Role of silicon nutrition in salinity tolerance of Puccinellia distans and Brassica napus

1. Role of silicon nutrition in
salinity tolerance of
Puccinellia distans and
Brassica napus
Gorgan University of Agricultural Sciences
and Natural Resources , Iran.
Ahmad Abdolzadeh
In the name of God

2. Introduction
Canola Puccinellia

3. Salt marsh
Saline soils in arid
The distribution of saline soils
in the world (Chapman, 1975)
Distribution of salt affected
lands in Iran (15 percent)
Saline soils and salt marsh exist in over 100 countries
Salt affected soils cover about 10% of total lands
Importance of salinity

4. Plant response to salinity
Adverse effects Adverse effects
Adaptation Adaptation
Water deficit
Cell expansion
CO2 fixation
Enhanced
synthesis of
organic solutes
Decrease in
surface area
Salt compartmentation
Synthesis of compatible
solutes
K+/Na+ replacement
Succulence
Salt excretion
Leaf drop
Ion toxicity
(Ion imbalance)
Cl- toxicity
Na+ toxicity
K+ deficiency
Ca+ deficiency
Excluder Includer
Avoidance of
internal water
Depletion of
natural vegetation
Reduction of crop
productivity

5. Silicon is a beneficial
element in plants
 Silicon is considered as an essential elements in
diatoms, Equisetaceae and Gramineae.
 Silicon deprived plants are weaker than silicon
replete plants, abnormal in growth , development,
viability and reproduction.
Analyses of many plants led to rough division of
plants into three groups based on silicon content:
 Wetland Gramineae have the highest value, 10-
15% silicon on a dry weight basis
 Dry land grasses, intermediate, about 1-3%
 Dicots, less than 0.1 %

6. (E. Epstein 1999)
Poales
Commelinales
Silicon in
plants

7. Roles of silicon in plants
 Silicon deposits in the forms of silica , SiO2.
nH2O, in the cell walls.
 Reduction of water loss by lower
transpiration.
 Protection of plants against fungal and
insect attacks.
 Resistance to herbivores rangeing from
phytophagous insects to mammals.
 Alleviation of certain metal toxicities and
salinity stress

8.  Motoh et al., (1986) reported mitigation of salinity
induced damage in rice plants.
 Ahmad et al., (1992) reported that salt tolerance of
wheat markedly increased by the addition of small
amount of soluble silicon.
 Bradbury and Ahmad (1990) reported similar results
in mesquite (Prosopis juliflora)
 Also, Liang et al., (1996) Liang (1999) reported silicon
could enhance salt tolerance of barley cultivars.
 (Al-aghabary et al., (2004) reported increase of
chlorophyll content, and cntioxidative enzyme
activities in tomato plants under salt stress by silicon
supply
Several investigators reported alleviation
of salt stress in plants by silicon nutrition

9. Objective
The main objective of this study was to
investigate the effects of silicon nutrition on
the growth of
Puccinellia distans (monocotyledon) and
Brassica napus (Dicotyledon)
under salinity and
evaluation of the possible mechanisms by
which silicon nutrition alleviates salt stress.

10. Material
and
methods

11. Plant material
Puccinellia distans (jacq.) parl from Poaceae
Brassica napus L. (canola or oilseed rape) from
Brassicaceae
Poccinellia distans is a
perennial and salt tolerant
species .It is a forage plant in
saline and alkaline sites
Brassica napus is
dicotyledonous crop, its oil is
now the third largest source
of edible oil

12. Completely randomized deign as a Factorial
Factor 1: Salinity as NaCl
Factor2: Silicon as Na2SiO3
Max temperature: 30 degree
Min temperature: 21 degree
Relative humidity: 50%-70%
Plants were grown in greenhouse, in sand
culture or hydroponics with modified Hoagland
solution.

