Table 3.

Negative effects of metal and metal oxide NPs on seed germination and seedling growth.

	Plant Name	Size of NM	Type and Chemical Composition of NM *	Duration of Pre-Cultivation	Concentration of the NM Exposure	Time of Exposure	Growth Conditions	Main Effects on Germination and Early Growth **	Reference
Negative effects	Cucumis sativus L.	29.2 ± 1.1 nm	Ag NP	-	100 µg mL−1	7 days	Petri dishes (germination test)	Germination index ↓	[105]
	Lolium multiflorum L.	35 ± 7 nm	Ag NP	-	10 ppm	6 days	Petri dishes (germination test)	Root length ↓ns but physical separation from NPs caused ↑	[108]
	Lolium multiflorum L.	44 ± 7 nm	Ag NC					Root length ↓ns but physical separation from NCs caused ↑
	Phaseolus radiatus L.	no data	Cu NP	24 h	200–1000 mg L−1	48 h	Petri dishes (germination test, agar)	Seedling growth and root growth ↓ concentration-dependently	[135]
	Triticum aestivum ssp. aestivum	no data	Cu NP					Seedling growth and root growth ↓ concentration-dependently
	Solanum lycopersicum L. ‘Pomodoro’	7 nm	CeO2 NP	-	500–4000 mg L−1	6 days	Petri dishes (germination test)	Germination % ↓ns and ↓; root elongation ↓ at 1000–4000 mg/L conc.	[121]
	Avena sativa L.	<50 nm	Co3O4 NP	-	269.3–1000 mg kg−1 soil (DW)	14 days	Germination test in pot experiment	Germination % ↓ns at higher conc.	[110]
	Solanum lycopersicum L.							Germination % ↓ns but ↓ at 1000 mg/kg conc.
	Oryza sativa L. Jijing No.6.	<50 nm	CuO NP	2 h priming	25–2000 mg L−1	Germination for 5 days after priming	Petri dishes (germination test)	Root length ↓ at all conc.	[136]
	Zea mays L. Zhengdan No. 958.	<50 nm	CuO NP	2 h priming	25–2000 mg L−1	Germination for 7 days after priming	Petri dishes (germination test)	Root length ↓ at all conc.	[136]
	Arabidopsis thaliana ‘Col-0’	<50 nm	Fe3O4 NP	5 days at 4 °C (in dark)	400, 2000 and 4000 mg L−1	18 days	1/2 MS medium	Seed germination % ↓ns at 400 and 2000 mg L−1; root elongation ↓	[137]
	Cucumis sativus L.	7.57 ± 5.6 nm	Fe3O4 NP	-	116 µg mL−1	7 days	Petri dishes (germination test)	Germination index ↓	[105]
	Lactuca sativa L.							Germination index ↓
	Vicia narbonensis L.	<100 nm	TiO2 NP	Soaking seed for 24 h in the test solutions	0.2–4.0‰	72 h	Petri dishes (germination test)	Germination % ↓ ns; root elongation ↓ ns and ↓, chromosomal aberration index in root tip meristem ↑ with conc.	[138]
	Zea mays L.
	Arabidopsis thaliana ‘Col-0’	~44 nm	ZnO NP	5 days at 4 °C (in dark)	400, 2000 and 4000 mg L−1	18 days	1/2 MS medium	Seed germination % ↓ and root elongation ↓	[137]
	Brassica napus L. cv. Hayola 401	<50 nm	ZnO NP	-	5–500 mg L−1	6 days	Petri dishes (germination test)	Germination % ↓ns	[139]
	Cucumis sativus L.	≤50 nm	ZnO NP	2 h	10–500 mg/L	5–12 days	Petri dishes (filter paper or soil)	Germination % ↓ns	[130]
	Oryza sativa L. Jijing No. 6.	<50 nm	ZnO NP	2 h priming	25–2000 mg/L	Germination for 5 days after priming	Petri dishes (germination test)	Germination % was not affected at 2000 mg L−1conc.; root length ↓ at 100–2000 mg L−1	[136]
	Solanum lycopersicum L. ‘Roma FV’	8 nm	ZnO NP	-	50–1600 mg L−1	Until 65 % of the seeds were germinated	Petri dishes (germination test)	Germination % ↓ at 800–1600 mg L−1conc.	[115]
	Solanum lycopersicum L.	<50 nm	ZnO NP	-	100–1000 mg L−1	7 days	Petri dishes (germination test)	Germination % ↓ at 750–1000 mg L−1	[131]
	Triticum aestivum L.							Germination % ↓ from 250 mg L−1 ZnO NP
	Triticum aestivum L.	≤50 nm	ZnO NP	2 h	10–500 mg L−1	5–12 days	Petri dishes (filter paper or soil)	Germination % ↓ ns	[130]
	Vigna radiata L.
	Zea mays L. Zhengdan No. 958.	<50 nm	ZnO NP	2 h priming	25–2000 mg L−1	Germination for 7 days after priming	Petri dishes (germination test)	Germination % was not affected at 2000 mg L−1 conc.; root length ↓ at 500–2000 mg L−1	[136]

* Abbreviations: NC—nanocubes, NP—nanoparticles, NW—nanowires, LR—long nanorods, SR—short nanorods. ** ↑ indicates significant and ↑ns indicates non-significant increase, while ↓ refers to significant decrease and ↓ns to non-significant reduction.