Growing and Harvesting Fourwing
Saltbush (Atriplex canescens [Pursh]
Nutt.) Under Saline Conditions
Earl F. Aldon
J. Rafael Cavazos Doria
other species of this genus are grown throughout the world
in sparsely vegetated areas where extreme conditions of
high temperature, soil salinity, and drought persist. Without irrigation these lands often are marginal for anything
but grazing (Hyder 1981, Richardson and McKell 1980).
Methods of establishing fourwing saltbush by direct
seeding, vegetative propagation, and seedling planting
have been determined (Springfield and Bell 1967, Nord
and others 1970, Weisner and Wallace 1977, Aldon 1984).
Under nonsaline water conditions, it exhibits high germination at 19-21 °C (Aldon 1970).
Direct seeding is less successful than transplants due
to low seed germination, inadequate seed bed preparation,
and depredation by rodents and lagomorphs (such as rabbits). Transplants can be grown under controlled conditions
and planted when soil moisture is optimum and the probability of precipitation is greatest. Repellents can protect
transplants from wildlife until the transplants become
established (Aldon 1984).
These studies used distilled water or water low in naturally occurring salts. But many lands that were once used
for growing crops now have little vegetation because of declining water tables, brackish groundwater, saline soil conditions, or combinations of these factors. In these areas of
sparse vegetation, brackish water is sometimes more readily
available than fresh water. If plants could tolerate brackish
water, then fresh water supplies can be extended. Fourwing
saltbush has been shown to be tolerant of highly saline conditions (Osmond and others 1980, Wilkins and Klopatek
1984).
As an example, Stewart (1967), using sprinkler and flood
irrigation of saline water on well-drained observational
plots in New Mexico found fourwing saltbush transplants
grew up to 75 cm in the first growing season and were considered firmly established after 11⁄2 years.
The objectives of the studies reported here were:
Abstract—Fourwing saltbush is an important species in arid and
semiarid plant communities. It is palatable to domestic livestock,
is drought resistant, and provides good soil protection and food for
wildlife. In many areas of the world, lands once used for growing
crops are now without any vegetation because of declining water
tables, brackish groundwater, saline soil conditions, or combinations of these. Fourwing saltbush can grow in such areas and improve site productivity and stability.
This paper reports the results of studies that explored ways of
germinating, growing, and harvesting this plant under varying
saline conditions in Baja California. Management implications
of these findings are discussed.
In order to determine ways to grow fourwing saltbush
under saline conditions, the Rocky Mountain Forest and
Range Experiment Station and the Instituto Nacional de
Investigaciones Forestales y Agropecuarias have recently
conducted three cooperative studies at the Todos Santos
Experiment Station near La Paz, Baja California Sur,
Mexico. This paper summarizes these studies and outlines management strategies that might be used to grow
fourwing saltbush on degraded sites or on abandoned agricultural sites that are no longer able to grow crops due
to saline soil conditions resulting from saline irrigation or
saline groundwater encroachment.
Fourwing saltbush is a valuable and common shrub on
western ranges in the United States and Mexico. It is
widely distributed from North Dakota to Oregon and as
far south in Mexico as the States of Zacatecas and Baja
California (Vines 1960). It occurs in arid and semiarid
habitats and is common in grassland and pinyon-juniper
woodlands. Scattered individuals may be found in pine
and fir forests. It is commonly associated with other Atriplex species (Wagner and Aldon 1978). This species and
Study 1. To test the effect of water salinity on fourwing
saltbush seed germination at a temperature
known to promote high germination (Agredano
and Aldon 1993).
Study 2. To test saline irrigation methods and the survival of two ages of fourwing saltbush seedlings
(Cavazos and Aldon 1993).
Study 3. To determine survival and growth of fourwing
saltbush subjected to two levels of crown biomass removal using minimum amounts of
supplemental saline and fresh water irrigation
(Cavazos and Aldon, in press).
