沙漠研究 24-1, 213-221 (2014)
Ἃ₍◊✲ 24-1, 213 -221 (2014)
Journal of Arid Land Studies
Journal of Arid Land Studies－ DT11 Refereed Paper －㸫DT11 Refereed Paper㸫Effects of Saline Irrigation on Four Native Texas Plant Species with
Ornamental Potential for Coastal and Arid Climate Landscapes
Sean T. CARVER*1), Michael A. ARNOLD1), David H. BYRNE1), Anna R. ARMITAGE2),
R. Daniel LINEBERGER1) and Andrew R. KING1)
Abstract: Effects of saline irrigation were tested on four taxa with potential as native landscape plants for saline or arid
environments: Borrichia frutescens (L.) DC., Erigeron procumbens (Houst. ex Mill.) G.L. Nesom, Oenothera drummondii Hook., andSesuvium portulacastrum (L.) L. In four separate experiments, plants were grown in 2.3 L containers and irrigated with fourconcentrations (0, 8.75,17.5, 35 and 70 g L-1) of saline water, representing electrical conductivities (EC) of 0.8, 15.1, 23.8, 51.3 and92.5 mS cm-1, either applied sub-canopy or over the foliage. Salinity was derived from 2NaCl:1CaCl2 and concentrations roughly
represent the salinity of quarter, half, full and double the salinity of seawater. Treatments above half the salinity of seawater decreased
most growth measures, with notable exceptions for S. portulacastrum. All four species tolerated regular irrigation with watercontaining salinity of as much as half or more of seawater and showed minimal damage with one quarter seawater. Growth
responses, mineral nutrient content, Na content, and K/Na ratios were consistent with reports of the halophytic nature of S.
portulacastrum. Research herein demonstrates that these potential new landscape plants can tolerate the application of saline waterwith salt concentrations of up to one quarter that of seawater with minimal aesthetic impacts and show potential for landscape testing inchallenging coastal and arid region environments where the use of recycled water is necessary.
Key Words: Borrichia frutescens, Erigeron procumbens, Mineral nutrition, Oenothera drummondii, Sesuvium portulacastrum

1. Introduction
With the decreasing availability of high quality irrigationwater in urban areas in arid environments new ornamental
plants need to be developed for landscapes that will thrive withuse of lower quality irrigation water. A strategy often
employed in built environments in arid regions is to stretch
water supplies via utilization of recycled or poorer quality
non-potable water sources, which are often higher in salinity,
for landscape irrigation (Miyamoto et al., 2001, 2002). An
important ingredient in successfully implementing such a
strategy will be the identification and development of suitablelandscape taxa capable of thriving with saline irrigation water.
Texas and the Southwestern USA have regions that are classic
arid environments and even the more mesic portions are prone
to extended droughts and limited water resources (Arnold,2008).
Demand for high quality water for humanconsumption may make the use of recycled water to irrigate
urban landscapes inevitable (Niu and Rodriguez, 2006). The
composition of treated waste water varies among communities
and depends on composition of the original source of water,
and type and number of industrial, commercial and residential
users that are contributing to the source of treated waste water(Harivandi, 2000). With recycled water, such as treatedeffluent, the major concern is elevated salinity which can be as
much as two to three times the level of potable water (Khurram
and Miyamoto, 2005). After most recycled water treatment
processes, sodium chloride is the most deleterious chemicalremaining (Wu et al., 2001). Foliar necrosis and plant death
are major concerns of using irrigation water with highconcentrations of salts (Fox et al., 2005; Miyamoto et al., 2001,
2002).
Salts can induce a number of stress responses in plants:
salts can affect general water balance, ion toxicity especially
Na+, Cl-, or SO42-, and inhibit nutrient uptake. Water balancein the plant is affected by the dissolved solutes in the root zone
causing a low osmotic potential which reduces soil water
potential. This results in an analogous situation to water
deficit even when an otherwise sufficient amount of water isavailable (Taiz and Zeiger, 2006). Plants can adjust, to someextent, to prevent a loss of turgor pressure through a reduced
osmotic potential, however growth may be slowed and often
plants exhibit stress responses similar to adjustment to water
deficit (Taiz and Zeiger, 2006). Ions of Na+, Cl-, or SO42- canaccumulate to toxic levels in plants in saline environments(Marschner, 1995). The accumulation of ions, especially ahigh ratio of Na+ to K+, can inhibit protein synthesis and㸦Received, September 14th, 2013; Accepted, December 10th, 2013㸧

* Corresponding Author: scarver@neo.tamu.edu
HFSB TAMU 2133, College Station, TX 77843-2133
1) Department of Horticultural Sciences, Texas A&M University, USA

2) Department of Marine Biology, Texas A&M University, USA214

Table 1. Transplant dates and mean greenhouse temperatures for each separate salinity experiment with the four species tested.
P lanted in 0.47 L P lanted in 2.3 L

Species

Cuttings Rooted

B. frutescens

13-Feb-11

2-Mar-11

1-Apr-11

9-Apr-11

5-Mar-11

31.6

17.2

24.7

E. procumbens

25-Apr-11

2-Mar-11

16-Mar-11

25-Mar-11

23-Jun-11

31.9

20.5

27.1

P ots

pots

Treatment Started

HarvestMax. Temp (ºC)

Min. Temp (ºC)

Mean Temp (ºC)

O. drummondii

9-Mar-11

16-Mar-11

31-Mar-11

9-Apr-11

29-Apr-11

31.6

18

24.6

S. portulacastrum

18-Mar-11

23-Mar-11

7-Jun-11

15-Jun-11

14-Jul-11

32.7

22.3

28

inactivate enzymes and may eventually lead to cell death (Taizand Zeiger, 2006).
All of these responses to salt stress can lead to a loss ofornamental appeal. A buildup of ions from the transpirational
stream can lead to leaves with necrotic margins, chlorosis, orleaf abscission giving the plant a general unhealthy appearance
that is unacceptable for ornamental use (Maas, 1993;
Marschner, 1995; Sykes, 1993). Salt ions interfering orinteracting with nutrient absorption can also lead to chlorotic
plants that are unacceptable in ornamental applications (Arnold,
2008; Maas, 1993; Marschner, 1995; Sykes, 1993).
The appearance of plants in the landscape is extremely
important to landscape managers, designers, and people using
the space (Fox et al., 2005). The use of salt tolerant or
halophytic species could potentially reduce the ornamental
liabilities of salt stress, allowing lower quality irrigation water
to be used in production of plant materials and landscapeirrigation without a loss of ornamental function.
Sesuvium portulacastrum (L.) L., Borrichia frutescens (L.)
DC., Oenothera drummondii Hook. and Erigeron procumbens(Houst. ex Mill.) G.L. Nesom. are species native to Texas
coastal regions (Richardson, 2002) and were selected for thesestudies because of their natural tolerance to salinity, especiallyin the form of sodium and chlorine ions, associated withseawater exposure in their coastal ranges. All of these species
offer interesting foliage, form and/or flowering attributes which
would make them potentially desirable landscape plants.
Native plants were also selected because they pose a low
potential for invasiveness compared to exotics. The purposeof this study is to quantify the salinity tolerances of these four
potential landscape species in support of cultivar selection
research.

