes from animal droppings as bioremediation alternative for soils spiked with waste-lubricating oil (spent oil). The total hydrocarbon contents (THC) with time of sampling were markedly reduced with addition of cow dung (CD), poultry manure (PM) and pig wastes (PW). The general trend in the first year indicated that PW stimulated the highest net percentage loss in THC for soils polluted with 5000 mg kg⁻¹ (0.5%SP) and 50,000 mg kg⁻¹ (5%SP) oil levels. Poultry manure induced the highest reduction in soils polluted with medium, i.e. 2.5%SP (25,000 mg kg⁻¹) oil concentration. The overall net loss mediated by each organic waste in the 2nd year showed that PM addition was better irrespective of total oil loading. For example, at 3 months PM led to 16.1% and 14.6% net reduction in THC for soils treated with 50,000 mg kg⁻¹ (5%) and 100,000 mg kg⁻¹ (10%) total oil loading, respectively; whereas at same period, the performance of the organic wastes were relatively similar in soils with 10,000 mg kg⁻¹ oil loading. At 6 and 12 months, PM reduced the oil levels better than CD and PW. Further evaluation by first-order kinetic model which utilized combine data for the entire periods for each year indicated that PW was better at low oil pollution level, while PM performed better at high oil pollution levels. Overall, the differential performance of these organic amendments followed PM > PW > CD.     

The response of an emergent sedge Bolboschoenus medianus to salinity and nutrients

The potential for nutrient load (30, 100 and 350 g N m⁻² per year) to alter plant performance under saline conditions (control, 4.5, 9 and 13 dS m⁻¹) was examined in the sedge Bolboschoenus medianus. Relative growth rates (RGR) across nutrient loadings ranged from 30.2 to 41.8 mg g⁻¹ per day in controls and were reduced to 20.9–28.5 mg g⁻¹ per day by salinities of 13 dS m⁻¹. Whilst higher nutrient loads generally increased RGR, the response was smaller at higher salinities. Responses to salinity and nutrient load were specific. Nutrient load increased the RGR via increases in the leaf area ratio (LAR). The LAR ranged from 1.9 to 2.1 m² kg⁻¹ across salinity treatments at 30 g N m⁻² per year, and increased to 2.5–2.8 m² kg⁻¹ at 350 g N m⁻² per year. Salinity reduced the RGR via a reduction in the net assimilation rate (NAR). The NAR in control plants ranged from 14.7 to 16 g m⁻² per day across nutrient loadings and decreased to 11–12 g m⁻² per day at 13 dS m⁻¹. Carbon isotope discrimination of leaves decreased by 2–3‰ in response to 13 dS m⁻¹ at the lower nutrient loadings. A prominent response of B. medianus to salinity was a change in biomass allocation from culms to tubers. In contrast, the response to nutrient load was characterised by a shift in biomass allocation from roots to leaves.     

Phenol inhibition of biological nutrient removal in a four-step sequencing batch reactor

Nutrient removal from synthetic wastewater was investigated using a four-step sequencing batch reactor (SBR) at different phenol (C₆H₅OH) concentrations in order to determine the inhibition effects of phenol on biological nutrient removal. The nutrient removal process consisted of anaerobic, oxic, anoxic, and oxic phases with hydraulic residence times (HRT) of 1 h/3 h/1 h/1 h and a settling phase of 3/4 h. Solids retention time (SRT) was kept constant at 10 days in all experiments. Initial phenol concentrations were varied between 0 and 600 mg l⁻¹ at seven different levels. The effects of phenol on COD, NH₄-N, and PO₄-P removals and effluent nutrient levels were investigated. Phenol was almost completely degraded up to 400 mg l⁻¹ phenol concentration resulting in almost negligible inhibition effects on COD, NH₄-N, and PO₄-P removals. Nutrient removals were adversely affected by phenol at concentrations above 400 mg l⁻¹. Above 95% COD, 90% NH₄-N and 65% PO₄-P removal was obtained for phenol concentrations below 400 mg l⁻¹. The sludge volume index (SVI) was almost constant around 45 ml g⁻¹ for phenol concentrations below 400 mg l⁻¹ but increased to 90 ml g⁻¹ at a phenol level of 600 mg l⁻¹.     