In: Roundy, Bruce A.; McArthur, E. Durant; Haley, Jennifer S.; Mann,
David K., comps. 1995. Proceedings: wildland shrub and arid land restoration symposium; 1993 October 19-21; Las Vegas, NV. Gen. Tech. Rep.
INT-GTR-315. Ogden, UT: U.S. Department of Agriculture, Forest Service,
Intermountain Research Station.
Earl F. Aldon, retired, was a Research Forester at the Rocky Mountain
Forest and Range Experiment Station, 2205 Columbia SE, Albuquerque,
NM 87106. J. Rafael Cavazos Doria is a Range Scientist for the Instituto
Nacional de Investigaciones y Agropecuarias Plaza Comerical “Altamirano,”
Locales 9A Y 10A, La Paz, Baja California Sur, Mexico.
299
Methods
Tests were conducted in a germinator set at a constant
21 °C (Aldon 1970). Scarified and nonscarified seeds (50)
were tested in petri dishes. Scarification was done manually with a knife by giving the seed coat a single cut about
1 mm in depth. Treatments consisted of mixtures of distilled water with 0, 10, 15, 25, 50, 75, or 100% by volume
of Pacific Ocean seawater. Germinated seeds were counted
every day for 30 days. Seeds were considered germinated,
and then removed, when roots extended at least 4 mm.
Study Location
The experiments were conducted at the Todos Santos
Experiment Station near La Paz, Baja California Sur,
Mexico. Todos Santos, located about 111 km south of
La Paz at 15 m above sea level, receives an average of
182 mm of precipitation per year. Average temperature
is 22.1 °C with 1738 mm of evaporation per year. The
topography is made up of small, gentle hills and crossed
with irregular ridges with arroyos, which run after summer thunderstorms. Major associated native vegetation
consists of Pachycereus pringlei, Bursera microphylla,
Fouqueria diguetii, Cytocarpa edulis, Lemaireocereus
thurberi, Jatropha cinerea, Opuntia cholla, Yucca valida,
Cercidium floridum, Simmondsia chinensis, and Turnera
diffusa. The dominant soil series is Sierosem, a darkbrown, sandy-textured soil about 2 m deep with a pH of
7.3 to 8.9, low in organic matter, nitrogen, and phosphorous, but rich in potassium.
Daily maximum and minimum temperatures and precipitation are measured at the weather station at the Todos
Santos Experiment station yearlong.
Details of the methods used in each study can be found
in the references. Only brief outlines of methods will be
given here to familiarize the reader with general techniques used.
Study 2 (Cavazos and Aldon 1993)
The same source of seeds used in study 1 was used here.
Seeds were germinated in a sandy nursery soil having a
texture of 97% sand, 0.44% silt, and 2.56% clay that had
been fumigated with methyl bromide. The seed bed was
saturated with fresh water every other day. All seedlings
were transplanted into 800-cm plastic, well-drained containers containing the same soil. Seedlings were grown
in nursery beds under plastic shade screens (33% shade).
The containers were irrigated three times weekly with
100 ml of fresh water per plant. Two groups of seedlings
were grown. One group (small plants) began receiving saline irrigation after 48 days of growth. Plant mean height
for this group was 5.2 cm at 48 days. The other group
(large plants) began receiving irrigation after 70 days of
growth. Plant mean height was 18.6 cm at 70 days. Plant
height was measured weekly during the course of the study
from the basal stem at ground level to the apical leaf bud.
Plant survival and height were measured weekly. During the eighth week after saline irrigation started, plants
were harvested from the containers, washed, dried at 60 °C,
and measured for top and root weight.
Seventeen irrigation treatments were conducted on the
two plant sizes (Table 1). Treatments consisted of variation in the salinity concentration of the irrigation water
and variation in the length of time plants were subjected
Study 1 (Agredano and Aldon 1993)
Dewinged seeds obtained from the USDA Soil Conservation Service Material Center in Los Lunas, New Mexico,
were used. The seed (from SCS lot number 478837) had
98.95% pure live seed with 40% germination. This New
Mexico ecotype was used because it is commercially available and was certified disease-free.