2. Materials and Methods
Four separate experiments were conducted with the samegeneral protocols but on different dates (Table 1). Tip
cuttings, 4-6 cm long, were taken from containerized stock
plants of single accessions maintained in a gravel nursery inCollege Station, TX. Basal ends of cuttings were dipped intalc based IBA at the concentration of 1 g·kg-1 (Hormodin® 1,
OHP, Inc., Mainland, PA). Cuttings were placed in 36 cm ×51 cm × 10 cm deep flats (Kadon Corp., Dayton, Ohio) filledwith coarse perlite (Sun Gro Horticulture Canada Ltd, Seba
Beach, AB). Intermittent mist was applied at 16 min intervals
for 15 sec duration using reverse osmosis water from 1 h
before sunrise to 1 h after sunset. Rooted cuttings were
potted in 0.47 L black plastic pots (Dillen Products,
Middlefield, OH) containing calcined clay amended with 6.53
kg m-3 15N-3.9P-9.9K controlled release fertilizer (Osmocote®
Plus, Scotts Co., Marysville, Ohio), 0.89 kg m-3 micronutrient
fertilizer (Micromax®, Scotts Co., Marysville, Ohio), 1.78 kg
m-3 CaSO4 (United States Gypsum Co., Chicago, Ill.) and 4.15
kg m-3 CaMgCO3 as per the methods of Denny (2007).
Liners were later potted into 2.3 L containers filled with themedia described above and placed on greenhouse benches in acompletely randomized design with five replicates of eachtreatment. Mean temperature, minimum, and maximum
temperature were recorded for each experiment (Table 1).
Treatments were 2NaCl:1CaCl2 (Denny, 2007; Solis-Perez,2009) added at the rates of 0.00, 8.75, 17.50, 35.00, or 70.00 g
L-1 to reverse osmosis water, representing electricalconductivities (EC) of 0.8, 15.1, 23.8, 51.3 and 92.5 mS cm-1,
applied either over the top of the canopy contacting the foliage
or sub-canopy not contacting the foliage. Irrigation waterwith a salt concentration of 35 g L-1 roughly represents thesalinity of seawater (Denny, 2007; Miyamoto et al., 2004;
Southorn, 1995).
All treatments were wateredsimultaneously as needed with 800 mL (> 25% leaching
factor).
At the time of harvest, plant heights, widths, leaf count, leaf
area and internode lengths were recorded. Chlorophyll
content was sampled spectrophotmetrically by removing fiveleaf discs from each plant and extracting in 80% acetone(Bryan, 2008; Harborne, 1984). A foliar damage rating of 1-5
was taken by the same observer at harvest, with 1) representing
a dead plant or plant near death (unacceptable for ornamentaluse), 2) plant with severe damage to the canopy but surviving(unacceptable for ornamental use with 50-90% of the foliage
exhibiting necrotic regions), 3) plant with severe to mild
damage to the canopy, (20-40% of the foliage exhibiting
necrotic regions), 4) very mild damage to the plant canopy,
canopy is full with <10% of the foliage having necrotic regions(acceptable ornamental landscape plant) and 5) no damage tothe plant canopy (acceptable ornamental landscape plant).
Fresh and dry shoot and root weights were recorded. Shoots

215

Table 2. Main effects of salinity on growth measures for individual species in individual studies.
Leaf Area (cm 2)
B. frutescens

O. drummondii

S. portulacastrum

Height (cm)Internode (cm)Shoot Mass (g)Foliar Damage

E. C. of Media

Rating (1-5)(mS·cm -1)

Control (0 g·L -1 )521.3±44.3 x125.3±8.9

36.0±1.265.7±1.6

Low (8.75 g·L -1 )498.0±46.0

132.4±12.1

33.4±1.154.8±1.5

Medium (17.5 g·L -1 )307.4±29.0

111.3±10.6

29.2±1.0

Med-High (35 g·L -1 )123.5±18.8

42.7±6.1

18.6±1.4---

Linear

*** z

***

***

***

***

-

***

Quadratic

***

***

***

***

***

-

***
2.2±0.2

High (70 g·L -1 )E. procumbens

Leaf Count

7.9±0.8

5.0±0.0 y

0.5±0.2

7.9±0.8

5.0±0.0

4.3±0.942.7±1.6

5.4±0.5

5.0±0.0

7.7±0.4

28.0±1.5

2.4±0.3

5.0±0.0

12.2±1.5---

16.1±1.8

Control (0 g·L -1 )684.8±59.5

614.5±52.0

6.1±0.3

22.8±1.0

9.1±0.6

4.9±0.1

Low (8.75 g·L -1 )232.5±25.6

238.5±28.3

5.6±0.4

19.9±1.0

3.3±0.5

4.5±0.2

7.7±1.1

Medium (17.5 g·L -1 )121.9±20.7131.9±21.4

5.1±0.3

12.5±0.6

2.4±0.4

3.7±0.2

10.5±1.1

Med-High (35 g·L -1 )26.2±8.528.5±9.2

5.2±1.24

8.9±1.0

0.7±0.2

2.8±0.6

15.7±2.1

High (70 g·L -1 )

-

-

-

-

-

-

32.3±1.8

Linear

***

***

n.s.

***

***

-

***

Quadratic

***

***

n.s.

***

***

-

**

Control (0 g·L -1 )1033.2±41.1

565.0±26.7

12.6±1.0

12.2±0.6

7.9±0.8

5.0±0.0

0.9±0.1

Low (8.75 g·L -1 )491.5±39.0

275.1±18.7

17.8±1.0

9.0±0.4

7.9±0.8

4.5±0.5

6.6±0.5

Medium (17.5 g·L -1 )192.6±28.5

99.2±12.1

11.7±0.9

6.6±0.6

5.4±0.5

3.6±0.3

8.9±0.6

Med-High (35 g·L -1 )

-

-

-

-

2.4±0.3-

14.2±1.0

High (70 g·L -1 )

-

-

-

-

-

-

25.6±1.3

Linear

***

***

n.s.

