Ahmed Douaik

Chemical Polymorphism of Origanum compactum Grown in All Natural Habitats in Morocco

Origanum compactum L. (Lamiaceae) is one of the most important medicinal species in term of ethnobotany in Morocco. It is considered as a very threatened species as it is heavily exploited. Its domestication remains the most efficient way to safeguard it for future generations. For this purpose, wide evaluation of the existing variability in all over the Moroccan territory is required. The essential oils of 527 individual plants belonging to 88 populations collected from the whole distribution area of the species in Morocco were analyzed by GC/MS. The dominant constituents were carvacrol (0 – 96.3%), thymol (0 – 80.7%), p‐cymene (0.2 – 58.6%), γ‐terpinene (0 – 35.2%), carvacryl methyl ether (0 – 36.2%), and α‐terpineol (0 – 25.8%). While in the Middle Atlas region and the Central Morocco mainly carvacrol type samples were found, much higher chemotypic diversity was encountered within samples from the north part of Morocco (occidental and central Rif regions). The high chemical polymorphism of plants offers a wide range for selection of valuable chemotypes, as a part of breeding and domestication programs of this threatened species.

Evaluation of groundwater suitability for irrigation in the Skhirat region, Northwest of Morocco.

Morocco has arid and semiarid climates. Irrigation is an imperative for agriculture. Skhirat region is known for the production of vegetables. Intensive peri-urban agriculture is associated with inconsiderate pumping of groundwater, and water becomes less abundant and of poor quality resulting in degradation of soil and water quality. Therefore, the objective of this research work was the assessment of the quality of irrigation water. The study site is located in a coastal area and dedicated to intensive land use for growing vegetables in a peri-urban agricultural zone. Monitoring of physicochemical parameters of water was carried out in 77 wells. Parameters like pH, electrical conductivity, and piezometric level were measured in situ while others like total dissolved solids and ionic balance were measured in laboratory whereas other parameters were calculated from those measured. Results showed that Na and Ca are predominant cations while Cl and SO4 are predominant anions. Piper diagram reveals two facies: sodic and calcic chlorinated. Regarding the permeability index, all wells are suitable for irrigation. The US Salinity Laboratory (USSL) diagram reveals that irrigation water has high salinization risk and low to medium alkalinization risk. The groundwater in the region is classified as very hard category; however, it does not present any risk of sodicity. These waters have a high risk of toxicity to chloride ions. In summary, although the groundwater in the Skhirat region presents a high risk of salinization, it is of good quality suitable for irrigation. Agricultural practices should be well managed to secure safe use of the water resource for a sustainable development of the agriculture in the region.

Influence of Environmental Factors on Essential Oil Variability in Origanum compactum Benth. Growing Wild in Morocco

The present study aimed to evaluate the influence of environmental factors on essential oils (EOs) composition of Origanum compactum populations sampled all over the distribution area of the species in Morocco, and to determine the extent of the chemical profiles throughout the geographical distribution of the species. The chemical compositions were submitted to canonical correlation analysis and canonical discriminant analysis that indicated a significant relationship between oil components and some environmental factors. According to their chemical composition and edapho‐climatic characteristics, two major groups of populations were differentiated. The first group was composed of samples growing in regions with humid climate, clayey, sandy, and alkaline soils. These samples showed high thymol, α‐terpineol, linalool, and carvacryl methyl oxide content. The second group consisted of plants belonging to semi‐arid climate, and growing at high altitudes and silty soils. These samples were characterized by high carvacrol, α‐thujene, α‐terpinene, and myrcene content. However, populations exposed to sub‐humid climate, appeared less homogeneous and belong mainly either to the first or second group. A significant correlation between some edaphic factors (pH, K2O content, soil texture) and the EOs yield of O. compactum plants was evidenced. In spite of the correlation obtained for the oil composition with edapho‐climatic factors and the variance explained by the environmental data set, the observed EO diversity might be also genetically determined.

