African Journal of Biotechnology Vol. 10(68), pp. 15278-15286, 2 November, 2011
Available online at http://www.academicjournals.org/AJB
ISSN 1684–5315 © 2011 Academic Journals
Full Length Research Paper
Effect of salinity and seed priming on growth and
biochemical parameters of different barely genotypes
Shazma Anwar1, Mohammad Shafi1, Jehan Bakht2*, Mohammad Tariq Jan1 and Yousaf Hayat3
1Agronomy Department, KPK Agricultural University Peshawar, Pakistan.
2Institute of Biotechnology and Genetic Engineering, KPK Agricultural University Peshawar, Pakistan.
3Department of Statistics, KPK Agricultural University Peshawar, Pakistan.
Accepted 6 October, 2011
An experiment was conducted to investigate the interactive effect of salinity and seed priming on barely
genotypes at the Institute of Biotechnology and Genetic Engineering (IBGE), Khyber Pakhtun Khwa
Agricultural University Peshawar Pakistan. The experiment was carried out in completely randomized
design (CRD) with three replications consisting of twelve barely genotypes (Haider-93, Soorab-96,
Arabic Asward, NRB-37, Frontier-87, Jau-83, Balochistan-Local, NRB-31, KPK-Local, Sanober-96,
Awarn-2002 and AZ-2006) at two seed conditions (seed priming with 30 mM NaCl or no seed priming)
under four salinity levels (0, 50, 100 and 150 mM). The results revealed that seed priming and salinity
had significantly (p≤0.05) affected all the parameters under study. However, the effect of seed priming
was non significant (p>0.05) on shoot chlorophyll a content (mg g-1 fresh weight) and root sugar content
(mg g-1dry weight). Salinity stress had adversely affected growth and biochemical parameters of barley
genotypes, however, seed priming with NaCl had diminished the negative impact of salt stress.
Maximum shoot dry weight plant-1 (1.81 g), root dry weight plant-1 (0.42 g), shoot K+ content (1.41 mg g-1
dry weight), root sugar content (7.55 mg g-1dry weight) were recorded in Balochistan-Local. Similarly,
Haider-93 produced highest root K+ content (0.67 mg g-1 dry weight), shoot sugar content (16.36 mg g-
1dry weight), shoot chlorophyll a content (3.44 mg g-1 fresh weight) and shoot chlorophyll b content
(1.78 mg g-1 fresh weight). Maximum shoot Na+ content (1.20 mg g-1) and root Na+ content (1.47 mg g-1)
was recorded in Frontier-87. Seed priming had significantly (P<0.05) enhanced all the aforementioned
parameters. The positive effect of seed priming was more profound in Balochistan-Local followed by
Haider-93 as compared to other genotypes.
Key words: Barely, salinity, seed priming, Na+, K+, chlorophyll a and b.
Soil salinity is one of the major environmental stresses
limiting crop production in many countries of the world
(Munns, 2005; Rengasamy, 2006; Ashraf et al., 2008;
Katerji et al., 2009). Excess salts severely damage plant
growth and the land beyond economic repair (Flower,
2004; Munns et al., 2006). Out of 271 million ha of
irrigated lands about 40 million ha is affected by salinity
worldwide (Chaudhary and Ehrenreich, 2000). Gradually,
vast agricultural area is becoming uncultivable due to
salinity than the new or reclaimed lands are brought
under agriculture (Vose, 1983; Barret-Lennard, 2000).
*Corresponding author. E-mail: firstname.lastname@example.org.
Salinity is a problem particularly in low lying areas where
evaporation concentrate the salts received from more
elevated locations in surface water and rainfall is
insufficient to cause leaching of these salts beyond the
root-zone, resulting in their accumulation in soil profile.
One possible strategy to cope with salinity is the use of
salt tolerant crop varieties with improved cultural
practices to enhance production from saline areas (Mass
and Hoffman, 1977; Ashraf and Leary, 1996). Salt
tolerance of barley is the highest (Mass and Hoffman,
1977; Mano and Takeda, 1998; Forster et al., 2000).