***

***

-

***

Quadratic

***

***

**

***

***

-

**

Control (0 g·L -1 )607.7±26.3

288.1±20.2

23.5±2.568.2±2.626.4±1.1

5.0±0

1.0±0.2

Low (8.75 g·L -1 )837.7±32.1

331±18.2

15.6±0.8

69.7±1.8

33.1±1.1

5.0±0

8.1±0.3

Medium (17.5 g·L -1 )617.2±21.1

278.6±12.7

18.5±0.863.5±1.929.5±0.8

4.9±0.1

15.0±1.2

Med-High (35 g·L -1 )357.5±9.2

153.6±8.3

19.8±1.363.5±1.719.3±0.4

4.9±0.1

18.4±1.4

High (70 g·L -1 )75.0±8.954.8±5.5

9.6±0.833.7±1.8

8.0±0.4

1.8±0.227.8±1.7

Linear

***

***

***

***

***

-

**

Quadratic

***

***

***

***

***

-

*

x

Values represent means (± standard errors) of 10 observations. Lack of observations indicates mortality.
Foliar damage ratings range from a 1 (most severe damage) to a 5 (no observable damage). Unable to apply linear or quadratic regression due tonon-normal data.
z *,**,***, or n.s. indicates significance of the linear or quadradic regression component at P  0.05, 0.01, 0.001, or not significant, respectively.
yfrom three plants in each treatment were rinsed in distilledwater to remove external salts and analyzed for N, P, K, Ca,
Mg, S, Na, Fe, Mn, Zn, Cu and B content (Texas A&M
AgriLife Ext. Ser. Soil, Water and Forage Testing Laboratory,
College Station, TX). Electrical conductivity of the media
was determined using the 1:5 method described by Lang
(1996).
An analysis of variance for the interactions among
application methods and salinity level treatments within eachstudy was conducted using JMP 2009 and SAS 9.3 (SASInstitute Inc., Cary, NC) for continuous variables. If
interactions were not significant, then data were pooled into themain effects and they were analyzed for significance. All
non-normal data was analyzed using permutations in thelmPerm package (Wheeler, 2010) in R (R Core Team, 2013),
set to defaults.

3. Results and Discussion
3.1. Growth responses
Interactions among application modes and salinity levels
were not significant (P0.05) for any of the growth measures,
thus only main effects are presented. The main effects ofsalinity level were significant (P0.05) for all growth measuresand media EC (Table 2). Increasing salinity levels generally
resulted in progressive decreases in all growth measures
recorded except for those of S. portulacastrum and height of O.
drummondii (Table 2). Sesuvium portulacastrum leaf area,leaf number, and shoot mass were stimulated by the lowest
salinity exposure (38%, 15% and 25%, respectively, comparedto the controls), consistent with reports that it is a halophyte(Lonard and Judd, 1997). Sesuvium portulacastrum was able

216

to survive regular irrigation with salinity at 70 g L-1, equivalent
to nearly twice the salinity of seawater, which resulted in anelevated mean substrate EC of 27.8 mS cm-1. This isconsistent with the natural occurrence of S. portulacastrum
immediately adjacent to the ocean on dunes. The meanheight of O. drummondii was increased 41% by low levels ofsalt in the irrigation solution, but other measurements
decreased with increasing salinity exposure and O.
drummondii typically succumbed to salinity of 35 g L-1 orgreater (Table 2). Treating B. frutescens and E. procumbens
with salt concentrations of 70 g L-1 killed them, but theysurvived regular irrigation with salinity equivalent to that ofseawater. However, E. procumbens plants treated with 35 g
L-1 foliar applied died while plants treated with same
concentration applied sub-canopy survived.
Internode length was reduced 51% at 70 g L-1 and only 7%
at 35 g L-1 for S. portulacastrum (Table 2). Salt treatments
also reduced internode length for E. procumbens (61% at 35 gL-1), O. drummondii (46% at 17.5 g L-1) and B. frutescens(57% at 35 g L-1). The reduction in internode extension could
be beneficial during nursery or greenhouse production by
reducing the need for plant growth retardants. The interaction
among application modes and salinity levels for O.
drummondii was significant (P0.001) for chlorophyll
concentrations, but only the main effects of salinity weresignificant (P0.05) for B. frutescens, E. procumbens and S.
portulacastrum. For all four species tested, chlorophyll
content increased with increasing salinity then declined (Fig. 1).
At the highest salinity level tested chlorophyll concentrationfor S. portulacastrum was reduced 36% compared to controls
at 70 g L-1. In O. drummondii there was an interaction among
the concentrations of total salts and modes of application inwhich chlorophyll concentration was reduced 4% at 17.5 g L-1
when applied foliarly but increased 67% when applied
sub-canopy at the same concentration. In all cases initial
treatment with saline water was accompanied by an increase in
the concentration of chlorophyll per unit of leaf area (Fig. 1).
This increase might be due to the decrease in leaf area and apossible increase in leaf thickness (Poljakoff-Mayber, 1975;
Longstreth and Strain, 1977).
3.2. Sesuvium portulacastrum mineral content
Phosphorus was not affected by the application of salt
solution in S. portulacastrum (Table 3). For all other mineral
concentrations tested there was not an interaction among themodes of application and amounts of salt solutions (Table 3).
In S. portulacastrum the application of salt solutions resulted in
an increase in the concentrations of N, K, Ca, Cu and Na at alllevels tested (Table 3). This is in contrast to results of
Teixeira and Carvalho (2009) in the salt tolerant Portulaca

Fig. 1. Chlorophyll Concentration. Interactions among salt (0, 8.75
and 17.5 g L-1) levels and application methods for O. drummondii
and main effects of salt levels for B. frutescens, E. procumbens
and S. portulacastrum. Symbols for O. drummondii representmeans (± s.e.) of n=5. Symbols for B. frutescens, E. procumbens
and S. portulacastrum represent means (± s.e.) of n=10.
Regressions equations are based on means and are presented
when significant at P0.05. Equations were not included for O.
drummondii due to mortality of the two most saline treatments.

