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Toxicity to terrestrial plants

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Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guidelines used, no statistics reported, NOEC is largest concentration tested with ≤10% inhibition. Measured concentrations used.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Toxicity of selenium to alfalfa plants grown in selenium-amended soil. Five Mollisols with slightly different characteristics were used.
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Soils from the pots with no plants (1 replicate per treatment) were air dried after being subjected to wetting and drying cycles for 4 weeks.
Vehicle:
no
Details on preparation and application of test substrate:
see test conditions
Species:
other: Medicago sativa
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Alfalfa
- Plant family: Fabaceae
- Variety: Ladack
Test type:
seedling emergence toxicity / vegetative vigour test
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Remarks:
until plant bloom stage
Test temperature:
No data
pH:
6.9-7.8
Moisture:
Field capacity
Details on test conditions:
TEST SYSTEM
- Testing facility: laboratory experiment in growth chambers
- Test container (type, material, size): pots in growth chambers
- Amount of soil: 800 g
- No. of seeds per container: No data
- No. of plants (retained after thinning): No data
- No. of replicates per treatment group: 4 (3 for planting of seeds)
- No. of replicates per control: 4 (3 for planting of seeds)

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: North Dakota
- Sampling depth (cm): No data
- Soil texture (if natural soil): silty clay loam
- Five different Mollisols with slightly different characteristics were used. Ranges of these characteristics are given in this endpoint study record.
- % sand: No data
- % silt: No data
- % clay: No data
- Soil taxonomic classification: Mollisol
- Organic carbon (%): 3.1-6.5% organic matter
- Se background concentration: 0.40-0.69 mg Se/kg dw

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): shoot dry yield
Nominal and measured concentrations:
Nominal: 0, 0.5, 1, 2, 4 mg Se/kg
Measured concentrations reported in Table 2.
Species:
other: Medicago sativa
Dose descriptor:
NOEC
Effect conc.:
>= 0.39 - <= 1.51 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Remarks:
Se (added concentration)
Basis for effect:
other: shoot dry yield
Remarks on result:
other: range of NOEC values for five slightly different Mollisols: test duration until bloom stage; NOECs based on total concentrations: 1.08-2.17 mg Se/kg.
Reported statistics and error estimates:
no statistics reported
Conclusions:
In this Klimisch 2 study, the toxicity of selenium to alfalfa plants grown in selenium-amended soil was studied in five Mollisols with slightly different characteristics. Based on shoot dry yield (shoots obtained at the bloom stage), the NOEC values based on added concentration ranged from 0.39-1.51 mg Se/kg, corresponding to total Se concentrations of 1.08 to 2.17 mg Se/kg soil dw.
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guidelines used, but well documented and well performed according to scientific standards. Se concentrations in soil not measured (nominal concentrations used). Unbounded NOEC as supportive information.
Qualifier:
no guideline followed
Principles of method if other than guideline:
In this study, alfalfa, barley, beet, and tomato plants were grown in soils with of without Se added as sodium selenate. Different plant parts were harvested at maturity and biomass production data were used for derivation of NOEC values. Alfalfa was grown in several soils with different charachteristics.
GLP compliance:
not specified
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
see test conditions
Species:
Lycopersicon esculentum
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Tomato
- Plant family: Solanaceae
- Variety: Early Girl
Species:
Beta vulgaris
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Beet
- Plant family: Chenopodiaceae
- Variety: Detroit dark red
Species:
Hordeum vulgare
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Barley
- Plant family: Poaceae
- Variety: not reported
Species:
other: Medicago sativa L.
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Alfalfa
- Plant family: Fabaceae
- Variety: Germain WL 512
Test type:
vegetative vigour test
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Remarks:
up to maturity
Test temperature:
No data
pH:
Panoche loam (Typic Torriorthents): 7.2
Ciervo sandy loam (Vertic Xerochrepts): 6.7
Lethent sandy clay loam (Typic Natrargids): 6.8
Lost Hills clay loam (Typic Haplargids): 5.6
Panhill clay loam (Typic Haplargids): 6.9
Moisture:
No data (plants were irrigated with deionized water as needed)
Details on test conditions:
TEST SYSTEM
- Testing facility: Laboratory pot experiment
- Test container (type, material, size): Pots lined with polyethylene bags
- Amount of soil: 6 or 10 kg (10 kg only for experiments with tomato)
- Beet, alfalfa, and barley were planted in pots with 6 kg soil, 1 tomato plant was transplated into each pot containing 10 kg soil.
- No. of seeds per container: No data
- No. of plants (retained after thinning): 10 alfalfa plants, 5 barley plants, 1 beet plant, 1 tomato plant
- No. of replicates per treatment group: 4
- No. of replicates per control: 4

