Content uploaded by Kirsten Butcher
Author content
All content in this area was uploaded by Kirsten Butcher on Oct 27, 2023
Content may be subject to copyright.
AgronomyJournal • Volume108,Issue6 • 2016 2189
S is the accumulation of excess ions [such
as calcium (Ca2+), magnesium (Mg2+), sodium (Na+)
sulfates (SO42–), and chlorides (Cl–)] in the soil that
inhibit plant function and growth (Keller et al., 1986). Soil
salinity interferes with biological uptake of nutrients and water,
thus disturbing necessary physiological functions required
for growth and development of plants (Munns, 2002). As a
result, salinization is a substantial contributor to land degrada-
tion and, consequently, a major threat to soil health. Globally,
approximately 831 million hectares of land are a ected by soil
salinity (Table 1; Martinez-Beltrán and Manzur, 2005), and
salinization is predicted to impact 50% of all arable land by
2050 (Wang et al., 2003). e global extent of salinization has
both social and economic implications. Given the propensity
of soil salinity to impede agricultural productivity, its impacts
threaten both the global food supply and agricultural pro ts.
Globally, US$12 to 27.3 billion are lost annually due to reduc-
tions in crop productivity (Qadir et al., 2014).
Saline soils are classi ed according to the electrical conduc-
tivity of the soil solution (ECe) and the sodium adsorption
ratio (SAR) or percent exchangeable sodium (ESP) (Richards,
1954). Saline soils have an ECe >4.0 dS m–1 and SAR <13
(or exchangeable sodium <15%; Richards, 1954). Electrical
conductivity is linearly related to the total dissolved salts in
the solution (Suarez, 2005). Typically, Na+, Ca2+, Mg2+, Cl–,
SO42–, and carbonate (CO32–) are the salt constituents associ-
ated with salinization (Volkmar et al., 1998), but relative pro-
portions of these ions vary in soil (Bernstein, 1975).
ere are two main causes of salinization: (i) primary sali-
nization and (ii) secondary salinization. Primary or dryland
salinity is caused by the natural accumulation of soluble salts
in soil from saline parent material or capillary rise from saline
ground water (Rengasamy, 2010). Dryland salinity generally
occurs in semiarid and arid regions where rainfall is low and
evapotranspiration is high (Richards, 1954). Secondary or irrigation
salinity is anthropogenic and can be caused by the accumulation
of salts from the use of poor quality irrigation water (Rengasamy,
2010). Regardless of the cause of salinity, salts accumulate in the soil
pro le as a result of poor drainage or leaching (Bernstein, 1975).
Plants typically demonstrate a two-phase response to soil
salinity (Munns, 2002). e rst stage results from osmotic
stress while the second stage involves ion toxicity from salt
SoilSalinity:AThreattoGlobalFoodSecurity
KirstenButcher,AbbeyF.Wick,ThomasDeSutter,*AmitavaChatterjee,andJasonHarmon
Published in Agron. J. 108:2189–2200 (2016)
doi:10.2134/agronj2016.06.0368
Received 22 June 2016
Accepted 19 Aug. 2016
Copyright © 2016 by the American Society of Agronomy
5585 Guilford Road, Madison, WI 53711 USA
All rights reserved
ABSTRACT
Soil salinity is a global issue threatening land productivity,
and estimates predict that 50% of all arable land will become
impacted by salinity by 2050. Consequently, it is important to
have a fundamental understanding of crop response to salinity
to minimize economic loss and improve food security. While an
immense amount of research has been performed assessing corn
(Zea mays L.) and soybean [Glycine max (L.) Merr.] response to
salinity, there are few, if any, comprehensive reviews compiling
previously published literature. is review provides a detailed
description of our current knowledge on the impacts of salinity
on corn and soybean growth and development. Both osmotic
stress and speci c ion toxicities with respect to corn and soy-
bean are addressed. Additionally, potential areas of future
research are recommended.
K. Butcher, A.F. Wick, T. DeSutter, and A. Chatterjee, Dep. of Soil
Science, North Dakota State Univ., Fargo, ND 58108; J. Harmon,
Dep. of Entomology, North Dakota State Univ., Fargo, ND 58108.
*Corresponding author (thomas.desutter@ndsu.edu).
Abbreviations: EC, electrical conductivity; ECe, electrical
conductivity of a saturated paste extract; ECi, electrical conductivity
of irrigation water; ECsw, electrical conductivity of soil solution;
ECT, threshold salinity tolerance; LAI, leaf area index; SAR, sodium
adsorption ratio.
Core Ideas
• Review of salinity’s e ects on corn and soybean growth and
development.
• Impacts of osmotic stress and speci c ion toxicities discussed.
• Potential areas of future research addressed.
REVIEW & INTERPRETATION
Published November 3, 2016
2190 AgronomyJournal • Volume108,Issue6 • 2016
constituents. However, the degree that salinity impedes crop
productivity is highly variable and depends on many factors,
including but not limited to soil texture and water content,
nutrient status of the soil, species and variety, growth stage of
the plant, pest pressures, and the ions contributing to salinity
(Bernstein, 1975; Maas, 1993; Volkmar et al, 1997; Suarez,
2005; Rengasamy, 2010). Inevitably, plant response to salinity
is incredibly complex. Currently, salinity studies commonly use
a threshold-slope model to describe plant yield response (Maas
and Homan, 1977). e threshold-slope model indicates the
threshold salinity tolerance of the crop (Maas, 1993). Above
this threshold, signicant crop declines occur (Maas, 1993).
While an immense amount of research has been performed
assessing corn and soybean response to salinity, there are few,
if any, comprehensive reviews compiling previously published
literature on their responses.
PURPOSE OF REVIEW
Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]
are major cash crops worldwide. Globally projections indicate
that 917 million Mg of corn and 102 million Mg of soybean
will be produced in 2016 and 2017 (USDA, 2016). Given the
importance of corn and soybean in agricultural production,
it is vital to understand the impacts of salinization on growth
and development of these crops in an eort to eectively man-
age and prevent further encroachment of soil salinity and
reduce economic losses attributed to salinization. is review
contains two major components. e rst section addresses
the main mechanisms impeding plant productivity in saline
soils, as well as potential acclimation strategies used by plants
to mitigate the negative eects of excess salts. e proceeding
sections address these mechanisms with respect to corn and
soybean productivity, with the aim to provide a comprehensive
understanding of corn and soybean responses to soil salinity.
IMPACT OF SOIL SALINITY ON PLANTS
Once salts accumulate in the soil prole, biological growth
is inhibited by two main mechanisms: (i) osmotic or drought
stress and (ii) specic ion eects (Munns, 2002). Declines in
crop productivity are attributed to these stressors, which can
cause both direct impacts on biological functions (Munns,
2002; Rath and Rousk, 2015), as well as indirect eects on
soil physical and chemical conditions (Bronick and Lal, 2005;
Horie et al., 2012).
OSMOTIC OR DROUGHT STRESS
Drought stress is attributed to the alteration of the osmotic
potential of the soil solution surrounding the root zone due
to excess soluble salts (Maas and Nieman, 1978). While the
osmotic potential generally does not inuence soil water move-
ment, it plays a signicant role in the interaction between the
membranes or diusive barriers of roots and the surrounding
soil solution (Cowan, 1965). Consequently, root water uptake
for plants becomes increasingly dicult given that the roots
must exert more energy to remove water from the surround-
ing soil solution across the root membrane and into the plant
(Volkmar et al., 1998).
e inability to uptake water from the soil solution causes
the physiological drought stress commonly observed in plants
aected by excess soluble salts (de Oliveira et al., 2013). Osmotic
stress induces two physiological impacts: (i) cellular dehydration
and (ii) ion cytotoxicity (Munns, 2002). Cellular dehydration
oen results in cessation of growth and inhibition of metabolic
processes (Gupta and Huang, 2014) because of the replacement
of potassium (K+) ions with Na+ in necessary biochemical reac-
tions (Horie et al., 2012). Potassium is essential for cell turgor
maintenance, and the replacement of K+ with Na+ in metabolic
processes during salinity stress inhibits K+ uptake by the cell
(Gupta and Huang, 2014). In an eort to maintain ionic balance
within cells, some plants exhibit salt extrusion mechanisms that
transport toxic ions, like Na+, to cell vacuoles for sequestration
(Munns and Tester, 2008). Plants can also use organic solutes
to osmoregulate and increase water intake (Empadinhas and da
Costa, 2008; Gupta and Huang, 2014). For plants, osmoregula-
tion maintains turgor pressure potential of cells by increasing the
accumulation of organic solutes within the cell cytosol (Munns
and Tester, 2008) that do not interfere with normal physiological
function (Gupta and Huang, 2014). e increase in osmolytes in
cells and membranes can facilitate water movement back into the
cell, reducing the impact of osmotic stress on cellular dehydra-
tion (Horie et al., 2012). However, salt extrusion and accumu-
lation of osmolytes are highly energetic processes that require
both exportation and importation of extracellular ions against
concentration gradients of membranes (Rath and Rousk, 2015).