oleracea L., Kachout et al. (2011) in the halophyte Atriplex L.,
and Carter and Grieve (2010) in Zinnia elegans Jacq. where
decreases were found in K and Ca concentrations when plants
were treated with saline irrigation water. Tissue levels of Na
were elevated in all salinity treatments compared to thecontrols for S. portulacastrum (Table 3) as was the case for O.
drummondii (Table 4), E. procumbens (Table 5) and B.
frutescens (Table 6). However, salinity levels in tissues of S.
portulacastrum were greatest at the lower salinity levels (Table3), rather than at the greater salinity levels as was seen with theother three species (Tables 4, 5 and 6). This suggests someNa accumulation may have taken place at lower salinity levels.
The K/Na ratios for S. portulacastrum were also different fromthat of the other three species (Fig. 2A, B, C versus D).
Foliar applied salinity resulted in a more rapid and severe dropin the K/Na ratio for the other three species (Fig. 2A, B, C)
than for S. portulacastrum in which the interaction was not
significant indicating similar effects for either foliar or substrate
exposure to elevated salinity (Fig. 2D). Competition between
Na and K uptake has been reported for a number of plants(Marschner, 1995).
Nitrogen concentration was increased 38% by theapplication of a salt solution of 70 g L-1 to S. portulacastrum.
Concentrations of Fe, Mg and S were decreased at all levels
tested (Table 3). Boron, Mn and Zn shoot contents decreased
with low levels of salt then increased with the application of
more concentrated salt solutions, as compared to controls(Table 3). In S. portulacastrum, Zn showed a decrease inshoot content at all levels except 70 g L-1 where Zn
concentration was increased 62% (Table 3). This was similar
to Teixeira and Carvalho (2008) who also found a decrease in217

Table 3. Mean shoot concentrations for minerals with significant interaction between mode of application and salt concentration for S.
portulacastrum grown in 2.3 L containers irrigated with varied concentrations of 2NaCl:CaCl2 solutions.
Macronutrients
Sub-Canopy

FoliarANOVA Effects

N (% )

P (ppm)K (ppm)Ca (ppm)

Mg (ppm)

S (ppm)0 g·L -1

2.6±0.1 y4285.7±334.8

30680.7±557.6

7731.3±870.54023±405.8

6019±495.5

8.75 g·L -1

2.4±0.1

4748.7±334.1

40327±702.99954±1192.4

2603±159.2

5125.7±627.4

17.5 g·L -1

2.5±0.04676.3±420.2

39953.3±1342.9 10678.3±1011.7

2459.3±1774408.3±219.7

35 g·L -1

2.8±0.14637±391.1

32051±406.5

11234±377

2153±24.8

4125.3±245.4

70 g·L -1

3.9±0.3

5415.3±20342433.3±1280.1

17855±1770.8

3981.3±68.7

5617.7±50.2

0 g·L -1

2.7±0.14910±167.1

33271.3±932.2

8499.3±1147.3

3876.3±168.8

6291.7±455.1

8.75 g·L -1

2.4±0.1

3910.7±259.8

39273.3±2750.8

7892±135.2

2275.7±274.2

4327.7±402.7

17.5 g·L -1

2.4±0.15006±157.9

37207±1812

11473.7±1154.5

2361.7±131.7

4181.7±403.1

35 g·L -1

2.8±0.1

5340.7±609.1

31920±798.8

11229.3±276.6

2182.7±40.63835.7±139.6

70 g·L -1

3.6±0.1

5266.7±222.7

37707.3±1234.4

21959±586.4

3792.3±1044987±371.9

Irrigation mode

0.583 z

0.401

0.172

0.322

0.165

0.192

Salt concentration<0.0001***

0.057<0.0001***<0.0001***<0.0001***<0.0001***

0.786

0.182

0.132

0.065

0.937

0.669

Mode x salt concentration

Micronutrients
Sub-Canopy

FoliarANOVA Effects

Zn (ppm)

Fe (ppm)

Cu (ppm)

Mn (ppm)

Na (ppm)

B (ppm)0 g·L -1

15.3±0.943.3±8.8

5.7±0.3

153.3±11.68.75 g·L -1

14.3±2.433.7±5.57±0.6

133±10.568.7±6.2

17.5 g·L -1

12.3±2.425±3

7.7±0.9

106.3±15.446860.7±476.6
82387.3±
82387.3±10881.1
10881 181218.7±7270.3

35 g·L -1

11.7±1.5

21.3±0.9

6.3±0.7101±1579868.3±4983.7

58.3±4.7

70 g·L -1

24±0.626.7±2.7

9.7±0.7

184±9.7

69476.7±1665.7

96.3±60 g·L -1

47433.7±1106.4

88±3.661±3.6z58.3±4.1

16±1.539±4.65.7±0.3

137.7±19.88.75 g·L -1

15.3±222±3.66.7±0.3

114.3±10.480804±8616.8

17.5 g·L -1

13.3±1.530±1.57±0.6

93.3±8.4

78715±4696.5

61±2

35 g·L -1

14.3±0.927.3±37±0

94.3±8.680388±6802.258.7±0.3

70 g·L -1

26.7±1.524.3±39±0.6

187.3±20.769478.7±4904

100.3±5.8

Irrigation mode

0.177

0.824

0.686

0.31

0.804

0.98

Salt concentration<0.0001***

0.006<0.0001***<0.0001***<0.0001***<0.0001***

1

0.239

0.913

1

1

0.665

Mode x salt concentrationy85±2.5

Values represent means (± standard errors) of 3 observations.
NS,*,**,***Non significant or significant at P  0.05, 0.01, or 0.001, respectively. Mode of application either foliar or sub-canopy. Level is 0, 8.75,
17.5, 35 and 70 g L-1 of 2NaCl:CaCl2. P values are permutation test p-values.

Zn, however they did not treat plants with irrigation water
having a total salt concentration near the greatest concentrationin this study.
3.3. Oenothera drummondii mineral content
For O. drummondii all mineral concentrations had
significant effects except for B (Table 4). There wereinteractions among the modes of application and salt
concentrations for N, Ca, Mg, Na, Zn, Fe and Cu in O.
drummondii (Table 4). Concentrations of Ca, Cu, Na and Zn
increased as compared to controls for both modes ofapplication and all salt concentrations tested. Potassium, Mg
and P had decreased mineral concentrations compared tocontrols for all salt concentrations in O. drummondii. Thissuggests Ca, Cu and Na were preferentially taken up by theplants as salt concentrations increased (Table 4). This issimilar to studies with Antirrhinum majus L., considered
tolerant of saline irrigation, which also showed increasing
concentrations of Ca and Na with decreasing concentrations of
K and P (Carter and Grieve, 2008) and Zinnia elegans which
also showed decreasing K with increasing salt concentrations(Carter and Grieve 2010). Nitrogen was decreased 17% by
the foliar application of irrigation water with a total salt
concentration of 8.75 g L-1, but increased 63% by sub-canopy
application of irrigation water at the same concentration with O.
drummondii (Table 4).
3.4. Erigeron procumbens mineral content
Treatments did not have effect on N, Mg, Cu, S or B in E.
procumbens. There were interactions among the modes ofapplication and salt concentrations for Na, Ca and P (Table 5).
Mode of application was only significant for P and Zn. Zinc

