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Background: SNP has recently been considered a new member
of the phytohormones, which plays an important role in different physiological

Objective: To evaluate the influence
of Sodium Nitroprusside (SNP) Foliar Spray on the Growth and Physiological
Processes of Zea mays L. and Lablab purpureus (L.) Sweet.

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Methodology: An experiment was
conducted to study the different concentration of SNP (1µM, 10 µM, 100 µM, 1mM and 10mM) foliar spray on 20 days old
seedlings of Zea
mays L. Lablab purpureus (L.).
treatment was carried out for 2 days, and analyzed the various growth
parameters, biochemical and enzymatic characters.

Results: Our results showed that application
of SNP led to significant increase of vegetative growth characters such as
shoot and root length, shoot and root fresh weights and dry weights, pigment,
composition and total soluble protein, total soluble glucose, free amino acid,
NRA, proline, peroxidase and catalase activity. On unit fresh weight basis, the
total chlorophyll content was found to increase at all concentrations. Also, SNP increased P and K, while Na, Ca and
Mg when compare to the control.

Conclusion: The exogenous application
of SNP to intact Zea
mays L. Lablab purpureus (L.)
was found to be beneficial in promoting growth and biochemical responses in


Key words: Sodium
nitroprusside (SNP), Zea
mays L. Lablab purpureus (L.),
Biochemical and Minerals.


Sodium nitroprusside (SNP) represents one of the most commonly used
nitric oxide (NO) donors. It was classified as a phytohormone
that might function as a gaseous endogenous plant growth regulator as well as a
non-traditional plant growth regulator. They are naturally produced within plants and used to regulate the
plant growth and developments.  NO acts as a signal molecule in plants
responsible for the regulation of the expression of many defense-related
enzymes. NO has gained increasing
interest as important intermediate and intracellular signaling molecule in
plant systems which mediates various
physiological, biochemical and developmental processes in plants, including seed dormancy, seed germination, primary lateral root growth,
floral transition, flowering, stomatal movement, photosynthesis, mitochondrial
functionality, senescence, plant metabolism and cell death as well as stress
response (Paraiz Ahmad et al., 2016). In the past few years, a growing amount of research
has provided evidence for the multiple physiological roles of this gaseous free
radical in plants (Delledonne, 2001; Wendehenne et al., 2004). The objective of the
present study was to investigate whether sodium nitroprusside (SNP), a NO
donor, plays an important role in plant growth and
developments on the selected crop seedlings.



Cultivation of seedlings

Healthy and uniform
seeds of Zea mays L. Lablab purpureus (L.) Sweets were purchased from Agricultural Research Centre, Kovilpatti. The
percentage of seed germination was found to be 80-85%. The seeds were sown in
pots containing a mixture of red soil, black soil and sand mixed in the
ratio of 2: 2: 1. Soon after emergence of the cotyledons, the seedlings were
shifted to daylight conditions.  Since the ambient climate was too hot for
the seedlings, a 40% cut off mesh filter was used to surround the pots for an
initial period of 2-3 days.

Sodium nitroprusside (SNP) treatment

nitroprusside was obtained from Sigma Chemical Co. (St. Louis, U.S.A). SNP was
initially dissolved in water and made up to 1µM, 10µM, 100µM, 1mM and 10 mM
containing 0.02% Tween-20 (Polyoxy ethylene sorbitanmonolaurate). Each seedling
required about 10ml of spray solution. The foliar spray was given for two days
early in the morning and growth analyses were done after 10 days of seedling growth.
The seedlings were sprayed with solutions until dropping with an atomic
sprayer. Plants sprayed with 0.02% Tween-20 served as the control.

After two days of the treatment the seedlings of Zea mays L. Lablab purpureus (L.)
Sweet were used for measuring the growth parameters such as such as root length,
shoot length, leaf area, fresh weight and dry weight were measured. The
biochemical and enzymatic characters were analyzed by the following methods:
chlorophyll and carotenoids (Wellburn and Lichtenthalar, 1984), Anthocyanin and
Flavonoid Mirecki and Teramura (1984), Total soluble sugar (Jayaraman, 1981),
Protein content (Lowry et al., 1951), in vivo nitrate reductase
activity (Jaworski, 1971), Catalase activity (Kar and
Mishra, 1976) and Peroxidase activity (Addy
and Goodman, 1972).





