Salt stress and leguminous crops: Present status and prospects - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 33

Mamo et al. (1996) discovered chloride concentrations
in chickpea plant parts at salt levels (0-8 dS/m) two to
five times that of Na + with substantial reductions in K +
concentration. Roots appeared to be more sensitive to
salinity than shoots, but only at the higher concentration
of salt. On the other hand, chickpea plants on submis-
sion to salt stress showed a greater drop in shoot dry
weights than the roots (Dua, 1998). Zurayk et al. (1998)
also observed significant reductions in the dry weight of
above-ground biomass in chickpea on treatment with
NaCl + Na 2 SO 4 salts. Nodule dry weight and N-fixation
also declined due to salinity. The symbiosis was found to
be more salt-sensitive than both the rhizobium and the
host plant themselves (Zurayk et al., 1998).
Soussi et al. (1998, 1999) found that chickpea plant
growth was reduced by salt. However, salt reportedly
boosted the accumulation of proline, amino acids and
carbohydrates in the leaves of chickpea (Soussi et al.,
1998). Soussi et al. (1999) compared the two cultivars of
chickpea with differential tolerance to salinity with
regard to nodulation and nitrogen fixation. The effect of
salt on nodulation and nitrogen fixation was more pro-
nounced in Pedrosillano (sensitive) than ILC 1919
(tolerant). Soussi et al. (2001) also observed reduced
nitrogenase activity in chickpea plants grown under
50 mM NaCl salinity. A rise in fermentative metabolism
in nodules suggested that the accumulation of proline,
lactate or ethanol may play a vital role in providing
energy-yielding substrates for bacteroids in chickpea.
Similarly Soussi et al. (2003) reported that salt treatment
in C. arietinum cultivars triggered a build-up of proline
and total soluble sugars in the radicles of the salt-toler-
ant cultivar ILC1919.
Seeds of chickpea when germinated in the presence
of NaCl displayed a reduction in K content, while higher
levels of Na eventually repressed shoot and seed yield of
all the cultivars (Sekeroglu et al., 1999). However,
chickpea grown under saline conditions exhibited high
yields in spite of low Na and Cl contents in the tissue
(Richter et al., 1999). Singh and Singh (1999) and Ozcan
et al. (2000) reported a build-up of proline in the tol-
erant genotypes of chickpea. Gholipoor et al. (2000)
reported a reduction in shoot water content with
increasing salinity in chickpea cultivars Jam, Hashem,
Kaka and Pirooz.
When two chickpea cultivars, differing in drought
tolerance, were exposed to salinity they showed insig-
nificant effects on the leaf water potential and osmotic

adjustment, which were higher for the drought-tolerant
variety (Katerji et al., 2001). Singh et al. (2001) investi-
gated variability in the four genotypes of chickpea under
salinity and found higher activities of POX and CAT in
the tolerant genotypes. Sadiki and Rabih (2001)
screened 200 Moroccan lines of chickpea subjected to
salt stress and studied nitrogenase activity, dry weight,
nodule mass, plant colour and total nitrogen under
NaCl treatment. The study revealed salt tolerance in
MCA 103, MCA 131 and MCA 250 lines. Welfare et al.
(2002) determined the effect of a saline environment on
two chickpea cultivars. The study revealed a consider-
able reduction in plant height, number of leaves and dry
weights of leaves, stems and roots. Rao et al. (2002)
have reported that with rising salinity there was a slight
decline in nodule number and nodule biomass in the
different genotypes of chickpea above 3 dS/m, but to a
lesser extent in the high nodulation selection, which
was characteristically superior under both non-saline
and stress conditions.
Garg (2004) reported higher amino acids, total soluble
sugars and chlorophyll pigments ( a , b and total chloro-
phyll) in the tolerant cultivars of chickpea as compared to
sensitive cultivars. Kukreja et al. (2005) reported
increased activities of SOD, POX, ascorbate peroxidase
(APX), glutathione transferase (GTase), GR and CAT in
roots of C. arietinum plants exposed to salinity stress.
Singla and Garg (2005) studied the influence of salinity
on growth and yield attributes in chickpea cultivars and
concluded that root growth was more adversely affected
than shoot growth, which also had an impact on the
root:shoot ratio and plant productivity. Singh et al. (2005)
analysed 10 genetically diverse chickpea lines for salt tol-
erance. They reported a decrease in shoot, root and single
plant weights with increasing levels of salt.
Nodule conductance to O 2 diffusion has been impli-
cated as a major factor in the suppression of N 2 fixation
by soil salinity that severely reduces the production of
grain legumes. L'taief et al. (2007) studied the effect of
salinity on nodule conductance and oxygen uptake by
the nodulated roots (inoculated with the strain
Mesorhizobium ciceri UPMCa7) of Amdoun 1 and INRAT
93-1 varieties of chickpea. Salinity induced a significant
reduction in shoot (30% vs 14%), root (43% vs 20%)
and nodule biomass (100% vs 43%) for Amdoun 1
relative to INRAT 93-1. Although salinity completely
inhibited nodule formation in the sensitive variety
Amdoun 1 , nodule number and biomass were higher in