Natural Resources, 2012, 3, 1-5 Published Online March 2012 ( 1
Early Growth Stages of the Rare Acridocarpus orientalis
in the UAE—A First Step towards Conservation
Taoufik Ksiksi1, Chedia Guenaoui2, Nael Fawzi1,3
1Biology Department, Faculty of Science, United Arab Emirates University, Al Ain, UAE; 2Arid Regions Institute, Medenine, Tuni-
sia; 3Flora & Phyto-Taxonomy Research Department, Agricultural Research Center, Giza, Egypt.
Received January 11th, 2012; revised February 14th, 2012; accepted February 25th, 2012
The seed germination and seedling estab lishment of the rare Acridocarpus orientalis were investigated to understand its
requirements for further seedlings estab lishment in the United Arab Emirates (UAE). It is an important first step in or-
der to try to conserve the species and prevent its disappearance. The experiments were carried out in a greenhouse and
in a laboratory under a temper ature of about 25˚C ± 4˚C. Seeds were soaked in water or kept in cold conditions. A con-
trol treatment was also included. Only a total of 9 seeds emerged during a period that exceeded eight months. Percent
germination in the laboratory experiment reached a maximum of 32%, 75 days into the trial. The rate of seed mortality
was 64%. It may be a problem of acclimation to the greenhouse environment. The results of this study showed that A.
orientalis seeds were not dormant. About 32% of seeds germinated and all others were viable. Soaking seeds in water
proved to be the best treatment for A. orientalis to emerge. Further investigations of the species germination and estab-
lishment are needed in order to improve our c ha nc es of protecting A. orientalis in the wild.
Keywords: Qafas; Seed Germination; Seed Mortality
1. Introduction
The United Arab Emirates (UAE), like the other Golf
states, is facing severe environmental challenges mainly
because of economic development and urbanization,
which resulted in higher pressures on demands for the
natural resources. Climatic cond itions coupled with anth-
ropogenic activities are causing much of the pressure on
the natural ecosystems. The anthropogenic factors are the
prime cause of degradation [1]. The UAE is chara-
cterized by a bi-seasonal Mediterranean climate with high
temperatures and low rainfall. Like in any desert domi-
nated regions, soils are poor in organic matter, with
relatively low biological activities. Such harsh cond itions
result in extreme losses of vegetation cover and floral
biodiversity [2]. Much of these ecosystems are becoming
increasingly degraded from Dubai to Abu Dhabi [3]. In
arid and semiarid climate zones, desertification, land
degradation and declining precipitation rates increasingly
limit crop cultivation [4]. Additionally, widespread soil
salinity restricts the potential of recovery in many parts
of the UAE desert ecosystems. For instance, Haloxylon
salicornicum, only slightly tolerant of salt, is replaced by
Zygophyllum qatarense as soil salinity is increasing [5].
Numerous recent studies indicated that the natural
heritage of Abu Dhabi is threatened by urbanization,
infrastructure development, population growth and over-
grazing. Habitat loss and degradation and species loss are
expected to be detrimental outcomes. Overgrazing, for
instance, had a serious effect on the natural vegetation,
especially palatable plant species as a result of increased
grazing pressures [6]. A decline in floral diversity is a
direct, and sometimes irreversible, outcome of such
increased pressure. Overgrazing has already led to the
disappearance of Rhanterium epapposum and Panicum
turgidum in many parts of the UAE [5]. In addition to R.
epapposum, some palatable perennial grasses have sub-
stantially declined due to overgrazing [7]. Some shrubs
may replace other more palatable ones as a result of
heavy grazing. Some studies reported that other species
are replacing R. epapposum in central Saudi Arabia [8],
northern Africa [9] and Kuwait [10]; due to overgrazing.
For instance, Zygophyllum manda villei was th ought to be
widespread in the interior of the UAE, is actually res-
tricted to a small area of Southern Arabia [11].
Long-term management decisions are to be adopted to
reverse the downward trend in species, cover and biodi-
versity loss in the UAE deserts. Much of the benefits of
biodiversity could be restricted. Acridocarpus orientalis
is one species that has many ecological as well as
medicinal advantages. It is rare and prone to extinction.