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Five soils were collected from the Panache Fan area of the San Joaquin Valley of California.
- The Panoche Fan is believed to be a major source of Se entering irrigation and drainage waters in the region.
- Sampling depth (cm): No data
- Ciervo sandy loam (Vertic Xerochrepts), Lethent sandy clay loam (Typic Natrargids), Lost Hills clay loam (Typic Haplargids), Panhill clay loam (Typic Haplargids), and Panoche loam (Typic Torriorthents)
- % sand: No data
- % silt: No data
- % clay: Ciervo sandy loam 17%, Lethent sandy clay loam 23%, Lost Hills clay loam 25%, Panhill clay loam 37%, and Panoche loam 27%
- Organic carbon (%): Ciervo sandy loam 6.4 g C/kg, Lethent sandy clay loam 5.3 g C/kg, Lost Hills clay loam 7.4 g C/kg, Panhill clay loam 6.4 g C/kg, and Panoche loam 4.9 g C/kg
- Maximum water holding capacity (in % dry weigth): No data
- CEC: No data
- Pretreatment of soil: Soil was air-dried, sieved, and thoroughly mixed with Na2SeO4. Nitrogen and P were added to the soil at a concentration of 100 mg/kg as NH4NO3 and KH2PO4.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): alfalfa: shoot dry yield at 0.25 bloom stage; barley: grain and shoot dry yield at maturity; beet: root and shoot dry weight 67 days after planting; tomato: fruit fresh yield, shoot dry yield
Nominal and measured concentrations:
Nominal: 0, 0.5, 1.5, and 3.0 mg Se/kg (added) (experiments with alfalfa in 4 different soils)
Nominal: 0, 0.5, and 1.5 mg Se/kg (added) (experiments with Panoche soil and 4 different species)
Key result
Species:
other: Medicago sativa L.
Dose descriptor:
NOEC
Effect conc.:
0.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry yield and root dry yield
Remarks on result:
other: Measured at maturity. Sandy loam (Vertic Xerochrepts). pH 6.7, organic matter 1.1%, clay 17%.
Species:
other: Medicago sativa L.
Dose descriptor:
NOEC
Effect conc.:
>= 3 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry yield and root dry yield
Remarks on result:
other: Measured at maturity. Sandy clay loam (Typic Natrargids). pH 6.8, organic matter 0.91%, clay 23%.
Species:
other: Medicago sativa L.
Dose descriptor:
NOEC
Effect conc.:
1.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry yield
Remarks on result:
other: Measured at maturity. Clay loam (Typic Haplargids). pH 5.6, organic matter 1.27%, clay 25%.
Key result
Species:
other: Medicago Sativa L.
Dose descriptor:
NOEC
Effect conc.:
0.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: root dry weight
Remarks on result:
other: Measured at maturity. Clay loam (Typic Haplargids). pH 5.6, organic matter 1.27%, clay 25%.
Key result
Species:
other: Medicago sativa L.
Dose descriptor:
NOEC
Effect conc.:
0.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry yield and root dry yield
Remarks on result:
other: Measured at maturity. Clay loam (Typic Haplargids). pH 6.9, organic matter 1.1%, clay 37%.
Species:
other: Medicago sativa L
Dose descriptor:
NOEC
Effect conc.:
>= 1.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry yield
Remarks on result:
other: Measured at maturity. Loam soil (Typic Torriorthents). pH 7.2, organic matter 0.84%, clay 27%.
Key result
Species:
Hordeum vulgare
Dose descriptor:
NOEC
Effect conc.:
>= 1.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry yield
Remarks on result:
other: Measured at maturity. Loam soil (Typic Torriorthents). pH 7.2, organic matter 0.84%, clay 27%.
Key result
Species:
Beta vulgaris
Dose descriptor:
NOEC
Effect conc.:
>= 1.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry weight
Remarks on result:
other: Measured at maturity. Loam soil (Typic Torriorthents). pH 7.2, organic matter 0.84%, clay 27%.
Key result
Species:
Lycopersicon esculentum
Dose descriptor:
NOEC
Effect conc.:
>= 1.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot dry weight
Remarks on result:
other: Measured at maturity. Loam soil (Typic Torriorthents). pH 7.2, organic matter 0.84%, clay 27%.
Reported statistics and error estimates:
Duncan's multiple range test.
Conclusions:
In this Klimisch study, alfalfa, barley, beet, and tomato plants were grown in soils with of without Se added as sodium selenate. Different plant parts were harvested at maturity and biomass production data were used for derivation of NOEC values. Alfalfa was grown in several soils with different charachteristics. The lowest NOEC obtained was for root and shoot dry yield of alfalfa at maturity and was 0.5 mg Se/kg soil dw in several soils. Barley, beet, and tomato plants did not show significant differences in yield and dry matter production up to the highest dose tested (1.5 mg Se/kg soil dw).
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: No guideline study, but well performed according to scientific standards. Se concentrations in soil not measured (nominal concentrations used).
Qualifier:
no guideline followed
Principles of method if other than guideline:
Effect of accumulated selenium on ryegrass (Lolium perenne) biomass production and antioxidant activity. Greenhouse pot experiment with 1.5 kg of soil treated with different Se concentrations.
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Soil samples were taken only for determination of background total Se concentration.
Vehicle:
no
Details on preparation and application of test substrate:
see test conditions
Species:
Lolium perenne
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: ryegrass
- Plant family: Poaceae
- Variety: cv. Aries
Test type:
seedling emergence toxicity / vegetative vigour test
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Total exposure duration:
55 d
Test temperature:
No data
pH:
5.75
Moisture:
No data (plants were watered daily with distilled water)
Details on test conditions:
TEST SYSTEM
- Testing facility: Greenhouse experiment
- Test container (type, material, size): No data
- Amount of soil: 1.5 kg
- Method of seeding: No data
- No. of seeds per container: 60
- No. of plants (retained after thinning): 40
- No. of replicates per treatment group: No data
- No. of replicates per control: No data

