Eco-physiological and biochemical characterization of Rhus tripartita (Ucria) Grande growing in Algerian Sahara under arid climate

Rhus tripartita (Ucria) Grande, is an Anacardiaceae autochthonous shrub of the Algerian Sahara. Its ecological, pastoral and therapeutics interests prompted us to carry out an eco-physiological and biochemical behavior in relation to aridity. Therefore, relative water content of shrub leaves were found on average 81.55% and the maximum of electrolyte leakage recorded was 14.29. The biochemical determination of proteins and sugars shows that leaves are a true source of protein (33.76 mg/g FM) and sugars (938.93 μg/g FM) while the proline assay gave a value of 824.40 μg/g. The quantitative study of flavonoids in the leaves gave a result of 36.53 mg/g. The analysis of photosynthetic pigments content showed respectively results of 28.1 μg/g, 31.24 μg/g, 56.47 μg/g and 11.23 μg/g for chlorophyll a, chlorophyll b, total chlorophyll and carotenoids. The total antioxidant capacity was evaluated and gave result of 95.5 mg GAE/g. Therefore, Rhus tripartita was found to accumulate high proportions of primary and secondary metabolites which showed a good adaptation to its arid environment. In conclusion, the plant can be considered as a xeromorphic plant, that is, a desert-adapted plant that is not limited by the water availability

Influence de différents traitements de prégermination des graines de Vigna unguiculata (L.) Walp. sur les performances germinatives et la tolérance au stress hydrique

Influence of different pre-germination treatments of Vigna unguiculata (L.) Walp. seeds on germination performance and water stress tolerance. Description of the subject. Priming or hardening is a pregermination treatment. This treatment consists of incorporating an osmotic seed treatment (osmopriming) or a hormonal (hormopriming) and/or a redehydration (hydropriming) treatment. The approach allows the elimination of dormancy, homogenization (synchronization) of germination, better growth, earlier flowering and a tolerance to abiotic stresses such as drought and salinity. In this kind of treatment, the seed is soaked and then dehydrated before radicle breakthrough, i.e. during the reversible phase of germination. Thus, the seed can return to its initial stage without any damage. Objectives. In this paper, we aimed to study the consequences of hydropriming and osmopriming (by PEG6000 at 10 and 30%) on cowpea seeds (Vigna unguiculata), on germination performance and on the water stress tolerance of plants from these seeds. Method. Vigna unguiculata seeds were hydroprimed, hydroprimed twice or osmoprimed (with PEG6000 10 and 30%). For each treatment, germination performance (germination capacity, speed) and the water stress tolerance of the plants were studied. Results. Results showed that increased hardness of the seed allowed a faster, more uniform germination and better growth of both the radicle and aerial parts. We also demonstrated that a double redehydration was more effective in improving these parameters. Conclusions. Application of these pretreatments, adapted according to the plant species, will has the capacity to improve seed germination and crop yield, as well as tolerance to water deficit