Nutritive value of peas for nonruminant diets

Peas, the seeds of Pisum sativum, are produced usually in temperate regions but are accepted as a food source worldwide. Traditionally, nonruminant diets utilized peas which had been rejected by the food industry but specific cultivars of feed (or field) peas also have been developed for livestock use. In view of the diversity of varieties, seeding times (spring or winter-sown) and agronomic conditions during the growing season, there is a considerable range in the composition and nutritive value of peas. The seed coat (hull) represents 70 to 140 g kg⁻¹ of the total weight and consists mainly of non-starch polysaccharides, while the major components of the dehulled pea are starch ( 450 g kg⁻¹) and protein ( 250 g kg⁻¹). Published energy values for the whole seed range from 12.2 to 16.6 MJ ME kg⁻¹ DM for pigs and 10.1 to 12.8 MJ TME_N kg⁻¹ DM for poultry. Reported analyses for crude protein vary from 156 to 325 g kg⁻¹ DM, while content and availability of the constituent amino acids vary also with cultivar, seed type and analytical methods. Most concerns about low digestibilities relate to the sulphur amino acids and tryptophan. Potentially detrimental constituents in raw peas include anti-proteases, haemagglutinins, phytic acid and tannins although these appear negligible in Canadian peas. When analytical data are lacking, the following limits to use of peas are suggested: 100, 200 and 350 g kg⁻¹, respectively, in pig starter, grower and finisher diets; 200 g kg⁻¹ in broiler, 250 g kg⁻¹ in turkey and 300 g kg⁻¹ in layer diets.     

Cadmium biosorption on Spirulina platensis biomass

Dry biomass of Spirulina platensis re-hydrated for 48 h was employed as a biosorbent in tests of cadmium(II) removal from water. Various concentrations of biomass (from 1 to 4 g l⁻¹) and metal (from 100 to 800 mg l⁻¹) were tested. Low biomass levels (X_o  2 g l⁻¹) ensured metal removal up to 98% only at Cd₀= 100 and 200 mg l⁻¹, while X_o  2.0 g l⁻¹ were needed at Cd₀ = 400 mg l⁻¹ to achieve satisfactory results. Whereas X_o = 4.0 g l⁻¹ was effective to remove up to Cd₀ = 500 mg l⁻¹, a further increase in metal concentration (Cd₀ = 600 and 800 mg l⁻¹) led to progressive worsening of the system performance. At a given biomass levels, the kinetics of the process was better at low Cd²⁺ concentrations, while, raising the adsorbent level from 1.0 to 2.0 g l⁻¹ and then to 4.0 g l⁻¹, the rate constant of biosorption increased by about one order of magnitude in both cases and the adsorption capacity of the system progressively decreased from 357 to 149 mg g⁻¹.     

Effect of lactic acid fermentation of wheat and barley whole meal flour on carbohydrate composition and digestibility in mink (Mustela vison)