Barley is an important crop used as feed for animals, malt
and human food. It has better ability to grow and produce
in marginal areas characterized by drought, low
temperature and salinity (Van Oosterom et al., 1993;
Maas and Hoffman, 1997; Baum et al., 2004) as
compared with other cereals. Higher salt concentrations
in upper layers of the soil reduces seed emergence and
is a major constraint for higher crop production (Harris et
al., 1999; Bakht et al., 2010). One of the most important
progresses in this connection is the halopriming that is a
pre-sowing soaking of seeds in salt solutions which
improves germination and seedling emergence under
adverse environmental conditions (Cantliffe, 1997). It has
been reported that salt tolerance in wheat has increased
by treatment of seeds with NaCl solutions before sowing
(Ashraf et al., 1999).
Halopriming alters plant physiological and biochemical
responses to salt stress (Cayuela et al., 1996; Bakht et
al., 2011). To encourage the use of salt tolerant crops,
the present study was designed to examine the effect of
seed priming and salinity stress on growth and salt
tolerance of difference barely genotypes.
MATERIALS AND METHODS
An experiment was conducted to study the interactive effect of
salinity and seed priming on barely genotypes at the greenhouse of
the Institute of Biotechnology and Genetic Engineering (IBGE),
Khyber Pakhtunkhwa Agricultural University, Peshawar during
winter 2007 to 2008. The experiment was carried out in completely
randomized design (CRD) with three replications, twelve barely
genotypes (Haider-93, Soorab-96, Arabic Asward, NRB-37,
Frontier-87, Jau-83, Balochistan-Local, NRB-31, KPK-Local,
Sanober-96, Awarn-2002 and AZ-2006) at two seed conditions
(seed priming with 30 mM NaCl and no seed priming) under four
salinity levels (0, 50, 100 and 150 mM). In case of priming, seeds of
barley genotypes were first primed with saline water (30 mM) for 12
h at 25°C. Sand was washed 3 times with water and sterilized
before using in pots. Twenty primed or unprimed seeds as per
treatment were grown in each pot containing sand salinized with the
desired salinity (NaCl) levels. After complete emergence, ten plants
per pot were maintained through thinning. Hoagland solution
(Hoagland and Arnon, 1950) salinized with the required NaCl levels
was applied to the pots periodically. The position of the replication
in the greenhouse was changed periodically so that all the
experimental units may be exposed uniformly to micro variation of
the green house. Plants were harvested 50 days after sowing. Data
were recorded on shoot dry weight (g plant-1), root dry weight (g
plant-1), shoot chlorophyll a content (mg g-1fresh weight), shoot
chlorophyll b content (mg g-1fresh weight), shoot sugar content (mg
g-1dry weight), root sugar content (mg g-1dry weight), shoot Na+
content (mg g-1 dry weight), root Na+ (mg g-1 dry weight), shoot K+
content (mg g-1dry weight) and root K+ content (mg g-1dry weight).
The shoots and root of three randomly selected plants in each
treatment were dried in an oven at 80°C for 48 h and at complete
drying weighed and averaged to record shoot dry weight. The dried
and grinded shoot and root samples in each treatment were used
for estimation of Na+ and K+ content according to the methods of US
Salinity Staff (1954). First digestion was carried out according to the
procedure of Benton et al. (1991).
For digestion, 10 ml of concentrated HNO3 (Nitric acid) was
added to 0.5 g sample in a volumetric flask and was kept overnight.