13. Under treatments
Identified parameters in plants
Before treatments
Fresh and dry weight
Na+, K+, Ca2+ and Si
concentration
Puccinellia distans
Polyphenol xidase (APx)
Cell wall peroxidase (G-OD)
and Catalase
Chlorophyll and
Soluble protein
Malondialdehyde (MDA)
as a lipid peroxidation
index

14. Na+ and K+ concentration
was measured by Flame
photometer
Ca2+ concentration was
measured by atomic
absorption spectrophotometer

15. Si in plant tissue was determined by the autoclave–
induced digestion method (Ellio et al., 1991).
 Autoclave –induced digestion
 Plant tissue digested with H2O2 and NaOH in
autoclave
 Si determination by colorimetric techniques
 Si was determined by recording absorbance at
820nm

16. Proteins, lipid peroxidation and
chlorophyll measurements
 Soluble protein was measured
spectrophotometrically at 595 nm by the
Bradford (1976)
 Chlorophyll content was measured using the
method of Arnon (1949).
 The extent of tissue lipid peroxidation was
determined as described by Heath and
Packer (1968) and expressed as the amount
of malondialdehyde (MDA) equivalents
produced.

17. Antioxidants enzyme assay
 All enzymes were extracted as described by Kar and
Mishra, (1976).
 Catalase (CAT) was estimated by decrease in the
absorbance at 240 nm due to H2O2 destruction for 2 min
 Peroxidase activity was estimated by tetraguaiacol
formation from guaiacol per min (Kar and Mishra, 1976;
Chen et al., 2000)
 Polyphenol oxidase activity was determined by
monitoreing changes in the absorbance of the solution at
420 nm as the amount of purpurogallin formed from
pyrogallol assuming (Resende et al., 2002).

18. and

19. Effects of salinity and silicon nutrition on growth of
Puccinellia distans plants following 80 days treatments
Cont NaCl 100 mM NaCl 200 mM NaCl
Cont Si
0.5 mM Si
1 mM Si Cont Si Cont Si
0.5 mM Si 0.5 mM Si
1 mM Si 1 mM Si

20. Effects of salinity and silicon nutrition on dry
mass Puccinellia distans
0
1
2
3
4
0 100 200
NaCl concentration (mM)
Shoot
dry
mass
(g)
cont Si 0.5 Si 1
ab
ab
a
ab ab
ab
b
ab ab
0.0
0.2
0.4
0.6
0.8
1.0
0 100 200
NaCl concentration (mM)
Root
dry
mass
(g)
cont Si 0.5 Si 1
ab ab
a
b
ab
a
b
ab
ab
Silicon nutrition resulted in a
higher dry mass in plants
under all salt treatments.

21. Effects of salinity and silicon nutrition on
dry mass canola
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0Si 2Si 0Si 2Si
Root
dry
mass
(g)
a
a
b
b
100 mM NaCl
0 mM NaCl
0
1
2
3
4
5
6
7
0Si 2Si 0Si 2Si
Shoot
dry
mass
(g)
a
ab
b
c
0mM NaCl 100 mM NaCl
The results indicate that
silicon can alleviate salinity
effects in plants.
Similarly, silicon nutrition lead to
higher dry mass in canola under
salinity.

22. Effects of salinity and silicon nutrition on
concentration of Na+ in Puccinellia distans
0
5
10
15
20
25
30
0 100 200
NaCl concentration (mM)
Na
+
Shoot
(mg
g
-1
dw)
cont Si 0.5 Si 1
c
c c
b
a
ab
a
b
ab
0
5
10
15
20
25
30
35
40
0 100 200
NaCl concentration (mM)
Na
+
root
(mg
-1
dw)
cont Si 0.5 Si 1
c
c c
a
a
b
a
a
ab
Silicon nutrition decreased
Na+ concentration in this
plant