Wheat and barley whole meal flours (WMFs) were subjected to treatment by fermentation, autoclaving, and fermentation followed by autoclaving. The WMFs were analysed for chemical composition, formulated into wet diets (282 g kg⁻¹) and fed to adult mink (Mustela vison) for determination of total tract digestibility of total starch, total carbohydrate, crude protein and fat. Fermentation of WMF/water mixtures inoculated with a Lactobacillus sp. (strain AD₂) was performed at 30°C for 16 h. Autoclaving was carried out for 60 min at 120°C. Fermentation increased colony-forming units (CFUs) to about 10⁸ g⁻¹ and lowered pH to 3.7–3.8 in both WMFs. All carbohydrate parameters were affected by type of cereal, and were, except for total starch, affected by treatment. Levels of total dietary fibre and β-glucans decreased by fermentation in both WMFs. The decrease in total β-glucans from 33.5 to 18.4 g kg⁻¹ in barley WMF, was mainly restricted to the soluble fraction. Glucose levels in barley WMF increased simultaneously from 0.6 to 12.3 g kg⁻¹. The main effects of autoclaving were increased levels of total dietary fibre, maltose, and increased hydration capacity. With fermentation prior to autoclaving, increases in levels of the fibre fractions and maltose were prevented while hydration capacity prevailed as an effect of autoclaving. Compared with fermentation alone, the combined treatment increased damaged starch levels and hydration capacity. Digestibilities of total carbohydrate, crude protein and fat were significantly higher for wheat than for barley. Fermentation had no effect on digestibility of total starch or total carbohydrate of wheat, but increased digestibility of total starch of barley significantly from 0.742 to 0.880, and of total carbohydrate from 0.457 to 0.616. Autoclaving had no significant effect on digestibility of total starch and total carbohydrate of wheat. Digestibility of total starch and total carbohydrate in barley increased significantly after autoclaving. Total starch and total carbohydrate digestibility of both wheat and barley were significantly enhanced by combined fermentation and autoclaving compared with fermentation alone. Compared with autoclaving alone, combined fermentation and autoclaving promoted no significant improvement of total starch and total carbohydrate digestibility in wheat, whereas total carbohydrate digestibility in barley increased from 0.605 to 0.672. Fat digestibility was slightly improved by both fermentation and autoclaving. Autoclaving of cereals reduced significantly the faecal dry matter contents of mink. This effect could be counteracted by preceding fermentation. In conclusion, lactic acid fermentation of wheat and especially barley provided chemical changes of benefit for carbohydrate digestion in the mink.     

Simultaneous production of anthocyanin and triterpenoids in suspension cultures of Perilla frutescens

When cultivated in Murashige & Skoog medium supplemented with 0.2 mg l⁻¹ 2,4-dichlorophenoxy acetic acid and 0.5 mg l⁻¹ 6-benzyladenine, Perilla frutescens cells in suspension culture grew rapidly reaching about 13.6 g dry wt l⁻¹ after 12 days. The cell line produced both anthocyanin 0.9 g l⁻¹ and triterpenoids: 16 mg l⁻¹ oleanolic acid (OA), 25 mg l⁻¹ ursolic acid (UA) and 14 mg l⁻¹ tormentic acid (TA). When P. frutescens cells of 7-day-old cultures were exposed to a yeast elicitor at 0.5–5% (v/v) for 7 days, it was found that anthocyanin content peaked at 10.2% of dry weight with yeast elicitor at 1% (v/v) whereas the maximum production of oleanolic acid and ursolic acid in cultures treated with 2% (v/v) yeast elicitor was 19 and 27 mg l⁻¹, a 46 and 24% increase over the control, respectively. This is the first report of simultaneous production of both anthocyanin and triterpenoids in a single culture system.     

Effect of oxygen supply on cell growth and saponin production in bioreactor cultures of Panax ginseng

The effects of oxygen supply within the range 20.8–50% (using pure oxygen and air), on cell cultures of Panax ginseng were investigated in a balloon-type bubble bioreactor (5 L capacity, containing 4 L Murashige and Skoog medium, supplemented with 7.0 mg L⁻¹ indolebutyric acid, 0.5 mg L⁻¹ kinetin and 30 g L⁻¹ sucrose). A 40% oxygen supply was found to be optimal for the production of both cell mass and saponin yielding values of 12.8 g (DW) L⁻¹, 4.5 mg (g DW)⁻¹ on day 25, respectively. Low (20.8%, 30%) and high (50%) oxygen concentration supplies were unfavorable to cell growth and saponin accumulation. The results indicate that oxygen supplementation to bioreactor-based ginseng cultures was beneficial for biomass accumulation and saponin production.     

