Comparative study of plant growth of two poplar tree species irrigated with treated wastewater, with particular reference to accumulation of heavy metals (Cd, Pb, As, and Ni).

Water is a scarce natural resource around the world which can hamper the socio-economic development of many countries. The Mediterranean area, especially north Africa, is known for its semi-arid to arid climate, causing serious water supply problems. Treated wastewater (TWW) is being used as an alternative strategy for recycling wastewater. It is also a potential source of nutrients for reforestation with certain plant species such as poplar trees, a useful wood resource, and even for phytoremediation purposes. In the present study, we used treated wastewater to irrigate two clones of 1-year-old poplar trees (Populus nigra cv. I-488 and Populus alba cv. MA-104) for 90 days. After a stipulated time, a comparative study was made of the effects of TWW on growth parameters, acquisition of essential minerals (Na, Fe and Zn) and pollutants (Cd, Pb, As and Ni) as well as the enrichment of secondary metabolites such as polyphenolic, flavonoid and tannin compounds which could contribute to the growth and development of poplar plants. The results of this study show that the use of TWW increased P. alba's biomass production by 36% and also enhanced its Cd and Pb accumulation capacity. We also found that P. alba has considerable potential to be used as an alternative plant species for reforestation and/or phytoremediation of toxic metals from contaminated water or effluent.

Content of carotenoids, tocopherols, sterols, triterpenic and aliphatic alcohols, and volatile compounds in six walnuts (Juglans regia L.) varieties.

The aim of this work was to study the content of tocopherols, sterols, triterpenic and aliphatic alcohols, carotenoids, and volatile compounds in the kernel oils from six walnut (Juglans regia L.) varieties. The levels of ß-carotene ranged between 0.22 and 0.62 mg/kg, followed by lutein (0.01-0.06 mg/kg). The total content of tocopherol ranged from 186.5 to 436.2 mg/kg of the extracted oil and the major isoform in all samples was γ-tocopherol. The most abundant phytosterol was ß-sitosterol (974-1494 mg/kg) followed by campesterol then Δ-5-avenasterol. The major triterpenic alcohol was cycloartenol (226.4-532.1 mg/kg). Hexacosanol (9.71-28.15 mg/kg) was the major aliphatic alcohol. The detected volatile compounds were pentanal, hexanal, nonanal, 2-decenal and hexanol. The statistical analysis showed significant differences between varieties, which are probably due to genetic factors.

Analysis of pecan nut (Carya illinoinensis) unsaponifiable fraction. Effect of ripening stage on phytosterols and phytostanols composition.

Changes in 4-desmethylsterol, 4-monomethylsterol, 4,4-dimethylsterol and phytostanol composition were quantitatively and qualitatively investigated during the ripening of three varieties of Tunisian-grown pecan nuts (Mahan, Moore and Burkett). These components have many health benefits, especially in lowering LDL-cholesterol and preventing heart disease. The phytosterol composition of whole pecan kernel was quantified by Gas Chromatography-Flame Ionisation Detection (GC-FID) and identified by Gas Chromatography-Mass Spectrometry (GC-MS). Fifteen phytosterols and one phytostanol were quantified. The greatest amount of phytosterols (2852.5mg/100g of oil) was detected in Mahan variety at 20 weeks after the flowering date (WAFD). Moore had the highest level of phytostanols (7.3mg/100g of oil) at 20 WAFD. Phytosterol and phytostanol contents showed a steep decrease during pecan nut development. Results from the quantitative characterisation of pecan nut oils revealed that ß-sitosterol, Δ5-avenasterol, and campesterol were the most abundant phytosterol compounds at all ripening stages.

Biomass production, photosynthesis, and leaf water relations of Spartina alterniflora under moderate water stress.

The perennial smooth cordgrass, Spartina alterniflora, has been successfully introduced in salty ecosystems for revegetation or agricultural use. However, it remains unclear whether it can be introduced in arid ecosystems. The aim of this study was to investigate the physiological response of this species to water deficiency in a climate-controlled greenhouse. The experiment consisted of two levels of irrigation modes, 100 and 50% field capacities (FC). Although growth, photosynthesis, and stomatal conductance of plants with 50% FC were reduced at 90 days from the start of the experiment, all of the plants survived. The water-stressed plants exhibited osmotic adjustment and an increase in the maximum elastic modulus that is assumed to be effective to enhance the driving force for water extraction from the soil with small leaf water loss. An increase in the water use efficiency was also found in the water-stressed plants, which could contribute to the maintenance of leaf water status under drought conditions. It can be concluded that S. alterniflora has the capacity to maintain leaf water status and thus survive in arid environment.