Phytochemical profile and antioxidant properties of leaves extracts from Posidonia oceanica (L.) Delile and their allelopathic potential on terrestrial plant species

Dichloromethane, chloroform, ethyl acetate and ethanol extracts obtained from Posidonia oceanica (L.) leaves, were examined in order to determine their total phenolic, flavonoid, flavonol, anthocyanin and condensed tannins contents as well as their antioxidant and allelopathic activities. The qualitative phytochemical analysis of crude extracts confirmed the presence of coumarins in dichloromethane, chloroform and ethyl acetate extracts. The antioxidant activity estimated using the DPPH assay was significantly more pronounced for the ethyl acetate extract (IC50 = 1.19±0.018 mg/mL) than that of the other extracts. The allelopathic effect against the seeds of Carum carvi (L.) and Foeniculum vulgare (Mill.) indicated that, depending on concentration, the extracts from the leaves of P. oceanic (L.) inhibited or stimulated at different concentrations the germination, shoot and root elongation of seedlings growth. The results of this study suggest that P. oceanica (L.) extracts could be useful as a natural source of health-promoting effects and herbicides.                     KEY WORDS: Posidonia oceanic (L.), Phytochemical profile, Phenolic compounds, Antioxidant activity, Carum carvi (L.), Foeniculum vulgare (Mill)   Bull. Chem. Soc. Ethiop. 2020, 34(3), 437-447. DOI: https://dx.doi.org/10.4314/bcse.v34i3.

Effects of nitrogen rates on grain yield and nitrogen agronomic efficiency of durum wheat genotypes under different environments

Durum wheat is an important staple food crop in Tunisia and other Mediterranean countries and is grown in various climatic conditions. Production and yield are however severely limited not only by drought events but also by reduced levels of nitrogen fertilisation. A study was carried out at two locations in the sub-humid area of Tunisia: Mateur in 2009–10 and 2010–11 and Beja in 2011–12 and 2012–13 under rainfed conditions. Four durum wheat genotypes (landraces: Bidi, Azizi; improved: Om Rabia, Khiar) were evaluated for nitrogen agronomic efficiency and related agronomic traits under various nitrogen rates: 0, 50, 100, 150, 200 and 250 kgNha−1, with three replications. There was a significant interaction effect (P ≤ 0.001) environments × genotypes ×N treatments for grain yield (GY), biomass yield (BY), harvest index (HI), partial factor productivity of applied nitrogen (PFPN) and nitrogen agronomic use efficiencies (NAE). GY was the most affected trait by nitrogen applied showing an increase of 94% under high N treatment (250 kgNha−1) compared to control plots without N treatments. A significant linear regression exists between GY (0 N) and GY for the different N rates (r =0.70; P < 0.001). This effect was more pronounced for improved genotypes than landraces for all parameters excepting BY and NAEBY. BY showed +11% increase in landraces than improved genotypes. PFPN showed an average decrease of 65% under high-N fertilisation with 10% prevalence for improved genotypes. Landraces tend to promote vegetative growth while grain filling efficiency was higher for improved genotype

Changes in volatiles of olive tree Olea europaea according to season and foliar fertilization

In the present study, four foliar fertilizers (FF1, FF2, FF3 and FF4) were separately sprayed on Chemlali olive trees at different moments of the vegetative cycle. FF1 (rich in nitrogen) was applied during the vegetation stage (Last January-February) at a dose of 5 L/ha per spray (three sprays per season). FF2 (rich in boron, magnesium and sulphur), FF3 (rich in phosphorus and potassium) and FF4 (rich in phosphorus and calcium) were applied respectively during the stages of flowering (Last March-April), fruit growth (July-August) and ripening (October-November), at a dose of 3 L/ha per spray (three sprays per season for each fertilizer).The volatile fraction was analysed by GC-MS, 46 volatile compounds were identified and their amount were expressed as relative abundance (%). In a general view, the most abundant volatiles in Chemlali olive leaves across the vegetative cycle were (E)-2-hexenal, nonanal, (E)-β-damascenone, 3-ethenyl pyridine and β-caryophyllene. The levels of these main compounds and the general composition of the volatile fraction varied significantly through season.The volatile levels were mainly affected by the two foliar fertilizers enriched with nitrogen and Boron respectively. The most affected volatiles were (E)-2-hexenal, nonanal, 3-ethenyl pyridine, (E,E)-α-farnesene, and (E)-nerolidol. Less impact was noticed after the use of the other foliar fertilizers.Our study is the first investigation bringing data about the variation of leaf volatile profile of Chemlali cultivar across a vegetative cycle and showing the impact of nutrient foliar sprays on olive leaf volatile

Efecto del extracto de cáscara de granada tunecina sobre la estabilidad oxidativa del aceite de maíz en condiciones de calentamiento