Aerobic chromate reduction by chromium-resistant bacteria isolated from serpentine soil

A group of 34 chromium-resistant bacteria were isolated from naturally occurring chromium percolated serpentine soil of Andaman (India). These isolates displayed different degrees of chromate reduction under aerobic conditions. One of the 34 isolates identified as Bacillus sphaericus was tolerant to 800 mg l⁻¹ Cr(VI) and reduced >80% Cr(VI) during growth. In Vogel Bonner broth, B. sphaericus cells (10¹⁰ cells ml⁻¹) reduced 62% of 20 mg l⁻¹ of Cr(VI) in 48 h with concomitant discoloring of yellow medium to white one. Reduction of chromate was pronounced by the addition of glucose and yeast extract as electron donors. In the presence of 4.0 g l⁻¹ of glucose, 20 mg l⁻¹ of Cr(VI) was reduced to 2.45 mg l⁻¹ after 96 h of incubation. Optimum pH and temperature for reduction were 6.0 and 25 °C, respectively. Increase in cell density and initial Cr(VI) concentration increased chromate reduction but was inhibited by metal ions like, Ni²⁺, Co²⁺, Cd²⁺ and Pb²⁺. Experiments with cell-free extracts indicated that the soluble fraction of the cell was responsible for aerobic reduction of Cr(VI) by this organism.     

Influence of sucrose on the rheology and granule size of cross-linked waxy maize starch dispersions heated at two temperatures

Cross-linked waxy maize (CWM) starch dispersions (STDs) of concentration 50 g kg⁻¹ were heated in sucrose solutions containing 0–600 g kg⁻¹ (g sucrose/kg dispersion) at 85 °C at low shear and in intermittently agitated cans at 110 °C. The STDs heated in 0–300 g kg⁻¹ sucrose exhibited antithixotropic behavior, while those heated in 400–600 g kg⁻¹ sucrose exhibited thixotropic behavior. The mean starch granule diameter of the starch dispersions did not show strong dependence on sucrose concentration. The dispersions, especially those with high sucrose concentrations and heated at 110 °C, exhibited G′ versus frequency (ω) profiles of gels. The STDs exhibited first normal stress differences that increased in magnitude with the concentration of sucrose. Values of the first normal stress coefficient of canned dispersions calculated from dynamic rheological data plotted against ω and experimental values plotted against shear rate of some of the STDs overlapped.     

Biological phosphorus removal in sequencing batch reactor with single-stage oxic process

The performance of biological phosphorus removal (BPR) in a sequencing batch reactor (SBR) with single-stage oxic process was investigated using simulated municipal wastewater. The experimental results showed that BPR could be achieved in a SBR without anaerobic phase, which was conventionally considered as a key phase for BPR. Phosphorus (P) concentration 0.22–1.79 mg L⁻¹ in effluent can be obtained after 4 h aeration when P concentration in influent was about 15–20 mg L⁻¹, the dissolved oxygen (DO) was controlled at 3 ± 0.2 mg L⁻¹ during aerobic phase and pH was maintained 7 ± 0.1, which indicated the efficiencies of P removal were achieved 90% above. Experimental results also showed that P was mainly stored in the form of intracellular storage of polyphosphate (poly-P), and about 207.235 mg phosphates have been removed by the discharge of rich-phosphorus sludge for each SBR cycle. However, the energy storage poly-β-hydroxyalkanoates (PHA) was almost kept constant at a low level (5–6 mg L⁻¹) during the process. Those results showed that phosphate could be transformed to poly-P with single-stage oxic process without PHA accumulation, and BPR could be realized in net phosphate removal.     

Kinetics of adsorption of Zn(II) ion on chitosan derivatives

The adsorption of Zn(II) ions from aqueous solution by chitosan derivatives (KCTS and HKCTS) was studied in a batch adsorption system. The adsorption capacities and rates of Zn(II) ions onto chitosan derivatives were evaluated. The adsorption isothermal data could be well interpreted by the Langmuir and Freundlich models. The kinetic experimental data properly correlated with the second-order kinetic model, which indicates that the chemical adsorption is the rate-limiting step. The apparent adsorption activation energy were 25.47 kJ mol⁻ and 5.473 kJ mol⁻, respectively, and the second-order adsorption constant for KCTS and HKCTS were 0.00311 g (mg min)⁻¹ and 0.005 g (mg min)⁻¹, respectively.     