4 ml of concentrated HClO4 (Perchloric acid) was added to the
solution and heated at 350° C until the solution became colorless
and produced colorless white fumes. On cooling, filtration was done
and volume was adjusted to 100 ml by adding distilled water. The
flame photometer (Jenway PFP-7) was calibrated against standard
Anwar et al. 15279
solutions, Na+ and K+ content was determined in the samples. The
sugar content was determined according to the method of Fales
(1951). Shoot and root samples in each treatment were taken
separately. Dried tissue powder (50 mg) from each sample was
taken and heated in water bath at 100°C for 15 min after adding
HCl. The solution was cooled in ice bath and transferred to a 100
ml measuring flask after filtration and make up the volume by
adding distilled water. The anthrone solution was prepared by
dissolving 0.4 g of anthrone in 200 ml of sulphuric acid. The acid
solution was then slowly added to flask containing 60 ml of distilled
water and 15 ml of 95% ethyl alcohol. The solution was cooled and
mixed during the addition. About 4.5 ml of anthrone reagent was
added to 0.5 ml of the prepared solution in a clean dried test tube,
heated at 97°C for 10 min cooled in ice bath and read in UV
spectrophotometer at 625 nm. Chlorophyll a and b was estimated
according to the methods of Lichtenthaler (1987). Briefly, 5 to 10
fresh leaves were collected from each treatment and then were cut
into small pieces (0.5 cm) with a pair of scissors. A sample of 0.30 g
was transferred to cleaned dried glass colored tubes immediately
after weighing. 80% acetone was added to the sample and then
transferred the samples to refrigerator for extraction overnight. The
samples were protected from light by using colored bottle or tubes
wrapping them in aluminum foil or black polythene sheet. The lid
must be properly placed on tubes and sealed by para film to avoid
The extract of each sample was centrifuged at 14000 × g for 5
min. The absorbance of the supernatant was measured at 646 and
663 nm by using spectrophotometer.
Shoot dry weight (g plant-1)
Statistical analysis of the data revealed significant
(P<0.05) effect of various salinity levels, seed priming
and genotypes on shoot dry weight (Table 1). All possible
interactions except seed priming x salinity x genotypes
were also significant (P<0.05). Maximum shoot dry
weight was produced by Balochistan-Local (1.81 g plant-
1). Haider-93 and KPK-Local ranked 2nd and 3rd with
shoot dry weight of 1.77 and 1.74 g plant-1 respectively.
Minimum shoot dry weight was recorded in Frontier-87
(1.35 g plant-1). Primed seeds proved superior and
enhanced shoot dry weight by 9.68% in primed seed
(1.66 g plant-1) than un-primed seed (1.51 g plant-1).
Shoot dry weight was reduced by 20.32, 32.98 and
49.01% at salinity level of 50, 100 and 150 mM
respectively when compared with the control.
Root dry weight (g plant-1)
Table 1 shows significant (P<0.05) effect of various
salinity levels, genotypes and seed priming on root dry
weight. All possible interactions except seed priming x
salinity x genotypes were also significant (P<0.05).
Highest root dry weight was recorded in Balochistan-
Local (0.42 g plant-1). Haider-93 and KPK-Local ranked
2nd and 3rd with root dry weight of 0.39 and 0.38 (g
plant-1) respectively. Lowest root dry weight was
produced by Frontier-87 (0.23 g plant-1). The treatment of
15280 Afr. J. Biotechnol.
Table 1. Plant weight and photosynthetic pigments of barely genotypes as affected by salinity and seed priming.
Shoot dry weight
Root dry weight
a content (mg g-1 fresh
b content (mg g-1 fresh
Frontier-87 1.35k 0.23l 2.20j 1.03e
Jau-83 1.39j 0.25k 2.23ij 1.05e
Balochistan-Local 1.81a 0.42a 3.33b 1.74a
NRB-31 1.56f 0.31g 2.70f 1.43c
KPK-Local 1.74b 0.38c 3.23c 1.69a
Un-primed 1.51b 0.30b 2.76 1.35b
Primed 1.66a 0.33a 2.80 1.47a
LSD(0.05) for G 0.027 0.008 0.086 0.035
LSD(0.05) for S 0.016 0.004 0.050 0.020
LSD(0.05) for P 0.011 0.003 0.035 0.014
G x P S s ns s
P x S S s ns s
G x S S s s s
P x S x G Ns ns ns ns
s and ns represent significant and non significant at P<0.05 level respectively. G = genotypes, P = seed priming, S = salinity. Means of same category
followed by same letters are not significantly different at P≤0.05 using LSD test.
seed priming enhanced root dry weight by 8.88% in
primed seed (0.33 g plant-1) than un-primed seed (0.30 g
plant-1). Application of each additional increment of
salinity had gradually reduced root dry weight. Salinity
levels of 50, 100 and 150 mM had significantly decreased
root dry weight by 26.65, 37.66 and 57.23% respectively
when compared with the control.
