In the Mediterranean region, reforestation programs record failures following successive drought periods. The use of different plant-growth-promoting amendments and the understanding of drought-induced physiological and biochemical responses of carob will contribute to the reforestation program’s success. In this study, the effects of arbuscular-mycorrhizal-fungi (AMF), vermicompost (VC), and rock phosphate (RP) on carob seedlings under drought stress (DS) and recovery (REC) conditions were evaluated. A greenhouse experiment was conducted with carob seedlings grown in the presence of AMF, VC, and RP, applied alone or in combination under well-watered (WW), DS (by stopping irrigation for 12 days), and recovery (REC) conditions. The obtained results indicated that the triple combination (AMF + VC + RP) presented the highest improvement in water potential, photosynthetic pigment content, stomatal conductance, and chlorophyll fluorescence compared to the controls under DS and after REC. In addition, this combination resulted in improved tolerance of carob seedlings to DS and a high potential for rapid recovery after rehydration due to a high accumulation of sugars, proteins, and antioxidant enzymes. In summary, the results underline the importance of inoculating carob with AMF in combination with (in)-organic amendments in improving its tolerance to DS and its recovery performances.

The argan (Argania spinosa L. Skeels) ecosystem is severely degrading in arid and semi-arid lands due to climate change, particularly in terms of density loss and reforestation failure. Thus, it is important to adopt innovative effective sustainable practices to optimize the densification and reforestation success of the argan tree. The purpose of the present research was to investigate the combined effect of subsurface water retention technology (SWRT) and the use of native arbuscular mycorrhizal fungi (AMF) on edaphic, growth, physiological and biochemical parameters of field-grown argan seedlings in the Essaouira region, Morocco. In this experiment, one-year-old argan seedlings were transplanted in the absence and presence of biodegradable plastic and AMF. Our findings revealed that the application of SWRT enhanced soil profile moisture up to 640% at 40 cm depth compared to the control. The combination of this technology with AMF also improved soil fertility. Furthermore, the application of SWRT, with or without AMF, significantly enhanced argan seedling height (208 and 168%, respectively), stomatal conductance (54 and 33%, respectively), and chlorophyll fluorescence (21 and 20%, respectively). Similarly, the combined application of SWRT and AMF significantly improved protein and sugar content (36 and 57%, respectively), as well as antioxidant enzyme activities (peroxidase and polyphenol oxidase) and chlorophyll pigments content compared to the control. However, this treatment reduced malondialdehyde and H₂O₂ content in the argan leaves. As a summary, SWRT technology combined with AMF may be used as a valuable strategy to promote the success of argan reforestation and to limit soil erosion and desertification in arid and semi-arid climates.

The growing pressure exerted by global food demand, combined with the excessive use of chemical and synthetic inputs, is prompting the agricultural sector to seek innovative and sustainable solutions to improve, or at least maintain, crop yields in a context of increased abiotic stress linked to climate change. Among the promising approaches, biostimulants are attracting growing interest, particularly those derived from natural sources such as seaweed extracts, humic acids, and beneficial microorganisms. These products work through various mechanisms, including osmotic regulation, activation of antioxidant systems, stimulation of root growth, and improvement of nutrient absorption. Many recent research and review articles have explored the optimal combinations of raw materials, formulation processes, target crops, and environmental conditions to maximize beneficial effects on plant growth, soil health, and tolerance to abiotic stresses. As a result, a growing range of commercial products is emerging, with diverse chemical compositions, formulations, and modes of application. However, the precise relationships between the biochemical composition of biostimulants and their physiological effects remain poorly understood, suggesting a key role for molecular synergies. This review provides a concise overview of recent advances in biostimulant research and their potential to enhance food security by improving crop resilience in the context of climate change.

Argania spinosa L. Skeels is an ecological pillar of the arid zones of South-West Morocco, currently threatened by the drastic climate change. This study investigates the effect of the combined application of compost (C) and subsurface water retention technology (SWRT) on field performances of one-(1Y) and two-year-old (2Y) argan seedlings. A randomized field trial was performed with four treatments: Control, C, SWRT, and C + SWRT. We evaluated soil properties, growth, and physiology, alongside biochemical parameters including stress markers, compatible solutes, antioxidant enzyme activities, and secondary metabolites. The results reveal the significant effect of C and/or SWRT on argan seedlings performances, particularly in 1Y subjects. The C + SWRT strongly stimulated stem elongation (246% vs. 163%), stomatal conductance (75% vs. 99%), photosynthetic efficiency (18% vs. 11%), and chlorophyll a content (80% vs. 65%) in 1Y and 2Y seedlings, respectively, compared to their corresponding controls. Under the same treatment, malondialdehyde levels were significantly reduced by 37% in 1Y seedlings and 23% in 2Y seedlings. In addition, catalase activity and soluble sugar, protein, and polyphenol content increased by 38, 43, 26, and 21%, respectively, in the younger seedlings and by 53, 51, 18, and 19%, respectively, in the elder seedlings. In terms of soil health, C + SWRT significantly enhanced total organic carbon and matter, available phosphorus, and reduced electrical conductivity. In summary, the C + SWRT application significantly improved argan plant performances, with a particularly marked effect on 1Y seedlings, which makes this combination an alternative solution to enhance the resilience of the argan tree in the era of climate change and promote the success of the reforestation program.

In the context of climate change, alterations to the physico-chemical properties of soils, particularly in Mediterranean regions, are a growing source of preoccupation. This study analyzes the ecological plasticity and biochemical adaptability of Thymus saturejoides to changes in soil physico-chemical properties in four contrasting environments in Morocco’s western High Atlas (TM: Tidili msfioua, SF: Sti fadma, TA: Taouss, TN: Tisi ntast). It highlights the influence of edaphic characteristics on the physiology and metabolic composition of the species, revealing marked soil heterogeneity between sites. The results for the physico-chemical characteristics of the soil revealed marked heterogeneity between sites. Tisi ntast and Taouss soils had the highest values in terms of electrical conductivity (TN: 0.25 dS/m, TA: 0.18 dS/m), available phosphorus (TN: 18.58 ppm and TA: 26.06 ppm) and total nitrogen (TN: 0.27% and TA: 0.14%), associated with a silty texture, suggesting higher fertility. Conversely, the soil at the TM site was characterized by low total nitrogen content (0.09%), a high C/N ratio (24.4) and a sandy-silty texture, indicating more constraining conditions for plant growth. From a physiological standpoint, plants from the TA site had the lowest chlorophyll levels (17.10 mg g⁻¹FW), while those from the TN site showed the highest levels (31.08 mg g⁻¹FW), accompanied by increased protein content and reduced polyphenol oxidase and peroxidase. In contrast, TM plants showed significant accumulation of total soluble sugars (30 mg g⁻¹FW), proline (22.53 µmol g⁻¹FW), hydrogen peroxide (1.33 nmol g⁻¹FW) and malondialdehyde (62.97 nmol g⁻¹FW), reflecting strong activation of oxidative stress responses. On the other hand, plants from the TA site displayed significantly lower levels of these stress markers compared to other sites, suggesting greater physiological resilience. These results highlight the pivotal role of interactions between edaphic and environmental conditions in modulating plant physiological and biochemical responses, shedding light on the ecological adaptation mechanisms of plant species to the contrasting ecosystems of the Western High Atlas.