Salt stress and leguminous crops: Present status and prospects - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 32

osmotic adjustment. Pea and faba bean plants inoculated
with the same salt-tolerant (GRA19) or salt-sensitive
(GRL19) Rhizobium leguminosarum strain and treated
with 100 mM l-1 NaCl showed higher levels of nodule
mass and reduced nitrogen fixation in response to
salinity (Cordovilla et al., 1999).
El-Hamdaoui et al. (2003) reported that salinity pro-
duced a reduction of B, Ca, K and Fe contents in the
shoots of pea plants. Nodulation, calculated as number
of nodules and nitrogen fixation (measured as ARA),
was almost completely repressed in pea plants. When
examined under the electron microscope the salt-
stressed nodules seemed to have a very changed
structure, without tissue differentiation and with errati-
cally shaped cells (El-Hamdaoui et al., 2003). Figueira
and Caldeira (2005) investigated the influence of differ-
ent nitrogen forms on salt tolerance of P. sativum and
reported that it is probable that a functional symbiosis
can be established under saline conditions, provided
that a salt-tolerant Rhizobium isolate with good N 2 -fixing
ability is utilized. Ahmad and Jhon (2005) reported a
reduction in the RWC in P. sativum leaves subject to dif-
ferent concentrations of NaCl. Okcu et al. (2005)
reported that all cultivars of pea were able to germinate
at all NaCl levels without significant decrease in germi-
nation. Bolaños et al. (2006) examined pea root nodules
under salinity stress. The nodule number and weight
diminished in salt-stressed nodules of pea plants and
most of them appeared pale in contrast with the control
pink nodules. ARA was not detected in pea nodules
developing in plants treated with 75 mM NaCl.
Salt stress distinctly increased the activities of SOD
and peroxidase (POD), levels of total phenolics and γ-
and Δ-tocopherols, and reduced the total soluble
proteins and CAT activity, while the internal levels of
H 2 O 2 continued unaffected in pea cultivars. Salt-induced
oxidative stress occurred in all pea cultivars. However,
the response of salt-tolerant and salt-sensitive cultivars
with respect to the generation of enzymatic and non-
enzymatic metabolites was found to be inconsistent. Of
the various antioxidant enzymes and metabolites exam-
ined, only CAT activity was found to be a dependable
marker of salt tolerance in the set of pea cultivars
studied (Noreen & Ashraf, 2009).
The effect of salicylic acid (SA) treatment on the
response of pea plants to salinity was studied (Barba-
Espin et al., 2011). NaCl-induced damage to leaves was
increased by SA, which was correlated with a reduction

in plant growth and the contents of ascorbate and gluta-
thione in leaves of salt-treated plants. An increase in
hydrogen peroxide also occurred in leaves of salt-
exposed plants. Salinity reduced glutathione reductase
(GR) activity, but enhanced glutathione S-transferase
(GST) and CAT activity. The results showed that SA
treatment harmfully affected the response of pea plants
to NaCl, and this response was connected with an imbal-
ance in antioxidant metabolism. The data also showed
that SA treatment could increase the resistance of salt-
stressed plants to probable opportunistic pathogen
attack, as offered by increased PR-1b gene expression
(Barba-Espin et al., 2011).
A study was conducted to document parental germ-
plasm that could be utilized for development of tolerance
to NaCl in field pea. An initial screening experiment of 780
globally distributed Pisum L. accessions identified significant
variation in response to applied NaCl, based on plant
symptoms. Lines with relatively higher tolerance as com-
pared to commercial varieties grown in Australia were
most frequently recognized within landraces originating
from the central, eastern and southern provinces of China.
The most tolerant classified accession was an unadapted
landrace 'ATC1836' originating from Greece. Salinity-
induced toxicity symptoms were closely connected with
decreases of plant growth rate, height, and shoot and root
dry matter, and with enhanced concentration of Na + at the
plant growing tip (Leonforte et al., 2013).

2.4.4 Chickpea
The genus Cicer is native to the Middle East and Asia.
Its best known and only domesticated member is Cicer
arietinum L., also commonly known as chickpea,
garbanzo bean or Bengal gram, which is commonly used
for making dhal. Elsheikh and Wood (1990) reported
that salinity significantly reduced the dry weights of both
shoots and roots in chickpea. Further, roots appeared to
be more sensitive to salinity than shoots even at very
low salinity levels of 1.0 dS/m. Sharma et al. (1990)
observed the negative effect of chloride and sulphate
types of salinity on the starch and protein contents of
leaves in two chickpea cultivars, whereas accumulation
of amino acids, particularly proline, was enhanced
with increases in salinity levels (Sharma et al., 1990).
Chickpea seedlings when grown in NaCl solution
culture suffered a decrease in their carbohydrate
concentration at the two highest salinity levels (Ahmed &
Bano, 1992; Sheokand et al., 1995).