Mohamed Hédi El Aouni

Generalized biomass equations for the main aboveground biomass components of maritime pine across contrasting environments

Abstract• IntroductionIn order to predict the biomass of aerial components of maritime pine stands (Pinus pinaster Ait.), generalized allometric equations were developed using data collected from the southern and northern margins of its geographical area.• MethodsThe data comprised biomass values divided into foliage, branch, stem and minor components collected from 26 trees in Tunisia and 152 trees in France. Some trees were taken from plots receiving fertilisation and irrigation. The equation W = aDb, where W is the biomass, D the stem diameter and a and b are fitted parameters, explained 98% of the variations in the total aerial biomass. The addition of tree age reduced significantly the residual sum of squares for the foliage component. This model explains 79% of the variations in foliage biomass observed.• ResultsTo a lesser extent, the age variable also improved the stem and branch models that explain 98% and 71% of the observed sum of squares, respectively. Site variables such as the stocking density, stand basal area, fertilisation or annual precipitation did not reduce the residual sum of squares, suggesting that their putative effects are conveyed through tree growth rate.

Chemical composition and antioxidant activity of essential oil from aerial parts of Teucrium flavum L. subsp. flavum growing spontaneously in Tunisia

The objectives of this study were to chemically characterise and evaluate the antioxidant potential of the essential oil from Teucrium flavum L. subsp. flavum growing spontaneously in Tunisia. The volatile oil was extracted by hydrodistillation of the aerial parts in a Clevenger type apparatus. Forty constituents were identified via GC and GC-MS analysis. β-caryophyllene (32.5%) and α-humulene (17.8%) were the most abundant components. The evaluation of free radical scavenging activity using stable DPPH free radical showed that the volatile oil exhibits a moderate antioxidant activity and reduces DPPH to 50% at EC50 value of 1230 μg mL− 1.

Volatile Profile of Herniaria fontanesii Growing Spontaneously in Tunisia

The essential oil extracted from Desfontaines rupturewort, Herniaria fontanesii J. Gay subsp. fontanesii growing wildly in Tunisia, was analyzed using GC and GC-MS techniques. The free radical scavenging capacity and total phenol contents of three crude extracts having different polarities (n-hexane, ethyl acetate and methanol) were examined. Thus, a total of 35 constituents were identified in the Desfontaines rupturewort essential oil representing 89.8% of the whole constituents. The oil was dominated by hexadecanoic acid, caryophyllene oxide, terpin-4-ol, khusimone and trans-sabinene hydrate. The total phenolic contents ranged from 16.91 to 92.27 mg of gallic acid/g of dry weight and they were found to be significantly higher in methanol than in polar ethyl acetate and hexane extracts. Correlations were observed between the phenolic contents and the antioxidant properties. Thus, the antioxidant activity of the methanol extract was superior to that of all samples tested (IC50 = 0.21 ± 0.04 mg/mL).

Taxonomic notes and distribution of taxa of Orobanche gr. minor (Orobanchaceae) from Tunisia

Abstract New records for the flora of Tunisia and, in part, for North Africa of taxa of Orobanche sect. Orobanche subsect. Minores (Beck) Teryokhin, are reported. These records come from field research carried out between 2010 and 2014 in the Kroumiria region in northwestern Tunisia and herbarium studies. Infraspecific taxa and chorological data about the identified taxa (Orobanche amethystea Thuill., Orobanche canescens C. Presl, Orobanche hederae Duby, Orobanche litorea Guss., Orobanche minor Sm. and Orobanche pubescens d’Urv.) are reported. Literature data on host and distribution are also revised. Orobanche litorea is new to North Africa, and O. canescens has been confirmed for North Africa more than 100 years after the only known collection. Orobanche hederae and O. pubescens are new to Tunisia.