218

Table
Table 4.
4. MeanMean shoot
shoot concentrations
concentrations forfor minerals
minerals with
with significant
significant interaction
interaction between
between mode
mode ofof application
application andand salt
salt concentration
concentration forfor O.
O.
drummondii grown
grown inin 2.32.3 L
L containers
containers irrigatedirrigated with
with variedvaried concentrations
concentrations ofof 2NaCl:CaCl
2NaCl:CaCl22 solutions.
solutions.
drummondii
Sub-Canopy
Sub-Canopy

FoliarFoliar

N
N (%
(% ))
y
2.6±0.3
2.6±0.3 y

P
P (ppm)(ppm)
5402.7±501.5
5402.7±501.5

17.5 g·L
g·L -1-1
17.5

4.2±0.2
4.2±0.2
4.0±0.2
4.0±0.2

5097.3±181.8
5097.3±181.8
5047.3±153.7
5047.3±153.7

g·L -1-100 g·L
8.75 g·L
g·L -1-18.75

3.4±0.4
3.4±0.4
2.8±0.2
2.8±0.2

17.5
17.5 g·L
g·L -1
Irrigation
Irrigation mode
mode
Salt
Salt concentration
concentration

3.0±0.2
3.0±0.2
Z
0.028*
0.028* Z
0.097
0.097

5019.3±12.75019.3±12.74573.3±277.1
4573.3±277.1
3966.3±298.8
3966.3±298.8

Mode
Mode xx salt
salt concentration
concentration

0.002**
0.002**

0.77
0.77

Zn
Zn (ppm)(ppm)
47.3±1.847.3±1.8

Fe
Fe (ppm)(ppm)
112±11.2
112±11.2

17.5 g·L
g·L -1
-1
17.5

108±8
108±8
91.7±12.2
91.7±12.280.3±15.780.3±15.7
125.7±25.7
125.7±25.7

g·L -1-100 g·L
8.75 g·L
g·L -1-18.75

55.7±6.7
55.7±6.7
68.7±1.2
68.7±1.2

17.5 g·L
g·L-1
17.5
Irrigation
Irrigation mode
mode
Salt
Salt concentration
concentration-100 g·Lg·L -1-1
8.75
g·L
8.75 g·L -1

-1

ANOVA
ANOVA Effects
Effects

Sub-Canopy
Sub-Canopy

FoliarFoliar-1
00 g·Lg·L -18.75 g·L
g·L -1-1
8.75

-1

ANOVA
ANOVA Effects
Effects

Mode
Mode xx salt
salt concentration
concentration

Macronutrients
MacronutrientsK
K (ppm)(ppm)
29439±1234.7
29439±1234.7
24035±260.724035±260.7

Ca
Ca (ppm)(ppm)
17240.3±1229.9
17240.3±1229.9
22062.3±668.8
22062.3±668.8

Mg
Mg (ppm)(ppm)
3597±92.53597±92.5
2518.3±128.7
2518.3±128.7

S
S (ppm)(ppm)
6568.7±261.2
6568.7±261.2
7005.3±305.2
7005.3±305.2

23667.3±837.6
23667.3±837.6

26425.3±897.8
26425.3±897.8

2661±53.2
2661±53.2

5366±420.1
5366±420.1

30272.3±483.5
30272.3±483.5
24509.7±583.6
24509.7±583.6

15585.7±652.4
15585.7±652.4
24090±761.9
24090±761.92984±162.3
2984±162.3
2160.3±1502160.3±1507258.7±549.9
7258.7±549.9
5159.3±529.2
5159.3±529.2

22500.7±980.3
22500.7±980.3
0.922
0.922

31809±1930.5
31809±1930.5
0.055
0.055

2892.3±76.2
2892.3±76.2
0.018*
0.018*

5070±644
5070±644
0.198
0.198

<0.0001***<0.0001***
0.5
0.5<0.0001***<0.0001***
0.026
0.026

<0.0001***<0.0001***
0.009
0.009

0.007**
0.007**
0.073
0.073

13.7±1.2
13.7±1.2
32±3.632±3.6Mn
Mn (ppm)(ppm)
312.7±53.5
312.7±53.5
306±32.8306±32.8

Na
Na (ppm)(ppm)
8045±868.3
8045±868.3
15523.3±1259.1
15523.3±1259.1

B
B (ppm)(ppm)
71±0.671±0.622±2.522±2.5226.3±6.3
226.3±6.317995.7±1801.1
17995.7±1801.1

69.3±3.3
69.3±3.3
67.3±3.867.3±3.880.7±1.980.7±1.997±33.597±33.515.3±2.3
15.3±2.319±1
19±1

85.7±10.2
85.7±10.2
0.075
0.075

25.7±1.225.7±1.2
0.028
0.028

21±2.321±2.30.047
0.047

258.7±20.7
258.7±20.7
220.7±23.7
220.7±23.7
260.7±34260.7±3410033.3±339.1
10033.3±339.1
16485.7±304.2
16485.7±304.2
36851.7±5320.5
36851.7±5320.5

68±4.268±4.258.3±1.958.3±1.972±972±90.001**
0.001**
0.039*
0.039*

0.55
0.55
0.038*
0.038*

0.001**
0.001**
0.020*
0.020*

0.143
0.143
0.449
0.449

0.002**
0.002**<0.0001***<0.0001***
0.003**
0.003**

0.37
0.37
0.329
0.329
0.287
0.287

0.003**
0.003**
0.058
0.058

Micronutrients
MicronutrientsCu
Cu (ppm)
(ppm)

0.153
0.153

yy Values represent means (± standard errors) of 3 observations.
Values represent means (± standard errors) of 3 observations.
zz NS,*,**,***Non significant or significant at P ≤ 0.05, 0.01, or 0.001, respectively.

