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Ecotoxicological information

Toxicity to terrestrial plants

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Administrative data

Endpoint:
toxicity to terrestrial plants: short-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2011
Report date:
2011

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.4225 (Seedling Emergence Tier II)
Version / remarks:
April 1996
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Ammonium 2-amino-4-(hydroxymethylphosphinyl)butyrate
EC Number:
278-636-5
EC Name:
Ammonium 2-amino-4-(hydroxymethylphosphinyl)butyrate
Cas Number:
77182-82-2
Molecular formula:
C5H12NO4P.H3N
IUPAC Name:
ammonium 2-amino-4-(hydroxymethylphosphinyl)butyrate

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
The stock solution used for preparation of the spray solutions was analysed.

Test substrate

Vehicle:
no
Details on preparation and application of test substrate:
The test item was dissolved in deionised water and was applied once with 100 L/ha using a spray chamber. The spray solution was applied once, at test initiation on the soil surface. For the untreated controls a spray solution of 100 L deionized water/ha was applied.

Test organisms

Species:
Lactuca sativa
Plant group:
Dicotyledonae (dicots)

Study design

Test type:
seedling emergence and seedling growth test
Study type:
laboratory study
Substrate type:
artificial soil
Remarks:
mixture of standard silt loam soil + 30% washed sand
Limit test:
no
Total exposure duration:
21 d

Test conditions

Test temperature:
23 +- 8 °C day and 18 +- 8 ° C night
pH:
Soil pH = 7.24 (CaCl2)
Moisture:
Regulated to maintain 70  30%water
Details on test conditions:
Soil
Soil mixture The used soil is a mixture of standard silt loam soil + 30% washed sand from Bayer CropScience AG, Global Biology Herbicides, Horticulture, H 872, Industriepark Hoechst, D-65926 Frankfurt am Main. The soil was sieved to 2 mm. The soil was analysed separately with GLP in the laboratory of LUFA Speyer, Obere Langgasse 40, D-67346 Speyer.
Sterilisation: 120 degrees vapour for about 30 minutes.
Fertilization: 2.4 g Blaukorn per liter
Composition and particle size: <0.002 mm clay = 13.3 %
0.002 - 0.006 mm silt = 4.5 %
0.006 - 0.020 mm silt = 10.8 %
0.020 - 0.063 mm silt = 21.4 %
0.063 - 0.200 mm sand = 7.5 %
0.200 - 0.630 mm sand = 29.8 %
0.630 - 2.0 mm sand = 12.7 %
Cation capacity: 23.75 meq/100 g
Lime content: 0.7 % CaCO3
Organic carbon: 0.63 % Corg
pH – value: 7 .24 (CaCl2)

Climatic conditions
Light Regime: Regulated to maintain at least 16 h light
Light intensity: Natural daylight supplemented by artificial lighting.
Regulation: at light intensities >15000 lux the lamps turn off and when >50000 lux the shading closes.
Watering: Prior to spray application, pots were top watered to moisten the upper layer of soil. After the pots were sprayed and the exposure phase begun, water was given by subirrigation only. Irrigation was provided throughout the study via bottom watering. Pots were contained in saucers standing under each pot and water was given and retained within the saucer according to the need of the plants in order to have an optimal water supply for plant growth. This was checked daily.
Exposure Time: 21 days after application.
Liquid Fertilization: None.

Test vessels and sowing
Pots; Type and Size: Commercial plastic flower pots (10.5 cm diameter).
Number of Pots: 8 pots per treatment group.
Number of Seeds: Each pot contained 5 seeds. In total 40 seeds per treatment group were tested.
Sowing: The seeds were pressed into the soil surface and completely covered with a layer of a mixture quarz sand / used soil (ratio 1/1 v/v). Soil was top watered immediately to facilitate germination. Sowing and application of the pots occured during the same day.
Nominal and measured concentrations:
Application rates in kg active ingredient / ha
0.06, 0.12, 0.24, 0.48, 0.97, 1.93
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 1.93 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
seedling emergence
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
1.93 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
seedling emergence
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
0.65 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: Survival
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.24 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
other: Survival
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 0.97 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Shoot length
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.97 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Shoot length
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
> 0.97 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Shoot dry weight
Species:
Lactuca sativa
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.97 kg/ha
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth
Remarks:
Shoot dry weight
Details on results:
Analysis of stock solution
Measured concentrations of Glufosinate-ammonium in the highest application rate ranged from 100.0-100.4% of the nominal test concentration.

Test results
An application of the test substance to the soil surface of pots in which Lettuce (Lactuca sativa) seeds had been sown had no statistically significant effect on the emergence at any application rates tested. The NOER for this endpoint was calculated as the highest application rate tested of 1.93 kg a.i./ha.
As there were no significant effects observed on the emergence, no meaningful rate / response relation could be derived (p(F) > 0.05). Thus, the ER25 and ER50 values for emergence were set for both as >1.93 kg a.i./ha.

