JASEM ISSN 1119-8362 Full-text Available Online at J. Appl. Sci. Environ. Manage.

https://www.ajol.info/index.php/jasem Vol. 22 (4) 543 – 540 April 2018

All rights reserved
http://ww.bioline.org.br/ja

Influence of Salicylic Acid on the Growth of Lettuce (Lactuca sativa var longifolia)
During Reduced Leaf Water Potential
1*BANKOLE, AE; 1UMEBESE, CE; 2FEYISOLA, RT; 2BAMISE, TO
1*
Department of Botany, Faculty of Science, University of Lagos, P.M.B 1029 UNILAG Post Office, Akoka, Lagos State, Nigeria.
2
Department of Plant Science, Faculty of Science, Olabisi Onabanjo University, P. M. B. 2002 Ago Iwoye, Ogun State, Nigeria.
*E-mail: gbolabim@yahoo.com

ABSTRACT: Salicylic acid (SA) a signal molecule which is responsible for inducing defense mechanisms in plants
and also has a protective role in stress sensitivity. A study was conducted to determine the effect of water deficit stress
on the growth of Lactuca sativa L. (Lettuce) using SA (1 mM and 3 mM) during reduced leaf water potential. Plants
were subjected to 7 days drought after four weeks of growth. Stressed plants exhibited a lower leaf water potential (ψw)
of -0.499 MPa as compared with the control (ψw of -0.460 MPa). Plants with lower leaf ψw exhibited reduction in
almost all the parameters studied: 1 mM SA foliar treatment caused increase of 8 % in plant height and 53.16 % in
plant biomass. Foliar treatment of 3 mM SA of the relative water content stimulated 13 % increase in the growth as
compared to the control plant which was statistically significant at P<0.05. Overall, SA in stressed plant exhibited
higher ameliorative capacity which has the beneficial role of mediating defense response in plants under stress.

DOI: https://dx.doi.org/10.4314/jasem.v22i4.18

Copyright: Copyright © 2018 Bankole et al. This is an open access article distributed under the Creative
Commons Attribution License (CCL), which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.

Dates: Received: 06 March 2018; Revised: 10 April: 2018; Accepted: 22 April 2018

Keywords: Water stress, Salicylic acid, Growth, Lactuca sativa

Water stress in plant is an abiotic stress that is fast and development (Khan et al., 2015; Hayat et al.,
becoming a very critical issue facing terrestrial 2008; Horvath et al., 2007; Senaratna et al., 2000) .
ecosystem in many areas of the world. Substantial
losses have been recorded both in the natural Major role of salicylic acid include, increases in flower
ecosystem and agricultural production (Wu et al., life, inhibits seed germination, and promotes ethylene
2011). Water stress has the ability to affect cell synthesis (Singh and Usha, 2003). Studies has reported
enlargement more than cell division, as it is also the impact of salicylic acid to give a protective effect
reported to alter photosynthesis, stomata closure, in plants under the action of different abiotic stress
translocation, carbohydrates, respiration, ion uptake, such as, heat, chilling, osmotic and salt stress (Singh
nutrients metabolism and hormones (Chaves et al., and Usha, 2003; Borsani et al., 2001; Janda et al.,
2003). 1997).

Prolonged water stress affects both physiological and Lettuce (Lactuca sativa L.) a member of the
metabolic processes in plant, which can lead to Asteraceae family (formally Compositae) is a self-
reduction in plant productivity and eventual death. pollinating annual plant cultivated for its edible rosette
Osmotic adjustment is an important metabolic leaves and propagation is by seed (Wang et al., 2015;
processes in plant adaptation to drought stress as it Judd et al., 2007). They are generally lactiferous herbs
synthesis and accumulates small compatible solutes with height from 10 to 15 cm.
such as proline, glycine betaine, sugars and some
inorganic ions (Chaves at al., 2003; Hare et al., 1998; The different varieties of lettuce are simply
Bray, 1997). distinguished by their morphology and end users.
They are well grown both in the open field and under
Salicylic acid (SA) act as a signal molecule in the protection and some can adapt well to warm
induction of defense mechanisms in plants (Raskin, conditions or hot weather. Lettuce is an excellent
1992; Shah, 2003). It has been reported to be source of vitamin A, B, C, E, K, folate, iron and
responsible in the regulation of certain processes in vegetable. The study investigates the ameliorative
plants subjected to stress, thus improving the growth impact of salicylic acid on the growth of Lactuca
sativa during water stress.