NS,*,**,***Non significant or significant at P ≤ 0.05, 0.01, or 0.001, respectively. Mode
Mode ofof application
application either
either foliar
foliar oror sub-canopy.
sub-canopy. Level
Level isis 0,0, 8.75,
8.75,-1of
35 andvaluesarearepermutation
permutationtest
testp-values.
p-values.
17.5, 35,
35,
and70
70gggLL
L-1-1
of2NaCl:CaCl
2NaCl:CaCl222... P
PPvalues
valuesarepermutation
test
p-values.
17.5,
and
70
of
2NaCl:CaCl

Table 5.
5. Meanshoot concentrations
concentrations forfor minerals
minerals with
with significant
significant interaction
interaction between
between mode
mode ofof application
application andand salt
salt concentration
concentration forfor E.
E.
Table
Mean shootprocumbens
procumbens grown
grown inin 2.32.3 L
L containers
containers irrigatedirrigated with
with variedvaried concentrations
concentrations ofof 2NaCl:CaCl
2NaCl:CaCl22 solutions.
solutions.
Macronutrients
MacronutrientsK
K (ppm)(ppm)
20921.3±502.6
20921.3±502.6
15611.7±311.3
15611.7±311.3
19063.3±2066
19063.3±2066
16050.0±281.6
16050.0±281.6

CCa
a (ppm)(ppm)
7973.7±540.8
7973.7±540.8
13652±521.4
13652±521.4
14393.7±362.7
14393.7±362.7
25918.3±1253.0
25918.3±1253.0

Mg
Mg (ppm)(ppm)
2455.7±222.6
2455.7±222.6
2819.3±652819.3±652634.7±217
2634.7±217
3382.0±73.1
3382.0±73.1

S
S (ppm)(ppm)
4838±221
4838±2215445.3±1745445.3±1744829.7±268.4
4829.7±268.4
5723.0±223.3
5723.0±223.3

Sub-Canopy
Sub-Canopy

-1
0 g·L
g·L-1
0
-1
8.75 g·L
g·L-1
8.75
-1
17.5
g·L
17.5 g·L-1
-1
-1
35
g·L
35 g·L

FoliarFoliar

-1
0
0 g·L
g·L-1
-1
8.75 g·L
g·L-1
8.75
-1
17.5
g·L-1
17.5 g·L

3.4±0.1
3.4±0.1
3.2±0.1
3.2±0.1
3.3±0.1
3.3±0.14438±151.5
4438±151.5
4067.3±196.5
4067.3±196.5
4609.7±250.7
4609.7±250.7

20806±12820806±12815202.7±1811.3
15202.7±1811.3
16396.3±1953.1
16396.3±1953.1

8174.3±258.4
8174.3±258.4
16233±3302.6
16233±3302.6
24873.3±1526
24873.3±1526

2849±123.82849±123.82667±165.7
2667±165.7
2558.7±87.2
2558.7±87.2

5615.7±120.7
5615.7±120.7
5743.3±586
5743.3±586
4643±165.54643±165.5

ANOVA
ANOVA Effects
Effects

Irrig.
Irrig. mode
mode
Salt
Salt concentration
concentration
Mode x
x saltsalt concentration
concentration
Mode

z
0.784
0.784 z
0.697
0.697
0.578
0.578

0.014*
0.014*
0.013*
0.013*
0.015*
0.015*

0.667
0.667
0.002**
0.002**
0.635
0.635

0.302
0.302
<0.0001***<0.0001***
0.015
0.015

0.563
0.563
0.172
0.172
0.21
0.21

0.534
0.534
0.076
0.076
0.295
0.295

Fe (ppm)(ppm)
Fe74±16.1
74±16.1
115.7±33115.7±3358.3±4.458.3±4.4
252.7±38.6
252.7±38.6

Micronutrie
Micronutrie nts
nts
Cuu (ppm)(ppm)
C
19.7±0.7
19.7±0.7
21.7±1.7
21.7±1.7
19.7±1.2
19.7±1.2
26.3±2.0
26.3±2.0

Mn (ppm)(ppm)
Mn
302.7±15.6
302.7±15.6359.3±26.6359.3±26.6344.3±38.1
344.3±38.1
475.3±56.0
475.3±56.0

Na (ppm)(ppm)
Na
16917.3±1392.5
16917.3±1392.5
29346.3±466.7
29346.3±466.7
26757±1325.4
26757±1325.4
41780.0±1167.5
41780.0±1167.5

B (ppm)(ppm)
B
80.7±3.280.7±3.275±2.375±2.380.3±7.3
80.3±7.3
84.7±2.2
84.7±2.2

Sub-Canopy
Sub-Canopy

-1
0
0 g·L
g·L-1
-1
8.75
g·L
8.75 g·L-1-1
17.5 g·L
g·L-1
17.5
-1
35 g·Lg·L-1
35

Zn (ppm)(ppm)
Zn41.3±1.541.3±1.5
77±7.177±7.153.3±2.953.3±2.961.0±7.1
61.0±7.1

FoliarFoliar

-1
0
0 g·L
g·L-1
-1
8.75
g·L
8.75 g·L-1-1
17.5 g·L
g·L-1
17.5

38.3±0.938.3±0.956.3±9.856.3±9.855.3±3.555.3±3.579.3±17.3
79.3±17.3
138.3±10.7138.3±10.7
91±25.4
91±25.4

20.3±0.3
20.3±0.3
20.3±0.920.3±0.9
21±1.521±1.5293±10.6
293±10.6
349.7±44.8
349.7±44.8334.3±14.2
334.3±14.2

19410±549.9
19410±549.9
30932.7±5329.2
30932.7±5329.2
43436±2140.1
43436±2140.1

84±2.684±2.683±983±975.3±275.3±2ANOVA Effects
Effects
ANOVA

Irrig. mode
mode
Irrig.
Salt
Salt concentration
concentration
Mode
Mode x
x saltsalt concentration
concentration

0.021
0.021
0.005
0.005
0.127
0.127

0.332
0.332
0.045*
0.045*
0.778
0.778

0.583
0.583
0.544
0.544
0.468
0.468

0.643
0.643
0.010*
0.010*
1
1

0.473
0.473
<0.0001***<0.0001***
0.018*
0.018*

0.312
0.312
0.593
0.593
0.579
0.579

xx Values represent means (± standard errors) of 3 observations.
Values represent means (± standard errors) of 3 observations.
-1 foliar did not survive.
yy E. procumbens treated with 35 g L-1
zzP
P (ppm)(ppm)
3907±272
3907±272
4958.7±130.2
4958.7±130.2
4318.7±199.4
4318.7±199.4
3978.3±80.43978.3±80.4

N
N (%)
(%)
3.2±0.1 xx
3.2±0.1
3.4±0.2
3.4±0.2
3.3±0.3
3.3±0.3y
3.3±0.3
3.3±0.3 y

E.
E. procumbens
procumbens treatedtreated with
with 35
35 gg LL foliar
foliar did
did not
not survive.
survive.
 0.05,
NS,*,**,***Non significant
significant oror significant
significant at
at P
P≤
≤
0.05, 0.01,
0.01, oror 0.001,
0.001, respectively.
respectively. Mode
Mode ofof application
application either
either foliar
foliar oror sub-canopy.
sub-canopy. Level
Level isis 0,0, 8.75,
8.75,
NS,*,**,***Non-1-1 of2NaCl:CaCl
35 andvaluesarearepermutation
permutationtest
testp-values.
p-values.
17.5,
and
70
17.5, 35,
35,
and70
70gggLL
L-1ofof 2NaCl:CaCl
2NaCl:CaCl222... P
PPvalues
valuesarepermutation
test
p-values.

