. 2020 Dec 10;9(12):1745. doi: 10.3390/plants9121745

Table 1.

Positive 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	Conc. of the NM Exposure	Time of Exposure	Growth Conditions	Main Effects on Germination and Early Growth **	Reference
Positive effects	Cucumis sativus L.	10.1 ± 4.2 nm	Au NP	-	62 µg mL⁻¹	7 days	Petri dishes (germination test)	Germination index ↑ns	[105]
	Lactuca sativa L.	10.1 ± 4.2 nm	Au NP	-	62 µg mL⁻¹	7 days	Petri dishes (germination test)	Germination index ↑	[105]
	Pennisetum glaucum L.	14–35 nm	Au NP	Seed soaking for 2 h in test solution	20 and 50 µg mL⁻¹	5 days	Petri dishes (germination test)	Germination % ↑ns and ↑; total seedling length ↑ns	[106]
	Cucurbita pepo L.	20 nm	Ag NP	2 h seed priming	0.05–2.5 mg L⁻¹	12–16 days after priming	Petri dishes (germination test)	Germination % ↑ at 0.5–2.0 mg L⁻¹ conc.; root length ↑ at 0.05–1.5 mg L⁻¹	[107]
	Citrullus lanatus L.	20 nm	Ag NP	2 h seed priming	0.05–2.5 mg L⁻¹	12–16 days after priming		Germination % ↑ at 0.5–2.0 mg L⁻¹ conc.; root length ↑ at 1–2.5 mg L⁻¹	[107]
	Lolium multiflorum L.	Width: 122 ± 35 nm, length: 11,908 ± 6703 nm	Ag NW	-	10 ppm	6 days	Petri dishes (germination test)	Root length ↑ns and physical separation from NWs caused further increment	[108]
	Phaseolus vulgaris L. ‘Bali’ and ‘Delfina’	~10 nm	Ag NP	Seed priming for 1.5 h	0.25, 1.25 and 2.5 mg L⁻¹	5 days	Petri dishes (germination test)	Germination % ↑ at all conc.	[109]
	Zea mays L.	<50 nm	Co₃O₄	-	269.3–1000 mg kg⁻¹ soil (DW)	14 days	Germination test in pot experiment	Germination % ↑ns at all conc.	[110]
	Alyssum homolocarpum	10–25 nm	TiO₂ NP	-	10–80 mg L⁻¹	10 days	Petri dishes (germination test)	Germination % ↑ at 10–40 mg L⁻¹ conc.	[111]
	Nigella sativa L.							Germination % ↑ at 10–40 mg L⁻¹ conc.
	Salvia mirzayanii Rech. f. & Esfand							Germination % ↑ at all conc.
	Arachis hypogea L. var. ‘K-134’	25 nm	ZnO NP	100, 1000 and 2000 ppm for seed priming	2 or 30g/15 L for foliar spraying	3 h seed priming then 2x foliar spraying	Pot and field experiment	Germination % ↑, seedling vigour ↑	[112]
	Capsicum annuum L.	no data	ZnO NP	6 h seed priming	0.25, 0.5 and 0.75 g	14 days	Moistened blotter paper (in Petri dishes)	Concentration-dependent ↑ of seed germination %, root length ↑, seedling length ↑	[113]
	Capsicum chinense L. var. Chichen Itza	18 ± 8 nm	ZnO NP	-	100–500 mg/L	72 h seed priming; 14 day-long germination	Petri dishes (germination test)	Germination % ↑ with conc.; radicule length ↑ at 300 mg/L	[114]
	Cucumis sativus L. ‘Poinsett 76’	8 nm	ZnO NP	-	50–1600 mg L⁻¹	Until 65 % of the seeds were germinated	Petri dishes (germination test)	Germination % ↑ at 400–1600 mg L⁻¹ conc.	[115]
	Vigna radiata L.	~18 nm	ZnO NP	Seed priming for 3 h	20, 40, 60, 80 and 100 mg L⁻¹	Germinating for 7 days after priming	Petri dishes (germination test)	Germination % ↑	[116]
	Vigna unguiculata L.	30 nm	ZnO NP	-	250, 500 and 750 ppm	6 h seed treatment	Soil (pot experiment)	Seedling length ↑, germination % ↑, seedling fresh weight ↑ and vigour index ↑	[117]

* 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.