Among the plants studied, var. purpurea was the most efficient in accumulating Pb and Zn in its shoots, whereas var. rubra was most suitable for phytostabilization of sites contaminated with Cu and Ni.

This study examined the influence of salt levels on antioxidant activity and content of carotenoids and anthocyanins of the A. hortensis leaves using two varieties: green orach (var. purpurea) and red orach (var. rubra). Seeds of Atriplex were exposed to 0, 90, 180 and 260 mM NaCl for 3 months and seeds were sown in an earthen pot. Overall levels of ascorbate peroxidase (APX) and glutathione reductase (GR) activity were significantly elevated. Salt stress caused a significant decline in tissue concentrations of catalase (CAT) and superoxide dismutase (SOD). However, 90 mM NaCl did not modify these parameters, which remains similar to control values. Activities of APX and CAT were increase whether the shoots of A. hortensis var. purpurea were grown in the presence of 180 mM NaCl. Thus although some indications of oxidative stress accompany exposure of this salt-tolerant Atriplex varieties to salinity, mechanisms appear to exist within its shoot tissue to permit the tolerance of such oxidative stress. High salt concentration in the culture medium provokes oxidative damage in Atriplex leaves and induces a general increase in antioxidant enzyme activity. In particular, NaCl toxicity decreased content of carotenoids. It also decreased the concentration of anthocyanin pigments in leaves of Atriplex. This work therefore provides a starting point towards a better understanding of the role of antioxidant enzyme in the plant response against salt stress.

The impact of salinity and water stress was analyzed in the xero-halophyte Atriplex hortensis using two varieties: green orach (A. hortensis var. purpurea) and red orach (A. hortensis var. rubra). A. hortensis L. is a C 3 species well adapted to salt and drought conditions. To collect information on the physiological impact of different salt and water deficit levels on their water stress resistance, plants were exposed for 3 months to solution containing four levels of NaCl or to water stress regimes including four levels of field capacity. Osmotic potential at zero turgor W s 0 , osmotic potential at full turgor (W s 100 ), relative water content (RWC), ion concentration (Na ? , K ? , Ca 2? , Mg 2? , and Cl -), and malondialdehyde (MDA) were determined at the end of the treatment. The salinity and water stress induced a decrease in W s 100 , W s 0 , and RWC in both varieties, recorded changes being higher in plants of red variety than those of green variety. Both varieties specifically accumulated Na ? in response to drought and salt stress, suggesting that this element could play a physiological role in the stress response of this xero-halophyte species. In contrast, the presence of NaCl and water stress induced a decrease in K ? , Ca 2? , and Mg 2? concentration in both varieties. Salinity clearly induced an increase in Cl -concentration in all tissues, but water stress had no impact on this parameter. MDA concentration increased in response to water stress and exogenous NaCl. Based on these findings the more drought-tolerant red orach may be grown in water-limiting soils.

Background Drought is a major problem limiting the growth and development of plants in the world and especially in Tunisia. Halophytes constitute a renewable wealth and they offer great flexibility with regard to abiotic stresses, and they are evaluated for their ecological and potential food use. Results The proposed work identifies the response of Atriplex hortensis var. rubra to the germinal stage and the reproductive stage under a deficient water regime to measure the drought resistance of this plant that has very interesting forage production abilities. The morphological and water parameters are used to characterize the physiological response of this species to the effects of water deficit. For the germination test, four levels of osmotic potential caused by PEG-6000 solutions at different levels of water potential (− 0.1, − 0.5, − 1.0, − 1.5 MPa) were adopted in seed of A. hortensis germination media. The methodology adopted in the second experiment is based on the cultivation of potted plants stored in a semi-controlled greenhouse at flowering stage. The water deficit was imposed on the plants by watering stop for a week, and the control plants are subjected to a water regime maintained irrigated at 100% of the capacity in the field. Drought tolerance was scored 30 days after the drought stress commenced based on the number of branches and leaf, dry biomass, relative water content, leaf water potential, and nitrogen content. No significant difference was observed in germination rates for all PEG concentrations throughout the experiment which are still close to 60%. The results obtained for the second experiment show a high tolerance of A. hortensis under water stress. Drought induced decreases in two physiological parameters, the number of branches and leafs, and the relative water content of annual Atriplex. Heatmap and PCA data revealed that physiological parameters are more sensitive than morphological parameters in distinguishing the control and drought treatments. Conclusions Indeed, the orache is distinguished by a great ability to retain water potential after a month of stress. Thus, height, number of branches, leaf and shoot dry weight, and percentage of nitrogen were significantly similar for controls and stressed for A. hortensis. On the other hand, measured root length and basic and midday water potential show significant variability between controls and stressors. In addition, these results highlight the importance of the resistance of Atriplex halophyte forage to drought.