Impact of SA application on biochemical characteristics of plants under salinity
stress was also thoroughly studied (Ahanger et al. 2019; Khan et al. 2014). Ahanger
et al. (2019) examined the effect of exogenously applied salicylic acid (SA) and
nitric oxide (NO) on Vigna angularis exposed to salinity and concluded that SA and
NO application significantly enhanced plant growth and metabolism with
upregulation of the antioxidant system including superoxide dismutase (SOD),
catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase
(DHAR), and glutathione reductase (GR) and with increased osmolyte (proline)
accumulation. Foliar application of SA (0.5 mM) in mung bean (Vigna radiata L.)
under salinity resulted in alleviation of salt stress with increased glycinebetaine
(GB) and methionine (Met) accumulation in SA treated plants (Khan et al. 2014).
Ma et al. (2017) reported enhancement in salinity tolerance in Dianthus superbus
with improved photosynthetic activity under salinity stress (0.3, 0.6, and 0.9%
NaCl). This was achieved by exogenous application of salicylic acid (0.5 mM)
with significant improvement in photosynthetic activity and antioxidant system
activity in SA treated plants under salinity as compared to untreated plants. Consistent with the results of Ma et al. (2017) in Dianthus superbus, foliar application of
SA in two potato cultivars N-Y LARA and 720-110 NARC grown under salt stress
alleviates the harmful effects of salinity and resulted in increased photosynthetic
activity and antioxidant system activity. Faried et al. (2016) also observed similar
mitigation of salinity stress on exogenous application of salicylic acid (0.5 mM) on
potato cultivars N-Y LARA and 720–110 NARC under salt stress (50 mmol L
À1 )
with increased photosynthetic activity and antioxidant activity.
The exogenous application of jasmonic acid (JA) also proved useful in alleviating
the adverse effects of salinity as reported in various studies (Maryam et al. 2019;
Sadeghipour 2017). Maryam et al. (2019) observed that methyl jasmonate (0.1 and
0.5 mMMeJ) on the exogenous application on Carthamus tinctorius varieties IL111
and Isfahan exposed to salinity (6 and 12 ds m
À1 ) mitigated the negative effects of
salinity and improved plant growth and resulted in increased chlorophyll content,
proline content, etc.
Sadeghipour (2017) also investigated the effect of exogenously applied methyl
jasmonate (0, 25 and 50μM MeJA) for salinity tolerance in Vigna unguiculata
L. seedlings and observed that plants treated with MeJ showed improved growth,
increased chlorophyll content, stomatal conductance, proline accumulation and
relative water content (RWC) under salinity stress (50 and 100 mM) as compared
to controls.
Studies carried out by Kaur and Sirhindhi (2017) showed similar effects of
jasmonic acid (JA) in salinity stress alleviation in seedlings of Brassica napus
L. exposed to salinity (0, 140, 160, 180 mM NaCl) with jasmonic acid studied
under salinity stress. JA treatment (0, 6, 9, 12 M) resulted in reduced toxicity of salt
stress on seedling growth with increased proline content and decreased electrolyte
leakage and lipid peroxidation. Simultaneous application of both SA and JA was
found to result in better mitigation of salinity stress than their individual treatments
(Sheokand et al. 2018). Exogenous application of SA (10
À6 M), JA (0.5μM) and
24-Epibrassinolide (10
À7 M) on soybean plants exposed to salinity mitigate the
9 Phytohormones: A Promising Alternative in Boosting Salinity Stress Tolerance in. . .
289
stress was also thoroughly studied (Ahanger et al. 2019; Khan et al. 2014). Ahanger
et al. (2019) examined the effect of exogenously applied salicylic acid (SA) and
nitric oxide (NO) on Vigna angularis exposed to salinity and concluded that SA and
NO application significantly enhanced plant growth and metabolism with
upregulation of the antioxidant system including superoxide dismutase (SOD),
catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase
(DHAR), and glutathione reductase (GR) and with increased osmolyte (proline)
accumulation. Foliar application of SA (0.5 mM) in mung bean (Vigna radiata L.)
under salinity resulted in alleviation of salt stress with increased glycinebetaine
(GB) and methionine (Met) accumulation in SA treated plants (Khan et al. 2014).
Ma et al. (2017) reported enhancement in salinity tolerance in Dianthus superbus
with improved photosynthetic activity under salinity stress (0.3, 0.6, and 0.9%
NaCl). This was achieved by exogenous application of salicylic acid (0.5 mM)
with significant improvement in photosynthetic activity and antioxidant system
activity in SA treated plants under salinity as compared to untreated plants. Consistent with the results of Ma et al. (2017) in Dianthus superbus, foliar application of
SA in two potato cultivars N-Y LARA and 720-110 NARC grown under salt stress
alleviates the harmful effects of salinity and resulted in increased photosynthetic
activity and antioxidant system activity. Faried et al. (2016) also observed similar
mitigation of salinity stress on exogenous application of salicylic acid (0.5 mM) on
potato cultivars N-Y LARA and 720–110 NARC under salt stress (50 mmol L
À1 )
with increased photosynthetic activity and antioxidant activity.
The exogenous application of jasmonic acid (JA) also proved useful in alleviating
the adverse effects of salinity as reported in various studies (Maryam et al. 2019;
Sadeghipour 2017). Maryam et al. (2019) observed that methyl jasmonate (0.1 and
0.5 mMMeJ) on the exogenous application on Carthamus tinctorius varieties IL111
and Isfahan exposed to salinity (6 and 12 ds m
À1 ) mitigated the negative effects of
salinity and improved plant growth and resulted in increased chlorophyll content,
proline content, etc.
Sadeghipour (2017) also investigated the effect of exogenously applied methyl
jasmonate (0, 25 and 50μM MeJA) for salinity tolerance in Vigna unguiculata
L. seedlings and observed that plants treated with MeJ showed improved growth,
increased chlorophyll content, stomatal conductance, proline accumulation and
relative water content (RWC) under salinity stress (50 and 100 mM) as compared
to controls.
Studies carried out by Kaur and Sirhindhi (2017) showed similar effects of
jasmonic acid (JA) in salinity stress alleviation in seedlings of Brassica napus
L. exposed to salinity (0, 140, 160, 180 mM NaCl) with jasmonic acid studied
under salinity stress. JA treatment (0, 6, 9, 12 M) resulted in reduced toxicity of salt
stress on seedling growth with increased proline content and decreased electrolyte
leakage and lipid peroxidation. Simultaneous application of both SA and JA was
found to result in better mitigation of salinity stress than their individual treatments
(Sheokand et al. 2018). Exogenous application of SA (10
À6 M), JA (0.5μM) and
24-Epibrassinolide (10
À7 M) on soybean plants exposed to salinity mitigate the
9 Phytohormones: A Promising Alternative in Boosting Salinity Stress Tolerance in. . .
289