The current field work led by the authors show that only
Copyright © 2012 SciRes. NR
Early Growth Stages of the Rare Acridocarpus orientalis in the UAE—A First Step towards Conservation
less than 200 individuals are present in the wild. It is
only restricted to a small area within Jebel Hafit [12]. But
its current status in the UAE is unknown. Informatio n on
its growth habits will be a good start for proper mana-
gement. Combined laboratory and field approaches are
believed to be an adequate strategy to try to understand
the growth habits of A. orientalis. Transplanting green-
house grown plants could be an effective method to in-
troduce A. umbellata, a rare and threatened species
indigenous to the Pacific Coast of North America [13].
This will assist successes of reintroduction for con-
servation purposes, especially for species with few
remaining wild populations [13]. Descriptions of effe-
ctive procedures for these plant propagation and estab-
lishment in the field are decisive to progress the practice
of species re-establishment [14]. The efficiency of this
alternative was also justified by [15].
The present project attempts at understanding some of
the germination requirements of A. orientalis. The study
of seed germination is the first step in such conservation
approach [16]. Specifically here in the UAE, wher e there
is a lack of knowledge about the vegetation [3]. Improved
understanding of the germination requirements of any
plant species, and in particular the rare and endemic spe-
cies, is of crucial importance for its conservation and
management. The primary objective of this work is to
understand the germination characteristics of A. orient-
talis and ultimately create a nursery of that could be used
to rehabilitate ecosystems where it was once growing
within the UAE. In this part we focused on the germina-
tion from seeds as a step to produce seedlings.
2. Material and Methods
2.1. Study Site
United Arab Emirates (UAE) is surrounded by the Per-
sian Gulf to the north, Sultanate of Oman and Saudi Ara-
bia to the south, the Gulf of Oman and Sultanate of
Oman to the east, and Qatar and Saudi Arabia to the west.
The UAE is located between latitudes 22 degrees and
26.5 degrees north, and longitudes 51 degrees and 56.5
degrees east. Abu Dhabi is the largest Emirate in the
UAE, with an area of 67,340 km2, which constitute about
87% of the UAE total area. The remaining few wild A.
orientalis individuals are concentrated in a small wadi (a
dry river) within Jabal Hafeet mountain (E55˚46' and N
24˚05'), the highest peak in Abu Dhabi Emirate.
2.2. Variables Measured
Seeds of A. orientalis were collected between September
2009 and February 2010. Two different experiments we re
carried out. The first was conducted in the UAE Uni-
versity greenhouse (October 2009), in which temperature
was controlled by cooling chillers, and the second was
conducted in the ecology labo ra tory (February 20 10) . For
the greenhouse trial, seeds were d ivided into th ree gro up s.
The first group was sown directly without submitting any
treatment (Control), the second group was soaked in water
and the third group was treated by cold temperature before
their germination. The aim was to assess the best pre-
plantation treatment on emergence. Seeds were then planted
directly in 5-liter pots and placed in the greenhouse,
where the ambient temperature was 25˚C (±4˚C) and
under the natural day/night cycle.
For the laboratory trial, seeds of A. orientalis were
soaked in water during 48 hours at ambient temperature
(25˚C to 28˚C). After soaking, ten seeds per replicate
were placed within an incubator (Binder ®) in 9 cm di-
ameter Petri dishes, with a cotton layer that was regularly
moistened to saturation with distilled water. The aim was
to prevent dehydration during germination. The incubator
was pre-set to a constant temperature of 23˚C with a cycle
of 10 hours light and 14 hours dark. For this second as-
say, 250 seeds were used with 25 replicates. Seeds were
considered as germinated when the radical reached more
than 1 mm in length [17]. Recording of germinated seeds
was stopped when there was no further germination for
one week. The number of germinated seeds was recorded
daily and the Mean Time to Germinate (MTG) and the %
germination were determined. Photos were taken for
germinated seeds in all germination stages.