Chlorophyll a content (mg g-1fresh weight)
Different salinity levels and genotype x salinity interaction
had significantly (P<0.05) affected chlorophyll a content
of different barely genotypes (Table 1). The main effect of
seed priming and all remaining possible interactions were
non-significant (P>0.05). Maximum chlorophyll a
concentration was measured in genotype Haider-93 (3.44
mg g-1) followed by Balochistan-Local and KPK-Local
with chlorophyll a content of 3.33 mg g-1 fresh weight and
3.23 mg g-1
fresh weight respectively. Minimum
chlorophyll a content was observed in genotype Frontier-
87 (2.20 mg g-1). Non-significantly higher chlorophyll a
content was maintained in primed seed when compared
with un-primed seed (2.80 vs. 2.76 mg g-1). Application of
salinity levels had gradually reduced chlorophyll a
content. Chlorophyll a content was reduced by 41.78%
with the application of 150 mM NaCl (2.04 vs. 3.51 mg g-
1) and 26.42% at 100 mM ((2.58 vs. 3.51 mg g-1) as
compared with the control.
Chlorophyll b content (mg g-1 fresh weight)
It is evident from mean values that application of
increasing salinity stress and seed priming had
significantly (P<0.05) affected chlorophyll b content of
barley genotypes (Table 1). Interaction of genotypes x
seed priming, genotypes x salinity and seed priming x
salinity was significant (P<0.05). Highest chlorophyll b
concentration was maintained by genotype Haider-93
(1.78 mg g-1) which was statistically at par with
Balochistan-Local (1.74 mg g-1) and KPK-Local (1.69 mg
g-1). Lowest chlorophyll b concentration was recorded in
genotype Frontier-87 (1.03 mg g-1) which was statistically
equal to Jau-83 (1.05 mg g-1) and Sanober-96 (1.07 mg
g-1). The data further revealed 8.79% high chlorophyll b
content from the treatment of primed seed when
compared with un-primed seed (1.47 vs. 1.35 mg g-1
fresh weight). Chlorophyll b content was decreased by
48.21% at 150 mM salinity as compared with the control
(1.88 vs. 0.98 mg g-1) and 31.22% at 100 mM (1.88 vs.
1.30 mg g-1).
Shoot sugar content (mg g-1dry weight)
Analysis of the data explicated that different salinity levels
and seed priming had significantly (P<0.05) affected
endogenous shoot sugar content of barely genotypes
(Table 2). All possible interactions were non significant
except seed priming x genotypes x salinity. Mean values
of the data showed maximum shoot sugar concentration
in genotype Haider-93 (16.36 mg g-1). Balochistan-Local
and KPK-Local ranked 2nd and 3rd with shoot sugar
concentration of 15.97 and 15.44 mg g-1 dry weight
respectively. Minimum shoot sugar concentration was
recorded in genotype Frontier-87 (11.57 mg g-1) and Jau-
83 (11.64 mg g-1). Shoot sugar content was 12.10% more
accumulated in primed seed when compared with un-
primed seed (14.59 vs. 13.02 mg g-1). Application of
increasing salinity levels had persistently enhanced shoot
sugar concentration. Shoot sugar content was 127.95%
increased in plants treated with 150 mM NaCl (19.52 vs.
Anwar et al. 15281
8.56 mg g-1) followed by 74.19% at 100 mM salt stress
(14.92 vs. 8.56 mg g-1) when compared with control.
Root sugar content (mg g-1dry weight)
Table 2 reveals significant (P<0.05) effect of various
salinity levels, genotypes and genotype x salinity
interaction on endogenous root sugar content. The main
effect of seed priming and all remaining possible
interactions were non-significant (P>0.05). Balochistan-
Local produced highest (7.55 mg g-1) root sugar content
which was statistically at par with Haider-93 (7.41 mg g-1)
while minimum was maintained from genotype Frontier-
87 (5.50 mg g-1) which was statistically at par with Jau-83
(5.63 mg g-1). Seed priming non-significantly increased
(6.51 mg g-1) root sugar content when compared with un-
primed seed (6.44 mg g-1). In case of salinity, sugar
content enhanced with increasing salt stress. Root sugar
content was 64.97% higher in plants treated with 150 mM
NaCl when compared with control (8.00 vs. 4.85 mg g-1)
followed by 38.13% at 100 mM salt stress (6.70 vs. 4.85
Shoot Na+ content (mg g-1dry weight)
Significant (p<0.05) differences in shoot Na+ content was
observed due to salinity levels, genotypes and seed
priming on shoot Na+ content (Table 2). Interaction of
genotypes x seed priming, genotypes x salinity and seed
priming x salinity were also significant (P<0.05).