219

Table
Table 6.
6. MeanMean shoot
shoot concentrations
concentrations forfor minerals
minerals with
with significant
significant interaction
interaction between
between mode
mode ofof application
application andand salt
salt concentration
concentration forfor B.
B.
frutescens
frutescens grown
grown inin 2.3
2.3 L
Lcontainers
containers irrigatedirrigated with
with variedvaried concentrations
concentrations ofof 2NaCl:CaCl
2NaCl:CaCl22 solutions.
solutions.
PP (ppm)(ppm)
2292.3±1762292.3±1763326.7±320.2
3326.7±320.2
3579±222.7
3579±222.7
2810.7±305.6
2810.7±305.6

Macronutrients
MacronutrientsK
K (ppm)(ppm)
33226±1924
33226±1924
38315.7±420.3
38315.7±420.3
38057±859.2
38057±859.2
25893.7±1637.1
25893.7±1637.1

Ca
Ca (ppm)(ppm)
8721.7±599.2
8721.7±599.2
10765±461
10765±461
10899±421.3
10899±421.3
11212.7±372.7
11212.7±372.7

Mg
Mg (ppm)(ppm)
3773±213
3773±213
3209.3±93.6
3209.3±93.6
2536.7±170.1
2536.7±170.1
2628.7±144.7

SS (ppm)(ppm)
18024.3±717.4
18024.3±717.4
16770±557
17052.7±1366.8
14537±1317.7

Sub-Canopy
Sub-Canopy

00 g·Lg·L-1-1
8.75
8.75 g·L
g·L-1-1
17.5
17.5 g·L
g·L-1-1
35
35 g·Lg·L-1-1

N
N (%)
(%)
2.7±0.2
2.7±0.2yy
2.7±0.1
2.7±0.1
2.8±0.1
2.8±0.1
3±0.3
3±0.3

FoliarFoliar00 g·Lg·L-1-1
8.75
8.75 g·L
g·L-1-1
17.5
17.5 g·L
g·L-1-1
35
35 g·Lg·L-1-1
Irrig.
Irrig. mode
mode
Salt
Salt concetration
concetration
Mode
Mode xx salt
salt concentration
concentration

3.0±0.4
3.0±0.4
2.2±0.1
2.2±0.1
2.5±0.1
2.5±0.1
3.2±0.1
3.2±0.1
0.583
0.583zz
0.029*
0.029*
0.153
0.153

2543.3±203.4
2543.3±203.4
2602.3±108.7
2602.3±108.7
3115.7±209.1
3115.7±209.1
3056.7±164.2
3056.7±164.2
0.564
0.564
0.002**
0.002**
0.128
0.128

32554.7±2596.3
32554.7±2596.3
35874.3±1817
35874.3±1817
33544.3±1176.5
33544.3±1176.5
29400.3±2370.2
29400.3±2370.2
0.47
0.47
<0.0001***<0.0001***
0.184
0.184

9883.7±1492.4
9883.7±1492.4
10115.7±916.5
10115.7±916.5
11547.3±215.2
11547.3±215.2
18296±1977.7
18296±1977.7
0.006
0.006
<0.0001***<0.0001***
0.01
0.01

4025.3±332.6
2860±102.1
2798.3±34.43629±603.6
0.115
0.115
0.005**
0.159
0.159

16885.3±449.1
13112.3±746.6
15702.7±266.6
17444.3±2183.9
0.205
0.205
0.179
0.052
0.052

Sub-Canopy
Sub-Canopy

00 g·Lg·L-1-1
8.75
8.75 g·L
g·L-1-1
17.5
17.5 g·L
g·L-1-1
35
35 g·Lg·L-1-1

Zn
Zn (ppm)(ppm)
13.3±0.3
13.3±0.3
24.3±0.3
24.3±0.3
31±4.731±4.721.7±1.921.7±1.9Fe
Fe (ppm)(ppm)
26.3±1.2
26.3±1.243.3±23.843.3±23.8
28.3±4.1
28.3±4.1
34±9.634±9.6Micronutrients
MicronutrientsCu
Cu (ppm)(ppm)
11.3±0.7
11.3±0.715.3±0.715.3±0.7
15.7±0.7
15.7±0.7
13±0.613±0.6Mn
Mn (ppm)(ppm)
194.3±13.9
194.3±13.9
201±8.1
201±8.1
212.7±39.9
212.7±39.9
202.7±27.3
202.7±27.3

Na
Na (ppm)(ppm)
24046±1414.1
24046±1414.1
28007.7±828.8
28007.7±828.8
28653.7±2323.2
28653.7±2323.2
34355.7±3063.4
34355.7±3063.4

B
B (ppm)(ppm)
120±11.0
86.7±0.7
83.7±9.8
108.7±5.2

FoliarFoliar00 g·Lg·L-1-1
8.75
8.75 g·L
g·L-1-1
17.5
17.5 g·L
g·L-1-1
35
35 g·Lg·L-1-1
Irrig.
Irrig. mode
mode
Salt
Salt concentration
concentration
Mode
Mode xx salt
salt concentration
concentration

13.7±0.7
13.7±0.7
16.7±0.9
16.7±0.918.7±218.7±245.3±5.845.3±5.8
0.706
0.706
<0.0001***<0.0001***<0.0001***<0.0001***24.3±1.2
24.3±1.2
21.7±0.921.7±0.922.3±1.822.3±1.830.7±1.530.7±1.5
0.451
0.451
0.842
0.842
0.875
0.875

11.7±0.3
11.7±0.3
12.7±0.3
12.7±0.3
13±0.613±0.617±1.517±1.5
0.522
0.522
0.001
0.001
0.002
0.002

