Selenium treatment alters the effects of UV radiation on chemical and production parameters in hybrid buckwheat

Figures & data

Table 1. Anatomical parameters of the buckwheat leaves under the four treatments, and impact on the measured parameters of Se and UV, and their interaction (Se×UV).

Parameter	Experimental group				Factorial ANOVA
	−Se−UV	−Se+UV	+Se−UV	+Se+UV	Se	UV	Se×UV
Spec. leaf area (cm^2 mg^−1)	0.23 ± 0.01^a	0.27 ± 0.02^b	0.26 ± 0.03^ab	0.24 ± 0.01^ab	ns	ns	**
Water content (%)	82.3 ± 0.47^b	81.1 ± 0.80^ab	80.9 ± 0.63^a	79.9 ± 0.33^a	**	**	ns
Leaf thickness (µm)	187 ± 7^b	168 ± 7^a	185 ± 4^b	174 ± 4^a	ns	**	ns
Palisade mesophyll (µm)	50.2 ± 2.0^ab	45.0 ± 4.5^ab	50.4 ± 1.5^b	46.1 ± 1.8^a	*	**	*
Spongy mesophyll (µm)	94.4 ± 5.8^ab	94.7 ± 7.7^ab	99.0 ± 1.1^b	90.0 ± 4^a	ns	ns	ns
Adaxial leaf surface
Cuticle thickness (µm)	2.49 ± 0.10^b	2.25 ± 0.09^a	2.52 ± 0.07^b	2.36 ± 0.06^a	ns	**	ns
Epidermis thickness (µm)	21.4 ± 0.8^a	21.2 ± 0.7^a	21.9 ± 0.5^a	21.2 ± 0.6^a	ns	ns	ns
Stomata density (mm^−2)	25.2 ± 1.7^c	18.8 ± 1.3^a	20.4 ± 2.5^ab	23.7 ± 2.5^bc	ns	ns	**
Stomata length (µm)	30.3 ± 1.0^ab	30.3 ± 3.3^ab	31.5 ± 0.6^b	29.6 ± 0.8^a	ns	ns	ns
Stomata width (µm)	11.0 ± 1.5^a	9.4 ± 0.7^a	10.3 ± 0.4^a	9.9 ± 0.2^a	ns	**	ns
Trichomes density (mm^−2)	11.7 ± 1.5^a	15.3 ± 0.7^b	12.6 ± 0.8^a	15.2 ± 0.9^b	ns	**	ns
Trichomes length (µm)	162 ± 10^a	167 ± 8^a	195 ± 5^b	199 ± 10^b	**	ns	ns
Abaxial surface
Epidermis thickness (µm)	12.3 ± 0.3^a	12.4 ± 0.6^a	12.0 ± 0.3^a	11.6 ± 0.4^a	*	ns	ns
Stomata dens. (mm^−2)	74.4 ± 4.8^b	71.4 ± 19.0^ab	58.3 ± 5.0^a	70.7 ± 6.5^ab	ns	ns	ns
Stomata length (µm)	32.5 ± 0.6^a	31.3 ± 2.7^ab	35.2 ± 0.9^b	32.9 ± 1.5^ab	**	ns	ns
Stomata width (µm)	9.8 ± 0.2^a	9.9 ± 0.2^ab	10.4 ± 0.3^b	9.5 ± 0.3^a	ns	*	**
Trichomes density (mm^−2)	3.9 ± 0.7^a	4.3 ± 1.9^a	3.3 ± 0.8^a	3.7 ± 1.0^a	ns	ns	*
Trichomes length (µm)	200 ± 12^a	229 ± 14^b	249 ± 9^b	246 ± 15^b	**	ns	ns

Notes: Data are means ± standard deviation (n = 4 for each). Different letters indicate significant differences between the different treatments (p < 0.05, Tukey tests); *, p < 0.05, for influence of factor on selected variable; **, p < 0.01; ns, not statistically significant; DM, dry matter; ETS, electron transport system activity.

Table 2. Biochemical and physiological parameters of the buckwheat leaves under the four treatments, and impact on the measured parameters of Se and UV, and their interaction (Se×UV).