3. Results
The results of the greenhouse trial demonstrated that the
different seed treatments did not result in high sprouting
rates. Only a total of 9 seeds emerged during a period
that exceeded eight months. The first plants emergence
was recorded in 25/11/2009 where 2 seedlings emerged
from the water treated seeds and 1 plant emerged from
the cold treated ones. Four more plants emerged later in
9/12/2009 then 2 more plants emerged in 16/12/2009, all
from the water treated seeds. No plants emerged from the
non treated seeds. In 15//03/2010 one plant from the
water treated died. In 25/03/2010 two other plants (also
water treated seeds) were dead. There were no significant
differences between plants issued from water and cold
treated seeds (Figure 1) that reached the same growth
stage and all of them reached 8 leaves in May 2010.
The laboratory experiment showed a relatively higher
percent germination of 32%, 75 days into the trial
(Figure 2). However, the rate of seed mortality was 64%.
The majority of the mortality cases occurred right after
seeds germination. Seeds germinated after 2 to 7 days
and the MTG in this assay was 27 days.
The beginning of the radical emergence occurred one
week into the trial. Close observations of the seed
germination processes revealed that this species has lon g
and well developed roots. As it is shown in Figure 3,
Copyright © 2012 SciRes. NR
Early Growth Stages of the Rare Acridocarpus orientalis in the UAE—A First Step towards Conservation
Copyright © 2012 SciRes. NR
25-02-2010 19-03-2010 23-04-2010 06-05-2010
21-02-2010 19-03-2010 06-05-2010
Figure 1. Acridocarpus or ientalis gro wth sta ges in the gr eenhou se as a res ult of cold tr eated s eeds (a) and wate r trea ted seeds (b).
Figure 2. Cumulative germination and mortality rates of Acridocarpus orientalis seeds.
1 9
13 1726
54 59
Figure 3. Acridocarpus orientalis germination and radical emergence stages. Days since start of germination are shown.
Early Growth Stages of the Rare Acridocarpus orientalis in the UAE—A First Step towards Conservation
the emergence and the growth rate of these roots is very
fast. The aerial part showed also a rapid growth rate. The
first leaf emerged 1 to 3 weeks after root emergence. The
plants continued to develop its root system even after leaf
The biggest problem encountered during this germi-
nation trial is the mortality of germinated and non-ger-
minated seeds. Many seeds died before their germination,
but a considerable number died at the stage of 2, 3 and
even 6 leaves.
Even if the laboratory essay showed a higher rate of
seed germination, no seedlings could survive to the end
of the experiment. However, six plants issued from the
directly sowed seeds in pots in the greenhouse are still
surviving. It may be a problem of acclimation to the
greenhouse environment.
4. Discussion
The results of this study showed that A. orientalis seeds
were not dormant. In fact, 32% of seeds germinated and
all the non-germinated seeds were viable. The higher
percent germination was observed with seeds soaked in
water. This can be explained by the removal of the
viscous layer coating all seeds of A. orientalis, after
being soaked in water. This result confirmed that of re-
ports [18] indicating that all the priming treatments
improved the emergence, seedling growth and reserve
The rate of germinated seed mortality, underline the
need for further future investigations into post germi-
nation conditions and acclimation.
Observations of root growth revealed the ability of this
species to survive in dry regions. It developed long
principal roots with many secondary roots, which high-
light the ability of A. orientalis to extract soil moisture
even in deep substrate levels. The potential water uptake
in any soil layer depends on the soil water content and
the root density, and for whole soil profiles water uptake
depends on the rooting depth and total root length [19].
5. Conclusion
This study provided some much needed information
about the germination conditions and the growth stages
of the rare plants species A. orientalis. However, the lack
of information on its growth requirements is urgently
needed to be addressed, in order to overcome A. orien-
talis rare status in the UAE. Additionally, improved un-
derstanding of the species soil and habitat preferences,
through soil nutrient analysis within its niche in Jabal
Hafeet are also required. Ecological interactions of the
species could offer more information about the growth
conditions of A. orientalis, which will certainly improve
the rate of success to protect it.
6. Acknowledgements
The funding by the Mohamed bin Zayed Species Con-
servation Fund is much appreciated (Fund No. 21S031).
The investigators would also like to express their sincere
appreciation to the Office of Research Support and
Sponsored Projects at the United Arab Emirates Univer-
sity for their support and the management of this project.
The support from the Biology Department and the Fac-
ulty of Science is also much appreciated. Assistance from
all students in any parts of this project is appreciated.
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