Furthermore, for salt exclusion mechanisms, the rate of salt
exclusion must exceed the rate of salt uptake by plant roots for
organisms to eectively compartmentalize salts into cell vacuoles
(Munns, 2002). If rates of uptake exceed rates of exclusion, salt
constituents can be distributed to aboveground portions of the
plant or throughout the cells (Munns, 2002; Wong et al., 2010).
As non-sequestered salt constituents accumulate in the cells and
tissues of organisms, specic ion eects begin to impede physi-
ological function (Munns, 2002).
SPECIFIC ION EFFECTS
Specic ion eects caused by soil salinity are physiologi-
cal eects of the individual salt constituents accumulating in
organic tissue (Läuchi and Epstein, 1984). While most salt
constituents are necessary for growth and development, they
can become lethal to cells and tissues of organisms in excess
(Table 2; Epstein, 1972, 1999). e eects of ions vary based
on the species and concentration of the ion contributing to the
toxicity. However, a common symptom of most excessive ion
concentrations is membrane damage (Volkmar et al., 1998).
Table1.Previousestimatesoftheglobaldistributionoflandim-
pactedbysoilsalinity.
Regions Extentofsalinization†
millionha
Africa 122.9
Asia 193.8
Australia 17.6
Europe 6.7
MiddleEast 91.5
NorthAmerica 6.2
CentralandSouthAmerica 71.5
†EstimatesoflandimpactedbysalinizationprovidedbyFAO(2015).
AgronomyJournal • Volume108,Issue6 • 2016 2191
Membrane damage results in several secondary eects includ-
ing, but not limited to, reduced cell and leaf expansion, stoma-
tal closure, photosynthetic inhibition, protein destabilization,
and cell death (Aslam et al., 2011). e secondary eects are
attributed to the replacement of K+ with Na+ in biochemical
reactions, as well as alterations in protein structure as a result
of excessive Na+ and Cl– (Shrivastava and Kumar, 2015). For
example, salinity stress triggers stomatal closure in response
to decreases in leaf turgor (Chaves et al., 2009). Stomatal clo-
sure results in a reduction in ambient CO2 assimilated by the
plant from inhibition of photosynthesis (Brugnoli and Lauteri,
1991). Because of the reduction in photosynthesis, chloroplasts
within the cell become excited and produce reactive oxygen
species (ROS; Aslam et al., 2011). Reactive oxygen species dam-
age biomolecules required for normal physiological function and
ultimately result in cell death (Das and Roychoudhury, 2014).
Sodium and Calcium
Sodium has the most negative impact on plant growth and
development when compared with other cation constituents
of salts because of its ability to induce Ca2+ and K+ decien-
cies (Bernstein, 1975). For example, Na+ displaces Ca2+ on
cell walls of plant membranes (Cramer et al., 1985; Kinraide,
1998). Displacement of Ca2+ from the plant membrane causes
protein denaturation and destabilization (Cramer et al., 1985).
Calcium ions enable mechanisms of cell detoxication to
counter the negative eects of Na+ (Lahaye and Epstein, 1969;
Kinraide, 1998; Tas and Basar, 2009) and restore K+ levels for
biochemical function (Cramer et al., 1985; Tuna et al., 2007),
but the ameliorative eect is reduced when Na+ concentrations
in an external solution exceed 250 mM (Cramer et al., 1985).
Despite its potential ameliorative eects, prolonged exposure
to excessive Ca2+ in the soil solution can still induce stressful
conditions on plants (Parida and Das, 2005). Higher concen-
trations of both Na+ and Ca2+ reduce the osmotic potential
of the soil solution and contribute to drought stress (Kinraide,
1998; Tölgyessy et al., 1993).
Magnesium
While Mg2+ is oen associated with salinity, little is known
about its toxic ion eects on plants. Similar to Ca2+, Mg2+ is also
recognized as an essential macronutrient for plants, as it plays a
role in enzyme activation, chlorophyll structure, and stomatal
maintenance and photosynthesis (Shaul, 2002). Additions of
dissolved MgSO4 to nutrient solutions have been linked to
improved photosynthetic capacity in maize plants grown under
Mg-decient conditions (Jezek et al., 2015). Magnesium can also
reduce the impacts of Na+-induced salinity using mechanisms
similar to Ca2+ detoxication of Na+, but its eects are reduced
in comparison to the benecial eects of Ca2+ (Kinraide, 1998).
Alternatively, substantially larger declines in aboveground
biomass of germinating corn was observed when corn seed-
lings were irrigated with dissolved MgSO4 compared to NaCl,
CaCl2, MgCl2, and Na2SO4 (Kaddah and Ghowail, 1964). At
isosmotic concentrations of these salts, percent weights declined
to 15.6, 41.3, 42.1, 40.2, and 31.7% relative to the non-saline
control, respectively (Kaddah and Ghowail, 1964). Furthermore,
indirect eects of excessive Mg2+ can induce environmental
stressors. For example, high levels of Mg2+ in the soil solution
contribute to the alteration of the osmotic potential, facilitat-
ing drought stress (Tölgyessy et al., 1993). Some studies have
also observed an indirect eect of Mg2+ on soil structure and,
consequently, soil water movement. For example, Mg2+–rich
soils are oen structurally degraded (Zhang and Norton, 2002).
e degradation can be similar to Na+-induced dispersion of
soil particles in sodic soils (Bronick and Lal, 2005). As soil par-
ticles disperse, water inltration and hydraulic conductivity are
reduced, which could exacerbate osmotic stress experienced by
the soil organisms (Qadir et al., 2013). However, the dispersive
eects of Mg2+ on soil structure are still controversial. Other
studies reported that Mg2+ did not signicantly increase disper-
sion in pure montmorillonite clays when compared to excess
Ca2+ (He et al., 2014) or reduce hydraulic conductivity in soils
dominated by montmorillonite or kaolinite clays (Rowell and
Shainberg, 1979).
Chloride and Sulfate
Both Cl– and SO42– have detrimental eects on plant
growth and development (Bernstein, 1975; Läuchi and
Epstein, 1984). Chloride is an essential micronutrient for
enzyme regulation and photosynthesis, but in excess of
800 mg soil kg–1 (Jing et al., 1992) or 15 mmol Cl L–1 in the
extract from a saturated paste (Maas, 1986), it becomes toxic to
salt sensitive species like corn and reduces yield to 95% relative
to the non-saline control (Jing et al., 1992). Chloride toxicity is
attributed to interference with nitrate (NO3–) uptake (Grattan
and Grieve, 1998) and chlorophyll degradation (Tavakkoli et
al., 2010). Chlorophyll degradation reduces photosynthetic
capacity in plants (Tavakkoli et al., 2010), and declines in pho-
tosynthesis ultimately diminish the plant’s supply of carbohy-
drates that can be used for growth (Munns and Tester, 2008).
Sulfate is considered a macronutrient (Leustek and Saito,
1999). Sulfate taken up by plants is reduced and incorporated
into two amino acids, cysteine and methionine (Leustek and
Saito, 1999). Studies addressing the impacts of excess sulfate
salts on plant growth are rare (Curtin et al., 1993) and results
vary between species. For example, aboveground biomass of
corn seedlings (G.H. 67 cultivar) irrigated with an NaCl solu-
tion with an osmotic potential of 2 atm (electrical conductivity
[EC] = 5.1 dS m–1) was reduced to 62% relative to the non-
saline control (Kaddah and Ghowail, 1964). e weight was
reduced to 52% relative to the control when the same variety
was irrigated with a 2 atm solution of Na2SO4 (Kaddah and
Ghowail, 1964). Alternatively, soybean was found to be more
tolerant to SO42– salinity when compared to Cl–-dominated
salinity (Gupta and Gupta, 1984). Dry matter yield of
Table2.Selectedmineralnutrientconcentrationsintissuesof
mostplantsrequiredforgrowthanddevelopment(Epstein,
1972,1999).
Mineral Concentration
%ormgL–1
Calcium† 0.5
Magnesium† 0.2
Sulfur† 0.1
Sodium‡ 10
Chloride‡ 100
†Macronutrientmeasuredasapercentage.
‡MicronutrientmeasuredinmgL–1.