23. Effects of salinity and silicon nutrition on
concentration of Na+ in canola
0
5
10
15
20
25
30
35
40
0Si 2Si 0Si 2Si
Na
+
shoot
(mg
g
-1
dw)
a
b
c
c
100mM NaCl
0mM NaCl
0
5
10
15
20
0Si 2Si 0Si 2Si
Na
+
Root
(mg
g
-1
dw)
a
a
b b
100mM NaCl
0mM NaCl
Shoot
Root
Similarly, silicon nutrition
decreased Na+concentration
in shoots of canola

24. 0
5
10
15
20
25
30
35
0 100 200
NaCl concentration (mM)
K
+
shoot
(mg
g
-1
dw)
cont Si 0.5 Si 1
b
a
a
b
b
b b b b
0
2
4
6
8
10
12
0 50 100
NaCl concentration (mM)
K
+
root
(mg
g
-1
dw)
cont Si 0.5 Si 1
a
a
a
a a
a a
a
a
Effects of salinity and silicon on concentration of
K+ in Puccinellia distans
Silicon treatments did not
change K+ concentration

25. Effects of salinity and silicon on
concentration of K+ in Canola
0
20
40
60
80
0Si 2Si 0Si 2Si
K
+
(mg
g
-1
dw)
a a
b b
0 mMNaCl 150 mMNaCl
0
10
20
30
40
50
60
70
0Si 2Si 0Si 2Si
K
+
(mg
g
-1
dw)
a
a
b b
0 mMNaCl 150 mMNaCl
Shoot
Root
Silicon treatments did not
change K+ concentration

26. Effects of salinity and silicon on concentration of
Ca2+ in Puccinellia distans
0
5
10
15
20
25
30
35
0 100 200
NaCl concentration (mM)
Ca
2+
root
(mg
g
-1
dw)
cont Si 0.5 Si 1
a
b a
b
a
bc
c
b
a
b
c
c
0
5
10
15
20
25
30
35
0 100 200
NaCl concentration (mM)
Ca
2+
shoot
(mg
g
-1
dw)
cont Si 0.5 Si 1
a
b
bc
ab
bc
c
a
bc
d
b
•Silicon nutrition induced more
severe decrease in Ca2+
concentration under high salt
treatments

27. Effects of salinity and silicon on concentration of
Si in Puccinellia distans
0
1
2
3
4
5
6
0 50 100
NaCl concentration (mM)
Si
shoot
(mg
g
-1
dw)
cont
Si 0.5
Si 1
bc
d
a
d
b
a
d d
c
0
1
2
3
4
5
0 50 100
NaCl concentration (mM)
Si
root
(mg
g-1dw)
cont Si 0.5 Si 1
c
a
a
c
a
b
c c
bc
•Silicon nutrition increased
Si concentration in plant

28. 0.0
0.1
0.1
0.2
0.2
0.3
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
mol/min.gFw
a
ab
bc
c
0 mM NaCl 150 mM NaCl
Root catalase
0.0
0.2
0.4
0.6
0.8
1.0
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
mol/min.gFw
a
ab
ab
b
alpha=0.1
0 mM NaCl 150 mM NaCl
Shoot catalase
Effects of salinity and silicon on concentration
of catalase activity in Canola
Silicon nutrition could
recover catalase under
salinity (scavenge more
hydrogen peroxide)
Enhanced activity of CAT
may protect the plant
tissues from oxidative
damage induced by salt

29. 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
mol/mingfw
a
a
b
b
0 mM NaCl 150 mM NaCl
Shoot celll wall peroxidase
0
8
16
24
32
40
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
mol/mingfw
a
b
c
c
0 mM NaCl 150 mM NaCl
Root celll wall peroxidase
Effects of salinity and silicon on concentration of
cell wall peroxidase activity in Canola
Both salinity and silicon
nutrition solely decreased
cell wall peroxidase activity
but together recovered its
activity