Effect of tree leaf as supplementation on nutrient digestion and rumen fermentation pattern in sheep grazing semi-arid range of India – II

A study was conducted to evaluate the effects of supplementing with different tree leaves on nutrient digestion, rumen fermentation and blood parameters of sheep. Thirty adult Malpura rams (39.0 ± 0.56 kg) were divided into five groups of six each. They were grazed as a single flock on a semi-arid rangeland and after the end of routine grazing period (08:00–17:00 h), first group (G1), which was not provided with any supplementation, served as control group. Second group (G2) was supplemented with 200 g of a conventional concentrate mixture per head per day, whereas third, fourth and fifth groups (G3, G4 and G5) were supplemented with approximately 200 g dry matter (DM) per day freshly cut foliage from Ailanthes excelsa, Azardirachta indica and Bauhinia racemosa, respectively. Protein content (g kg⁻¹ DM) in A. excelsa, A. indica and B. racemosa foliage was 197, 128 and 132, respectively. A. indica and B. racemosa foliages also contained 123.2 and 211.2 g kg⁻¹ DM condensed tannin (CT) with protein precipitating capacity (PPC) of 16.5 and 46.5 g kg⁻¹ DM. None of the tree leaves contained hydrolysable tannin (HT). Dry matter intake (DMI, g day⁻¹) was 591, 766, 865, 974 and 939 in G1, G2, G3, G4 and G5, respectively. Digestible crude protein (DCP) and metabolisable energy (ME) intakes in supplemented groups G2–G5 were higher (P < 0.05) compared to control (G1). Supplementation improved digestibility of all nutrients in all groups. Rumen fermentation study indicated lower (P < 0.05) ammonia and total N in the rumen liquor collected from G5 sheep compared to the other supplemented groups. Although haemoglobin (Hb, g dl⁻¹) levels showed small changes among groups, blood urea nitrogen (BUN, mg dl⁻¹) was lowest in G5 compared to the other groups. Initial BW were similar among the groups. After 60 days of experimental feeding, all animals maintained their BW, except sheep in the control group (G1), which lost BW. Results indicate that for adult sheep grazing on a semi-arid range, supplementation with a concentrate mixture could be replaced by tree leaves like A. excelsa, A. indica and B. racemosa, during the lean season to maintain their BW. In addition, supplementing with tree leaves containing condensed tannin has advantages in terms of N utilization.     

Purification and immobilization of recombinant variants of Brevundimonas diminuta glutaryl-7-aminocephalosporanic acid acylase expressed in Escherichia coli cells

Cyclotides are naturally occurring mini-proteins that have a diverse range of therapeutically useful biological activities. Although a choice of approaches is available for cyclotides synthesis; most studies have involved the use of peptides extracted from plants. In order to facilitate the screening for structure-activity studies or to exploit them in drug development, a convenient and reliable route for the biosynthesis of cyclotides is of vital importance.

Callus, suspension cultures and hydroponic plants of Oldenlandia affinis were established and have been evaluated for effective cyclotides production processes. The specific accumulation of kalata B1 was affected by cell differentiation as well as agitation; highest accumulation of 2.7 mg g⁻¹ dry weight was detected in agitated hydroponic plant cultures resulting in a productivity of 1.4 mg kalata B1 l⁻¹ day⁻¹.     

Effects of two sterol biosynthesis inhibitor fungicides (fenpropimorph and fenhexamid) on the development of an arbuscular mycorrhizal fungus

The effects of different concentrations (0.2, 2, 20, 200 mg l⁻¹) of two sterol biosynthesis inhibitor (SBI) fungicides, i.e. fenpropimorph and fenhexamid, were evaluated on the spore germination, germ tube elongation, sporulation, and root colonization of Glomus intraradices grown monoxenically in association with transformed carrot roots. The percentage of germinated spores incubated on the SBI fungicides and the length of the germ tubes decreased with increasing concentrations of both fungicides. However, for spore germination this impact was fungistatic rather than fungicidal. Extraradical mycelium architecture and spore production in contact with the SBI fungicides were also strongly impacted at high concentration (20 mg l⁻¹). Conversely, the colonization of roots developing in the fungicide-free compartment, but interconnected with the extraradical mycelium developing on the SBI fungicides, appeared unaffected. Our results demonstrated that the monoxenic culture system could be used as a standardized, reproducible technique to compare the impacts of different molecules on arbuscular mycorrhizal fungi, and for the initial screening of new candidate molecules before registration.     