2192 AgronomyJournal • Volume108,Issue6 • 2016
soybean (variety Black Tur) remained relatively constant up to
4224 mg SO42– L–1 (EC = 6.50 dS m–1; Gupta and Gupta,
1984). Despite the reduction in vegetative corn biomass during
germination, most studies typically attribute more detrimental
specic ion toxicities to Cl– ions because biochemical com-
pounds containing SO42–, like glutathione, are oen consid-
ered defense compounds that can alleviate eects of abiotic
stressors on plants (Leustek and Saito, 1999). Additionally,
other biochemical compounds, like glutamine, can reduce
excess SO42– accumulation in the plant which can reduce
detrimental impacts of SO42– (Kowalska, 2005). However,
similar to cations in the soil solution, increases in concentra-
tions of either anion can still contribute to the reduction in the
osmotic potential of the soil solution associated with drought
stress (Tölgyessy et al., 1993).
It should also be noted that soils dominated by sulfate salts
may exhibit structural degradation. Ion pairing of SO42– with
Ca2+ and Mg2+ can exacerbate Na+–induced dispersion in
SO42––dominated soils compared to Cl––dominated soils
(Springer et al., 1999). Removal of Ca2+ and Mg2+ ions from
solution facilitates adsorption of Na+ on the exchange sites of
soil particles (Springer et al., 1999). Because dispersion ulti-
mately impacts soil water movement (Wong et al., 2010), osmotic
stress could become more pronounced in SO42––dominated
soils. Furthermore, in addition to ion pairing, the relatively
low solubility of gypsum (CaSO4·2H2O) could also induce
Ca2+-deciencies in sulfate-dominated soils (Curtin et al.,
1993). Consequently, it is possible that declines in plants grown
in soils with excessive sulfate concentrations are partially attrib-
uted to deciencies in Ca2+ ( Janzen and Chang, 1987).
SOIL SALINITY AND
AGRICULTURAL PRODUCTIVITY
While research has been performed assessing the eects of
most salt constituents on plant growth and development, it is
important to acknowledge the inuence of the inherent genetic
tolerances of species and their varieties to osmotic stress and
specic ion toxicities (Munns, 2002). e combined eects of
drought stress and specic ion eects manifest themselves as
distinctive phenotypic eects on plant growth and develop-
ment (Munns, 2002). e physiological impacts on plants vary
not only with the composition and concentration of dissolved
salts contributing to salinity (Maas and Nieman, 1978; Curtin
et al., 1993), but also on the species of interest and the growth
stage of the crop (Bernstein, 1975; Maas, 1993; Rath and
Ro usk, 2015) .
CORN
Aboveground Biomass
In general, corn is most susceptible to salinity during the
vegetative stages of its life cycle, but the impact of salinity var-
ies among vegetative growth stages (Maas et al., 1983). Corn is
less susceptible to salinity stress during germination compared
to later vegetative growth stages (Table 3; Maas et al., 1983). In
a study assessing germination of hybrid G.H. 67 corn grown
in coarse sand to Na, Ca, and Mg chloride and sulfate salts,
Kaddah and Ghowail (1964) reported that almost all corn
plants successfully emerged despite a reduction in germination
rate. However, sulfate salts (Na2SO4 and MgSO4) induced
greater reductions in germination rate of seedlings compared
to chloride salts (Kaddah and Ghowail, 1964). Percent ger-
mination of Funk G4141, Pioneer 3369A, and Northrup
King PX32 cultivars was also delayed, but percent emergence
Table3.Corngrowthresponsestosalinityfromselectedpublications.
Authors Lifestage† Parameter‡ Medium§ ECx¶ Salt# ECT†† Slope‡‡
dSm–1 %perdSm–1
Maasetal.,1983 Vegetative Germination Topsoil,peat ECeNaCl/CaCl28.0 –
Blancoetal.,2007 Vegetative Germination Sandyloam ECiNaCl/CaCl2>5.9 –
KaddahandGhowail,1964 Maturity Yield Sandyclay,
Loam-sandyclay
ECeNaCl/CaCl22.0 20
MaasandHoffman,1977 Maturity Yield Topsoil,peat ECeNaCl/CaCl21.7 12
Katerjietal.,2000 Maturity Yield Loam ECsw NaCl/CaCl21.3 10.5
Blancoetal.,2008 Maturity Yield Sandyloam ECiNaCl/CaCl21.7 21
Maasetal.,1983 Vegetative Height Unknown ECeNaCl/CaCl20.7 4.9
Shalhevetetal.,1995 Vegetative Height Peat,siltloam,
sand
ECeNaCl/CaCl24.02 6.9
Blancoetal.,2008 Reproductive Height Sandyloam ECiNaCl/CaCl2– 8
Blancoetal.,2007 Vegetative Leafweight Sandyloam ECiNaCl/CaCl21.9 14
Katerjietal.,1996 Reproductive Leafarea Loam ECsw NaCl/CaCl2– 9.7
Amer,2010 Reproductive Leafarea Clayloam ECiMixture 1.92 8.2
Shalhevetetal.,1995 Vegetative Rootlength Peat,siltloam,
sand
ECeNaCl/CaCl24.09 9
†Growthstagecornmeasurementswerecollectedfrom.
‡Cropparametermeasured.
§Mediumusedtogrowcorn.
¶Typeofsalinitymeasured.ECeistheelectricalconductivity(EC)ofasaturatedpasteextr act ,ECiistheelectricalconductivityoftheirrigationwater
appliedtocorn,andECswistheelectricalconductivit yofthesoilsolutionwithinthepores.
#Speciesofsaltusedtoinducesalinity.MixtureofsaltscomposedofCa2+,Na+,Mg2+,Na+,K+,CO32–,HCO3–,Cl–,andSO42–.
††Thresholdsalinitytoler ancereportedbythestudy.
‡‡Slopeofdeclineobservedaf terthresholdsalinitytolerance.
AgronomyJournal • Volume108,Issue6 • 2016 2193
was not signicantly reduced until an ECe of 8.0 dS m–1 (1:1
NaCl/CaCl2; Maas et al., 1983). Even more, some cultivars
tested could germinate under salinities reaching 15.0 dS m–1
(Maas et al., 1983). Similarly, percent emergence of corn hybrid
AG-6690 grown in sandy loam soils was not aected by EC
of irrigation water (ECi) up to 5.9 dS m–1 (1:1 NaCl/CaCl2;
Blanco et al., 2007).
Aer germination, corn seedlings become increasingly more
susceptible to salinity stress (Fig. 1; Kaddah and Ghowail,
1964; Maas et al., 1983). At later vegetative growth stages,
signicant declines in shoot growth of Funk G4141, Pioneer
3369A, and Northrup King PX32 cultivar seedlings occurred
at an ECe above 0.7 dS m–1 by 5% per unit increase in ECe
(Maas et al., 1983). Dry matter of these varieties at the seedling
stage was reduced between 44 and 59% relative to a non-saline
control (Maas et al., 1983). e same corn varieties at mature
growth stages (tasseling or grain-lling) were substantially
more tolerant to increasing ECe and maintained 90 to 100%
relative biomass up to 9.3 dS m–1 (Maas et al., 1983). Relative
grain yield of these varieties at mature growth stages only
dropped below those of the non-saline control when ECe at the
vegetative stages exceeded 3.0 dS m–1 (Maas et al., 1983).
Despite an increased tolerance of corn at germination and
mature growth stages, greenhouse studies on the eects of soil
salinity on corn yield indicate a lower tolerance threshold to
excess soluble salts in the soil when corn was subjected to salin-
ity stress throughout the growing season. For example, irriga-
tion water with a 2:1 NaCl and CaCl2 concentration applied
at seeding signicantly decreased corn yield aer a threshold
ECe (ECT) of approximately 2.0 dS m–1 by 7.0% per dS m–1
increase (Kaddah and Ghowail, 1964). If salinity was initiated
21 d aer seeding (during the seedling stage), yields declined by
20% per dS m–1 aer 2.0 dS m–1 (Kaddah and Ghowail, 1964).
Salinity induced during reproductive or tasseling stages resulted
in declines of 10% per unit increase aer an ECT of 2.0 dS m–1
(Kaddah and Ghowail, 1964). In addition to the dependence of
tolerance on life stage, both the threshold and slope of decline
in corn yield seem to vary depending on the soil texture and N
application rate (Khalil et al., 1967; Beltrão and Asher, 1997).
For example, in modeled simulations for corn grown in non-
leached soils, corn yield declined aer ECe values of 1 dS m–1
in sandy soils and 2 dS m–1 in clay and loam soils (Beltrão and
Asher, 1997). Regardless of texture, tolerance thresholds of corn
yield to salinity increased with increasing N applications (Khalil
et al., 1967; Beltrão and Asher, 1997; Azizian and Sepaskhah,
2014). However, yields of salinity-stressed corn at the highest
rate applications of N were still lower than the non-saline control
at the same application rate (Fig. 2; Khalil et al., 1967). A review
of the eects of soil salinity on crop development and yield by
Katerji et al. (2000) reported results congruent with the studies
by Kaddah and Ghowail (1964) and Beltrão and Asher (1997):
declines in hybrid Asgrow 88 yield began at a threshold ECe
of 1.3 dS m–1 and decreased by 10.5% per unit increase in pore
water salinity (ECsw) for a lysimeter experiment. Salt tolerance
data compiled by Maas and Homan (1977) also substantiated
these values with a threshold salinity tolerance of 1.70 dS m–1
and a 12% decrease in relative corn yield for every dS m–1
increase in salinity.