Parameter	Experimental group				Factorial ANOVA
	−Se−UV	−Se+UV	+Se−UV	+Se+UV	Se	UV	Se×UV
Chlorophyll a (mg dm^−2)	3.13 ± 0.09^b	3.10 ± 0.11^ab	3.51 ± 0.16^c	2.84 ± 0.16^a	ns	**	**
Chlorophyll b (mg dm^−2)	1.79 ± 0.10^a	1.78 ± 0.13^a	2.09 ± 0.04^b	1.73 ± 0.11^a	*	**	**
Carotenoids (mg dm^−2)	0.88 ± 0.05^b	0.85 ± 0.06^ab	0.88 ± 0.06^b	0.75 ± 0.04^a	ns	**	ns
Anthocyanins (rel. units dm^−2)	67.9 ± 5.1^a	81.7 ± 3.6^b	89.2 ± 5.1^b	103.6 ± 6.5^c	**	**	ns
UVA-AC (rel. units cm^−2)	30.8 ± 1.1^a	36.4 ± 2.4^b	36.4 ± 1.3^b	42.8 ± 1.3^c	**	**	ns
UVB-AC (rel. units cm^−2)	14.9 ± 0.4^a	17.1 ± 0.9^b	18.1 ± 1.5^b	20.7 ± 0.4^c	**	**	ns
Transpiration (mmol H2O m^−2 s^−1)	463 ± 74^a	496 ± 78^a	550 ± 40^a	593 ± 67^a	*	ns	ns
Fv/Fm	0.74 ± 0.02^b	0.70 ± 0.02^ab	0.70 ± 0.01^a	0.68 ± 0.01^a	**	**	ns
	0.34 ± 0.06^a	0.30 ± 0.05^a	0.30 ± 0.04^a	0.33 ± 0.06^a	ns	ns	ns
ETS (µL O2 mg^−1 DM h^−1)	9.6 ± 0.6^a	12.4 ± 1.2^b	12.0 ± 0.8^b	11.1 ± 0.6^ab	ns	*	**

Notes: Data are means ± standard deviation (n = 4 for each). Different letters indicate significant differences between the different treatments (p < 0.05, Tukey tests); *, p < 0.05, for influence of factor on selected variable; **, p < 0.01; ns, not statistically significant; DM, dry matter; ETS, electron transport system activity.

Figure 1. Heights of the buckwheat plants grown under the different treatment conditions. Different letters indicate statistically significant differences between conditions (p < 0.05; Tukey tests). Se and UV in brackets indicate the results of factorial ANOVA, showing the factors that significantly influence plant height (p < 0.05).

Figure 2. Biomass of the buckwheat plant parts (as indicated) under the four conditions. Different letters indicate significant differences of plant parts between the different treatments (p < 0.05; Tukey tests). Se and/or UV and Se×UV in brackets indicate the results of factorial ANOVA, showing the factors and their interaction that significantly influence biomass of different plant parts (p < 0.05).

Table 3. Elemental analysis of the buckwheat leaves under the four conditions, and impact of Se and UV and their interaction (Se×UV) on the parameters measured.

Element	Experimental group				Factorial ANOVA
	−Se−UV	−Se+UV	+Se−UV	+Se+UV	Se	UV	Se×UV
Silicon (mg g^−1 DM)	3.46 ± 1.48^b	1.57 ± 0.51^a	4.84 ± 1.61^b	3.25 ± 1.53^ab	*	*	ns
Calcium (mg g^−1 DM)	28.9 ± 2.2^a	25.2 ± 4.2^a	29.6 ± 2.0^a	28.3 ± 4.5^a	ns	ns	ns
Phosphorus (mg g^−1 DM)	0.73 ± 0.15^a	0.96 ± 0.37^a	0.79 ± 0.12^a	0.97 ± 0.18^a	ns	*	ns
Potassium (mg g^−1 DM)	20.7 ± 2.3^a	19.3 ± 3.0^a	22.7 ± 2.7^ab	25.6 ± 1.9^b	**	ns	ns
Sulphur (mg g^−1 DM)	1.08 ± 0.18^a	1.09 ± 0.61^a	1.02 ± 0.2^a	1.19 ± 0.49^a	ns	ns	ns

Notes: Data are means ± standard deviation (n = 4 for each). Different letters indicate significant differences between the different treatments, (p < 0.05; Tukey tests); *, p < 0.05, for influence of factor on selected variable; **, p < 0.01; ns, not statistically significant; DM, dry matter.

Table 4. Se levels in the plant parts under the different conditions of the buckwheat plants, and the impact of Se and UV and their interaction (Se×UV) on the parameters measured.

Plant part	Se content (ng g^−1 DM) in experimental group				Factorial ANOVA
	−Se−UV	−Se+UV	+Se−UV	+Se+UV	Se	UV	Se×UV
Leaves	41 ± 2^a	44 ± 3^a	963 ± 91^b	854 ± 187^b	**	ns	ns
Stems	14 ± 1^a	20 ± 1^b	311 ± 82^c	252 ± 28^c	**	ns	ns
Roots	192 ± 6^a	202 ± 7^a	653 ± 34^c	534 ± 19^b	**	**	**
Grain	41 ± 2^a	49 ± 3^b	1075 ± 151^d	783 ± 69^c	**	**	**

Notes: Data are means ± standard deviation (n = 4 for each). Different letters indicate significant differences between the different treatments (p < 0.05; Tukey tests); **, p < 0.01; ns, not statistically significant; DM, dry matter.