*Corresponding author E-mail: gbolabim@yahoo.com

Influence of Salicylic Acid on….. 536

MATERIALS AND METHODS The change in weight was recorded and plotted against
Seed collection and planting: Pure and standardized solute potential of sucrose solution. The leaf water
seeds of Lactuca sativa L. (Eden cultivar) were potential (ψw) is estimated as equivalent to the solute
purchased from Agrotrophic seed store, Ibadan, Oyo potential of the solution in which there is no change in
State. The experiment was set up in the screen house weight (the intercept on the abscissa).
with 30 ± 5o C temperature, 20,000 lx light intensity
and 65± 5% relative humidity in the Department of Calculation Of Water Status Using Relative Water
Plant Science, Olabisi Onabanjo University, Ago- Content (Rwc): The water status of lettuce was
Iwoye, Ogun State, Nigeria from January 2016 - calculated as the relative water content, which is
March 2016. Lettuce seeds were planted in the evening expressed as a percentage of fully saturated shoot and
at about 2-3cm deep into the 80 pots of about 40 cm in root. In the determination of the relative water content,
diameter. They were filled with sieved 1kg topsoil and fresh shoots and roots were weighed and saturated by
manure was added to the soil in the preparation for immersing in distilled water at a temperature between
planting. Seedlings were thinned into 5 plants per pot 0 and 40°C. The saturated plants were then removed
after three weeks of planting. after four hours, surface dried and reweighed; it was
oven dried at 50°C for a period of 3 days and the dry
Growth Parameters: Plants were subjected to water weight measured, according to the method of Slayter,
stress for 7 days exactly 28 days after sowing. The (1967). RWC was calculated using the following
plants were grouped into four consisting of twenty formula:
(20) plants per treatment. Treatment include water FW − DW
RWC, % = x 100
deficit +1mM of SA, water deficit + 3mM of SA foliar TW − DW
spray; while the third were subjected to water deficit
only; and the fourth group served as control (i.e. no Where FW = fresh weight; DW = Dry weight; TW =
treatment). All plants were daily watered (300ml) Turgid weight
apart from the period of stress treatment and the plant
pots were kept in the screen house throughout the Determination Of Soil Moisture Content: The soil
period of the experiment. The plants were harvested moisture (θg) was determined after subjecting the
on the last day of the stress treatment. Measurements plants to 7 days water stress, using the gravimetric
such as plant height (shoot and root) and dry weight method outlined by Johnson, (1962). The soil was
(shoot and root) were taken immediately after weighted as fresh weight (FW) and then dried at 800C
harvesting. Plants (shoot and root) were then dried in for 48 h as dry weight (DW). The soil water content
a hot air oven for 3 days at a temperature of 50°C after (WC) was calculated using the following formula:
which the dry weight measurement was recorded.

Determination Of Leaf Water Potential: FW − DW

Determination of the leaf water potential measures the WC, % = x 100
DW
degree of stress in plants using the tissue weight-
change method outlined by Hopkins and Huner, Statistical Analysis: All experiments was done in a
(2004). About 0.5g of leaf from each treatment was completely randomized design. Data obtained were
immersed in each of a graded series of 0.2M, 0.4M, subjected to a one-way ANOVA. Each data point was
0.6M and 0.8M sucrose solution containing 10 ml in the mean average of three replicates (5
different test tubes. Immersed leaves were removed pots/replicates). Comparisons with P values <0.05
after one hour at equilibrium, then dried between filter were considered significantly different.
paper and reweighed.
RESULTS AND DISCUSSION
The Osmotic potential (ψs) of each sucrose solution Generally, water limitation significantly reduced
was calculated using van’t Hoff equation. entire growth of Lettuce that were subjected to water
deficit. The result for the response of lettuce under
ψs = -iCRT water stress to the exogenous application of salicylic
acid is as follows:
Where i =Ionization constant (for sucrose it is 1.0
because sucrose does not ionize in water); C = Molal
concentration; R = the gas constant (R = 0.08381 litres
bar/mole K); T = The absolute temperature (K) 273 +
°C of solution).
BANKOLE, AE; UMEBESE, CE; FEYISOLA, RT; BAMISE, TO
Influence of Salicylic Acid on….. 537

