Agriculture Reference
In-Depth Information
(
2012
) suggested that many species spread and diversified from this zone to exploit
the arid and saline habitats that were increasingly becoming available as a result of
changing climatic conditions through the Pliocene and Pleistocene in inland areas
of Australia. There are two species that are considered to be closely related to
A.
nummularia
that are found in the arid zones of Western and South Australia, respec-
tively:
A. amnicola
Paul G. Wilson and
A. incrassate
F Muell (Sampson and Byrne
2012
).
A. breweri
and
A. cansecens
are relatively close to
A. halimus
. Between 1920
and 1930,
A. nummularia
,
A. semibaccata
from Australia and
A. canescens
from
USA were introduced to Tunisia and Morocco (Ben Salem et al.
2010
). Only 13
species and subspecies are used for rangeland rehabilitation and fodder production:
A. halimus
subsp.
halimus
,
A. halimus
subsp.
schweinfurthii
,
A. mollis
,
A. glauca
,
A. leucoclada
,
A. nummularia
,
A. canescens
subsp.
canescens
,
A. canescens
subsp.
linearis
,
A. amnicola
,
A. undulata
,
A. repanda
,
A. semibaccata
, and
A. barclayana
(Ben Salem et al.
2010
).
The Importance of
Atriplex
Species for Saline Soil
Reclamation
Salt affected soils are widely spread in many arid and semi-arid regions of the world
and increasingly threatening agricultural expansion and productivity. Yet, in many
arid environments, high quality water in not available to support the establishment
of plants for revegetation projects. The removal of sodium salts from saline soils by
halophytes plants, as alternative for costly chemical amendments, has emerged as an
efficient low cost technology (Gharaibeh et al.
2011
). It is well known that
Atriplex
species actively accumulate soluble salts in leaves, especially sodium, in association
with a drought tolerance mechanism. For this reason it is also considered as an ex-
cellent species for reducing soil salinity in drylands, if cut and collected (Ben Salem
et al.
2005
). It was found that the dehydrated
A. halimus
accumulated more Na
+
than
the control plants even without the addition of NaCl to the stressed plants (Martinez
et al.
2003
). Glenn and Brown (
1998
) concluded that tolerance of
A. canescens
to
water and salt stress was linked through a common mechanism of accumulating
Na
+
for osmotic adjustment. By comparing salinity tolerance of three
Atriplex
spe-
cies in well-watered and drying soil Glenn et al. (
2012
) found that
A. hortensis
was
able to complete its life cycle on drying soil with a final salt content 85 g/l NaCl.
A.
lentiformis
was able to survive on drying soils with salinities five times higher than
seawater, whereas
A. canescens
had high survival on drying soils but was less salt
tolerant than either
A. hortensis
or
A. lentiformis
. It has been demonstrated that there
is a relationship between the habitat of the Mediterranean xero-halophyte species
A.
halimus
and the strategy adopted for NaCl and osmotic stress resistance. The coastal
(Monastir, salt-affected site) population is more tolerant of salinity than the inland
(Sbikha, non saline semi-arid area) population and displays a higher ability to ac-
cumulate glycinebetaine (GB) in response to this constraint. In contrast, the inland
population, exposed in its natural habitat to transient periods of drought, is more
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