Salt stress and leguminous crops: Present status and prospects - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 31

content and protein content of faba bean seedlings.
NaCl caused a rise in plant height at low and medium
concentrations and a reduction at the highest
concentration, in both measurement periods. No
significant effect was noticed in the number of leaves or
leaf area with a low concentration, while a reduction
was observed for each of the two higher concentrations
and in both measurement periods. Salinity enhanced
both fresh and dry weights of the shoot in the two
measurement periods. Osmotic potential showed a
significant decrease with increase in concentrations, and
with the duration of the stress periods. Salinity signifi-
cantly reduced chlorophyll a content in both
measurement periods. It also significantly diminished
chlorophyll b , total chlorophyll (chl), and carotenoid
contents after 10 days of treatment. An increase was
perceived in the protein content over the two
measurement periods due to the influence of salinity
stress. A directly proportional relationship was found
between protein content and the uplift in salt concen-
trations over the first measurement period, while it was
inversely proportional in the second (Amira & Qados,
2011).
Tavakkoli et al. (2012) assessed the genotypic varia-
tion of faba bean plants for tolerance to salinity stress
under controlled conditions and in the field, and the
suitability of various physiological traits to screen 11
faba bean genotypes for salt tolerance. The importance
of Na + and Cl − exclusion as mechanisms of salt tolerance
was diminished at 150 mM NaCl, and salt tolerance was
more strongly related to the osmotic potential of the
leaves: lower salt tolerance was associated with a lower
osmotic potential. The reduction in salt tolerance as the
external salt stress increased varied among varieties,
and this was associated with the ability to maintain high
levels of tissue water content. This study also suggested
salt exclusion coupled with a synthesis of organic sol-
utes as important components of salt tolerance in the
tolerant genotypes (Tavakkoli et al., 2012).
The PR10a gene isolated from the potato cultivar
Desirée was known for its role in enhancing salt and/or
drought tolerance in potato. This gene was transferred
into faba bean cv. Tattoo by an Agrobacterium tumefaciens -
mediated transformation system based upon direct
shoot regeneration after transformation of meristematic
cells derived from embryo axes. Fertile transgenic faba
bean plants were recovered. The results suggested that
introducing a novel PR10a gene into faba bean could be

a promising approach to improve its drought and salt
tolerance ability (Hanafy et al., 2013).

2.4.3 peas
The genus Pisum contains major human food crops and
is native to southwest Asia and northeast Africa. This
genus contains species like Pisum abyssinicum (syn. P.
sativum subsp. abyssinicum ), P. fulvum , P. sativum (pea)
and P. arvense (the field or garden pea), depending on
taxonomic interpretation (International Legume
Database). Sodium chloride reduced ARA by 77% and
Lb by 50% in pea nodules treated with 50 mM NaCl
(Delgado et al., 1993, 1994).
Hernandez et al. (1993) reported that in the leaf mito-
chondria from pea plants grown with NaCl, the
salt-induced enhanced rate of mitochondrial O 2 − pro-
duction was concomitant with a strong decrease in the
mitochondrial Mn-SOD in NaCl-sensitive plants,
whereas in NaCl-tolerant plants this isozyme was
induced by salt treatments. The metabolism of chloro-
plasts and mitochondria under NaCl stress favours the
formation of O 2 − and H 2 O 2 in two pea cultivars differing
in NaCl sensitivity (Hernandez et al., 1995). Hernandez
et al. (1999) suggested that the salt stress was accompa-
nied by oxidative stress in pea. The tolerant cultivars
ensured cell turgor and enhancement of the antioxidant
defence system in mitochondria, chloroplast and cyto-
solic enzymes, with an increase in all components of
the ascorbate-glutathione (ASC-GSH) cycle and SOD
isozymes (Hernandez et al., 2000, 2001). The growth of
pea cv. Lincoln plants (shoot fresh weight and shoot dry
weight) was not affected by 50 mM NaCl in the nutrient
medium, but was reduced by about 30% and 50% in
the presence of 70 and 90 mM NaCl, respectively; the
pea cultivar Puget was relatively tolerant to 70 and
90 mM NaCl (Hernandez et al., 2001). In another study,
Hernandez and Almansa (2002) also studied the
short-term effects of salt stress on antioxidant systems of
pea leaves. Salt stress brought about a decrease in
osmotic potential, Na + concentration and stomatal con-
ductance, but at 48 and 24 h post-stress, respectively,
both parameters recovered control values.
Olmos and Hellin (1996) studied the effect of salt
stress on two lines of P. sativum cv. Challis, one salt-
sensitive and the other adapted to 85.5 mM NaCl. The
results showed that average concentrations of reducing
sugars, total free amino acids and ascorbic acid increased
in the line adapted to NaCl and suggested their role in