However, interaction of seed priming x salinity x
genotypes was non significant (P>0.05). Highest shoot
Na+ content was recorded in Frontier-87 (1.20 mg g-1)
and was statistically at par with Jau-83 (1.19 mg g-1 dry
weight). This was followed by Sanoobar-96 and Awarn-
2202 with shoot Na+ content of 1.17 and 1.14 mg g-1 dry
weight respectively. Lowest shoot Na+ content was
observed in Balochistan-local (0.97 mg g-1). The
treatment of seed priming reduced shoot Na+ content by
14.23% (1.01 mg g-1) than un-primed seed (1.17 mg g-1).
Significant (P<0.05) increase in shoot Na+ was noted with
the application of each additional increment of salinity.
Shoot Na+ content enhanced by 503.68, 614.91 and
795.85% with the application of 50, 100 and 150 mM
salinity levels respectively when compared with the
Root Na+ content (mg g-1 dry weight)
Significant (P<0.05) effect of salinity, seed priming and
genotypes was noted on root Na+ (mg g-1 dry weight). All
possible interactions except salinity x seed priming x
seed priming were significant (P<0.05). Highest root Na+
contents (1.47 mg g-1) were recorded from Frontier-87
15282 Afr. J. Biotechnol.
Table 2. Biochemical parameters of barely genotypes as affected by salinity and seed priming.
Shoot sugar content
(mg g-1 dry weight)
Root sugar content
(mg g-1 dry weight)
Shoot Na+ content
(mg g-1 dry weight)
Root Na+ content (mg
g-1 dry weight)
Shoot K+ content
(mg g-1 dry weight)
Root K+ content (mg
g-1 dry weight)
LSD(0.05) for G
LSD(0.05) for S
LSD(0.05) for P
G x P
P x S
G x S
P x S x G
s and ns represent significant and non significant at 95% probability level respectively. G = genotypes, P = seed priming, S = salinity. Means of same category followed by same letters are not significantly
different at P≤0.05 using LSD test.
followed by Jau-83 and AZ-2006 with root Na+ content of
1.43 and 1.41 mg g-1 dry weight respectively. Lowest root
Na+ content was recorded in Balochistan-Local (1.09 mg
g-1). Primed seed had reduced root Na+ content by
11.52% (1.23 mg g-1) than un-primed seeds (1.39 mg g-1
dry weight). Statistical analysis of the data also revealed
steady raise in root Na+ content with the application of
each additional increment of salinity. Maximum root Na+
content (2.10 mg g-1 dry weight) was recorded from 150
mM NaCl when compared with other treatments (Table
Shoot K+ content (mg g-1dry weight)
Mean values of the data described significant (P<0.05)
effect of salinity levels and seed priming on shoot K+
content of barely genotypes (Table 2). Interaction of
genotypes x seed priming, genotypes x salinity and seed
priming x salinity was significant (P<0.05). Highest shoot
K+ content was produced from Balochistan-local (1.41 mg
g-1) followed by Haider-93 with shoot K+ content of 1.37
mg g-1. Lowest shoot K+ content (1.02 mg g-1) was
observed in Frontier-87. Shoot K+ content was 8.57%
more in the treatment of primed seeds (1.26 mg g-1) than
un-primed seeds (1.16 mg g-1). Shoot K+ content was
decreased by 20.07, 31.97 and 49.05% with the
application of salinity levels of 50, 100 and 150 mM
respectively when compared with the control.
Root K+ content (mg g-1 dry weight)
Analysis of the data indicated that root K+ content of
barely genotypes was significantly (P<0.05) affected by
different salinity levels and seed priming (Table 2). All
possible interactions except seed priming x salinity x
genotypes were significant (P≤0.05). Maximum root K+
content of 0.67 mg g-1 dry weight was recorded from the
treatment of Haider-93 followed by Balochistan-Local and
KPK-Local with root K+ content of 0.65 and 0.64 mg g-1
respectively as compared with minimum root K+ content
from Frontier-87 (0.43 mg g-1). Root K+ content was
enhanced by 6.15% in primed seed (0.57 mg g-1) than
un-primed seeds (0.53 mg g-1). Mean values of the data
indicated gradual reduction in root K+ content with
application of enhancing salinity levels. Root K+ content
(mg g-1) increased by 15.04, 23.96 and 34.67% with the
application of salinity level of 50, 100 and 150 mM
respectively when compared with the control.