The effect of pomegranate peel extract (PPE) on the oxidative stability of corn oil during heating was studied. Oxidation was followed by determining peroxide value (PV), p-anisidine value (p-AV), free fatty acid value (FFA), conjugated dienes (CD), conjugated trienes hydroperoxides (CT) and the calculated total oxidation value (TOTOX). Polyphenol (TPC) and ortho-diphenol (TOPC) contents as well as the antioxidant activity of each oil sample were evaluated before and after heating. PPE showed a significant inhibitory effect on lipid oxidation. Heating samples for 8 hours supplemented by PPE to a level of 1000 ppm resulted in the highest significant decreases in investigated indices compared to the control and BHT values. It was concluded that the antioxidant activity of PPE delayed oxidation and can be used in the food industry to prevent and reduce lipid deterioration in oil.Se estudió el efecto del extracto de cáscara de granada (ECG) sobre la estabilidad oxidativa del aceite de maíz durante condiciones de calentamiento. La oxidación se siguió mediante la determinación del índice de peróxido (IP), el índice de p-anisidina (p-AV), el índice de acidez (IA), los dienos conjugados (DC), los hidroperóxidos de trienos conjugados (TC) y el valor calculado de la oxidación total (TOTOX). Se evaluó el contenido de polifenoles totales (PT) y de orto-difenoles (o-DF), así como la actividad antioxidante de cada muestra de aceite, antes y después del calentamiento. El ECG mostró un efecto inhibidor significativo sobre la oxidación de lípidos. El calentamiento de las muestras, durante 8 horas suplementadas con ECG a un nivel de 1000 ppm, dio como resultado una significativa disminución de los índices investigados en relación con los valores de control y con BHT. Se concluyó que la actividad antioxidante de los ECG retrasó la oxidación y que se puede utilizar en la industria alimentaria para prevenir y reducir el deterioro de los lípidos del aceite

Three Phenolic and a Sterol Glycosides Identified for the First Time in Matthiola longipetala Growing in Tunisia

Three phenolic glycosides: 4-O-ß-D-glycopyranosyl zingerone 1, 4-O-ß-D-glycopyranosylhomovanillyl alcohol 2 and eugenol glycoside 3, together with 3-O-ß-D-glycopyranosyl sitosterol 4, were isolated and identified for the first time from the flowers of Matthiola longipetala (Crucifers) growing in Tunisia. The structures of 1, 2 and 3 were identified via their acetylated derivatives on the basis of the 1 and 2D NMR data analysis, mass spectrometry and IR spectroscopy

Low-temperature rate constants for rotational excitation and de-excitation of C3 (X 1∑g +) by collisions with He (1S)

The low-temperature rotational (de-) excitation of C3 (X 1∑g 1) by collisions with He (1S) is studied using an ab initio potential energy surface (PES). This PES has been calculated using the single- and double-excitation coupled-cluster approach with noniterative perturbational treatment of triple excitations [CCSD(T)] and the augmented correlation-consistent triple-ζ basis set (aug-cc-pVTZ) with bond functions. This PES is then incorporated in full close-coupling quantum scattering calculations for collision energies between 0.1 and 50 cm -1 in order to deduce the rate constants for rotational levels of C3 up to j = 10, covering the temperature range 5-15 K. © 2008. The American Astronomical Society. All rights reserved.The Agencia Española de Cooperación Internacional (project A/8083/07, CSIC-Université Tunis El Manar) and the Spanish Ministerio de Educación y Ciencia (project AYA 2005-00702) are thanked for financial supportPeer Reviewe

Variation of Grain Yield, Grain Protein Content and Nitrogen Use Efficiency Components under Different Nitrogen Rates in Mediterranean Durum Wheat Genotypes

Nitrogen (N) is a crucial nutrient for plant growth and development. To optimize agricultural environments, N fertilizers represent a critical tool to regulate crop productivity. The improvement of nitrogen use efficiency (NUE) represents a promising tool that may enable cereal production to meet future food demand. Wheat reported contrasting behaviors in N utilization showing specific abilities depending on genotype. This study selected two landraces and two improved genotypes from Northern Africa to investigate grain yield (GY), grain protein content (GPC) and NUE. Plants were grown under three levels of N supply: 0, 75, 150 kg N ha−1 and for two consecutive years. Results reported a better NUE (0.40 kg.kg N−1) obtained under 150 kg N ha−1, while N utilization efficiency (NUtE) showed a 13% increase using 75 kg N ha−1 compared with 150 kg N ha−1. Under low nitrogen rate (0 N), crop N supply (CNS) and N uptake efficiency (NUpE) were shown as determinant factors for improved genotypes GY (R2 = 0.72), while NUtE represented the most determinant component for GPC in landraces (R2 = 0.92). Multivariate regression models explained the dependence in GPC on NUE, NUpE, and NUtE. In conclusion, our results recognize GPC and NUtE as suitable selection traits to identify durum wheat with higher NUE

Rethinking justice beyond human rights. Anti-colonialism and intersectionality in the politics of the Palestinian Youth Movement

This article discusses the politics of the Palestinian Youth Movement (PYM) – a contemporary social movement operating across a number of Arab and western countries. Unlike analysis on the Arab Uprisings which focused on the national dimension of youth activism, we explore how the PYM politics fosters and upholds an explicitly transnational anti-colonial and intersectional solidarity framework, which foregrounds a radical critique of conventional notions of self-determination based on state-framed human rights discourses and international law paradigms. The struggle becomes instead framed as an issue of justice, freedom and liberation from interlocking forms and hierarchies of oppression. KEYWORDS: Palestine, transnational social movements, intersectionality, human rights, anti-colonialis