Previous literature has also reported decreases in corn
height, leaf area index (LAI), and leaf N content in response
to increasing soil salinity. Declines in growth are potentially
a result of the reallocation of energy for growth processes to
osmotic maintenance of cells in the plant (Läuchi and Epstein,
1984). Alternatively, declines in growth could be attributed to
hormone signals from the root (Munns and Termaat, 1986).
Growth hormones, like cytokinin and abscisic acid (ABA), are
Fig.1.Effectofisosmoticconcentrationsofdifferentsaltsandtheircombinationsoncornseedlingbiomass.Osmoticpotentialsof1,2,
and3atmareequivalentto2.5,5.1,and7.6dSm –1,respectively.Allbiomassmeasurementsplottedarerelativetothenon-salinecontrol
withnosaltadded(100%).DatacompiledfromKaddahandGhowail(1964).
2194 AgronomyJournal • Volume108,Issue6 • 2016
produced in roots and could thus be used as a signal to regulate
shoot growth in water-stressed plants (Munns and Termaat,
1986). Height of corn hybrid AG 6690 exposed to salinity
at vegetative life stages decreased by 13% per unit increase
in ECe above a threshold of 1.9 dS m–1 in sandy loam soils
(Blanco et al., 2008). e threshold before decline increased to
4.02 dS m–1 and the slope of decline decreased to 6.9% per unit
increase in ECe when vegetative corn was grown in a mixture
of peat, silt loam, and sand (Shalhevet et al., 1995). Height of
hybrid cultivar SC704 mature corn decreased by 3.5% per unit
increase in ECe with no thresholds before decline in silty loam
soils (Azizian and Sepaskhah, 2014). Similarly, mature AG
6690 decreased linearly by 8% per unit increase in ECe with no
reported threshold (Blanco et al., 2008). While no exact over-
laps of data appear to occur among studies on corn height in
response to salinity, the general pattern of decreased height was
reported between all studies examined for both vegetative and
reproductive life stages of corn.
General declines in LAI have also been observed for corn
grown under saline conditions. Similar to declines in height,
declines in leaf area can be attributed to decreases in cell
and membrane turgor (Curtis and Läuchli, 1987). Another
study demonstrated that declines in LAI may be the result of
the reductions in photosynthesis during stressful conditions
(Aslam et al., 2011). Reduction in photosynthesis contributes
to a reduction in plant growth (Brugnoli and Lauteri, 1991)
which would ultimately result in reduced leaf area (Munns
and Tester, 2008). Alternatively, the decline in leaf area could
be an adaptation mechanism, which suggests that reduced cell
size in response to decreased turgor facilitates more ecient
maintenance of turgor at low water potentials (Cutler et al.,
1977). In a silty loam soil, LAI of cultivar SC704 declined by
3.4% per unit increase in ECe (Azizian and Sepaskhah, 2014),
but the slope of decline in LAI nearly tripled per unit increase
in ECe when corn was grown in a clay loam soil (Amer, 2010).
Similarly, canopy dry matter of hybrid Asgrow 88 grown in a
loam declined by 9.7% per unit increase in ECe, and the slope
of decline increased to 11.4% when grown in clay soil (Katerji
et al., 1996). Again, while thresholds and slopes of decline vary
among studies, a general decline in leaf area was reported for all
research examined.
Plant uptake of nutrients is generally diminished by increas-
ing levels of salinity because of the reduced osmotic potential
of the soil solution surrounding the root zone of plants (Fageria
et al., 2011). Nutrient uptake is both a function of transpira-
tion rate and the ability of roots to absorb nutrients under
water stress conditions (Tanguilig et al., 1987). However, stud-
ies examining the response of plant N-content have reported
contradictory results. For example, total soluble N of a pure
strain of corn grown in a 2:1 clay and sand mixture contained
150, 200, and 204% N relative to the control when irrigated
with 50, 100, and 200 mM of NaCl, respectively (EC = 6.2,
12.5, and 25.0 dS m–1, respectively; Bassuony et al., 2008).
However, total N-content decreased by 1.4% per unit increase
in EC (Bassuony et al., 2008). A lack of signicant dierences
in N-content of both leaves and roots of an RX 770 hybrid was
demonstrated by Tas and Basar (2009) whereby regardless of
the salts contributing to salinity, corn grown in a mixture of
peat and silt maintained 1.44 to 2.26% N in leaves and 1.08
to 1.85% N in roots (Fig. 3). While not signicant, higher N
contents in leaves and roots were observed when salts con-
tributing to salinity contained nitrate (NO3–; Tas and Basar,
2009). Similarly, Giza 310 corn grown in quartz sand had no
signicant changes in N-content in shoot dry mass up to an
osmotic potential of –0.9 MPa (EC = 22.5 dS m–1; Hamdia
and El-Komy, 1997). However, N assimilation from the air
and uptake from fertilizers by corn was signicantly decreased
at –1.2 MPa (EC = 30.0 dS m–1) to 41.3% relative to the non-
saline control (Hamdia and El-Komy, 1997). e discrepancies
among results could potentially be attributed to the types of N
Fig.2.EffectofincreasingNfertilizationoncorndrymatterinincreasinglysalinesoil.Salinitymeasuredusingasaturatedpasteextract
(ECe).Highestyieldsobtainedatlowestsalinity(ECe=3.5dSm–1)andhighestapplicationrate(2.9gN).Comparableyieldsmaintainedat
higherlevelsofsalinityifadequateNsupplied.DatacompiledfromKhaliletal.(1967).
AgronomyJournal • Volume108,Issue6 • 2016 2195
compounds analyzed. For example, N-containing amino acids,
proteins, and ammonium compounds accumulate in plants
in response to increasing levels of salinity (Mansour, 2000),
whereas NO3– decreases because of decreased photosynthetic
activity and Cl– inhibition (Tas and Basar, 2009).
Belowground Biomass
Generally, belowground biomass is less susceptible to salinity
stress than the aboveground portion of plants (Bernstein and
Hayward, 1958; Munns and Termaat, 1986). e increased
tolerance of roots to salt stress is likely attributed to an ability to
rapidly adjust the osmotic gradient of the root membrane when
salt stress occurs (Hsiao and Xu, 2000). However, both corn root
length and biomass have declined in response to increasing levels
of dissolved NaCl. Corn (B73 variety) root length at the seedling
life stage was signicantly dierent between three levels of salin-
ity, and biomass decreased by approximately 69 and 87% in 100
mM (12.5 dS m–1) and 200 mM (25.0 dS m–1) of NaCl, respec-
tively (Hoque et al., 2015). Khatoon et al. (2010) corroborated
these results at the germination stage of EV-1098 and Agaiti
varieties, but found that the impact of salinity on root length was
alleviated at later growth stages of the vegetative cycle. Similarly,
root weight of a mature corn grown in a sandy loam soil declined
by 11% per unit increase in depth weighted average ECe
(ECDWA ) in moist soils and 13% per unit increase in ECDWA in
dry soils (Al-Khafaf et al., 1989). Root growth in this study was
completely inhibited in layers of the soil that exceeded an ECe of
12.0 dS m-1 (Al-Khafaf et al., 1989).
Despite declines in both root biomass and length being
previously observed, it is important to reiterate that roots
can recover from osmotic stress induced by salinity (Munns,
2002). In a study assessing the rate of root extension in corn
seedlings in a nutrient solution, root extension of Pioneer 3906
in solutions up to 150 mM of NaCl (18.7 dS m–1) was not
signicantly dierent from the control with 0 mM of NaCl
(0 dS m–1) when the salt solution was added incrementally
(Rodríguez et al., 1997). Signicant dierences in the exten-
sion rate only occurred when corn seedlings were subjected
to salt shock, in which the desired concentration of NaCl was
added in one step to the nutrient solution (Rodríguez et al.,
1997). Furthermore, the salt shock treatment resulted in a sig-
nicant decline in root diameter of newly grown roots, whereas
this eect was not observed when corn seedling roots were
gradually introduced to salinity stress (Rodríguez et al., 1997).
SOYBEAN
Aboveground Biomass
Similar to corn, the growth stage of soybean dictates its
ability to tolerate salinity stress. Typically, germination is
more tolerant to salt stress than later vegetative growth stages
(Table 4; Phang et al., 2008). However, growth stage tolerance
is highly dependent on soybean variety (Phang et al., 2008).