Mapping the Risk of Soil Salinization Using Electromagnetic Induction and Non-parametric Geostatistics

The knowledge about the magnitude, the spatial extent, the distribution and the evolution of salinity over a period of time is essential for the better management of salt-affected soils. Soil salinity is determined, conventionally, by measuring the electrical conductivity of a saturated past extract (ECe). However, given the spatio-temporal variability of salinity, numerous samples are necessary, which makes the conventional procedure laborious and expensive. As an alternative, the apparent electrical conductivity of soil (ECa) can be measured in the field by the use of the electromagnetic induction (EMI) method. This method is fast and allows making extensive ECa determination in space and monitoring. In the present study, an area of 2,060 ha has been investigated in the irrigation district of Tadla, central Morocco. Twelve soil samples were collected for ECe measurement, while 92 ECa measurements were realized with EM38. The pairs of ECe-ECa values allowed establishing the calibration equation permitting to convert the ECa into ECe values and for other ECa values for which ECe was not accomplished. The geostatistics was used to develop maps for the risk of soil salinization. Initially, a threshold for the risk of soil salinization was determined, and indicators were built. Later, the spatial variability of these indicators was described and modelled using the variogram. Finally, the maps were generated based on a non-parametric method of geostatistical interpolation, that is, indicator kriging. The results showed that the study area presents various degrees of soil salinization risks. The south-eastern part and small areas in central west and east of the study area have a low risk of salinization. In contrast, the south-western, the north-western and the central parts have a high risk of salinization. All the remaining parts of the study area have a moderate risk of salinization. It is concluded that the combined use of ECe and ECa-EM38 values and geostatistics allowed establishing a reliable soil salinization risk map and help to develop rehabilitation plan for the salt-affected soils.

Assessment of Heavy Metal Pollution and Ecological Risk of Roadside Soils in Tlemcen (Algeria) Using Flame-Atomic Absorption Spectrometry

ABSTRACT In Algeria, few studies have been conducted on the evaluation of roadside soil pollution. A total of 34 soil samples (28 roadside and 6 off-road) was obtained at 0–20 cm depth along the RN 35 national road. Heavy metal (Cd, Cr, Cu, Fe, Ni, Pb, and Zn) contents were extracted using aqua regia digestion and determined using atomic absorption spectrometry. Background values of heavy metal contents were determined using the robust statistical method of median plus two times the median absolute deviation. Single- and multi-element pollution and ecological risk indices were calculated. The results showed that background values were 2.5 ± 0.3, 64.9 ± 8.1, 28.0 ± 4.1, 29371.5 ± 4403.0, 32.9 ± 4.4, 72.2 ± 12.8, and 445.1 ± 62.9 mg/kg for Cd, Cr, Cu, Fe, Ni, Pb, and Zn, respectively. The results were all higher than their corresponding median values. Single-element pollution indices (enrichment factor and geoaccumulation index) showed that the pollution is primarily due to Pb and Zn. Multi-element pollution index (Nemerow index) indicated that only 3% of the soil samples are strongly contaminated, whereas 23% are seriously contaminated. The potential ecological risk index showed that Cd is the most harmful element, followed by Pb and Zn. 65% of the soil samples had moderate potential ecological risk, while only 3% had considerable potential ecological risk. This study may be used as a baseline for future monitoring and as a tool for decision-making regarding environmental protection policies and sustainability of this semiarid agroecosystem.

Diversity of fungal assemblages in roots of Ericaceae in two Mediterranean contrasting ecosystems

The plants belonging to the Ericaceae family are morphologically diverse and widely distributed groups of plants. They are typically found in soil with naturally poor nutrient status. The objective of the current study was to identify cultivable mycobionts from roots of nine species of Ericaceae (Calluna vulgaris, Erica arborea, Erica australis, Erica umbellate, Erica scoparia, Erica multiflora, Arbutus unedo, Vaccinium myrtillus, and Vaccinium corymbosum). The sequencing approach was used to amplify the Internal Transcribed Spacer (ITS) region. Results from the phylogenetic analysis of ITS sequences stored in the Genbank confirmed that most of strains (78) were ascomycetes, 16 of these were closely related to Phialocephala spp, 12 were closely related to Helotiales spp and 6 belonged to various unidentified ericoid mycorrhizal fungal endophytes. Although the isolation frequencies differ sharply according to regions and ericaceous species, Helotiales was the most frequently encountered order from the diverse assemblage of associated fungi (46.15%), especially associated with C. vulgaris (19.23%) and V. myrtillus (6.41%), mostly present in the Loge (L) and Mellousa region (M). Moreover, multiple correspondence analysis (MCA) showed three distinct groups connecting fungal order to ericaceous species in different regions.