Fatiha Aid

As salt-sensitive crops, the performance of legumes in resisting salinity should be improved through accessible, less expensive and commonly practiced alternatives. Our study investigated the potential benefits of coupling the activation of endogenous phosphate-solubilizing bacteria with calcium phosphate amendment, focusing on saline soil fertility, the activation of the plants' antioxidant defense mechanisms, and the phosphate solubilization efficiency of the PSBs in plants growing under salinity conditions. There were four factors in the experimental treatments; i) control (C), ii) two levels of salinity (NaCl) 0.3% and 0.9%, iii) two levels of calcium-phosphate (Ca-P): (21% Ca x 41%P), (48% Ca x 92% P) and iii) combined application (NaCl x Ca P), applied at the seedling stage. Salinity significantly reduced water uptake, physiological parameters and affected root growth strategy (-60%). PCA confirmed that stressed plants showed a positive association between antioxidant parameters which could related to overproduction of ROS, decreased phosphate solubilizing activity, destroyed soil and reduced plant tolerance to salt stress. Application of combined (NaCl x Ca-P) significantly improved the antioxidant response with accumulation of proteins and proline, increase in water uptake, chlorophyll pigments, maintain cell turgor, root hair density (70%), root hair length (71%), complete histological root formation, improved the physicochemical quality of the soil where EC decreased by about 20 % and pH became neutral, and increased the PSB number (80%). The use of Ca-P with salinity could reestablish physiological homeostasis, complete anatomy, and better plant growth. It also enhanced the physicochemical and biological properties of the saline soil. Interactivity in the plant-soil-rhizobacteria system could be a viable option to positively influence plant resilience against salt stress and saline soil rehabilitation.

Malgré l’importance des représentants du genre Lotus en Algérie, leur statut symbiotique et la nature des rhizobia qui leurs sont associés sont méconnus. Cette étude portant sur 39 plants de Lotus appartenant à 15 espèces nous a permis de vérifier qu’ils sont tous nodulés et fixateurs d’azote et d’isoler à partir de leurs nodules 38 souches de bactéries nodulant les légumineuses qui ont été authentifiées. Le séquençage du gène de l’ARNr 16 S de ces 38 souches de rhizobia montre une prédominance de souches du genre Mesorhizobium représenté par 10 espèces parmi lesquelles M. erdmanii, M. ciceri et M. jarvisii se sont montrées les plus importantes. La nodulation des espèces de Lotus examinées est assurée dans une moindre mesure par des souches des genres Bradyrhizobium et Ensifer, tous deux représentés par deux espèces. Cette étude a permis, d’une part, de révéler la diversité des rhizobia associés aux Lotus d’Algérie, et d’autre part, de mettre en évidence une faible implication dans la nodulation des souches du genre Bradyrhizobium et l’absence de celles de l’espèce Mesorhizobium loti, deux groupes de rhizobia considérés comme les microsymbiotes les plus communs chez les représentants du genre Lotus.

La plantation d’espèces diversifiées adaptées aux zones des massifs forestiers de l’Atlas saharien permettrait une meilleure lutte contre la désertification du couvert végétal de ces zones fragilisées. Grâce à sa croissance rapide sur des sols dégradés, Robinia pseudoacacia L. présente un avantage certain dans le repeuplement de ces zones en voie de désertification. La scarification des graines de Robinia pseudoacacia L. est nécessaire pour permettre l’absorption de l’eau par les semences. Nos résultats indiquent que les scarifications manuelles par l’acide sulfurique (75 minutes), par l’eau bouillante (90 minutes), ainsi que la scarification par les micro-ondes (700 W) (105 secondes) permettent d’obtenir les meilleurs taux de germination. La présence de PEG ₆₀₀₀ dans les solutions d’imbibition réduit considérablement le taux de germinations des graines de R . pseudoacacia L. Une diminution de 70 % du taux optimal de germination est observée lorsque le potentiel osmotique de la solution d’imbibition est à –4,65 bar.

Chickpea is considered among the most sensitive grain legumes to salinity. The improvement of tolerance of lines in combination with tolerant rhizobial strains depends on various environmental and cultural conditions such as soil properties. This investigation was undertaken to evaluate the effect of phosphorus fertilization (0, 90 and 200 kg ha⁻¹ of P₂O₅) on biomass, nodular traits and grain yield (GY) of chickpea (cv. Flip 84-79C) growing under salinity (0 and 150 mM NaCl). The trial was laid out following a randomized block design with three replicates during 2010–2012, at the experimental farm of Oued Smar (Algiers). Salinity did not significantly decrease the dry biomass of the plants but the relative shoot growth was more affected than control, P and SP1 treatments. Besides, salinity significantly reduced GY (−20%) and nodulation traits compared to the control plants while an inversely proportional relationship was found between protein, leghemoglobin and MDA content, K/Na ratio and the increase in salt concentration. Application of two P levels to saline soil enhanced growing conditions of plants. Particularly, the (90 kg ha^–1 of P × 150 mM NaCl) combination significantly increased leghemoglobin (92%), reduced proline content (−69%) and protected membranes against peroxydation compared to saline conditions. A significant increase was observed in the GY (about 30%) of plants at both P doses combined with salt stress compared to other cases. Statistically, the low P level combined with salinity induced similar responses of plants and sometimes better responses to control plants. Finally, our results support the roles of phosphorus fertilizer in the alleviation of salt stress and enhancing the soil quality for better symbiosis efficiency and yield of chickpea.