Seed priming and salinity levels had significantly affected
shoot dry weight (g plant-1) of barely genotypes.
Balochistan-Local performed better by maintaining
Anwar et al. 15283
maximum shoot dry weight while Frontier-87 produced
least quantity of dry weight. Shoot weight decreased with
the rise of stress level compared with the control plants in
barely (El-Tayeb, 2005; Niazi et al., 1992), sugar beet
plants (Ghoulam et al., 2001) and wheat (Shafi et al.,
2010). At high salt levels, physical damage to roots and
toxic effect of sodium decreased the ability of roots to
absorb water and nutrient and thus created marked
reduction in photosynthesis, enzymatic process and
protein synthesis (Tester and Davenport, 2003), this all
results in stunted growth, less leaf area development and
reduced shoot fresh and dry weight (Shafi et al., 2009). It
is evident from results, that primed seeds in comparison
with dry seeds resulted in more crop growth rate. The use
of salt as an osmoticum can lead to greater plant weight
(Cantliffe, 1997; Brocklehurst et al., 1987; Harris et al.,
2001; Basra et al., 2003). Barely genotypes, seed priming
and salinity produced marked effect on root dry weight.
This effect was highest in Frontier-87 and least in
Balochistan-Local and Haider-93. Under salinity stresses,
ion toxicity, water deficiency and lower production and
availability of photosynthates to roots causes marked
decrease in root volume, diameter and density in wheat
(Shafi et al., 2010). Salts in the rooting media create
water deficiency by generating low external water
potential. It also reduces xylem transport of water and
solutes (Marschner, 1981). Cell wall modifies the
metabolic activities of the cell due to salt accumulation
and limits the cell wall elasticity and becomes rigid as a
consequence, the turgor pressure efficiency in cell
enlargement decreases. These processes may also
reduce growth and dry matter of roots and shoot. Our
results are in agreement with those reported by Rottella
and Martinez (1997), Ashraf et al. (2005) and Munns et
al. (2006). Ashraf et al. (1999) also reported that higher
EC values were observed in seeds treated with NaCl
than in the non-primed seeds. Photosynthetic pigments
(chlorophylls a and b) of all barely genotypes were
significantly affected by salinity stress and seed priming.
Magnitude of loss in photosynthetic pigments was highest
in sensitive genotypes (Frontier-87 and Jau-83) than
tolerant genotypes (Haider-93 and Balochistan-Local).
The photosynthetic pigments (chlorophylls a and b) as a
chief component of the photosynthetic system governing
the dry matter participation, decreased significantly in
NaCl treated barely plants in comparison to controls (El-
Growth performance of plants growing under saline
conditions depends on their ability to minimize the
accumulation of toxic Na+ and to have lower Na+: K+ in
their leaves (Schatchman and Munns, 1992: Rashid et
al., 1999; Saqib et al., 1999). This will lead to higher
photosynthetic rate and stomatal conductance and hence
relatively higher growth resulted. Reduction in chlorophyll
level might be due to enhancement of chlorophyllase
activity or due to reduction in ‘de novo’ chlorophyll
synthesis (Sudhakar et al., 1991). Seeds preconditioning
15284 Afr. J. Biotechnol.
has lessen damage to photosynthetic pigments more in
tolerant than sensitive species (Hamid et al., 2008).