Germination of soybean grown in coarse-textured soil was
reduced in all varieties studied aer an ECe of 8.1 dS m–1, but
the rate of reduction varied depending on the cultivar (Fig. 4;
Abel and MacKenzie, 1964). For example, germination of Lee
soybean was reduced by 6.6% per dS m–1 increase aer 20 d,
whereas germination of N53-509 was reduced by 8.7% per
unit increase in salinity (Abel and MacKenzie, 1964). Blanco
et al. (2007) corroborated a reduction in emergence, but
Fig.3.EffectofdifferentsaltcombinationsonNcontentinleavesandrootsofcorn.Foreachcombinationofsalts,NaClcontributed
12.5dSm–1toirrigationsolutionconductivity.Theremainingchlorideandnitrate(NO3–)saltscontributednegligibleconductivitytothe
totalEC.Nitrogencontentwasrelativelyconstantacrossallcombinationsofsalts,butincreasedabovecontrollevelswhenNO3–salt
appliedtocorn.DatacompiledfromTasandBasar(2009).
2196 AgronomyJournal • Volume108,Issue6 • 2016
observed lower thresholds of ECi before decline. Reduction in
percent emergence and speed of emergence of Conquista soy-
bean occurred at a threshold ECi of 2.7 dS m–1 and declined
by 20% per unit increase in ECi aer this threshold (Blanco
et al., 2007). Soybean yield response to soil salinity follows
similar patterns to corn, but thresholds before yield declines
are notably higher, indicating that higher levels of salinity
must be reached before declines in soybean productivity occur
(Steppuhn et al., 2005). Typically, discrepancies among results
oen cited the impact of soybean variety on tolerance to
explain the inconsistencies with threshold tolerances and the
slopes of yield declines (Abel and MacKenzie, 1964; Katerji et
al., 2000; Papiernik et al., 2005). For example, the Lee cultivar
(a salt-tolerant variety) declined linearly by 15.6% per unit
increase in atm NaCl (Bernstein and Ogata, 1966) or 20% per
unit increase in ECe (Maas and Homan, 1977) in a gravel
culture. Percent stem dry matter of the same variety declined
by 8.2% per unit increase in ECe aer an ECT of 5.0 dS m–1
Table4.Soybeangrowthresponsestosalinityfromselectedpublications.
Authors Lifestage† Parameter‡ Medium§ ECx¶ Salt# ECT†† Slope‡‡
dSm–1 %perdSm–1
AbelandMacKenzie,1964 Vegetative Germination Coarse,Gypsiferoussoil ECeNaCl 8.1 –
Blancoetal.,2007 Vegetative Germination Sandyloam ECiNaCl/CaCl22.8 19
AbelandMacKenzie,1964 Maturity Plantdensity Siltyclay ECeNaCl/CaCl25.0 30§§
MaasandHoffman,1977 Maturity Yield Topsoil,peat ECeNaCl/CaCl25.0 20
Katerjietal.,2000 Maturity Yield Loam ECsw NaCl/CaCl22.0 11.4
Blancoetal.,2007 Vegetative Height Sandyloam ECiNaCl/CaCl20.9 14
Shalhevetetal.,1995 Vegetative Height Peat,siltLoam,sand ECeNaCl/CaCl25.70 5.3
Blancoetal.,2007 Vegetative Leafweight Sandyloam ECiNaCl/CaCl21.0 21
Queirozetal.,2012 Vegetative Leafarea Nutrientculture ECiNaCl – 2.2
AbelandMacKenzie,1964 Reproductive Leafwidth Siltyclay ECeNaCl 6.5 5¶¶
Shalhevetetal.,1995 Vegetative Rootlength Peat,siltloam,sand ECeNaCl/CaCl25.08 6.6
BernsteinandOgata,1966 Reproductive Nodulation Fieldsoils ECeNaCl 7.0 –
†Growthstagesoybeanmeasurementswerecollectedfrom.
‡Cropparametermeasured.
§Mediumusedtogrowsoybean.
¶Typeofsalinitymeasured.ECeistheelectricalconductivityofasatur atedpasteextract,ECiistheelectricalconductivityoftheirrigationwater
appliedtosoybean,andECswistheelectricalconductivityofthesoilsolutionwithinthepores.
#Speciesofsaltusedtoinducesalinity.
††Thresholdsalinitytoler ancereportedbythestudy.
‡‡Slopeofdeclineobservedaf terthresholdsalinitytolerance.
§§SlopeofdeclineappliestoJacksonvariet ysoybean.
¶¶SlopeofdeclineappliestoLeevarietysoybean.
Fig.4.Effectofsoilsalinityonpercentgerminationafter20donfivesoybeanvarieties.Percentgerminationrelativelyunaffecteduntilan
ECeof8.1dSm–1.Afterthisthreshold,germinationofsalt-sensitivevarieties( JacksonandN53-509)wassubstantiallyreduced.Percent
germinationreducedbelow25%forallvarietiesat13.7dSm–1.DatacompiledfromAbelandMacKenzie(1964).
AgronomyJournal • Volume108,Issue6 • 2016 2197
in a silty clay soil (Abel and MacKenzie, 1964). Yield of Talon
soybean (a slightly salt-sensitive variety) declined by 11.4%
per unit increase in ECsw aer an ECT of 2.0 dS m–1 in loam
(Katerji et al., 2000), and percent stem dry matter of Jackson
soybean (a salt sensitive variety) declined by 56.7% per unit
increase in ECe in a silty clay soil up to 7.3 dS m–1 (Abel and
MacKenzie, 1964). Aer 7.3 dS m–1, complete stand loss of
Jackson variety soybean occurred (Fig. 5; Abel and MacKenzie,
1964). While inconsistencies in soybean tolerance exist among
cultivars, the generally accepted threshold tolerance and slope
of decline for soybean are 5.0 dS m–1 and 20% per unit increase
in ECe, respectively (Maas and Homan, 1977).
Similar to corn, soybean height also decreases with increas-
ing salinity because of the decline in turgor pressure attributed
to the osmotic adjustment of the plant with increasing soluble
salts (Curtis and Läuchli, 1987). Height of vegetative Elf soy-
bean grown in an equal ratio of perlite, peat, silt loam, and sand
declined by 5.3% per dS m–1 increase aer a threshold ECe of
5.70 dS m–1 (Shalhevet et al., 1995). Alternatively vegetative
Conquista variety soybean in a sandy loam soil declined by
approximately 14% per unit increase in ECi, with a substan-
tially lower threshold of 0.9 dS m–1 before decline (Blanco
et al., 2007). Height of mature Essex and Manokin varieties
grown in a coarse-textured soil decreased by 20% at an ECsw
of 7 dS m–1 compared to the non-saline control, whereas shoot
height of NA 4613 soybean plants near maturity in a sandy
loam soil irrigated with a solution at 8.0 dS m–1 were 75%
shorter than controls plants irrigated with water at an ECe of
0.01 dS m–1 (Bustingorri and Lavado, 2011). Similar to yield,
while discrepancies in height reductions appear across all stud-
ies examined, the general decline in height of soybean occurs
with increasing salinity. Furthermore, dierences among
results could be attributed to the dierent soybean varieties
studied (Phang et al., 2008).
Declines in leaf area have been correlated with increasing
levels of salinity in soybean plants. Khan et al. (2014) attrib-
uted signicant declines in leaf area to the low turgor pres-
sure induced by salinity stress, which ultimately resulted in
senescence of leaves. Similar to the reduction in photosynthesis
with increasing salinity in corn, declines in photosynthesis in
soybean also result from stomatal closure (ueiroz et al., 2012).
However, stomatal closure could also be a potential adapta-
tion to acclimate to saline conditions (ueiroz et al., 2012).
By closing stomatal apertures, plant transpiration is reduced
(Hsiao, 1973), allowing water to accumulate inside the plant
(Davenport et al., 1977). Conseqeuntly, while the decline in
photosynthesis reduces leaf area of the plant (Greenway and
Munns, 1980), it is possible that the reduction in leaf growth
is a response to decreasing water availability from soluble
salts (Davenport et al., 1977). Leaf dry weight of Conquista
soybean grown in a sandy loam soil declined by 21% per unit
increase in ECi aer a threshold of 1.0 dS m–1 (Blanco et al.,
2007). Similarly, leaf area of soybean cultivar IAC 17 decreased
2.2% per unit increase in ECi when irrigated with dissolved
NaCl with no observed threshold (ueiroz et al., 2012). Leaf
width of Lee soybean (a salt tolerant variety) declined by
approximately 6.5% per unit increase in ECe aer an ECT of
5.0 dS m–1(Abel and MacKenzie, 1964).