Survival was statistically significantly affected at application rates including and above 0.48 kg a.i./ha. The NOER for this endpoint was calculated as 0.24 kg a.i./ha. The LR25 value was calculated as 0.37 kg a.i./ha. The LR50 value was calculated as 0.65 kg a.i./ha.

Shoot length was not affected at any application rates tested. No computations were performed by the program due to the absence of shoot length inhibition observed. The NOER for this endpoint was set as 0.97 kg a.i./ha, the ER25 and ER50 values for shoot length were set for both as >0.97 kg a.i./ha as there was 100% mortality at the application rate of 1.93 kg a.i./ha.

Shoot dry weight was not statistically significantly affected at any application rates tested. The NOER for this endpoint was calculated as 1.93 kg a.i./ha but is considered as being an artefact as there was 100% mortality at the application rate of 1.93 kg a.i./ha and set as 0.97 kg a.i./ha. No meaningful rate / response relation could be derived (p(F) > 0.05), thus, the ER25 and ER50 values for shoot dry weight were set for both as >0.97 kg a.i./ha.
At the application rate of 0.97 kg a.i./ha, marginal phytotoxic symptoms visualised as chlorosis and stunting at day 21.
There were no effects on growth stage of emerged seedlings in comparison with the untreated controls up to the application rate of 0.97 kg a.i./ha.
There was 100% mortality at the application rate of 1.93 kg a.i./ha.

Any other information on results incl. tables

Results tables

Emergence

Treatm.[kg a.i./ha]

Prepared

Emerged

Not-emerged

%Not-emerged

%Emerged

Control

40

33

7

17.5

82.5

0.06

40

30

10

25.0

75.0

0.01

40

32

8

20.0

80.0

0.24

40

34

6

15.0

85.0

0.48

40

27

13

32.5

67.5

0.97

40

29

11

27.5

72.5

1.93

40

27

13

32.5

67.5

Post-emergence survival after 21 days

Treatm.[kg a.i./ha]

Emerged

Survived

Not-survived

%Mortality

%Survival

Control

33

33

0

0.0

100.0

0.06

30

29

1

3.3

96.7

0.12

32

30

2

6.3

93.8

0.24

34

33

1

2.9

97.1

0.48

27

21

6

22.2

77.8

0.97

29

9

20

69.0

31.0

1.93

27

0

27

100.0

0.0

 

Shoot length after 21 days

Treatm.[kg a.i./ha]

Mean in cm

Std. Dev.

n

%Reduction

Control

7.556

1.7418

8

0.0

0.06

8.779

0.5114

8

-16.2

0.12

8.419

0.5000

8

-11.4

0.24

8.531

0.7188

8

-12.9

0.48

8.675

0.5792

8

-14.8

0.97

8.083

0.8010

6

-7.0

1.93

n.d.

n.d.

0

n.d.

n.d. = not determinable due to 100 % post-emergence mortality

 

 

Shoot dry weight after 21 days

Treatm.[kg a.i./ha]

Mean in g

Std. Dev.

n

%Reduction

Control

0.176

0.1718

8

0.0

0.06

0.153

0.1699

8

13.2

0.12

0.101

0.0204

8

42.8

0.24

0.111

0.0225

8

36.7

0.48

0.126

0.0361

8

28.2

0.97

0.127

0.0542

6

27.6

1.93

n.d.

n.d.

0

n.d.

n.d. = not determinable due to 100 % post-emergence mortality

 

Phytotoxicity after 21 days

Day 21 phytotoxicity summary (mean % damage)

kg a.i./ha

Lactuca sativa

Control

0

0.06

0

0.12

0

0.24

0

0.48

0

0.97

3.3 (af)*

1.93

*Phytotoxicity was assessed according to EPPO Standard 135 (a= chlorosis (yellowing of green shoot tissue;f= stunting (plant height reduced with shorter internode length)

: 100% mortality

 

Effect on growth stages

BBCH* Min-Max at application rates (kg a.i. /ha)

plant species

control

0.06

0.12

0.24

0.48

0.97

1.93

Lactuca sativa

12-15

14-15

14-15

14-15

14-15

14-15

* Biologische Bundesanstalt, Bundessortenamt and Chemical Industry

††: 100% mortality

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The seedling emergence study in which the effect ofglyfosinate ammoniumon Lettuce (Lactuca sativa) was tested under glasshouse conditions resulted in a lowest NOER of 0.24 kg a.i./ha (based on survival), a lowest ER50 of 0.65 kg a.i./ha (based on survival) and a lowest ER25 of 0.37 kg a.i./ha (based on survival).
Executive summary:

The seedling emergence study in which the effect ofglyfosinate ammoniumon Lettuce (Lactuca sativa) was tested under glasshouse conditions resulted in a lowest NOER of 0.24 kg a.i./ha (based on survival), a lowest ER50 of 0.65 kg a.i./ha (based on survival) and a lowest ER25 of 0.37 kg a.i./ha (based on survival).