Fig 1: The plant height (cm) of lettuce subjected to water stress and
salicylic acid (SA) treatment. Mean values with similar alphabet are Figure 3: Dry root weight of lettuce subjected to water stress (WS)
not significantly different at P < 0.05. and Salicylic acid (SA), values having similar alphabet are not
significantly different at P < 0.05
Plant biomass was significantly reduced by water
stress which correspond to the low water potential
induced by the 7 days water deficit (Figure 2). Growth
which is an energy requiring process are limited by
water stress since there is reduction of CO2 fixation
and NADP+ regeneration of the calvin cycle resulting
to an over reduced photosynthetic electron transport
chain (Kalra, 1995). However, treatment with 1mM
SA significantly increased (P<0.05) plant biomass
values to the control value Fig 1 and 2.

Figure 4: Relative water content (RWC) of lettuce subjected to

water stress (WS) and Salicylic acid (SA), values having similar
alphabet are not significantly different at P < 0.05.

There was however no significant difference between

the mean fresh and dry root weight as compared to the
control group which was statistically higher at P <
0.05.

However, there was no significant different (P > 0.05)

in 1mM SA and the control plants. On the other hand,
Fig 2: Dry shoot weight of lettuce subjected to water stress (WS) there was no significant difference in the mean values
and Salicylic acid (SA), values having similar alphabet are not
significantly different at P < 0.05
of fresh and dry shoot weight and shoot turgid weight
plant (Table 1). Water stress reduced the percentage
Consideration of the relative water content in the relative water content of the shoot. However, 3mM SA
leaves is probably the most appropriate measure of slightly enhanced the shoot relative water content of
plant water status for the physiological consequences lettuce than the control, while, 1mM SA treated plant
of cellular water deficit. Relative water content was briefly enhanced, but with a value lesser to that of
(RWC) of the experimental plants was significantly the control.
higher (P < 0.05) in 3mM SA as shown in Table 2.

BANKOLE, AE; UMEBESE, CE; FEYISOLA, RT; BAMISE, TO

Influence of Salicylic Acid on….. 538

Fig 6: Soil moisture content of lettuce subjected to water deficit in

sucrose solutions of varied potential was graduated on the Y- axis.

Table 2: Soil pH of plants subjected to water stress. Water stress

increased the soil pH of the stressed plants in comparison with the
Fig 5: Leaf water potential of lettuce subjected to water deficit control group.
Treatment Soil pH
Table 1: Leaf water potential of Lettuce subjected to water stress Control 8.92
(WS) and salicylic acid (SA) treatment. Water stress 9.65
Treatment Water Potential (MPa) Water stress + 1mM SA 9.03
Control -0.450a Water stress + 3mM SA 9.44
Water stress 0.466a
Water stress + 1mM SA -0.499b
Water stress + 3mM SA -0.461a However, SA application slightly alleviated the effect
of water potential in lettuce which caused much
Superscripts with same letters at each treatment are not growth and yield reduction during water stress.
significantly different at p<0.05. Figure 5 and Table 1
show the values of the leaf water potential of lettuce This finding corroborates the report of Krause, 1994,
subjected to water stress and SA treatment. The values that water stress significantly reduced the plant height
of the leaf water potential are indicated by the of Allium cepa, but the stress was alleviated through
intercepting figures of the X –axis abscissa on the exogenous application of salicylic acid. Biomass of
graph. The change in the weight of the tissues of the lettuce plant suffered a significant reduction during
plants subjected to water stress Overall, water stress water deficit. This is in agreement with the findings of
caused a decrease in the leaf water potential of the Ahmad et al., (2014) that plant biomass was
stressed plant. significantly reduced by water deficit which
corresponds to the low water potential induced by the
Soil moisture content in dry weight basis of lettuce 7 days water deficit. However, exogenous application
subjected to water stress and SA treatment. Figure 6 of 3mM SA alleviated the effect of water stress; as
indicates the level at which moisture is lost in each of reported by Umebese and Bankole, (2013) that
the treatment during water stress. No loss of water was salicylic acid induced salinity tolerance and increased
observed in the control, however, a significant and biomass of Torreya grandis. The leaf water potential
relatively loss of moisture content was observed in the of the stressed plants was significantly reduced during
3mM SA treated plant. the water deficit. Senaratna et al., (2000) explained
that water stress caused a significant reduction in the
Plant growth and development is a complex water potential of tomato plants, while SA treatment
phenomenon that is often determined by different increase the water potential value of the plants at about
exogenous and endogenous factors. The role of 20.9% higher than the control. According to Li et al.,
salicylic acid in the regulation of the physiological (2014), who reported that leaf relative water content is
processes as well as on the growth and development of an important physiological indicator that helps in the
plants has been reported. determination of the tolerance of plants to stress.
Exogenous application of SA boosted the relative
This study has shown that exogenous application of water content of water stressed plants. SA treatment
SA has positive effects on Lactuca sativa (Eden has been reported to be able to enhance the
cultivar) plant during water stress. maintenance of high relative water content of stressed
plants compared to the ones without SA (Capitani et
al., 2009). In a contrast report by Sanchez- Blanco et
BANKOLE, AE; UMEBESE, CE; FEYISOLA, RT; BAMISE, TO
Influence of Salicylic Acid on….. 539