Reductions in nutrient uptake in soybeans have also been
previously reported and are likely attributed to declines in N2
xation (Delgado et al., 1994). Salinity reduces root nodula-
tion (Bernstein and Ogata, 1966), which reduces plant avail-
able N for uptake (Delgado et al., 1994). In eect, declines in
root nodulation reduce the eciency of N2 xation in legumes
(Phang et al., 2008). For example, root nodulation of Lee soy-
bean supplied with only a starter application of N (–NO3) was
reduced by 6.3% per unit increase in atm NaCl (Bernstein and
Ogata, 1966). Yields of –NO3 soybean declined by 15.6% per
Fig.5.Percentstand(populationdensity)ofmaturesoybeancultivarswithincreasingsalinity(ECe).Completelossofstandoccurred
at7.3dSm–1forsalt-sensitiveImprovedPelicanandJacksonvarieties.Salttolerantvarieties(LeeandN53-509)maintainedpopulation
densitiescomparabletothecontrolatanECeof10.2dSm–1.DatacompiledfromAbelandMacKenzie(1964).
2198 AgronomyJournal • Volume108,Issue6 • 2016
unit increase in atm NaCl because of declines in symbiotic N2
xation (Bernstein and Ogata, 1966). is decline was only
11.4% per unit increase in atm NaCl when Lee soybeans were
supplied adequate amounts of NO3 (Bernstein and Ogata,
1966). Similarly, N uptake in Talon variety soybean declined
by 18.1% in loam and 23.6% in clay per unit increase in ECi
(van Hoorn et al., 2001). e declines in N uptake were veried
by relatively constant values of N content in plant tissues aer
79 d (van Hoorn et al., 2001).
Belowground Biomass
Similar to corn, both root length and biomass of soybean
have declined in response to increasing levels of NaCl, but the
reduction in growth is less severe than aboveground compo-
nents of the plant (Bernstein and Ogata, 1966; Shalhevet et
al., 1995; Bustingorri and Lavado, 2011; ueiroz et al., 2012).
For example, Elf soybean root growth during vegetative stages
in equal parts perlite, peat, silt loam, and sand decreased aer
a threshold ECe of 5.08 dS m–1 by 6.6% per dS m–1 increase
(Shalhevet et al., 1995). Similarly, at an ECe of 4.0 dS m–1
in sandy loam soils, root biomass of the NA 4613 cultivar
at maturity (R8) was at least 50% of the non-saline control
(Bustingorri and Lavado, 2011). Alternatively, Bernstein and
Ogata (1966) observed no signicant dierences in root dry
weight up to an ECe of approximately 15.2 dS m–1, but instead
found that root nodulation of soybean declined nonlinearly.
Root fresh mass of IAC 17 soybean was also relatively constant
and maintained masses of 2.65 to 3.70 g up to NaCl concentra-
tions of 200 mM (EC = 25.0 dS m–1; ueiroz et al., 2012).
While contrasting results have been reported on root growth
in soybean subjected to salinity stress, it is possible that these
discrepancies are attributed to inherent tolerances of dierent
varieties (Phang et al., 2008). For example, salt-sensitive vari-
eties of soybean demonstrated more pronounced declines in
nodulation when compared to salt-tolerant varieties (Abd-Alla
et al., 1998). Consequently, it is possible that root growth of more
tolerant species is less impacted by salinity (Phang et al., 2008).
CONCLUSIONS
Previous studies indicate that corn yields begin to decline aer
an ECT of 1.7 dS m–1 by 12% per unit increase in ECe. Soybean
yield declines by 20% per dS m–1 aer an ECT of 5.0 dS m–1.
Accordingly, corn is typically considered more salt-sensitive to
soil salinity compared to soybean. However, the response of
soybean to excess soluble salts varies depending on variety. e
composition of soluble salts contributing to salinity also inu-
ence the response of corn and soybean growth and development.
For example, aboveground biomass of corn at germination was
lower when salinity was induced by SO42– salts compared to
Cl– salts, whereas soybean was able to better tolerate excessive
concentrations of SO42– salts up to 6.5 dS m–1. Growth stage of
the crop, nutrient availability, and soil texture also complicate
the responses of corn and soybean growth and development to
salinity. As a result, the impact of soil salinity on crop productiv-
ity is an immensely complicated interaction.
e majority of studies reported assessed corn and soybean
response to Cl–-based salinity. In most regions, chloride salts
are the dominant constituents contributing to soil salinity
(Munns and Termaat, 1986). However, other regions are
dominated by SO42– salts and our current understanding of
crop response to sulfate salinity is limited. Furthermore, the
use of a saturated paste extract (ECe) assumes saturated water
contents of the soil (Maas, 1986; Rengasamy, 2010). For dry-
land salinity, soil saturation is rarely achieved throughout the
growing season. Consequently, future research should also
address interactions of salinity and soil water and how those
conditions impact crop growth and development. Ultimately,
developing a more complete foundation of corn and soybean
response to salinity will provide better management guidelines
for improving productivity of salt-aected soils.
REFERENCES
Abd-Alla, M.H., T.D. Vuong, and J.E. Harper. 1998. Genotypic dier-
ences in dinitrogen xation response to NaCl stress in intact and
graed soybeans. Crop Sci. 38:72–77. doi:10.2135/cropsci1998.001
1183X003800010013x
Abel, G.H., and A.J. MacKenzie. 1964. Salt tolerance of soybean vari-
eties during germination and later growth. Crop Sci. 4:157–161.
doi:10.2135/cropsci1964.0011183X000400020010x
Al-Khafaf, S., K. Al-Janabi, I.A. Hussain, F.S. Manky, and L.H. Saliem.
1989. Maize root development under various levels of salin-
ity and water distribution. Agric. Water Manage. 15:377–385.
doi:10.1016/0378-3774(89)90053-X
Amer, K.H. 2010. Corn crop response under managing dierent irri-
gation and salinity levels. Agric. Waste Manage. 97:1553–1563.
doi:10.1016/j.agwat.2010.05.010
Aslam , R., N. Bostan, N .E. Amen, M. M aria, and W. Safdar. 2011. A criti-
cal review on halophytes: Salt tolerance plants. J. Med. Plants Res.
5:7108–7118.
Azizian, A., and A.R. Sepaskhah. 2014. Maize response to water, salin-
ity, and nitrogen levels: Physiological growth parameters and gas
exchange. Int. J. Plant Prod. 8:107–130.
Bassuony, F.M., R.A. Hassanein, D.M. Baraka, and R.R. Khalil. 2008.
Physiological eects of nicotinamide and ascorbic acid on Zea mays
plant grown under salinity stress II- Changes in nitrogen constitu-
ents, protein prole s, protease enzyme and cer tain inorganic cations.
Aust. J. Basic Appl. Sci. 2:350–359.
Beltrão, J., and J.B. Asher. 1997. e eect of salinity on corn yield
using the CERES-maize model. Irrig. Drain. Syst. 11:15–28.
doi:10.1023/A:1005726701554
Bernstein, L. 1975. Eects of salinity and sodicity on plant growth.
Annu. Rev. Phytopathol. 13:295–312. doi:10.1146/annurev.
py.13.090175.001455
Bernstein, L., and H.E. Hayward. 1958. Physiology of salt toler-
ance. Annu. Rev. Plant Physiol. 9:25–46. doi:10.1146/annurev.
pp.09.060158.000325
Bernstein , L., and G. Ogat a. 1966 . Eects of sali nity on nodulation, nitro-
gen xation, and growth of soybeans and alfalfa. Agron. J. 58:201–
203. doi:10.2134/agronj1966.00021962005800020025x
Blanco, F.F., M.V. Folegatt i, H.R. Ghey i, and P.D. Ferna ndes . 2007. Emer-
gence and growth of corn and soybe an under saline stress . Sci. Agric.
64:451–459. doi:10.1590/S0103-90162007000500001
Blanco, F.F., M.V. Folegatti, H.R. Gheyi, and P.D. Fernandes. 2008.
Growth and yield of corn irrigated with saline water. Sci. Agric.
65:574–580. doi:10.1590/S0103-90162008000600002
Bronick, C. J., and R. Lal . 2005. Soil str ucture and management: A rev iew.
Geoderma 124:3–22. doi:10.1016/j.geoderma.20 04.03.005
Brugnoli, E., a nd M. Lauteri. 1991. Eects of sali nity on stomatal conduc-
tance, photosynthetic capa city, and carbon isotop e discrimi nation of
salt-tolerance (Gossypium hirsutum L.) and salt-sensitive (Phaseolus
vulgaris L .) C3 non-halophytes. Plant Physiol. 95:628–635.
Bustingorri, C., and R.S. Lavado. 2011. Soybean grown under sta-
ble versus peak salinity. Sci. Agric. 68:102–108. doi:10.1590/
S0103-90162011000100015
AgronomyJournal • Volume108,Issue6 • 2016 2199
Chaves, M.M., J. Flexas, and C. Pinheiro. 2009. Photosynthesis under
drought and sa lt stress: Regulation mechanisms from whole plant to
cell. A nn. Bot. (Lond.) 103:551–560. doi:10.1093/aob/mcn125
Cowan, I.R. 1965. Transport of water in soil-plant-atmosphere system. J.