Table 1—Irrigation schedules and saline concentrations
Weeks
Treatment
1
2
3
4
5
6
7
8
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Saline concentration %- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
0a
75b
100c
75
100
75
100
75
100
75
100
75
100
75
100
75
100
0
75
100
75
100
75
100
75
100
75
100
75
100
75
100
0
0
0
75
100
75
100
75
100
75
100
75
100
75
100
0
0
0
0
0
75
100
75
100
75
100
75
100
75
100
0
0
0
0
0
0
a
0% seawater (fresh water)
75% seawater (by volume)
100% seawater
b
c
300
0
75
100
75
100
75
100
75
100
0
0
0
0
0
0
0
0
0
75
100
75
100
75
100
0
0
0
0
0
0
0
0
0
0
0
75
100
75
100
0
0
0
0
0
0
0
0
0
0
0
0
0
75
100
0
0
0
0
0
0
0
0
0
0
0
0
0
0
to these concentrations. The control plants received fresh
water for 8 weeks from a well that was used for agricultural
crops. The other treatments were designed to test two saline concentrations (75% and 100%) for a varying number
of weeks, after which fresh water was used for varying number of weeks (1 to 8). The 75% seawater, by volume, was
diluted with the same well water. The seawater was obtained from the Pacific Ocean near Todos Santos. Plants
were watered three times per week with 100 ml of the designated treatment water.
schedule was planned, but was not possible due to slow
growth and high mortality after cutting.
Plant height (from the soil surface to tallest part of the
plant) and crown diameter (largest diameter plus smallest
diameter/2) was measured monthly on eight randomly selected plants in each sub-plot and averaged. When harvested, the eight plants were divided into leaf/small-branch
(<0.05 cm) and large stem portions. Green and air-dry
weights of these portions were determined.
Statistical Analysis
Study 3 (Cavazos and Aldon, in press)
An analysis of variance and Tukey’s multiple comparisons were conducted in all studies to evaluate treatments.
Regression analysis was conducted in study 1.
Seedlings were grown by the same method as in study 2.
A 3 X 2 factorial experiment in a randomized block design
was used in the field at the Todos Santos Experiment Station. A 1.0-ha area was cleared of all vegetation and leveled. Irrigation furrows 15 cm deep and 24 m long were
constructed at 2.0-m intervals over the area. The furrowed
area was divided into three blocks to evaluate irrigation
water quality. Each block was further subdivided into two
2
harvesting intensity sub-plots (144 m each) replicated
nine times. The irrigation water quality levels were:
Results
Study 1
Overall, germination percentages were highest in scarified seeds, regardless of saline concentration (Table 2).
Scarified seed averaged 39.1% germination versus 16.4%
for nonscarified seeds, for all treatments combined. Both
nonscarified and scarified seeds showed primarily a linear
decrease in germination percentage with increasing saline
concentrations (R = –0.65 and R = –0.83, respectively). However, with scarification there is a general improvement in
germination percentage. Mean germination percentages
ranged from 16% to 54% in scarified seed, but only from 3%
to 22% in nonscarified seed, depending on saline concentrations. These results indicate that it would be possible to
germinate fourwing saltbush seeds in areas of high soil
salinity concentrations treated with nonsaline water or
to use brackish water in nonsaline soils.
• Saline well water (Electrical conductivity [E.C.] =
–1
–1
5160 mmoh cm and NaCl = 2715 mg L ).
• Fresh water from the experiment station’s water
supply.
• No irrigation; natural precipitation only.
The harvesting intensities were:
• 50% of total plant height removed.
• 100% of total plant height removed (everything
10 cm above the soil surface).
Fourwing saltbush transplants averaging 28 cm high
were planted 1.5 m apart and 15 cm deep on the ridges
above the furrows in October 1990. The planted experi2
ment covered 7776 m and contained 2592 plants.