al., (2004), the relative water content of Zea mays Chaves, MM; Maroco, JP; Pereira, JS (2003).
during water stress was not altered. Understanding plant responses to drought from
genes to the whole plant. Functional Plt Biol 30:
From the study, the screen house experiment show that 239–264.
water stress led to a great reduction in the soil moisture
content. The rate of transpiration is highly dependent Doussan, C; Pierret, A; Garrigues, E (2006). Water
on the temporal in soil moisture content. High uptake by plant roots: II. Modelling of water
moisture content leads to increased flow from bulk soil transfer in the soil–root system with explicit
to root area (Wallach et al., 2010; Doussan et al., 2006; account of flow within the root system:
Kramer and Boyer, 1995). However, reduction in soil comparison with experiments. Plt and Soil 283:
water content during stress results in reduction of the 99–117.
flow rate of water from soil bulk to root area, arising
from soil resistance to water flow. Transpiration rate Farooq, M; Wahid, A; Kobayashi, N; Fujita, D; Basra,
of the plant therefore reduced despite the increase in SMA (2009). Plant drought stress: effects,
the evaporation demand (Wallach et al., 2010). mechanisms and management. Agronomy for
Decrease in soil water content also reduces inflow of Sustainable Development, Springer Verlag/EDP
carbon dioxide into the leaves; and spares more Sciences/INRA vol. 29 (1), pp.185-212.
electrons for the formation of active oxygen species
(Farooq et al., 2009). Reduction in the soil water Hare, PD; Cress, WA; Van Staden, J (1998).
content also led to the decrease in the absorption (in Dissecting the role of osmolyte accumulation
ionic form) and utilization of nutrients, since water is during stress. Plt Cell and Environ 21: 535-553.
needed to dissolve and transfer nutrients from the soil
bulk to the root area. Hayat, S; Hasan, SA; Fariduddin, Q; Ahmad, A
(2008). Growth of tomato (Lycopersicon
Conclusion: Water stress has been recognized as a big esculentum) in response to salicylic acid under
threat to plant survival. Plants therefore induce several water stress. J. Plant Interact 3(4): 297-304.
physiological, biochemical processes and molecular
mechanism to survive these threats. This study has Hopkins, WG; Hüner, NPA (2004). Introduction to
shown that water deficit results in the reduction of plant physiology. John Wiley and Sons, Inc. USA.
available moisture (water) in the soil and leaf water pp. 539-540.
potential. Also, salicylic acid is a compound capable
of reducing the effect of the stress. Overall, 3mM Horvath, E; Pal, M; Szalai. G; Paldi, E; Janda, T
exogenous application of salicylic acid proved to be (2007). Exogenous 4- hydroxybenzoic acid and
more effective in the reduction of the effect of water salicylic acid modulate the effect of short term
stress on Lactuca sativa L. in this study. drought and freezing stress on wheat plants. Biol.
Plant 51: 480- 487.
REFERENCES
Ahmad, MA; Murali, PV; Marimuthu, G (2014). Janda, T; Szalai, G; Tari, I; Paldi, E (1999).
Impact of salicylic acid on growth, photosynthesis Hydroponic treatment with salicylic acid
and compatible solute accumulation in Allium decreases the effect of chilling injury in maize
cepa L. Subjected to drought stress. Int Jour of (Zea mays L.) plants. Planta 208: 175–180.
Agric and Food Sci 4(1): 22-30.
Johnson, AI (1962). Methods of Measuring Soil
Borsani, O; Valpuesta, V; Botella, MA (2001). Moisture in the Field, contributions to the
Evidence for a role of salicylic acid in the hydrology of the United States geological survey
oxidative damage generated by NaCl and osmotic water-supply, Third printing U.S. Government
stress in Arabidopsis seedlings. Plt Physiol. 126: printing office: 899pp.
1024–1030.
Bray, EA (1997). Plant responses to water deficit. Judd, WS; Campbell, C; Kellogg, EA; Stevens, PF;
Trends in Plt Sci 2: 48–54. Donoghue, MJ (2007). Plant systematics: a
phylogenetic approach. Sinauer Assoc,
Capitani, D; Brilli, F; Mannina, L; Proietti, N; Loreto, Sunderland 620pp.
F (2009). In Situ Investigation of Leaf Water
Status by Portable Unilateral Nuclear Magnetic
Resonance. Plt Physiol 149: 1638–1647.
BANKOLE, AE; UMEBESE, CE; FEYISOLA, RT; BAMISE, TO
Influence of Salicylic Acid on….. 540