App. Eco. 2:221-239.
Cramer, G.R., A. Läuchli, and V.S. Polito. 1985. Displacement Ca2+ by
Na+ from the plasmalem ma of root cells. Plant Physiol. 79:207–211.
doi:10.1104/pp.79.1.207
Curtin, D., H. Steppuhn, and F. Selles. 1993. Plant responses to sulfate
and chloride salinity: Growth and ionic relations. Soil Sci. Soc. Am.
J. 57:1304–1310. doi:10.2136/sssaj1993.03615995005700050024x
Curtis, P.S., and A. L äuchli. 1987. e eect of moderate salt stress on lea f
anatomy of Hibiscus cannabinus (Kenaf ) and its relation to leaf area.
Am. J. Bot. 74:538–542. doi:10.2307/2443833
Cutler, J.M., D.W. Rains, and R.S. Loomis. 1977. e importance of cell
size in the water relations of plants. Pla nt Physiol. 72:931–937.
Das, K., and A. Roychoudhury. 2014. Reactive oxygen species (ROS) and
response of antioxidants as ROS-scavengers during environmental
stress in plants. Front. Environ. Sci . 53:1–13.
Davenport, D.C., R .M. Haga n, and K. Urlu. 1977. Reducing transpi ration
to conserve water in soil and plants. Calif. Agric. 31:40– 41.
Delgado, M.J., F. Ligero, and C. Lluch. 1994. Eects of salt stress
on growth and nitrogen xation by pea, faba-bean, common
bean and soybean plants. Soil Biol. Biochem. 26:371–376.
doi:10.1016/0038-0717(94)90286-0
de Oliveira, A.B., N.L.M. Alencar, and E. Gomes-Filho. 2013. Compari-
son between the water and salt stress eects on plant growth and
development. In: S. Akinci, editor, Responses of organisms to water
stress. InTech, Rijeka, Croatia.:p. 67–94.
Empadin has, N., and M. S. da Costa. 20 08. Osmoadaptation mecha nisms
in prokaryotes: Distribution of compatible solutes. Inter. Microbio.
11:151–161.
Epstein, E. 1972. Mineral nutrition of pants: Principles and perspectives.
John Wiley & Sons , New York.
Epstein, E. 1999. Silicon. Annu. Rev. Plant Physiol. Plant Mol. Biol.
50:641–664. doi:10.1146/annurev.arplant.50.1.641
Fageria, N.K., H.R . Gheyi, and A. Moreira . 2011. Nutrient bioavailabil ity
in salt aected soils. J. Plant Nutr. 34:945–962. doi:10.1080/01904
167.2011.555578
Food and Agricultural Organization. 2015. Status of the world’s soil
resources . FAO, Rome.
Grattan, S.R., and C.M. Grieve. 1998. Salinity-mineral nutrient rela-
tions in horticultural crops. Sci. Hortic. (Amsterdam) 78:127–157.
doi:10.1016/S0304-4238(98)00192-7
Greenway, H., and R. Munns. 1980. Mechanisms of salt tolerance in non-
halophytes. Annu. Re v. Plant Physiol. Plant Mol. Biol. 31:49–90.
Gupta, V.K., and S.P. Gupta. 1984. Eect of zinc sources and levels on
the growth and Zn nutrition of soybean (Glycine max L.) in the
presence of chloride and sulphate salinity. Plant Soil 81:299–304.
doi:10.1007/BF02197164
Gupta, B., a nd B. Huang. 2014. Mechanism of sa linity tolerance in pl ants:
Physiological, biochemical, and molecular characterization. Int. J.
Genet . 2014 :1–18. doi:10 .1155/2014/ 701596
Hamdia, M.A., and H.M. El-Komy. 1997. Eect of salinity, gibberellic
acid, and Azospirillum on growth and nitrogen uptake of Zea mays.
Biol. Plant. 40:109-120.
He, Y., T.M. DeSutter, and D.E. Clay. 2014. Dispersion of pure clay min-
erals as i nuenced by calcium/magnesiu m ratios, sodium adsorpt ion
ratio, and electr ical conductivity. Soil Sci . Soc. Am. J. 77:2014–2019.
Hoque, M.M.I., Z. Jun, and W. Guoying. 2015. Evaluation of salinity tol-
erance in maize (Zea may L.) genotypes at seedling stage. J. Biosci.
Biotechnol. 4:39–49.
Horie, T., I. Karahara, and M. Katsuhara. 2012. Salinity tolerance mech-
anisms in glycophytes: An overview with the central focus on rice
plants. R ice (N. Y.) 5:11–27. doi:10.1186/1939-8433-5-11
Hsiao, T.C. 1973. Plant responses to wate r stress. Annu. Re v. Plant Physiol.
24:519–570. doi:10.1146/annurev.pp.24.060173.002511
Hsiao, T.C., and L .K. Xu. 20 00. Sensitivit y of growth of roots versus leaves
to water stress: Biophysical a nalysis and relation to water tra nsport. J.
Exp. Biol. 51:1595–1616.
Janzen, H.H., and C. Chang. 1987. Cation nutrition of barley as inu-
enced by soil solution composition in a saline soil. Can. J. Soil Sci.
67:619– 629. doi:10.4141/cjss87-058
Jezek, M., C.M. Geilfus, A. Bayer, and K.H. Mühling. 2015. Photosyn-
thetic capacity, nutrient status, and growth of maize (Zea mays L.)
upon MgSO4 lea f-application. Front. Plant Sci. 5:1–10. doi:10.3389/
fpls.2014 .00781
Jing, A.S., B.C. Guo, and X.Y. Zhang. 1992. Chloride tolerance and its
eects on yield and quality of crops. Chinese J. Soil S ci. 33:257–259.
Kaddah, M.T., and S.I. Ghowail. 1964. Salinity eects on the growth
of corn at dierent stages of development. Agron. J. 56:214–217.
doi:10.2134/agronj1964.00021962005600020028x
Katerji, N., J.W. van Hoorn, A. Hamdy, F. Karam, and M. Mastro-
rilli. 1996. Eect of salinity on water stress, growth, and yield
of maize and sunower. Agric. Water Manage. 30:237–249.
doi:10.1016/0378-3774(95)01228-1
Katerji, N., J.W. van Hoorn, A. Hamdy, and M. Mastrorilli. 2000. Salt
tolerance classication of crops according to soil salinity and
to water stress day index. Agric. Water Manage. 30:237–249.
doi:10.1016/0378-3774(95)01228-1
Keller, L.P., G.J. McCarthy, and J.L. Richardson. 1986. Mineralogy and
stability of soil evaporites in North Dakota. Soil Sci. Soc. Am. J.
50:1069–1071. doi:10.2136/sssaj1986.03615995005000040047x
Khalil, M .A., F. Amer, and M.M . Elgabaly. 1967. A salinity-ferti lity inter-
action study on corn and cotton. Soil Sci. Soc. Am. Proc. 31:683–
686. doi:10.2136/sssaj1967.03615995003100050021x
Khan, S.A., A.A. Mamun, A.A. Mahmud, M. Bazzaz, A. Hossain, S.
Alam et al. 2014. Eects of salt and water stress on leaf production,
sodium and potassium ion accumulation in soybean. J. Plant Sci.
2:209–214.
Khatoon, T., K. Hussain, A. Majeed, K. Nawaz, and M.F. Nisar. 2010.
Morphologica l var iations in maize (Zea mays L .) under d ierent lev-
els of NaCl at germinating stages. World Appl. Sci. J. 8:1294–1297.
Kinra ide, T.B. 1998. ree mechan isms for the calcium a lleviation of min-
eral toxicities . Plant Physiol. 118:513–520. doi:10.1104/pp.118.2.513
Kowalska, I. 2005. Eects of sulphate level in nutrient solution on
plant growth and sulphur content in tomato plants. Folia Hortic.
17:91–100.
LaHaye, P.A., and E. Epstein. 1969. Salt toleration by plants: Enhance-
ment with calcium. Science (Washington, DC) 166:395–396.
doi:10.1126/science.166.3903.395
Läuchi, A., and E. Epstein. 1984. Mechanisms of salt tolerance in plants.
Ca lif. A gric . 18:18–20 .
Leustek, T., and K. Saito. 1999. Sulfate transport and assimilation in
plants. Plant Physiol. 120:637–64 4. doi:10.1104/pp.120.3.637
Maas, E .V. 1986. Physiological response to chloride. In: T.L. Jackson, edi-
tor, Special bulletin on chloride and crop production. Potash. Phos-
phate Inst., Atlanta, GA. p. 4 –20.