30. 0.0
0.2
0.4
0.6
0.8
1.0
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
mol/mingfw
a
a
a a
0 mM NaCl 150 mM NaCl
Shoot
5.0
5.5
6.0
6.5
7.0
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
mol/mingfw
a
a
a
a
0 mM NaCl 150 mM NaCl
Root
Effects of salinity and silicon on concentration of
polyphenol oxidase activity in Canola

31. 0
20
40
60
80
100
0 mM Si 2 mM Si 0 mM Si 2 mM Si
nmol
g
-1
fw
a
ab
bc
c
0 mM NaCl 150 mM NaCl
Shoot
Effects of salinity and silicon on concentration of
malondialdehyde as an indicator of lipid peroxidation
in Canola
Silicon nutrition could
decreased lipid peroxidation
under salinity that indicated
higher membran stability
Salinity increased lipid
peroxidation in plants
0
8
16
24
32
40
0 mM Si 2 mM Si 0 mM Si 2 mM Si
nmol
g
-1
fw a
ab
bc
c
0 mM NaCl 150 mM NaCl
Root

32. 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0 mM Si 2 mM Si 0 mM Si 2 mM Si
Chl
b
(mg/gFw)
a
a
ab
b
0 mM NaCl 150 mM
NaCl
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 mM Si 2 mM Si 0 mM Si 2 mM Si
Chl
a
(mg/gFwg)
a
a
a
b
0 mM NaCl 150 mM NaCl
Effects of salinity and silicon on concentration
of chlorophyll in Canola
Salinity decreased
chlorophyll content in
plants
Supplemental silicon could
ameliorate these adverse
effect

33. 0.0
0.4
0.8
1.2
1.6
2.0
0 mM Si 2 mM Si 0 mM Si 2 mM Si
Total
chl
(mg/
gFw)
a
a
a
b
0 mM NaCl 150 mM NaCl
Effects of salinity and silicon on concentration
of chlorophyll in Canola
Silicon nutrition could increased
chlorophyll content under salinity

34. 0
800
1600
2400
3200
4000
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
g
g
-1
fw
a a
a
a
0 mM NaCl 150 mM NaCl
Shoot Soluble protoin
Effects of salinity and silicon on concentration
of soluble protein in Canola
0
900
1800
2700
3600
4500
5400
0 mM Si 2 mM Si 0 mM Si 2 mM Si
m
g
g
-1
fw
a
ab
ab b
0 mM NaCl 150 mM NaCl
Root Soluble protoin

35. Higher Si
concentration
Lower oxidative
stress
Lower toxicity
Lower Na+
concentration
Silicon nutrition
under Salinity
Higher growth
Lower Ca2+
concentration
Cell wall and
Membrane
Lower
transpiration
?
The proposed scheme for the alleviation of salinity
effects by silicon

36. ‫كمتر‬‫اكسيداتيو‬ ‫تنش‬
‫بيشتر‬‫رشد‬
‫د‬‫ويژه‬‫به‬ ‫گياه‬‫در‬ ‫سيليسيم‬‫انباشتگي‬
‫ر‬
‫سلول‬‫ديواره‬
‫كمتر‬‫سميت‬
‫سديم‬ ‫يون‬ ‫انباشتگي‬ ‫و‬ ‫جذب‬‫كاهش‬
‫سيليكون‬‫تغذيه‬
‫شوري‬ ‫تحت‬
‫و‬ ‫جذب‬‫كاهش‬
‫كلسيم‬‫يون‬ ‫انباشتگي‬
‫تعرق‬ ‫كاهش‬
‫وندي‬‫ا‬ ‫غير‬‫مسير‬‫از‬
‫انتقال‬‫ي‬‫تواناي‬‫ايش‬‫ز‬‫اف‬
‫ي‬‫هواي‬‫بخش‬‫به‬‫ب‬‫ا‬
‫استوانه‬‫قطر‬‫نسبت‬‫ايش‬‫ز‬‫اف‬
‫ساقه‬‫قطر‬‫به‬ ‫وندي‬‫ا‬

37. Thank you very much
for your attention