plants showed better shoot growth, root elongation and more proline accumulation
as compared to plants treated with only NaCl.
Almayahi (2016) also investigated the effect of Salicylic acid (50 mgl
À1 ) and
Ascorbic acid (100 mgl
À1 ) in micro-propagated shoots of Phoenix dactylifera
cv. Nersy under salinity stress. Their investigation revealed salinity tolerance and
improved growth with increased antioxidant activity of SOD and APX in Phoenix
dactylifera cv. Nersy on application of Salicylic acid (50 mgl
À1 ) and Ascorbic acid
(100 mgl
À1
). Studies carried out by Mozafari et al. (2018) showed similar expression
of Salicylic acid (0.0, 0.01, 0.05 mM) conferring salinity stress alleviation on
strawberry explants in better growth, increased pigment content, increased relative
water content, etc. and thereby mitigate harmful effects of salinity. Another tissue
culture-based study also reported salinity stress alleviation in two potato cultivars,
i.e. Cardinal and Desiree under in vitro conditions by application of Salicylic acid
(0.125, 0.25, 0.50 and 0.75 mM (Sajid and Aftab 2012).
Gunalp et al. (2011) investigated the effect of Jasmonic acid (10 and 20μM JA) on
embryos of eggplant grown invitro conditions under salinity stress and their observation revealed salinity tolerance with better growth in JA (10μM) treated plants as
compared to controls under salinity. Hence, phytohormones can be effectively
employed to develop salt-tolerant plants (Table 9.1).
9.4.1.2 Exogenous Application of Phytohormone to Enhance Salinity
Stress Tolerance in Plants
Salinity is one of the major constraints that limit plant growth and development and
to overcome this problem, several approaches have been applied; one is exogenous
phytohormone application at the optimum concentration. Several researches have
been done where the exogenous application of phytohormones at optimum concentration conferred tolerance against salinity stress. Some of them are depicted in
Table 9.2. Several studies are available which reported the positive role of salicylic
and jasmonic acid in salinity stress alleviation in crop plants. Khan et al. (2010)
reported the positive role of SA (0.1, 0.5, and 1.0 mM) in tolerance of salinity
(50 mM NaCl) in Vigna radiata L. (Wilczek) cultivar Pusa Vishal. The salt stressinduced high K
+
/Na
+ ratio in plants while the SA treatment alleviated the effect of
salinity with a reduction in Na
+
, Cl
À
, H 2 O 2 content. Also, SA treated plants
exhibited increased N, P and K contents, increased antioxidant activity and increased
photosynthesis.
Hussein and co-workers (Hussein et al. 2007) examined the effect of salicylic
acid (200 ppm) on growth parameters in maize plants cv. Single Hybrid 10 under
salinity (2000 and 4000 ppm NaCl) and observed improved growth parameters
including plant height, the number of green leaves, the diameter of stem and dry
weight on SA application under salinity. In another study by Idrees et al. (2012), they
observed reduction in growth in two varieties of Cymbopogon (Krishna and Neema)
exposed to salinity (50, 100 and 150 mM of NaCl) and reported that SA treatment
(10
À5 M) resulted in mitigation of salinity stress along with improvement in the
activities of carbonic anhydrase and nitrate reductase enzymes of salicylic acid
(1 mM) and nitric oxide (100μM) on Vigna angularis. SA and NO application
9 Phytohormones: A Promising Alternative in Boosting Salinity Stress Tolerance in. . .
287
as compared to plants treated with only NaCl.
Almayahi (2016) also investigated the effect of Salicylic acid (50 mgl
À1 ) and
Ascorbic acid (100 mgl
À1 ) in micro-propagated shoots of Phoenix dactylifera
cv. Nersy under salinity stress. Their investigation revealed salinity tolerance and
improved growth with increased antioxidant activity of SOD and APX in Phoenix
dactylifera cv. Nersy on application of Salicylic acid (50 mgl
À1 ) and Ascorbic acid
(100 mgl
À1
). Studies carried out by Mozafari et al. (2018) showed similar expression
of Salicylic acid (0.0, 0.01, 0.05 mM) conferring salinity stress alleviation on
strawberry explants in better growth, increased pigment content, increased relative
water content, etc. and thereby mitigate harmful effects of salinity. Another tissue
culture-based study also reported salinity stress alleviation in two potato cultivars,
i.e. Cardinal and Desiree under in vitro conditions by application of Salicylic acid
(0.125, 0.25, 0.50 and 0.75 mM (Sajid and Aftab 2012).
Gunalp et al. (2011) investigated the effect of Jasmonic acid (10 and 20μM JA) on
embryos of eggplant grown invitro conditions under salinity stress and their observation revealed salinity tolerance with better growth in JA (10μM) treated plants as
compared to controls under salinity. Hence, phytohormones can be effectively
employed to develop salt-tolerant plants (Table 9.1).
9.4.1.2 Exogenous Application of Phytohormone to Enhance Salinity
Stress Tolerance in Plants
Salinity is one of the major constraints that limit plant growth and development and
to overcome this problem, several approaches have been applied; one is exogenous
phytohormone application at the optimum concentration. Several researches have
been done where the exogenous application of phytohormones at optimum concentration conferred tolerance against salinity stress. Some of them are depicted in
Table 9.2. Several studies are available which reported the positive role of salicylic
and jasmonic acid in salinity stress alleviation in crop plants. Khan et al. (2010)
reported the positive role of SA (0.1, 0.5, and 1.0 mM) in tolerance of salinity
(50 mM NaCl) in Vigna radiata L. (Wilczek) cultivar Pusa Vishal. The salt stressinduced high K
+
/Na
+ ratio in plants while the SA treatment alleviated the effect of
salinity with a reduction in Na
+
, Cl
À
, H 2 O 2 content. Also, SA treated plants
exhibited increased N, P and K contents, increased antioxidant activity and increased
photosynthesis.
Hussein and co-workers (Hussein et al. 2007) examined the effect of salicylic
acid (200 ppm) on growth parameters in maize plants cv. Single Hybrid 10 under
salinity (2000 and 4000 ppm NaCl) and observed improved growth parameters
including plant height, the number of green leaves, the diameter of stem and dry
weight on SA application under salinity. In another study by Idrees et al. (2012), they
observed reduction in growth in two varieties of Cymbopogon (Krishna and Neema)
exposed to salinity (50, 100 and 150 mM of NaCl) and reported that SA treatment
(10
À5 M) resulted in mitigation of salinity stress along with improvement in the
activities of carbonic anhydrase and nitrate reductase enzymes of salicylic acid
(1 mM) and nitric oxide (100μM) on Vigna angularis. SA and NO application
9 Phytohormones: A Promising Alternative in Boosting Salinity Stress Tolerance in. . .
287