Maas, E.V. 1993. Testing crops for salinity tolerance. In: J.W. Maranville,
B.V. Baligar, R.R. Duncan, and J.M. Yohe, editors, Proceedings
Workshop on Adaptation of Plants to Soil Stresses, Lincoln, NE.
1–4 Aug. 1993. Vol. 94. INTSOR MIL, Lincol n, NE. p. 234–247
Maas, E.V., and G.J. Homan. 1977. Crop salt tolerance: Current assess-
ment. J. Irrig . Drain. Div. 103:115–134.
Maas, E.V., G.J. Homan, G.D. Chaba, J.A. Poss, and M.C. Shannon.
1983. Salt sensitivity of corn at various growth stages. Irrig. Sci.
4: 45–57. d oi:10.10 07/BF 002 85556
Maas, E .V., and R. H. Nieman. 1978. Physiology of plant tolera nce to salin-
ity. Vol. 32. G.A. Jung. Crop tolerance to suboptimal land condi-
tions. ASA , CSSA, and SSSA, Madison, WI. p. 277–299.
2200 AgronomyJournal • Volume108,Issue6 • 2016
Mansour, M.M.F. 2000. Nitrogen containing compounds and adap-
tations of plants to salinity stress. Biol. Plant. 43:491–500.
doi:10.1023/A:1002873531707
Martinez-Beltrán, J., and C.L. Manzur. 2005. Overview of salinity prob-
lems in the world and FAO strategies to add ress the problem. In: Pro-
ceedings of the International Salinity Forum, Riverside, CA. April,
2005. FAO, Rome. p. 311–313.
Munns, R. 2002. Comparative physiology of salt and water stress. Plant
Cell Environ. 25:239–250. doi:10.1046/j.0016-8025.2001.00808.x
Munns, R ., and A. Termaat. 1986. Whole plant resp onses to salinit y. Aust.
J. Plant Physiol. 13:143–160. doi:10.1071/PP9860143
Munns, R., and M. Tester. 2008. Mechanisms of salinity toler-
ance. Annu. Rev. Plant Biol. 59:651–681. doi:10.1146/annurev.
arplant.59.032607.092911
Papiernik, S.K., C.M. Grieve, S.M. Lesch, and S.R. Yates. 2005. Eects
of salinity, imazethapyr, and chlorimuron application on soybean
growth and yield. Commun. Soil Sci. Plant Anal. 36:951–967.
doi:10.1081/CSS-200050280
Parida, A.K., and A.B. Das. 2005. Salt tolerance and salinity eects
on plants: A review. Ecotoxicol. Environ. Saf. 60:324–349.
doi:10.1016/j.ecoenv.2004.06.010
Phang, T.H., G. Shao, and H.M. Lam. 2008. Salt toler-
ance in soybean. J. Integr. Plant Biol. 50:1196–1212.
doi:10.1111/j.1744-7909. 2008.00760.x
Qadir, M., E. uillerou, V. Nangia, G. Murtaza, M. Singh, R.J. omas,
P. Dreschel, and A.D. Noble. 2014. Economics of salt-induced land
degradation and restoration. Nat. Resour. Forum 38:282–295.
doi:10.1111/1477-8947.12054
Qadir, M., F. Vyshpolsky, K. Mukamedjanov, U. Bekbaev, S. Ibatullin, T.
Yuldashev et al. 2013. Enhancing the productivity of high-magne-
sium soil and water resources in Central Asia. Land Dev. Degrada-
tion 19:45–4 6.
ueiroz, H.M., L . Sodek, and C.R. Baptista Haddad. 2012. Eect of salt
growth and metabolism on Glycine max. Braz. Arch. Biol. Technol.
55:809–817. doi:10.1590/S1516-89132012000600002
Rath, K.M., and J. Rousk. 2015. Salt eects on microbial decomposer
community and their role in organic carbon cycling: A review. Soil
Biol. Biochem . 81:108–123.
Rengasamy, P. 2010. Soil processes aecting crop production in salt-
aected soils. Functional Plant Biol. 37:613–620. doi:10.1071/
FP09249
Richards, L.A., editor. 1954. Diagnosis and improvement of saline and
alk ali soils. USDA Agr ic. Handb. 60. U.S. Gov. Print. O ce, Wash-
ington, DC.
Rodríguez, H.G., J.K.M. Roberts, W.R. Jordan, and M.C. Drew. 1997.
Growth, water relations, and accumulation of orga nic and inorgan ic
solutes in roots of maize seedlings during salt stress. Plant Physiol.
113:881–893.
Rowell, D.L., and I. Shainberg. 1979. e inuence of magnesium and
easily weathered minerals on hydraulic conductivity changes in a
sodic soil. J. Soil Sci. 30:719–726. doi:10.1111/j.1365-2389.1979.
tb01021.x
Shalhevet, J., M.G. Huck, and B.P. Schroeder. 1995. Root and shoot
growth in response to salinity in maize and soybean. Agron. J.
87:512–516. doi:10.2134/agronj1995.00021962008700030019x
Shaul, O. 2002. Magnesium transport and function in plants: e tip of
the iceberg. B ioMeta ls 15:30 7–321. d oi:10.102 3/A:10160 91118585
Shrivastava, P., and R. Kumar. 2015. Soil salinity: A serious environmen-
tal issue and plant growth promoting bacteria as one of the tools
for its alleviation. Saudi J. Biol. Sci. 22:123–131. doi:10.1016/j.
sjbs.2014.12.001
Springer, G., B.J. Wienhold, J.L. Richardson, and L.A. Disrud. 1999.
Salinity and sodicity induced changes in dispersible clay and satu-
rated hydraulic conductivity in sulfatic soils. Commun. Soil Sci.
Plant Anal. 30:2211–2220. doi:10.1080/00103629909370366
Steppuhn, H. , M. . van Genuchten, and C. M. Grieve. 2005 . Root-zone
salinity: II. Indices for tolerance in agricultural crops. Crop Sci.
45:221–232. doi:10.2135/cropsci2005.0221
Suarez, D.L. 20 05. Chemistry of salt-aected soils. Chemical processes in
soils. SSSA, Madison, W I. p. 689–705.
Tanguilig, V.C., E.B. Yambao, J.C. O’Toole, and S.K. Dedatta. 1987.
Water-stress eects on leaf elongation, leaf water potential, transpi-
ration, and nutrient uptake of rice, maize, and soybean. Plant Soil
103:155–168. doi:10.1007/BF02370385
Tas, B., and H. Basar. 2009. Eects of various salt compounds and their
combinations on grow th and stress indicators in ma ize. Afr. J. Ag ric.
Re s. 4:15 6–161 .
Tavakkoli, E. , P. Rengasa my, and G. K. McDonald. 2010. Hig h concentra-
tions of Na+ and Cl- ion in solution have simultaneous detrimen-
tal eects on growth of faba bean under salinity stress. J. Exp. Bot.
61:4449– 4459. doi:10.1093/jxb/erq251
Tölgyessy, J., P. Pitter, M. Piatrik, and J. Prousek. 1993. e chemistry
of water. In: J. Tölgyessy. Chemistry and biology of water, air, and
soil: Environmental aspects. Elsevier Sci. Publ., Amsterdam, the
Netherlands.
Tuna, A.L., C. Kaya, M. Ashraf, H. Altunlu, I. Yokas, and B. Yagmur.
2007. e eects of calcium su lphate on growth, membrane stabi lity
and nutrient uptake of tomato plants grown under salt stress. Envi-
ron. Exp. Bot. 59:173–178. doi:10.1016/j.envexpbot.2005.12 .007
USDA. 2016. World ag ricultural supply and dem and estimates. WASDE-
553. USDA, Washington, DC .
van Hoorn, J.W., N. Katerji, A. Hamdy, and M. Mastrorilli. 2001. Eect
of salinity on yield and nitrogen uptake of four legumes and on bio-
logical nitrogen contribution from the soil. Agric. Water Manage.
51:87–98. doi:10.1016/S0378-3774(01)00114-7
Volkmar, K.M., Y. Hu, and H. Steppuhn. 1998. Physiological response of
plants to sal inity: A review. Can. J. Plant Sci. 78:19–27. doi:10.4141/
P9 7- 020
Wang, W., B. Vincour, and A. Altman. 2003. Plant response to drought,
salinity, and extreme temperatures: Towards genetic engineering for
stress tolerance. Pla nta 218:1–14. doi:10.1007/s00425- 003-1105-5
Wong, V.N.L., R.S.B. Greene, R.C. Dalal, and B.W. Murphy. 2010. Soil
carbon dynamics in saline and sodic soils: A review. Soil Use Man-
age. 26:2–11.
Zhang, X.C., and L.D. Norton. 2002. Eect if exchangeable Mg on
saturated hydraulic conductivity, disaggregation, and clay disper-
sion of disturbed soils. J. Hydrol. 260:194–205. doi:10.1016/
S0022-1694(01)00612-6
