Genotypic variations in ion homeostasis, photochemical efficiency and antioxidant capacity adjustment to salinity in cotton (Gossypium hirsutum L.)

Figures & data

Figure 1. Changes in the seedling dry weight of the cotton cultivars CCRI 49, CCRI 35 and Z 51504 after treatment with sodium chloride (NaCl) for 9 d. The different letters present on the columns indicate significant differences at P < 0.05 between the control and the treatment.

Figure 2. The (a) Na⁺ and (b) K⁺ concentrations, and (c) K⁺/Na⁺ ratios in the leaves of the cotton cultivars CCRI 49, CCRI 35 and Z 51504 after treatment with sodium chloride (NaCl) for 9 d. The different letters present on the columns indicate significant differences at P < 0.05 between the control and the treatment.

Figure 3. The effects of salt shock [100 mM sodium chloride (NaCl)] on (a) Na⁺ and (b) K⁺ flux kinetics of cotton seedlings of three different cultivars (CCRI 49, CCRI 35 and Z 51504) that were grown for 9 d in a sand medium (n = 8). The mean (c) Na⁺ and (d) K⁺ fluxes of steady state of cotton seedlings within the measuring periods are shown. The different letters present on the columns indicate significant differences at P < 0.05 between the control and the treatment.

Figure 4. Changes in (a) photosynthesis (P_n) and (b) photorespiration (PR) in the leaves of the cotton cultivars CCRI 49, CCRI 35 and Z 51504 after treatment with sodium chloride (NaCl) for 9 d. The different letters present on the columns indicate significant differences at P < 0.05 between the treatment and the control.

Table 1. Changes in the maximum photochemical efficiency of photosystem II (PSII; F_v/F_m), actual photochemical efficiency of PSII (Φ_PSII), photochemical quenching (qP), non-photochemical quenching (qN), electron transport rate (ETR) and ETR/P_n in the leaves of the cotton cultivars CCRI 49, CCRI 35 and Z 51504 after treatment with NaCl for 9 d.

NaCl treatment (mM)	Fv/Fm	ΦPSII	qP	qN	ETR (μmol m^−2 s^−1)	ETR/Pn
CCIR 49
0	0.799 a	0.712 a	0.969 a	0.222 c	149.5 a	15.24 c
150	0.791 a	0.651 c	0.907 c	0.282 a	136.6 c	21.78 a
CCIR 35
0	0.798 a	0.712 a	0.962 a	0.214 c	149.4 a	15.09 c
150	0.794 a	0.697 b	0.949 b	0.233 b	143.9 b	17.65 b
Z 51504
0	0.812 a	0.705 a	0.956 a	0.219 c	150.0 a	14.75 c
150	0.806 a	0.690 b	0.939 b	0.278 a	144.9 b	15.10 c

The different lowercase letters present in the columns indicate significant differences at P < 0.05 between the treatment and the control.

Table 2. Changes in the activity of superoxide dismutase (SOD), peroxidases (POD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) in the leaves of the cotton cultivars CCRI 49, CCRI 35 and Z 51504 after treatment with sodium chloride (NaCl) for 9 d.

NaCl treatment (mM)	SOD (U g^−1 FW)	POD (U g^−1 FW)	CAT (U mg^−1 FW)	APX (U mg^−1 FW)	GR (U mg^−1 FW)
CCIR 49
0	824.2 c	203.2 a	18.77 b	5.94 d	1.19 d
150	534.3 e	117.6 c	9.33 c	7.21 c	2.01 c
CCIR 35
0	821.3 c	196.6 a	21.02 b	6.03 d	1.50 cd
150	643.5 d	85.6 d	39.67 a	9.23 b	2.80 b
Z 51504
0	990.6 a	212.9 a	20.41 b	6.33 cd	1.35 d
150	936.2 b	134.9 b	38.67 a	13.39 a	3.52 a

FW: fresh weight. The different lowercase letters present in the columns indicate significant differences at P < 0.05 between the control and the treatment.

Figure 5. Changes in (a) O₂⁻, (b) H₂O₂ and (c) malondialdehyde (MDA) in the leaves of the cotton cultivars CCRI 49, CCRI 35 and Z 51504 after treatment with NaCl for 9 days. The different letters present on the columns indicate significant differences at P < 0.05 between different treatments.