Gravimetric soil moisture samples (0-30 cm) were taken
weekly at random locations along the furrows in each subplot. When moisture levels fell below 5% of field capacity,
the plots were irrigated. Irrigation water (saline and fresh)
was applied in the furrows at a rate of 1 L sec–1 for about
4-5 minutes to bring soil moisture up to field capacity. Three
irrigations were required; in March and July 1991, and in
July 1992. Plant crowns were harvested in October 1991
and again in July 1992. A more frequent plant harvesting
Study 2
All large plants survived for the 8 weeks except one plant,
regardless of watering regime. Survival showed the effects
of salinity on small plants after the second week. Several
treatments had zero survival after the second week. Survival of plants irrigated with 100% seawater was less (26%
survival, overall) than those irrigated with 75% seawater
or fresh water (56% and 100% survival). Little can be ascertained from the survival rates of these smaller plants to
Table 2—Mean germination of Atriplex canescens seed after 30 days of treatment with seawater solution at 21 °C constant temperature
Treatments
(% seawater)
0
10
15
25
50
75
100
pH of
solution
6.53
7.34
7.64
7.91
8.12
8.23
8.29
Saline concentrations
PPM/L
of dissolved
salts
Molarity/L
19
3,938
5,901
8,995
15,575
22,196
25,212
0.0060
0.1314
0.2040
0.3099
0.5402
0.7400
0.8810
301
Mean % seed germination + se
Scarified
Nonscarified
54.25 ± 3.67
46.85 ± 2.24
48.45 ± 4.06
41.33 ± 2.65
31.59 ± 2.86
36.78 ± 2.91
15.58 ± 1.62
21.80 ± 1.46
18.60 ± 2.46
19.80 ± 1.69
20.00 ± 1.90
10.80 ± 0.66
20.60 ± 1.86
3.00 ± 0.77
Between the first harvest and just prior to the second
harvest, treatment effects became evident. The 100%-cut
plants started smaller and stayed significantly smaller
than those cut 50% (21.07 versus 41.12 cm) (P ≤ 0.05).
Plant crown responses were similar to those for plant
heights. After a small growth increment in the month following transplanting, crowns remained stable until June of
1991 when branching began. Just prior to the first cutting,
there were no differences in average crown diameter due to
irrigation (saline water 101.08 cm and fresh water 93.80 cm),
but these crowns were significantly larger than crowns on
plants with natural rainfall only (69.01 cm) (P ≤ 0.05).
After 9 months regrowth, crown means were significantly
larger on plants cut 50% (59.47 cm) than those cut 100%
(37.11 cm). There were no significant differences between
the saline and fresh water irrigation treatments, but these
crowns were larger than those receiving only natural rainfall (Fig. 2).
Plant mortality was measured at the end of the study
(August 1992). Plants with crowns harvested at 50% experienced from 4% to 14% mortality. Plants with crowns
harvested at 100% suffered 66% mortality. Mortality was
not significantly different (P > 0.05) due to irrigation treatment. Termite activity was noted at the base of many of
the plants harvested at 100%. It is not known how much
these insects contributed to mortality.
As might be expected, soil salinity increased on plots
irrigated with saline water. At the 0-30 cm soil depth, the
three irrigations caused salinity to increase (E.C. = 698 to
–1
4580 mmohs cm ). At the 30-60 cm depth, E.C. values
from 2062 to 5320 mmohs cm–1 were measured at planting and after the third irrigation.
offer a recommended watering regime. Plants that survived to the end of 4 weeks made it to the end of the experiment. Therefore, if saline water is used to establish
fourwing saltbush, older larger seedlings should be used.
Initially, there was no significant difference in plant
height between treatments for large or small plants. After 8 weeks, there was no significant difference in plant
height among large plants (P > 0.05) (Table 3). Final plant
heights for large plants ranged from 24.9 cm to 37.6 cm,
with a mean height of 32.4 cm. The small plants showed
the effect of saline irrigation versus fresh water after
8 weeks. Those plants receiving saline irrigation grew
significantly less than the fresh water control. Small
plants continuously irrigated with 100% seawater only
grew to 10.9 cm in height, while the control (fresh water
only) grew to 36.6 cm.
