Physiological response of culture media-grown barley (Hordeum vulgare L.) to titanium oxide nanoparticles

Figures & data

Figure 1. XRD patterns of anatase powder with tetragonal symmetry.

Figure 2. SEM image of anatase-type TiO₂ nanopowder: TiO₂ particles form aggregates varying in size from several nanometers up to 50 µm.

Figure 3. TEM image of anatase-type TiO₂: particle size ranges from 5 to 25 nm with a mean size of 5–10 nm. There is no evidence that nTiO₂ have a dominant habit; individual grains have a tendency to form a spherical shape.

Figure 4. Average length of roots and shoots of barley (Hordeum vulgare L.) after six-day cultivation on agar medium (type I) under different nTiO₂ concentrations (%). The lengths of both roots and shoots diminish with rising nTiO₂ concentration. A significant change was observed at concentrations higher than 0.5% and 2.5% for roots and shoots, respectively. The error bars represent standard deviation from seven measurements (* statistically significant difference from control on significance level α = 0.05, ** statistically significant difference from control on significance level α = 0.01, *** statistically significant difference from control on significance level α = 0.001).

Table 1. Content of chlorophyll a and b, total and a:b ratio of leaf sections from the top of the first and second leaves of barley (Hordeum vulgare L.) after cultivation in agar medium (type I) or in hydroponics (type II).

	nTiO2 concentration in culture medium – type I (g L^−1)
	0	5	10	25	100	200
Chl a (µg mg^−1)	0.78 ± 0.09	0.78 ± 0.19	0.92 ± 0.24	0.71 ± 0.29	0.76 ± 0.13	0.82 ± 0.12
Chl b (µg mg^−1)	0.31 ± 0.02	0.27 ± 0.04	0.30 ± 0.07	0.24 ± 0.09	0.31 ± 0.06	0.31 ± 0.04
Chl total	1.09 ± 0.10	1.05 ± 0.23	1.22 ± 0.31	0.95 ± 0.15	1.07 ± 0.18	1.12 ± 0.16
a:b	2.52 ± 0.22	2.86 ± 0.43	3.02 ± 0.28*	2.90 ± 0.23	2.51 ± 0.33	2.64 ± 0.30
	nTiO2 concentration in culture medium – type II (mg L^−1)
	0	100	150	200	400	600	1000
Chl a (µg mg^−1)	1.05 ± 0.22	1.28 ± 0.13*	1.12 ± 0.12	1.40 ± 0.38	1.04 ± 0.19	1.04 ± 0.23	1.14 ± 0.24
Chl b (µg mg^−1)	0.25 ± 0.07	0.30 ± 0.04	0.29 ± 0.04	0.30 ± 0.09	0.24 ± 0.05	0.25 ± 0.08	0.25 ± 0.06
Chl total	1.30 ± 0.29	1.58 ± 0.16	1.41 ± 0.16	1.70 ± 0.50	1.28 ± 0.23	1.29 ± 0.31	1.39 ± 0.29
a:b	4.34 ± 0.44	4.35 ± 0.37	3.93 ± 0.24	4.71 ± 0.36	4.37 ± 0.44	4.36 ± 0.84	4.47 ± 0.10

Note: Standard deviation value was determined from seven measurements.

*Statistically significant difference from control on significance level α = 0.05.

Table 2. The dry weight of shoot biomass of barley (Hordeum vulgare L.) after cultivation in (a) agar medium (type I) or in (b) hydroponics (type II).

	nTiO2 concentration in culture medium – type I (g L^−1)
(a)	0	0.5	1	2.5	10	20
d.wt. (mg)	7.6 ± 0.9	8.5 ± 1.1*	9.6 ± 1.2***	7.08 ± 1.8	6.67 ± 1.76	5.5 ± 2.1
	nTiO2 concentration in culture medium – type II (mg L^−1)
(b)	0	100	150	200	400	600	1000
d.wt. (mg)	19.6 ± 3.0	14.7 ± 2.7**	22.7 ± 6.7	13.9 ± 4.2*	18.8 ± 3.9	18.7 ± 5.0	17.4 ± 4.8

Notes: Standard deviation value was determined from seven measurements.

*Statistically significant difference from control on significance level α = 0.05.

**Statistically significant difference from control on significance level α = 0.01.

***statistically significant difference from control on significance level α = 0.001.

Figure 5. Average lengths of roots and shoots of barley (Hordeum vulgare L.) after seven-day cultivation in hydroponics (type II) under different nTiO₂ concentrations (mg L⁻¹). Only root length is affected when concentration of nTiO₂ is above 150 mg L⁻¹. The error bars represent standard deviation from seven measurements (* statistically significant difference from control on significance level α = 0.05, ** statistically significant difference from control on significance level α = 0.01, *** statistically significant difference from control on significance level α = 0.001).

Table 3. Titanium concentrations (mg kg⁻¹ d wt.) in roots and shoots of barley (Hordeum vulgare L.) cultivated for seven days in nTiO₂-amended hydroponics (type II) and determined by ICP-MS.

nTiO2	Ti content
(mg L^−1)	Roots	Shoots
0	26.3	5.4
100	1030	7.4
150	166	5.8
200	949	5.6
400	1490	24.1
600	418	14.1
1000	508	11.5