Kalra, YP (1995). Determination of pH of Soils by Shah, K; Kumar, RG; Verma, S; Dubey, RS (2001).
Different Methods: Collaborative Study. J. Effect of cadmium on lipid peroxidation,
AOAC Inter. 78(2): 310-323. superoxide anion generation and activities of
antioxidant enzymes in growing rice seedlings.
Khan, MIR; Fatma, M; Per, TS; Anjum, NA; Khan, Plt Sci 161(6): 1135-1144.
NA (2015). Salicylic acid-induced abiotic stress
tolerance and underlying mechanisms in plants. Singh, B; Usha, K (2003). Salicylic acid induced
Front. Plant Sci. 6:46-52. physiological and biochemical changes in wheat
seedlings under water stress. Plant Growth Regal.
Kramer, PJ; Boyer, JS (1995). Water relations of 39: 137-141.
plants and soils. London: Academic Press.482pp.
Krause, GH (1994). The role of oxygen in Slatyer, RO (1967). Plant- Water Relationships.
photoinhibition in photosynthesis.In: Foyer, C.F London. Academic. 366pp.
and Mullaneaux, C.W (eds) causes of photo-
oxidative stress and amelioration of defence Umebese, CE; Bankole, AE (2013). Impact of
systems in plants. Pp43-76 CRC Press Boca salicylic acid on antioxidants, biomass and
Ratoa. osmotic adjustments in Vigna unguiculata (L.
walp) during water deficit stress. Afr J. Biotech
Li, T; Hu, Y; Du, X; Tang, H; Shen, C (2014). 12(33): 5200-5207.
Salicylic Acid Alleviates the Adverse Effects of
Salt Stress in Torreya grandis cv. Merrillii Wallach, R; Da-Costa, N; Raviv, M (2010).
Seedlings by Activating Photosynthesis and Development of synchronized, autonomous, and
Enhancing Antioxidant Systems. PLoS ONE self-regulated oscillations in transpiration rate of
9(10): e109492. a whole tomato plant under water stress. Jour of
doi:10.1371/journal.pone.0109492 Exptal Bot 61(12): 3439–3449.

Raskin, I (1992). Role of salicylic acid in plants. Ann Wang, X; Zhou, B; Sun, X; Yue, Y; Ma, W; Zhao, M
Rev of Plt Physiol and Plt Mol Biol 43: 439- 463. (2015). Soil Tillage Management Affects Maize
Grain Yield by Regulating Spatial Distribution
Sánchez-Blanco, MJ; Rodríguez, P; Morales, MA; Coordination of Roots, Soil Moisture and
Ortuño, MF; Torrecillas, A (2002). Comparative Nitrogen Status. PLoS ONE 10(6): e0129231.
growth and water relation of Cistus albidus and
Cistus monspeliensis plants during water deficit Wu, J; Liu, Y; Tang, L; Zhang, FL; Chen, F (2011). A
conditions and recovery. Plant Sci. 162, 107-113. study on structural features in early flower
development of Jatropha curcas L. and the
Senaratna, T; Touchell, D; Bunn, E; Dixon, K (2000). classification of its inflorescences. Afr. J. Agric.
Acetyl salicylic acid (aspirin) and salicylic acid Res. 6 (2): 275-284.
induce multiple stress tolerance in bean and
tomato plants. Plant Growth Regal. 30: 157-161.

BANKOLE, AE; UMEBESE, CE; FEYISOLA, RT; BAMISE, TO