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The decline in soil fertility and the poor distribution of precipitation during the growth and maturation of cereal crops are major constraints to improving yields in the Mediterranean zone in North Africa. The use of agroforestry species is one strategy for enhancing agronomic productivity and supporting a range of ecosystem services and environmental benefits. However, to our knowledge, the allelopathic effects of these agroforestry species on cereals are poorly documented under Mediterranean conditions. The effects of three aqueous extracts (leaves, roots and litter) from two agroforestry species (Casuarina glauca Sieb. Ex Spreng. and Populus nigra L.) have been evaluated for their allelopathic potential on seed germination and seedling growth of Triticum durum Desf. under laboratory conditions. These allelopathic effects were evaluated using several parameters including seed germination, total dry mass, root and shoot length, chlorophyll and protein concentrations in T. durum seedlings along with phenolic compounds in different parts (leaves, roots and litter) of the two allelopathic species. Exposure to the different extracts of C. glauca and P. nigra significantly reduced germination kinetics, dry mass production, root and shoot length, and chlorophyll and protein concentrations in T. durum seedlings. This reduction was significantly more pronounced for the different extracts from P. nigra. Our results showed a significant negative correlation between dry mass accumulation in T. durum seedling and polyphenol concentration. Overall, the findings of the present study support the introduction of C. glauca into the agroforestry system. However, field monitoring under natural conditions would be necessary to confirm in practice the results obtained with the bioassays. [ABSTRACT FROM AUTHOR]

The pollution of soils by heavy metals resulting from mining activities is one of the major environmental problems in North Africa. Mycorrhizoremediation using mycorrhizal fungi and adapted plant species is emerging as one of the most innovative methods to remediate heavy metal pollution. This study aims to assess the growth and the nutritional status of ectomycorrhizal Pinus halepensis seedlings subjected to high concentrations of Pb, Zn, and Cd for possible integration in the restoration of heavy metals contaminated sites. Ectomycorrhizal and non-ectomycorrhizal P. halepensis seedlings were grown in uncontaminated (control) and contaminated soils for 12 months. Growth, mineral nutrition, and heavy metal content were assessed. Results showed that ectomycorrhizae significantly improved shoot and roots dry masses of P. halepensis seedlings, as well as nitrogen shoot content. The absorption of Pb, Zn, and Cd was much higher in the roots than in the shoots, and significantly more pronounced in ectomycorrhizal seedlings—especially for Zn and Cd. The presence of ectomycorrhizae significantly reduced the translocation factor of Zn and Cd and bioaccumulation factor of Pb and Cd, which enhanced the phytostabilizing potential of P. halepensis seedlings. These results support the use of ectomycorrhizal P. halepensis in the remediation of heavy metal contaminated sites. [ABSTRACT FROM AUTHOR]