Effects of scion and rootstock genotypes on the anti-oxidant defense systems of grafted cucumber seedlings under NaCl stress

Figures & data

Figure 1 Salt injury index of the grafted cucumber seedlings under 0 mmol L−1 and 100 mmol L−1 NaCl stress. Leaf damage score: level 1 (0% area of yellow leaf), level 2 (1–25% area of yellow leaf), level 3 (26–50% area of yellow leaf), level 4 (51–75% area of yellow leaf) and level 5 (76–100% area of yellow leaf). Values are the mean ± standard error (n = 3). Bars with the same letters indicate no significant difference according to Duncan’s multiple range test (P < 0.05). J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd.

Table 1 Plant growth of grafted cucumber seedlings under 0 and 100 mmol L−1 NaCl stress

NaCl (mmol L^−1)	Graft combinations	Root dry weight (g)	Shoot dry weight (g)	Leaf area (cm^2)	RWC (%)
0	J1/C	0.52 ± 0.05	3.14 ± 0.20	744 ± 21.9	84.8 ± 2.25
	J1/F	0.35 ± 0.03	3.67 ± 0.32	714 ± 22.9	87.9 ± 1.09
	J2/C	0.50 ± 0.05	3.01 ± 0.29	706 ± 21.1	88.9 ± 0.95
	J2/F	0.41 ± 0.01	3.80 ± 0.29	723 ± 66.3	88.5 ± 0.83
100	J1/C	0.41 ± 0.02	1.39 ± 0.13	267 ± 11.9	78.2 ± 2.73
	J1/F	0.21 ± 0.02	1.13 ± 0.08	169 ± 0.5	74.1 ± 1.48
	J2/C	0.42 ± 0.05	1.30 ± 0.16	270 ± 21.5	77.5 ± 1.41
	J2/F	0.19 ± 0.01	1.07 ± 0.14	150 ± 11.0	75.3 ± 1.79
ANOVA (F-values)
Salinity		33.3***	403***	639***	81.7***
Scion		0.07ns	0.14ns	0.60ns	0.93ns
Rootstock		54.69***	3.69ns	6.87*	0.01ns
Salinity × scion		0.34ns	0.09ns	0.15ns	0.10ns
Salinity × rootstock		3.03ns	17.04***	7.50*	1.13ns
Scion × rootstock		0.22ns	0.45ns	0.01ns	0.38ns
Salinity × scion × rootstock		1.47ns	0.27ns	0.39ns	1.06ns
Data in the columns are the mean ± standard error (n = 6). *P < 0.05; ***P < 0.001; ns, not significant. J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd; RWC, relative water content.

Figure 2 Na+ contents in the roots and leaves of grafted cucumber seedlings under 0 mmol L−1 and 100 mmol L−1 NaCl stress. Values are the mean ± standard error (n = 3). Bars with the same letters indicate no significant difference according to Duncan’s multiple range test (P < 0.05). J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd; DW, dry weight.

Figure 3 H2O2 content in the leaves and roots of the grafted cucumber seedlings under 0 mmol L−1 and 100 mmol L−1 NaCl stress. Values are the mean ± standard error (n = 3). Bars with the same letters indicate no significant difference according to Duncan’s multiple range test (P < 0.05). J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd; FW, fresh weight.

Figure 4 Superoxide dismutase (SOD) activity in the leaves and roots of the grafted cucumber seedlings under 0 mmol L−1 and 100 mmol L−1 NaCl stress. Values are the mean ± standard error (n = 3). Bars with the same letters indicate no significant difference according to Duncan’s multiple range test (P < 0.05). J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd; FW, fresh weight.

Figure 5 Peroxidase (POD) activity in the leaves and roots of grafted cucumber seedlings under 0 mmol L−1 and 100 mmol L−1 NaCl stress. Values are the mean ± standard error (n = 3). Bars with the same letters indicate no significant difference according to Duncan’s multiple range test (P < 0.05). J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd; FW, fresh weight.

Figure 6 Catalase (CAT) activity in the leaves and roots of grafted cucumber seedlings under 0 mmol L−1 and 100 mmol L−1 NaCl stress. Values are the mean ± standard error (n = 3). Bars with the same letters indicate no significant difference according to Duncan’s multiple range test (P < 0.05). J1/C, Jinyu No. 1 grafted onto Chaojiquanwang; J1/F, Jinyu No. 1 grafted onto Figleaf Gourd; J2/C, Jinchun No. 2 grafted onto Chaojiquanwang; J2/F, Jinchun No. 2 grafted onto Figleaf Gourd; FW, fresh weight.

Table 2 Correlation coefficient between the salt injury index and the other parameters of the grafted cucumber seedlings under 0 and 100 mmol L−1 NaCl stress

	Salt injury index	Leaf					Root
		Na^+	H2O2	SOD	POD	CAT	Na^+	H2O2	SOD	POD
Leaf Na^+	0.791*
Leaf H2O2	0.760*	0.679ns
Leaf SOD	0.320ns	0.292ns	0.786*
Leaf POD	−0.481ns	−0.369ns	−0.501ns	0.004ns
Leaf CAT	0.637ns	0.584ns	0.970***	0.805**	−0.569ns
Root Na^+	0.377ns	0.353ns	0.874**	0.839**	−0.505ns	0.948***
Root H2O2	0.896**	0.882**	0.811*	0.411ns	−0.471ns	0.712*	−0.481ns
Root SOD	−0.873**	−0.725*	−0.644ns	−0.149ns	0.462ns	−0.484ns	−0.276ns	−0.782*
Root POD	−0.764*	−0.622ns	−0.226ns	0.212ns	0.201ns	−0.063ns	0.216ns	−0.519ns	0.746*
Root CAT	−0.641ns	−0.761*	−0.186ns	0.155ns	0.051ns	−0.051ns	0.248ns	−0.684ns	0.510ns	0.732*
*P < 0.05; **P < 0.01; ***P < 0.001 (n = 8); ns, not significant. CAT, catalase; POD, peroxidase; SOD, superoxide dismutase.