After 8 weeks, total dry matter production (tops and
roots) was significantly different in large plants (P ≤ 0.05)
and ranged from 1.02 ± .12 g (100% seawater only) to
2.95 ± .32 g (100% seawater for 1 week and fresh water irrigation for the remaining 7 weeks). Top weights increase
as time and amounts of salinity irrigation decrease.
Total dry matter production of small plants was significantly different (P ≤ 0.05) and ranged from a low of
0.30 ± .11 g to 2.42 ± .06 g in the control. Top weights
accounted for 80% of the total dry matter overall.
Study 3
Transplant height increased slowly during the first 6
months after planting. Transplants averaged 28 cm at
planting time and grew about 20 cm during the first winter
and spring. Growth accelerated from June to September
1991 (Fig. 1). By the first harvest (October 1991), the
plants irrigated with fresh water averaged 78.52 cm in
height, and plants irrigated with saline water averaged
82.61 cm. These values were not significantly different,
but the plants grown with natural precipitation only were
significantly shorter (52.06 cm) (P ≤ 0.05 ) (Fig. 1). This
would be expected since two irrigations (March and July
1991) had been applied, and after December 1990, very little natural precipitation fell until 80 mm fell in September
1991.
Management Implications
These studies have shown that it is possible to germinate,
grow seedlings, and harvest this plant under saline conditions. If possible, these sites should be managed to reduce
or eliminate saline soil and water conditions. Where this
is difficult, it is possible to germinate scarified seeds at
21 °C and expect more than 40% germination with 25%
saline water.
Table 3—Average plant height of small (5.2 cm) and large (18.5 cm) fourwing saltbush seedlings after 8 weeks under different irrigation
schedules
100% seawater
Trt. Plant Ht.
#
(cm)
3
5
7
9
11
13
15
17
1
2
1
10.9a
—2
—
—
16.9 a
—
22.8 a
—
Small plants
75% seawater
Trt.
Plant Ht.
0% seawater
Trt.
Plant Ht.
100% seawater
Trt.
Plant Ht.
Large plants
75% seawater
Trt.
Plant Ht.
0% seawater
Trt.
Plant Ht.
#
(cm)
#
(cm)
#
(cm)
#
(cm)
#
(cm)
2
4
6
8
10
12
14
16
18.8 a
11.7 a
19.4 a
18.1 a
19.8 a
13.2 a
—
27.6 a
1
36.6 b
3
5
7
9
11
13
15
17
24.9 a
31.2 a
28.3 a
33.6 a
31.4 a
34.4 a
35.1 a
35.9 a
2
4
6
8
10
12
14
16
33.2 a
31.2 a
29.5 a
37.6 a
31.8 a
32.2 a
32.1 a
34.2 a
1
34.6 a
Numbers followed by the same letter in a column are not significantly different at the 5% level.
Plant height was not measured due to low survival.
302
Figure 1—Plant height (cm) of fourwing saltbush grown under three water regimes from
planting to the first cut.
Figure 2—Average crown diameter of fourwing saltbush showing the effects of three water regimes and two harvesting intensities. Data taken after the first harvest to the end of the study.
303
A critical period then occurs when the seedling is between
30 and 70 days old. During this time, if transplanted seedlings are subject to saline irrigations, high mortality may
result. Larger (and older) seedlings tolerate saline irrigations of various concentrations and durations far better than
smaller seedlings.
Once plants have been established under saline irrigations, no more than 50% of their crown heights should be
harvested yearly. Higher harvesting percentages will result
in increased mortality of the plants when saline irrigations
are done after soil moisture falls below 5% of field capacity.
Plants survived when salt build-up in soils (0-30 cm) resulted in E.C. readings of 4580 mmhos cm–1 and (30-60 cm)
–1
5320 mmhos cm after 2 years.
Natural precipitation must be relied upon for sustaining
these plants in the long run. Infrequent heavy rainfall will
reduce saline build-up and maintain and perpetuate stands
of fourwing saltbush. Use of saline water should be considered a temporary step to establish this plant on areas now
devoid of productive vegetation.
References
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