Varietal differences in the response of durum wheat (Triticum turgidum L. var. durum) to irrigation strategies in a semi-arid region of Algeria

International audienceThe response of three durum wheat cultivars (C: Chen’s, V: Vitron, W: Waha) to irrigation was studied during 4 years in semi-arid Algeria (Chlef). The four treatments were NI (unirrigated), EI (early irrigation, up to heading), LI (late irrigation, from heading) and FI (full irrigation, over the entire season). FI increased rainfed grain yield (1,300 kg ha−1) by 270%, EI by 107%, and LI by 67%. The variety × irrigation interaction was significant each year. Under irrigation, cv. Vitron was generally the most productive cultivar while in rainfed conditions cv. Waha always resulted in the highest grain yield. Grain yield increased exponentially with seasonal evapotranspiration (r 2 = 0.741) and harvest index (r 2 = 0.873). Water use efficiency for grain ranged from 4.6–5.3 kg ha−1 mm−1 (NI) to 9.6–10.8 kg ha−1 mm−1 (FI) as a function of cultivar and irrigation, cv. Vitron and cv. Waha (full irrigation) and cv. Waha (rainfed) being the most efficient cultivars. According to the evaporation pan method, the seasonal crop coefficient (K c) values for the three cultivars were 0.64 (V), 0.62 (W) and 0.54 (C). The corresponding peak K c values were 1.0, 0.97 and 0.89, respectively. K c was closely related to leaf area index (LAI) and specific logarithmic relationships were calculated for each cultivar. Irrigation scheduling should be adapted to the type of cultivar in relation to its potential yield and LAI development pattern

Floristic Diversity Patterns in the Beni-Haoua Forest (Chlef, Algeria)

The purpose of this study was to provide an inventory and an analysis of plant species occupying Beni-Haoua, a mountainous coastal ecosystem, with a rarely studied well-developed forest. As a result, 87 species were recorded in 7 sites, the Jaccard classification resulted in 4 groups of sites with significantly different diversities. According to the ϕ-coefficient of association, which can be used as a measure of fidelity, among the 87 species, 34 diagnostic species were distributed over four plant communities, with a fidelity value ranging from 55 to 100%, 28 differential species, among which 16 species were common to 2 plant communities and 12 common to 3 plant communities. The redundancy analysis (RDA) showed that among the studied environmental variables, altitude and pH were the most important ones. Indeed, according to the detrended correspondence analysis (DCA), plant species occurrence and distribution in the study area were affected by a strong altitudinal gradient.La région de Beni-Haoua est un écosystème littoral, montagneux, avec un patrimoine forestier très développé, qui n’a fait l’objet que de très rares études. Le principal objectif de cette étude est l’inventaire des espèces végétales ainsi que l’identification des principaux groupements végétaux que comporte cet écosystème par le biais des méthodes statistiques comme le coefficient de fidélité ϕ et l’analyse canonique des redondances (RDA). Ainsi, le coefficient de Jaccard a permis l’identification de 4 groupes de relevés (sites) avec des diversités floristiques significativement différentes. Selon, le coefficient de fidélité ϕ, parmi les 87 espèces recensées, 34 espèces sont réparties sur 4 unités de végétations avec un degré de fidélité allant de 55 % à 100 % et considérées comme espèces caractéristiques, 28 espèces différentielles parmi lesquelles 16 espèces communes à 2 unités de végétation et 12 espèces communes à 3 unités de végétations. La RDA a montré une très forte corrélation entre les espèces végétales et les paramètres environnementaux : l’altitude et le pH sont les paramètres environnementaux les plus importants conditionnant la distribution de la végétation. En effet la DCA a montré que l’occurrence et la distribution de la végétation dans la région de Beni-Haoua sont influencées par un fort gradient altitudinal.Ababou Adda, Chouieb Mohammed, Bouthiba Abdelkader, Saidi Djamel, Mederbal Khalladi. Floristic Diversity Patterns in the Beni-Haoua Forest (Chlef, Algeria). In: Ecologia mediterranea, tome 41 n°2, 2015. pp. 73-84