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Vilcún Series of Southern Chile
- The soil was never amended with Se fertilizers.
- % sand: No data
- % silt: No data
- % clay: No data
- Soil taxonomic classification: Andisol
- Organic carbon (%): 16% organic matter
- Maximum water holding capacity (in % dry weigth): No data
- CEC: 11.1 cmolc/kg
- Se background concentration: 0.68 mg Se/kg dw
- Pretreatment of soil: Each soil sample (1.5 kg) was fertilized with 200 mg P/kg soil and 50 mg S/kg soil. After germination and thinning, 50 mg N/kg soil (as urea) was applied.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): total plant dry yield (samples dried at 65°C for 48 h)
Nominal and measured concentrations:
Nominal: 0-0.1-0.25-0.5-0.75-1.0-1.5-2.0-4.0-6.0-8.0-10.0 mg Se/kg (background Se concentration: 0.68 mg Se/kg, measured).
Key result
Species:
Lolium perenne
Duration:
55 d
Dose descriptor:
NOEC
Effect conc.:
2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se (added concentration)
Basis for effect:
other: total plant dry yield
Remarks on result:
other: total concentration: 2 mg Se/kg
Details on results:
55-d EC50 = 10.68 mg Se/kg soil dw (total plant dry yield)
Reported statistics and error estimates:
Comparisons between averaged values from different treatments were made by means of the standard deviation of each determination.
Conclusions:
This Klimisch 2 study reported a 55-d NOEC of 2.68 mg Se/kg soil dw for total plant dry yield of Lolium perenne cv. Aries obtained in a seedling emergence and growth test in natural soil amended with Na2SeO4.
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
In this study, pre-germinated wheat seeds (Triticum aestivum) were planted in pots with artificial growth medium (sand-based) either with or without addition of Se as sodium selenate. After 22-30 days, whole tops were harvested and dry and fresh weight recorded.
GLP compliance:
not specified
Analytical monitoring:
no
Vehicle:
no
Details on preparation and application of test substrate:
see test conditions
Species:
Triticum aestivum
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
- Common name: Wheat
- Plant family: Poaceae
- Variety: Janz
- Seeds were pre-germinated on filter paper
Test type:
early seedling growth toxicity test
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
no
Total exposure duration:
30 d
Remarks:
22-30 days, depending on the experiment
Test temperature:
10-23°C
pH:
5.5
Moisture:
12% water content
Mean relative humidity = 60-65°C
Details on test conditions:
TEST SYSTEM
- Testing facility: Laboratory experiment
- Test container (type, material, size): Trial 1: pots 19 cm diameter x 17 cm depth; Trial 2: pots 21 cm diameter x 17.5 cm depth
- Amount of soil: Trial 1: 2.5 kg per pot; Trial 2: 4 kg per pot
- Seeds were pre-germinated on filter paper and planted at 1.5 cm depth
- No. of seeds per container: 12, after six days the 4 smallest plants were removed, leaving 8 plants per pot
- No. of plants (retained after thinning): 8
- No. of replicates per treatment group: 2
- No. of replicates per control: 2