Phosphate biosorption characteristics of a submerged macrophyte Hydrilla verticillata

Phosphate biosorption of Hydrilla verticillata was investigated and compared with its bioaccumulation characteristics. Results obtained from the biosorption isotherms and kinetics showed that maximal phosphate biosorption was 286 mg kg⁻¹, approximately equal to 6–9% of the phosphate bioaccumulation. The biosorption mainly occurred within 5 h, and was highest during the first 30 min. The initial phosphate concentration was an important factor affecting the biosorption process. Phosphate biosorption on H. verticillata was not the main phosphate removal mechanism in our experiments, but it cannot be ignored.     

In vitro and in vivo antimalarial activity of peptidomimetic protein farnesyltransferase inhibitors with improved membrane permeability

A series of protein farnesyltransferase inhibitor ester prodrugs of FTI-2148 (17) were synthesized in order to evaluate the effects of ester structure modification on antimalarial activity and for further development of a farnesyltransferase inhibitor with in vivo activity. Evaluation against P. falciparum in red blood cells showed that all the investigated esters exhibited significant antimalarial activity, with the benzyl ester 16 showing the best inhibition (ED₅₀ = 150 nM). Additionally, compound 16 displayed in vivo activity and was found to suppress parasitemia by 46.1% at a dose of 50 mg kg⁻¹ day⁻¹ against Plasmodium berghei in mice. The enhanced inhibition potency of the esters is consistent with improved cell membrane permeability compared to that of the free acid. The results of this study suggest that protein farnesyltransferase is a valid antimalarial drug target and that the antimalarial activity of these compounds derives from a balance between the hydrophobic character and the size and conformation of the ester moiety.     

Morphological and physiological responses of canola (Brassica napus) siliquas and seeds to UVB and CO2 under controlled environment conditions

Combined effects of UVB radiation and CO₂ concentration on plant reproductive parts have received little attention. We studied morphological and physiological responses of siliquas and seeds of canola (Brassica napus L. cv. 46A65) to UVB and CO₂ under four controlled experimental conditions: UVB radiation (4.2 kJ m⁻² d⁻¹) with ambient level of CO₂ (370 μmol mol⁻¹) (control); UVB radiation (4.2 kJ m⁻² d⁻¹) with elevated level of CO₂ (740 μmol mol⁻¹); no UVB radiation (0 kJ m⁻² d⁻¹) with ambient level of CO₂ (370 μmol mol⁻¹); and no UVB radiation (0 kJ m⁻² d⁻¹) with elevated level of CO₂ (740 μmol mol⁻¹). UVB radiation affected the outer appearance of siliquas, such as colour, as well as their anatomical structures. At both CO₂ levels, the UVB radiation of 4.2 kJ m⁻² d⁻¹ reduced the size of seeds, which had different surface patterns than those from no UVB radiation. At both CO₂ levels, 4.2 kJ m⁻² d⁻¹ of UVB decreased net CO₂ assimilation (A_N) and water use efficiency (WUE), but had no effect on transpiration (E). Elevated CO₂ increased A_N and WUE, but decreased E, under both UVB conditions. At both CO₂ levels, the UVB radiation of 4.2 kJ m⁻² d⁻¹ decreased chlorophyll fluorescence, total chlorophyll (Chl), Chl a and Chl b, but had no effect on the ratio of Chl a/b and the concentration of UV-screening pigments. Elevated CO₂ increased total Chl and the concentration of UV-screening pigments under 4.2 kJ m⁻² d⁻¹ of UVB radiation. Neither UVB nor CO₂ affected wax content of siliqua surface. Many significant relationships were found between the above-mentioned parameters. This study revealed that UVB radiation exerts an adverse effect on canola siliquas and seeds, and some of the detrimental effects of UVB on these reproductive parts can partially be mitigated by CO₂.