Geoscience Reference
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growing on both loamy and sandy soils, which represent the dominant soil textures
in the region. As a result, at marginal sites where a shallow, slightly-to-moderately
saline groundwater is available throughout the growing season,
Elaeagnus angus-
tifolia
,
Robinia pseudoacacia
and newly introduced
Acacia ampliceps
showed the
fastest growth and highest water use. This indicates the suitability for planting on
low fertility saline lands. Preliminary outcomes of the study on salt-affected soils
have also indicated that tree plantations with
E
.
angustifolia
,
Populus nigra var
.
pyramidalis
,
Morus
spp. have potential for increasing the soil organic matter due
to the relatively rapid leaf litter decomposition.
Morus nigra
and
Cydonia oblonga
showed reasonable DM production on degraded land, with high biomass allocation
towards the root fraction. Among tree species, Poplar (
Populus alba
,
P
.
nigra var
.
pyramidalis
and
P
.
euphratica
) showed maximum growth for all parameters studied
followed by mulberry (
Morus nigra
).
Populus diversifoilia
which displayed high
rates of leaf and wood production appeared to be the most sensitive to saline
sandy-soil type. Similarly, it had slow longitudinal root growth and low root DM
production at sandy site while exhibiting superior below-ground development at the
sandy-loamy soils. Introduced coniferous species
Thuja occidentalis
was the only
species that showed poor growth under furrow irrigation at the Dashauz province
and at the second year died due to its high sensitivity to frosts
Evaluation of survival rate, performance and productivity including biomass and
seed production of non-conventional tree/shrubby halophytes firstly introduced in
Central Asian flora including:
Acacia ampliceps
,
Atriplex nummularia
,
A
.
undulata
and
A
.
amnicola
by International Center for Biosaline Agriculture showed its high
potential for the reclamation of salt-affected marginal lands. All species tolerated
average root-zone salinity of 8-16.8 dS m
1
. Seedlings of
Acacia ampliceps
were
obtained from by direct seed sowing in the field (February 2006) and through the
establishment in plastic bags. The growth rate was very fast @ 12-18 cm/month
at the rooting stage and 25-30 cm/month, when the basal stems develop a woody
character. Plant growth of
Acacia ampliceps
raised from direct seeding was much
higher than with similar plants grown after transplanting by seedlings (from plastic
bags). Among
Atriplex
spp. highest seed germination (approximately 89 %) under
field condition was observed for
Atriplex undulata
, which showed a rapid growth
rate and accumulation of biomass. Being grown at a high plant density of 10-12
plants m
2
(normal density of this shrub is 4 plants m
2
) in the first year, this
species with its large canopy can occupy the inter-row spaces forming a dense
mono-component halophytic pasture. The biomass produced in 1.5 years was 5.6 kg
m
2
and was readily browsed by cattle and small ruminants. Biomass of
Atriplex
undulata
at the Akdepe Experimental site increased with high density level of plant
per square meter (5.0-5.8 thousand. plant/ha). Replacement of 30 % of individuals
has been done in August 2006 in order to maintain the stand and decrease plant
density. Low seed germination of about 55 % was observed in
Atriplex nummularia
and
A
.
amnicola
(only four shrubs of the latter plant survived). Comparative studies
on seasonal plant performance, accumulation of green biomass in
Acacia ampliceps
and
A
.
nummularia
,
A
.
amnicola
and
A
.
undulata
was observed after transplantation
into the open field.
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