Despite the high economic value of safflower (Carthamus tinctorius), the potential of several wild related species as genetic resources is still poorly studied, in particular with regards to drought tolerance, a priority in safflower improvement. This situation is partially explained by the numerous and still discussed uncertainties in phylogenetic relationships within the safflower species complex. In this study, we focused on two rare Algerian wild species, Carthamus strictus and Carthamus chouletteanus. We aimed at: (i) clarifying their taxonomic status, and determining their phylogenetic relationships with safflower and other Mediterranean species of Carthamus sensu lato (s.l.) (Carthamus sensu stricto (s.s.) and Carduncellus genera) by using nucleotide diversity within the internal transcribed spacer region (ITS) and (ii) assessing the water use efficiency (WUE) of these species by determining their carbon isotope composition. Our results support the existence of two well supported different clusters among the safflower species complex: Carthamus s.s. including Eastern annual species and the vast Carduncellus group constituted by Western perennial species, including the two studied Algerian species. Also, significant differences for carbon isotopic composition between Carthamus s.s. and Carduncellus were revealed. Carduncellus species displayed significantly higher δ¹³C values (i.e., higher WUE) than Carthamus s.s. species. Carthamus chouletteanus displayed the highest average value of δ¹³C (highest WUE) among the species studied. Our data encourage for further studies on the possibility of hybridisations between species of the two genera and suggest that Carduncellus should be considered as potentially more interesting genetic resources to improve the WUE of safflower, rather than Carthamus s.s. species.

The goals of the present study were to obtain a first estimate of intraspecific variability of carbon isotope discrimination (Δ) in safflower, a thistle-like herbaceous plant, and to determine the statistical relationship between Δ and grain yield as well as its components in a collection of 45 accessions of different origins. Grain yield and aboveground biomass, harvest index, average grain weight, and Δ (measured on the bulk leaf organic matter) were investigated in experimental field conditions. A large variability was noted for all traits but a principal component analysis (PCA) allowed to identify several homogeneous groups of accessions. Average grain yield per plant varied between 1 and 39 g. Δ varied between 21.3 and 25.2 ‰, i.e. a large variation of 3.9 ‰. In our experiment, the variation of Δ was not significantly related to that of grain yield in the whole accession sample. However, we found contrasting trends for this relation within accession groups. These initial results motivate further experiments to assess more in depth correlation between Δ and yield in safflower and are encouraging regarding the possibility of using Δ as an effective selection index in safflower to obtain genotypes that efficiently consume water. This study also highlighted one accession that combines the two characters required in the Mediterranean regions, i.e. high yield performance and high water-use efficiency.

Water stress usually impairs photosynthesis and plant growth. Acacia tortilis subsp. raddiana is well adapted to dry environments. The aim of the present study was to determine the impact of a progressive decrease in soil water content on photosynthetic-related parameters at the young seedling stage. Drought-induced plant responses occurred according to two types of kinetics. Water potential, stomatal conductance, and transpiration rates were rapidly affected by a decrease in soil water content, while chlorophyll fluorescence-related parameters and chlorophyll concentrations decreased only when soil water content was lower than 40%. The maximal efficiency of PSII photochemistry in the dark-adapted state remained unaffected by the treatment, whatever the stress duration. A. raddiana accumulated high concentrations of soluble sugars in relation to a stress-induced early stimulation of sucrose-phosphate synthase activity, while stimulation of invertase and sucrose synthase led to fructose accumulation only at the end of the stress period. We suggested that sugar accumulation may be involved in osmotic adjustment and protection of stressed tissues. A. raddiana was thus able to protect its photosynthetic machinery under drought conditions and may be considered as a promising species for revegetation of dry areas.

Plants of Parkinsonia aculeata L. were dehydrated by withholding water for 13 days and then rehydrated. The leaves of control plants and stressed plants were analyzed every four days from the beginning of stress and 6, 24, and 48 h after stress relief. Analysis of leaf water status showed a decrease in relative water content of nearly 16% during dehydration and a return to its control value after 48 h of rehydration. The contents of chlorophylls, chloroplast lipids (monogalactosyldiacylglycerol and digalactosyldiacylglycerol), and neutral lipids increased by 38%, 20%, and 125% (in μg·mg dry mass⁻¹), respectively, when the daily decrease of relative water content reached 1.4%, while the mass of extra-plastidial lipids (phosphatidylcholine and phosphatidylethanolamine) increased by 25% (in μg·mg dry mass⁻¹) only when the daily water loss was 2.6%. In addition, incorporation of radioactive acetate in lipids showed a preferential synthesis of digalactosyldiacylglycerol, phosphatidylglycerol, and phosphatidylcholine. The unsaturation degree of galactolipids remained stable, while a slight increase of unsaturation of phosphatidylcholine and phosphatidylethanolamine was observed. After rehydration, the mass of chlorophylls fell sharply, while the amount of total lipids decreased slowly as the level remained 17% higher than in the control 6 h after stress relief. Our results show that Parkinsonia plants are sensitive to a slight variation of the water potential and respond with an increased synthesis of membrane lipids during stress and after rehydration.