Guanidinium nitrate

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

yes

Remarks:

Outcome of test is comparable to outcome of OECD208

Principles of method if other than guideline:

Toxic effects of the guanidines on germination and growth of wheat seedlings were determined by placing 200 g of each of the three soils into small pots (15 x 15 x 20 cm). The test compounds were mixed into the separate pot to give 200 µg N/g soil (GuNi 45.9%N; 444µgGuNi/g soil), and 25 seeds of wheat (var. Star) were sown into each pot. Three replications were maintained. The percent germination was determined a week after sowing. The twenty seedlings were then allowed to grow for another two weeks and they were cut at soil surface. The above ground plant portions were dried at 60 °C and dry weights were recorded. The dry weights of plants in each treatment was compared to the respective control and to the urea treatment using a ‘t’ test (Panse and Sukhatme, 1978).

GLP compliance:

not specified

Species:

Triticum aestivum

Plant group:

Monocotyledonae (monocots)

Details on test organisms:

Wheat seedlings (var. Star)

Test type:

other: wheat germination, seedling growth

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

yes

Total exposure duration:

14 d

Key result

Species:

Triticum aestivum

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

435 mg/kg soil ww

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: wheat germination, seedling growth

Guanidine nitrate concentration: 200 µg N/g soil, (GuNi 45.9%N; 435mgGuNi/Kg soil)

None of the guanidines adversely affect the wheat germination which was >90% in all cases (data not presented). The wheat seedling grew normally for two weeks except with GT which caused death soon after emergence. The toxicity of GT may be due to the thiocyanate group, from ionisation of Guanidine thiocyanate into guanidinium and thiocyanate. The 20 plants in a small soil volume rapidly deplete available soil N in the control, so there was more seedling growth from urea and from more quickly available guanidines (Figure 2). The responses of Guanidine nitrate, Aminoguanidine nitrate and Aminoguanidine carbonate were the same as with urea due to the immediate release of NH4+ or NO3-. Plant growth with Guanidine sulphate, Guanidine acetate, and Guanidine carbonate was lower than with urea, but, more than for the control. A similar trend was observed for DGS. Relatively less N response for Guanidine sulphate, Guanidine acetate, and Guanidine carbonate may be attributed to their slow mineralization (Table 3). However, the results with Dimethylguanidine sulphate are difficult to explain since it was the fastest mineralized derivative. Mineralization of Nitroguanidine and Tetramethyl guanidine was very slow (Table 4). So, their application did not effect plant growth.

Validity criteria fulfilled:

not applicable

Remarks:

Data from publication

Conclusions:

The effect of Guanidine nitrate on germination and growth of wheat seedlings was tested for 14 days. At a Guanidine nitrate concentration of 200 µg N/g soil, (GuNi 45.9%N; 435mgGuNi/Kg soil) there was no adverse affect in wheat germination. The response of wheat dry matter production was the same as with urea.

Executive summary:

The effect of Guanidine nitrate on germination and growth of wheat seedlings was tested for 14 days. At a Guanidine nitrate concentration: 200 µg N/g soil, GuNi 45.9%N; 435 mgGuNi/Kg soil) there was no adverse affect in wheat growth and germination. The response of wheat dry matter production was the same as with urea.

Reference 2

Endpoint:

toxicity to terrestrial plants: short-term

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

a short-term study does not need to be conducted because an appropriate long-term toxicity study on terrestrial organisms is available

Description of key information

The NOEC of Gunanidine nitrate on terrestrial plants is 435mg/kg soil.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

435 mg/kg soil dw

Additional information

The effect of Guanidine nitrate on germination and growth of wheat seedlings was tested for 14 days. At a Guanidine nitrate concentration: 200 µg N/g soil, GuNi 45.9%N; 435mgGuNi/Kg soil) there was no adverse affect in wheat growth and germination. The response of wheat dry matter production was the same as with urea. This test was used for NOEC derivation according to Guidance R7c, p. 112 (2008).