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International Journal of Horticulture 2014, Vol.4, No.7, 32
-
39
http://ijh.biopublisher.ca
32
Research Report Open Access
Tolerance of a Strandline Plant,
Alternanthera maritima
(mart.) A.ST.-HIL to
Foliar Salt Spray: Suitable for Beach Landscaping
Otitoloju Kekere
Department of Plant Science and Biotechnology, Adekunle Ajasin University, Akungba Akoko, Ondo State, Nigeria
Corresponding author email: kekereekunnoi@yahoo.com;
Authors
International Journal of Horticulture, 2014, Vol.4, No.7 doi: 10.5376/ijh.2014.04.0007
Received: 24 Mar., 2014
Accepted: 09 Apr., 2014
Published: 15 Apr., 2014
Copyright
© 2014 Kekere et al. This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Kekere et al., 2014, Tolerance of a Strandline Plant,
Alternanthera maritima
(mart.) A.ST.-HIL to Foliar Salt Spray: Suitable for Beach Landscaping,
International Journal of Horticulture, 2014, Vol.4, No.7 32-39 (doi: 10.5376/ijh.2014.04.0007)
Abstract
Salt spray tolerant plants are important to landscapers due to high mortality and low aesthetic value of ornamental plants in
coastal communities.
Alternanthera maritima
(Mart.) A.St.-Hil. a widely distributed strandline plant in West Africa, was treated with
salt spray to investigate its response and suitability for seaside landscaping. Plants were sprayed with seawater at: two sprays/week
(2SS), four sprays/week (4SS), six sprays/week (6SS) and control (CSS)-sprayed with deionized water. All plants survived, shoot
growth and total biomass increased, root\shoot ratio and leaf total chlorophyll decreased, while root growth was unaffected under
seawater treatments. Salt spray disrupted water balance through reduced xylem water potential and increased leaf and stem
succulence for ion dilution. It also caused nutrient imbalance by accumulating Na
+
and Cl
-
in the aerial parts and reduced some
essential nutrients. N increased in the aerial parts showing the presence of salt-related nitrogen compounds for osmotic adjustment.
Plants had reduced leaf area, stomata density and stomata number/leaf to minimize water loss. Except at 6SS, percentage necrotic
leaf area and plant visual ratings did not differ significantly from the control.
Alternanthera maritima
is a salt spray tolerant, with
adaptations for survival in the strandline. It is suitable for sea side landscaping.
Keywords
Growth; Ecophysiology; Adaptations; Necrosis; Landscape
Introduction
Strandlines are environments where litter, debris and
many discarded items are left behind by the previous
receding tide above the high water mark along the
seashore (Rozema et al., 1982). They are usually
colonized by few plant species due to the severity of
the abiotic factors affecting growth (Rozema et al.,
1982). Unlike the salt marsh, where plant species are
exposed to tidal inundation and thus to high salinity
(Flowers and Colmer 2008), the strandline is out of
reach of mean high tide and only rarely flooded with
seawater (Rozema et al., 1985). Thus, salt exposure at
the strandline is mainly composed of salt sprays
(Rozema et al., 1985; Griffiths et al., 2006; Griffiths,
2006; De Vos et al., 2010).
Much of the research conducted on salinity tolerance
have focused on saline soil or saline irrigation
(Alshammary et al., 2004; Hunter and Wu, 2005;
Marcum et al., 2005). However, very little attention
has been given to research on plant exposure to salt
spray under non-saline irrigation conditions. It is well
documented that plants are often more sensitive to
saline spray than to salt applied at the root zone
(Grattan et al., 1981; Elhaak et al., 1997). Salt spray
can suppress plant growth because it causes water
stress, disrupts membranes and enzyme systems,
inhibits the uptake of nutrients, causes necrosis or loss
of leaves and can lead to mortality (Scheiber et al.,
2008). Salt spray has been reported to cause reduced
shoot and root growth in
Triplasis purpurea
(Cheplick
and Demetri, 1999),
Leymus mollis
(Gagne and Houle,
2002),
Myrica
pensylvanica
(Griffiths and Orians,
2003) and
Crambe maritima
(De Vos et al., 2010).
Recently, reduced leaf size, number of leaves and
lateral branches and biomass were reported in
Diodia
maritima
(Kekere and Bamidele, 2012),
Commelina
erecta
subsp
maritima
(Kekere, 2013) and
Kylinga
peruviana (Kekere, 2014) sprayed with seawater. De
Vos et al (2010) stated that the reduced leaf size in
Crambe maritima
sprayed with seawater minimized
water loss through a reduction in surface area
available for transpiration. They also reported
accumulation of chloride and sodium ions which led
to ion toxicity, and nutrient deficiency, which resulted
in chlorophyll reduction. Salt spray was said to
increase water content in some plants, which is an
adaptation for ion dilution (Rozema et al., 1985; De
Vos et al., 2010). Also, salt spray disrupts water
balance in plants, and only the tolerant species can