179.0±8.7179.0±8.7
162.7±20.3
162.7±20.3
172.3±6.3
172.3±6.3
388.7±45388.7±450.002**
0.002**<0.0001***<0.0001***
0.003**
0.003**

24222.7±2317.4
24222.7±2317.4
30419.7±2950.730419.7±2950.7
32994.7±1726.1
32994.7±1726.1
38137.3±3541.1
38137.3±3541.1
0.706
0.706
<0.0001***<0.0001***111.3±5.2
82±6.593.7±3.8137±19.1
0.451
0.451
0.842
0.875

ANOVA
ANOVA Effects
Effects

ANOVA
ANOVA Effects
Effectsyy Values represent means (± standard errors) of 3 observations.
Values represent means (± standard errors) of 3 observations.

zz NS,*,**,***Non significant or significant at P  0.05, 0.01, or 0.001, respectively.
NS,*,**,***Non significant or significant at P ≤ 0.05, 0.01, or 0.001, respectively.

17.5,
valuesarearepermutation
permutationtest
testp-values.
p-values.
17.5, 35
35,andand70
70ggLL-1-1ofof2NaCl:CaCl
2NaCl:CaCl2.2. PPvalues

Mode
Mode ofof application
application either
either foliar
foliar oror sub-canopy.
sub-canopy. Level
Level isis 0,0, 8.75,
8.75,

was unaffected (Table 5).

Fig. 2. Ratios of K/Na. Ratios of K/Na with significant (P0.05)
interactions among application modes and salt levels for B.
frutescens (A), O. drummondii (B) and E. procumbens (C).
There was not a significant interaction or main effect of modes ofapplication for S. portulacastrum (D). Symbols for B. frutescens,O. drummondii and E. procumbens represent means (± s.e.) for
n=3; those for S. portulacastrum represent means (± s.e.) for n=6.
Absence of symbols indicates mortality.
All regression
equations were generated from the means.

and P were increased by as much as 86% and 27%,
respectively, in sub-canopy irrigation treatments of E.
procumbens at 8.75 g L-1 total salts. With foliar applications
at the same concentrations Zn was only increased 46% and P

3.5. Borrichia frutescens mineral content
Shoot concentrations of Fe and S of B. frutescens were notaffected by any of the treatments. There were interactions
among modes of application and salt concentrations for Ca, Zn
and Cu in B. frutescens, with Zn concentrations increasing by
as much as 230% at 35 g L-1 of salinity as compared to controls(Table 6). The increase in Zn could be the result of a defense
mechanism to elevated levels of Na in the irrigation water andsubstrate (Tavallali et al., 2009). Zinc has been shown tomitigate some effects of Na and Zn concentrations in tissues
have been shown to increase in other plants such as Capsicum
annuum L. (Cornillon and Palloix, 1997) and Pistacia vera L.
(Tavallali et al., 2009) in response to Na application. Modeof application did not affect all other minerals tested in B.
frutescens.
3.6. Foliar damage ratings
Sesuvium portulacastrum only had foliar damage ratings at
the highest level (70 g L-1), but exhibited essentially no signs ofdamage at levels equivalent to the salinity of seawater (Table 2).
Oenothera drummondii had increasing amounts of damaged
foliage with increasing salt concentrations with mean foliar

220

damage ratings decreased from 5 for controls to 3.5 at 17.5 g
L-1. Treatments with salt concentrations greater than 17.5 g
L-1 resulted in mortality of O. drummondii. The lesser
salinity tolerance of O. drummondii compared to S.
portulacastrum is consistent with its occurrence typicallyassociated with the landward side of the dunes, whereas S.
portulacastrum is often found on the seaward side of the dunes.
Surviving B. frutescens, while stunted, did not exhibit any
foliar damage up to 35 g L-1 salinity exposure, but were killedby treatments with salt concentrations of 70 g L-1. Mode ofapplication (either foliar application or sub canopy) only had
effect on E. procumbens. Increasing levels of salt in theirrigation water decreased the mean damage rating from 4.8 to
3.25 at 17.5 g L-1 for sub-canopy applications and from 5 to 2.8
Erigeron procumbens was killed at
at 35 g L-1.
concentrations greater than 35 g L-1.

4. Conclusions
Sesuvium portulacastrum had increasing levels of K whileother species treated with similar levels of saline irrigationwater either had decreasing concentrations of K or unchanged
concentrations of K while tissue concentrations of Na
increased. Salt tolerance seems to be linked with the abilityof the plant to maintain a high K/Na ratio (Navarro et al., 2008;
Taiz and Zeiger, 2006). As shown in Figure 2, S.
portulacastrum has a relatively steady K/Na ratio while allother species show a decrease in the ratio with treatment ofsalty irrigation water and death occurring with K/Na ratios
between 0.2-0.8 (Fig. 2). Continued growth and survival of S.
portulacastrum when irrigated with water containing salinity
approximately twice seawater, lack of adverse responses tofoliar application of salinity, and its enhanced growth at milder
elevations in substrate salinity are consistent with its
designation as a halophyte.
Although less tolerant to irrigation with saline water than S.
portulacastrum, the other three species included in thesestudies tolerated chronic exposure to irrigation water withsalinity half as salty as seawater and in some cases survived
even greater concentrations.
Borrichia frutescens, E.
procumbens and S. portulacastrum may use the accumulationof Zn as a method to mitigate increasing amounts on Na inshoot tissues.
A slight decrease in growth from the shortening ofinternodes could be a beneficial aspect of using saline irrigationwater on these species. The reduction in growth could
eliminate or reduce the amount of plant growth regulators
needed during a commercial production cycle where plant
retardants are regularly used to increase compactness of plants.
All four species in this study can be irrigated with water

resulting in a substrate EC of 15 mS cm-1 without affecting
their ability to perform as ornamentals in container production,
permitting the use of low quality irrigation water. Toleranceof these salinity levels may prove useful in landscape settings
with recycled irrigation water, in coastal restoration orlandscape development, and in areas where highway runoff orsplash of deicing salts would be encountered.
Acknowledgement
This study is to be included as part of a dissertation inpartial fulfillment of the requirements for the PhD. degree by S.
T. Carver. This work was supported in part by funds from
Texas A&M AgriLife Research. Mention of a trademark,proprietary product, or vendor does not constitute a guarantee
or warranty of the product by the authors, Texas A&M
University, or Texas A&M AgriLife Research and does not
imply its approval to the exclusion of other products or vendorsthat also may be suitable.

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