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Description: The growth medium used was University of California (UC) mix (Barker et al., 1998), Waite Campus version (University of Adelaide). This comprises 400 L of coarse washed sand, 300 L of peatmoss, 700 g calcium hydroxide, 480 g calcium carbonate and 600 g Nitrophoska 15:4:12 (which contains, inter alia, 5.3% sulphates), with pH (H2O) of 5.5.
- The growth medium was sieved (3 mm) before use.

GROWTH CONDITIONS
- Photoperiod: No data
- Light source: No data
- Day/night temperatures: Trial 1: 18/10°C; Trial 2: 23/13°C
- Relative humidity (%): Trial 1: 65%; Trial 2: 60%
- Water source/type: pure water (Milli-Q)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): dry and fresh shoot weight
Nominal and measured concentrations:
Trial 1: 0, 1, 2, 4, 8, 16, 32, 64 and 132 mg Se/kg
Trial 2: 0-0.01-0.1-0.5-1-2-4-8-16 mg Se/kg
Key result
Species:
Triticum aestivum
Duration:
22 d
Dose descriptor:
NOEC
Effect conc.:
2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot fresh weight
Remarks on result:
other: Trial 1
Key result
Species:
Triticum aestivum
Duration:
30 d
Dose descriptor:
NOEC
Effect conc.:
2 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
other: shoot fresh weight
Remarks on result:
other: Trial 2
Details on results:
The LOEC for both experiments was 4 mg Se/kg soil dw.
Reported statistics and error estimates:
ANOVA
Conclusions:
In this study, pre-germinated wheat seeds (Triticum aestivum) were planted in pots with artificial growth medium (sand+peatmoss) either with or without addition of Se as sodium selenate. After 22-30 days, whole tops were harvested and dry and fresh weight recorded. The NOEC and LOEC based on shoot fresh weight were 2 and 4 mg Se/kg soil dw, respectively, in both experiments.
Endpoint:
toxicity to terrestrial plants: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
- Principle of test: A pot experiment was conducted with two Prunus genotypes exposed to soil selenate.
- Short description of test conditions: Selenium (Se) was added as sodium selenate to 3-month-old micropropagated plants at a rate of 0 (con- trol), 1.0, 2.5, and 5.0 mg Se (kg soil)±1.
- Parameters analysed / observed: Plant growth, gas exchange, and Se accumulation were studied.
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
no
Species:
other: Prunus
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Peach
- Plant family: Rosaceae
- Variety: GF 667 and Mr.S.2/5 rootstocks

Three-month-old micropropagated Mr.S.2/5 and GF 677 plants were grown under greenhouse conditions in pots filled with 3.7kg of soil. Before transplanting, fresh weight (FW) and twig length (TL) of all plants were recorded.
Test type:
other: survival and growth of 3-month-old plants
Study type:
other: greenhouse
Substrate type:
not specified
Limit test:
no
Total exposure duration:
155 d
Remarks:
first harvest after 33 days, second harvest after 155 days
pH:
8.2
Details on test conditions:
TEST SYSTEM
- Testing facility:
- Test container (type, material, size): pot
- Amount of soil: 3.7 kg
- No. of replicates per treatment group: 24 of each rootstock
- No. of replicates per control: 24

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- % sand: 96
- % silt: 2.6
- % clay: 1.4
- Organic carbon (%): 0.9
- CEC: 6.25 cmol kg-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality, twig length, dry weight (roots, twigs + leaves) and total leaf area at 33 days and 155 days after start experiment

