Figure 66 Effect of salinity stress on chlorophyll content measured by SPAD instrument for
various WT and transgenic lines Statistical analysis showed a significant difference starting from day-12 to day-22 of
treatment. Construct of 35S::HbERF-IXc5 had a significant difference in day-12 until day-19 of treatment Table 51. Based on ecophysiological parameters, 35S::HbERF-IXc5
TS19A90 was more tolerant than wild-type line to salinity stress. Table 51 Effect of construct on chlorophyll content measured by SPAD instrument in salinity
stress
Construct Day of treatment No
1 5
7 12
15 19
22 Wild-type
61.23
a
60.69
a
60.45
a
60.84
a
51.81
a
50.13
a
46.74
a
44.57
a
HEV2.1::HbERF-IXc4 58.41
a
58.98
a
59.75
a
59.68
a
56.19
ab
53.35
ab
47.87
a
46.45
a
35S::HbERF-IXc5 58.12
a
58.69
a
59.37
a
59.76
a
59.28
b
59.6
b
57.64
b
52.18
a
HEV2.1::HbERF-IXc5 59.09
a
59.52
a
59.64
a
59.83
a
57.89
ab
55.95
ab
52.79
ab
54.40
a
The data were analysed with XLSTAT software. Statistical analysis was performed with an ANOVA followed by the Tukey test. Values with the same letter were not significantly different at the 0.05 probability level.
3.7.2.2 Effect of salinity stress on number of leaflets
Salinity stress can decrease number of leaflets. Figure 67 below showed the numbers of leaflets were slowly decreased from day-0 until day-92. The decrease of leaflets numbers
may be due to the accumulation of sodium chloride in the cell walls and cytoplasm of the older leaflets, and the capacity of vacuole sap to contain more salt. Decreasing the
concentration of salt inside the cells which lead quick dead of cells Munns 2002. TS18A13, TS19A90, and TS20A69 were performed the higher number of leaflets compared to control
and other transgenic lines during treatment. Some transgenic lines TS18A13, TS18A37, TS19A90, and TS20A69 developed the adaptation to salinity stress by growing new shoots.
Figure 67 Effect of salinity stress on mean of leaflets for various WT and transgenic lines
Table 52 showed a statistical analysis of effect promoters and genes in salinity stress. There was a significant difference start from day-0 until day-22 of observation.
HEV2.1::HbERF-IXc4 showed the highest number of leaflets in almost all day of observation. In the other hand, control wild-type performed the lowest number of leaflets.
Leaf senescence is affected by a range of external parameters including salinity stress. Salinity stress could lead to premature senescence of adult leaves Cramer and Nowak 1992.
The first noticed symptoms of excessive salt are wilting plants andor leaf “burn” or drying of the leaves, which are often caused by sodium andor chloride toxicity. In the last day of
observation there were no burned or wilting leaflets because the plants were fully abscission.
The observation of colour started at day-0 of NaCl treatment. There has been no changed in colour of leaflets since the beginning of observation but after day-12 of
observation the colour of leaflets started showing yellow strips. The salinity stress could have caused the damage of the leaflets of colour pigment. The yellow colours of leaflets were
correlated to lack photosynthetic activity McCormac et al. 1997. Figure 68 showed plant morphology between control and transgenic plant with construct HEV2.1::HbERF-IXc5.
Transgenic plant with construct HEV2.1::HbERF-IXc5 also showed a better performance to adapt with salinity stress compared control.
Table 52 Effect of constructs on the number of leaflets during salinity stress
Construct Day of treatment No
1 5
9 12
15 19
22 28
36 43
55 64
76 83
92
Wild-type 20.38
a
20.38
a
20.38
a
22.63
ab
20.88
a
19.38
a
13.13
a
6.75
a
2.25
a
2.25
a
0.49
a a
a a
a a
HEV2.1::HbERF-IXc4 28.08
a
28.08
a
28.08
a
28.67
ab
29.75
b
29.75
b
28.8
b
24.75
b
18.58
a
14.3
a
15
a
10.08
a
5.08
a
0.67
a
4.17
a
4.17
a
35S::HbERF-IXc5 21.13
a
21.13
a
21.13
a
22
a
23.38
ab
22
a
22
ab
22.38
b
19
a
15
a
9.13
a
3.63
a
1.88
a
1.13
a
1.88
a
0.88
a
HEV2.1::HbERF-IXc5 27.63
a
27.63
a
27.63
a
30.38
b
29.88
b
28
ab
26.25
ab
24.75
b
19.75
a
13.25
a
11.88
a
8.88
a
2.38
a
4.38
a
3.25
a
4
a
The data were analysed with XLSTAT software. Statistical analysis was performed with an ANOVA followed by the Tukey test. Values with the same letter were not significantly different at the 0.05 probability level.
Figure 68 Plants morphology between control wild-type and lineTS20A69 HEV2.1::HbERF-IXc5
3.7.3 Effect of ethephon on plant leaflets