Formerly, the plant hormone ethylene was the only gaseous
signaling molecule in the living world known to science
(Ferreira and Cataneo – ?2010DNS1 ).
However, work on nitric oxide fetched the Nobel Prize for Medicine in 1998
(Wojtaszek, 2000), and considered as a signalling molecule.
NO has been initially identified as an endothelium-derived relaxation factor
and later implicated in signal transduction pathways controlling
neurotransmission, cell proliferation, programmed cell death, and host
responses to infection (Wink and Mitchell, 1998). Although the history of studies
on NO in animals is considerably much more advanced, renewed attention has been
given to the mechanism of NO synthesis and its functions in plants in the last

of SNP on growth characteristics

The exogenous
application of SNP increased the level of shoot length, root length, shoot
fresh weight, root fresh weight and dry weights. There are several reports that
suggest the growth promoting activity of SNP. Huang and She (2003) reported that SNP induced adventitious
root formation in mung bean hypocotyl cuttings. Correa-Aragunde et al. (2004) demonstrated that NO and
its precursor SNP playing a key role in determining lateral root development in
tomato. In addition, NO and SNP promoted root elongation in maize (Gouvea et al., 1997).

root growth increased by about 30% in seedlings pre-treated with 0.4 mM SNP
(followed by10 ?M Al treatment) as compared to control (10 ?M Al alone). In
order to confirm the role of SNP in reducing Al-inhibited root growth, a root
growth recovery experiment was carried out. Roots pre-treated with 0.4 mM SNP
for 12 h followed by the 20 ?M Al treatment for another 12 h were found to be
less inhibited and recovered more rapidly than the roots without SNP
pre-treatment. After a 72 h period of recovery, the SNP-pre-treated root
elongation reached 60% of the control (–Al treatment), whereas the root
elongation without SNP pre-treatment was only 22% of the control. In the
present study all the concentrations of SNP increases the shoot fresh weight
and dry weight. The changes in shoot dry weight are a clear representation of
the vegetative growth.

Effect of SNP on biochemical

The chlorophyll a
and chlorophyll b were found to
increase with increase in concentration of SNP in Zea and Lablab purpureus. The level of
chlorophyll b which was high under
SNP treatment indicates changes in stoichiometry of PS II and PS I. As Chl b is associated more with PS II, any
significant change in Chl b levels,
would indirectly affect the efficiency of PS II rather than PS I.  Our results indicated that application of SNP
significantly increased Chl content in leaves which might be due to the
impairment of Chl biosynthesis. There are many processes in which hormones and
phytochrome interact or act separately to give the same response. NO also
triggers several of these responses. These overlapping roles raise the question
of whether light and hormones share common components in signal transduction
pathways to elicit the same response and whether NO role play in the signaling
cascade (Lamattina et al., 2003).   

         Treatment with SNP increasesd anthocyanin and flavonoids
content. The anthocyanin and flavonoids are non-photosynthetic pigments
taking part in plant defense mechanisms. The effect of these non-photosynthetic
pigments depends on the environmental factors like light temperature, drought,
radiation stress etc. Have suggested that the
concentration of surface flavonoids decrease with leaf age in all plants.
Both anthocyanin and flavonoids tend to accumulate more in foliar tissues at
times of abiotic stresses. High concentrations of the phytohormones lead to the
development of these pigments in order to protect the seedlings against the
action of SNP oxidase.

                Foliar application of SNP caused marked
increases in the total soluble proteins in exogenous application of SNP
subjected samples of Zea maysand Lablab purpureus.  This
result was supported by Nasrin et al.(2012).  It may be substantiated by the active
participation of an enzyme activity nitrate reductase (reduction of nitrate to
nitrite and then to aminoacids) and increase in the polyribosome and protein
synthesis. The changes in leaf nitrate content and in vivo nitrate reductase activity reveals the high concentration
of SNP favored the accumulation of may be due to enhancement of nitrogen or
nitrate uptake by plants.

 A key step in nitrate assimilation is the
reduction of this anion to nitrite in the reaction catalyzed by NR, an enzyme
that is highly regulated at the transcriptional and post- transcriptional
levels (Kaiser, 2001). NR has been studied extensively as a key enzyme of
nitrogen metabolism. NR activity was significantly enhanced by the addition of
SNP. NR activity was significantly stimulated by SNP at 100µM and 10mM.  The reason behind is that NO stimulate the
post translational regulatory pathway of NR. All this results indicate foliar
application of SNP is important for enhancing NR activity.

treated plants in our study showed increases in peroxidase activity at all the
concentration of SNP. The higher level of endogenous auxins could also lead to
early sprouting of leaves. The high rate of peroxidase activity may be due to
enhanced auxin catabolism triggering the root initiation process (Kochhar et al., 2005). While SNP oxidase seems to
be involved only in triggering and initiating the root / shoot primordia
peroxidase is involved in both root initiation and elongation processes and
oxidation products of auxin catabolism may be involved in the initiation of

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