TEST CONCENTRATIONS
- Test concentrations: 0(control), 1.0, 2.5, and 5.0 mg Se (kg soil)-1.
Nominal and measured concentrations:
nominal: 0(control), 1.0, 2.5, and 5.0 mg Se (kg soil)-1.
Species:
other: Prunus GF 677
Duration:
33 d
Dose descriptor:
NOEC
Effect conc.:
1 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, twig length
Species:
other: Prunus GF 677
Duration:
33 d
Dose descriptor:
LOEC
Effect conc.:
2.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, twig length
Species:
other: Prunus GF 677
Duration:
33 d
Dose descriptor:
NOEC
Effect conc.:
2.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total leaf area
Species:
other: Prunus GF 677
Duration:
33 d
Dose descriptor:
LOEC
Effect conc.:
5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total leaf area
Key result
Species:
other: Prunus GF 677
Duration:
155 d
Dose descriptor:
NOEC
Effect conc.:
1 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
twig length
Species:
other: Prunus GF 677
Duration:
155 d
Dose descriptor:
LOEC
Effect conc.:
2.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
twig length
Species:
other: Prunus GF 677
Duration:
155 d
Dose descriptor:
NOEC
Effect conc.:
2.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, total leaf area
Species:
other: Prunus GF 677
Duration:
155 d
Dose descriptor:
LOEC
Effect conc.:
5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, total leaf area
Species:
other: Prunus Mr.S.2/5
Duration:
33 d
Dose descriptor:
NOEC
Effect conc.:
>= 5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, twig length, total leaf area
Species:
other: Prunus Mr.S.2/5
Duration:
155 d
Dose descriptor:
NOEC
Effect conc.:
2.5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, twig length, total leaf area
Species:
other: Prunus Mr.S.2/5
Duration:
155 d
Dose descriptor:
LOEC
Effect conc.:
5 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
element
Remarks:
Se
Basis for effect:
growth
Remarks:
total dry weight, twig length, total leaf area
Details on results:
Thirty-three days after the addition of selenate, the rootstock GF 677 showed a high mortality rate at the Se dosage of 2.5 and 5.0 mg Se kg-1. At the Se-addition level of 5 mg Se kg-1, mortality of Mr.S.2/5 to acute Se toxicity was significantly lower than of GF 677. The fast growing rootstock GF 677 appeared to be more sensitive than Mr.S.2/5 to Se toxicity. In the following period, no further plants died, thus, 155 days after the treatment the mortality rate was unchanged.
Conclusions:
A pot experiment was conducted with two Prunus genotypes (GF 677 and Mr.S.2/5). Selenium (Se) was added as sodium selenate to 3-month-old plants at a rate of 0 (control), 1.0, 2.5, and 5.0 mg Se /kg soil. The lowest NOEC value after 155 d was 1.0 mg Se/kg dw for twig length of the GF 677 genotype..

Description of key information

Reliable NOEC values for chronic selenate toxicity to terrestrial plants species were retrieved from 5 studies (Soltanpour and Workman, 1980; Wan et al., 1988; Cartes et al., 2005; Lyons et al., 2005 and Pezzarossa et al., 2009). All data were derived from soils amended with disodium selenate. These data are based on yield for 7 different plant species (Beta vulgaris, Hordeum vulgare, Lollium perenne, Medicago sativa, Prunus, Lycopersicon escultentum and Triticum aestivum) from 5 different families (Amaranthaceae, Fabaceae, Poaceae, Rosaceae and Solanaceae). The lowest NOEC values per species vary between 0.39 mg Se/kg dw for Medicago sativa (alfalfa) and 2.0 mg Se/kg dw for Lollium perenne (ryegrass) and Triticum aestivum (wheat). All NOEC values are expressed based on added elemental Se concentrations in soil. All reliable NOEC values were taken forward to the derivation of the PNEC according to the statistical extrapolation approach.

Key value for chemical safety assessment

Additional information

Reliable results are available on toxicity of Na2SeO3 and Na2SeO4 to terrestrial plants. Two studies compare the toxicity of selenite and selenate to yield of Lolium perenne and Sorghum vulgare (Cartes et al., 2005; Carlson et al., 1991). Both studies confirm the higher toxicity of selenate compared to selenite, which is consistent with toxicity data to other terrestrial organisms and the difference in sorption to soil between selenite and selenate. Therefore, only the available reliable results for selenate are taken into account for the hazard assessment of hexavalent inorganic selenium substances.

Reliable chronic toxicity data for Na2SeO4 are available for the monocotyledon plants (Lolium perenne, Triticum aestivum, Sorghum vulgare and Hordeum vulgare) and dicotyledon plants (Medicago sativa, Beta vulgaris, Lycopersicon escultentum and a Prunus species) and vary between 0.39 and 2 mg Se/kg dw (added concentrations).

All results are based on nominal added or background corrected measured Se concentrations.