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Walker D.J.,Instituto Murciano Of Investigacion Y Desarrollo Agricola Y Alimentario | Lutts S.,Catholic University of Louvain
Emirates Journal of Food and Agriculture | Year: 2014

Atriplex halimus L. (Amaranthaceae) (Mediterranean Saltbush) is a perennial, halophytic shrub that possesses the C4 photosynthetic anatomy and physiology. It grows under semi-arid and arid conditions (annual rainfall < 600 mm) from Macaronesia, through the Mediterranean basin countries and into western Asia, being particularly common on saline and degraded soils. Many studies have shed light on the physiological and biochemical mechanisms that, together with the morphological and anatomical features of this species, contribute to its notable tolerance of important abiotic stresses: salinity, drought, extreme temperatures and soil contamination by trace elements. These will be discussed here, highlighting their shared and distinct features. Certain processes are common to two or more stress responses: for example, vacuolar accumulation of sodium and the cytoplasmic accumulation of compatible osmolytes - part of the process of osmotic adjustment - are vital components of the adaptation to drought, salinity and cold. Others, such as oxalate accumulation upon trace elements exposure, seem to be stress-specific, while leaf surface vesiculated hairs (trichomes) and abscisic acid have distinct functions according to the stress. The relevance of these mechanisms to the use of A. halimus in soil remediation and as livestock forage is discussed.

Martinez-Fernandez D.,Instituto Murciano Of Investigacion Y Desarrollo Agricola Y Alimentario | Walker D.J.,Instituto Murciano Of Investigacion Y Desarrollo Agricola Y Alimentario
Water, Air, and Soil Pollution | Year: 2012

In Southern Spain, as in other semi-arid zones, plants used for the phytoremediation of heavy metal-contaminated sites must be able to withstand not only the challenging soil conditions but also seasonal drought and high temperatures. A pot assay was carried out to determine the ability of soil amendments to promote the survival and growth of the seedlings of two native species, Atriplex halimus L. (Amaranthaceae) and Bituminaria bituminosa (L.) C.H. Stirton (Fabaceae), in two heavy metalcontaminated soils, one of which also had a high level of arsenic (As). Restriction of A. halimus shoot growth in the non-amended soils appeared to be due to deficiency of nitrogen, phosphorus (P) and potassium (K) and in the more highly contaminated soil to lead (Pb) toxicity. Shoot biomass of A. halimus in the more highly contaminated soil was increased significantly by compost addition, due to increased uptake of K and P and decreased tissue Pb. The lack of effect of compost on B. bituminosa growth in this soil, despite a large increase in tissue K, may have been due to elevated tissue levels of As and Pb and the high soil salinity. The combination of A. halimus and compost addition seems appropriate for the phytostabilisation of contaminated semi-arid sites. © Springer Science+Business Media B.V. 2011.

Walker D.J.,Instituto Murciano Of Investigacion Y Desarrollo Agricola Y Alimentario | Lutts S.,Catholic University of Louvain | Sanchez-Garcia M.,CSIC - Center of Edafology and Applied Biology of the Segura | Correal E.,Instituto Murciano Of Investigacion Y Desarrollo Agricola Y Alimentario
Journal of Arid Environments | Year: 2014

Atriplex halimus L. (Amaranthaceae) (Mediterranean saltbush) is a halophytic shrub that is widely distributed in arid and semi-arid regions around the Mediterranean basin and east to Saudi Arabia, at elevations less than 900m. It grows on a variety of soils, from fine to coarse texture, with varying degrees of salinity. There are two sub-species of A.halimus: halimus is diploid (2. n=2. x=18) and is found at semi-arid, less-saline sites, while schweinfurthii is tetraploid (2. n=4. x=36) and occupies arid, saline sites. Throughout its distribution, A.halimus is exposed to high light intensity and temperature and varying degrees of drought and salinity; it can also withstand sub-zero winter temperatures or soil contamination by trace elements. Some of its physiological and biochemical tolerance mechanisms - such as adjustment of plant water relations - are common to all or several of these environmental stresses, but others are specific to particular stresses. The importance of A.halimus in the functioning of ecosystems is reflected in its promotion of soil biota, while it also acts as a food plant for mammals and arthropods. Its deep root system decreases soil erosion in arid zones, due to stabilisation of the soil. The protein-rich shoot material of A.halimus makes it an important fodder species for livestock, particularly sheep and goats. However, its low energy value means that it should be supplemented with carbohydrate-rich material, such as cereal straw. Potential new uses of this versatile plant species include the phytoremediation of soils contaminated by trace elements and the exploitation of its biomass as a source of renewable energy. Such applications, together with its continued use in low-intensity farming systems, should ensure that A.halimus remains a vital plant species in low-rainfall regions. © 2013 Elsevier Ltd.

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