Perusal of the results revealed that salinity had a
significant effect on shoot and root sugar concentration
(mg g-1 dry weight) of barely genotypes. Sugar
accumulation was more in tolerant genotype of
Balochistan-Local and Haider-93 as compared with
sensitive genotypes of Frontier-87 and Jau-83. Sugar
accumulation under salinity stress is a common
phenomenon (Cheeseman, 1988; Khan et al., 1995;
Munns and James, 2003) and is responsible for osmotic
adjustment under salinity stress in grasses (Vacher et al.,
1994; Prado et al., 2000; Akhtar et al., 2004). During
stress, sugar protects the plant cells. The hydroxyl group
of sugars may substitute for water to maintain hydrophilic
interactions in membranes and proteins. Thus, sugar
prevents protein denaturation by interacting with protein
and membranes through hydrogen bonding (Sanchez et
al., 1995). Our results confirm that seed priming had
significant effect on shoot sugar content and to lesser
extent root sugar content. High salt tolerance of plants
from primed seeds is due to maintenance of higher
osmotic adjustment. Plants from primed seeds have more
sugars and organic acids in leaves and more Na+ and Cl-
in roots than plants from non-primed seeds (Cayuela et
al., 1996). Our findings reveal significant effect of salinity
levels and seed priming on shoot and root Na+ content
(mg g-1 dry weight) of different barely genotypes. Highest
Na+ was accumulated in the shoots and roots of sensitive
genotypes (Frontier-87 and Jau-83) while tolerant
genotypes (Balochistan-local) maintained the lowest Na+
content in their shoot and root. The Na+ content in shoots
increased markedly in all genotypes of barley with
increase in salinity stress (Willadino et al., 1994; Shadi et
al., 1999; Xia at al., 2000) and roots (El-Tayeb, 2005).
The ability of roots to exclude Na+ from uptake via
either restricting Na+ influx or enhanced Na+ extrusion
from the cytosol (Tyerman and Skerrett, 1999; Blumwald,
2000; Tester and Davenport, 2003) is considered a key
feature of salt tolerance. Under saline condition, Na+ and
Cl- concentration increased in the leaves of salt tolerant
species and is probably linked with the salinity tolerance
mechanism (Bajji et al., 1998; Chen et al., 1998; Heuer
and Nadler, 1998; Weimberg and Shannon, 1988; Yasin
and Zahid, 2000; Bakht et al., 2011). Sodium chloride
can exert its toxic effect on plants by interfering with
the uptake of other nutrient ions, especially K+ leading to
nutrient ion deficiency. Under saline condition in barely
cultivars, the ability to restrict entry of the potentially toxic
Na+ into the shoot is greater in the salt-tolerant than in
salt-susceptible cultivar. The ability to restrict entry of the
potentially toxic Na+ into the shoot, often termed as ion
exclusion is known to be the most useful trait for salt
tolerance in barley and wheat (Colmer et al., 2005).
Sodium ion in the xylem can be removed by the exclusion
system operating in the upper part of the root, stem,
petiole or leaf sheath (Munns, 2002; Tester and
Davenport, 2003). Metabolic toxicity of Na+ is largely
caused by competition with K+ for binding sites of protein
components essential for cellular processes where Na+
cannot substitute the role of K+. Our results depict that
with priming, Na+ concentration was reduced significantly.
Similar results were observed by (Afzal et al., 2006,
2008; Iqbal and Ashraf, 2007) who reported that salinity
tolerance is linked with reduced Na+ and enhanced K+ up
take and retention that in turn increased growth and yield.
The capacity of plants to counteract salinity stresses
depends on the status of their K+ nutrition (Maathuis and
Amtmann, 1999). Tolerant genotypes (Balochistan-local
and Haider-93) retained maximum K+ content in shoots
and roots as compared with sensitive genotype (Frontier-
87). Potassium plays an important role in regulating
osmotic pressure, activating
membrane potential and tropisms (Cherel, 2004).
Because of similarities in the physical and chemical
structures of Na+ and K+, elevated Na+ in the cytosol
causes destruction of K+ dependent metabolic processes.
Also, many K+ transport systems have some affinity for
Na+ transport (Blumwald, 2000; Véry and Sentenac,
2002; Shabala, 2003). Plant cells under salinity must
adjust their osmotic potential to prevent water loss. This
is achieved either by uptake of inorganic ions or by
synthesis of organic osmolytes (Serrano et al., 1999;
Shabala and Lew, 2002). Under mild saline conditions,
barley roots took up inorganic cations (specifically, K+)
instead of following the energy-expensive synthesis of
compatible solutes (Cerda et al., 1995; Huang and
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