Argania spinosa is among the most important species of the Moroccan forest in terms of ecological, environmental, and socio-economic aspects. However, it faces a delicate balance between regeneration and degradation in its natural habitat. Hence, the efforts to preserve and regenerate argan forests are crucial for biodiversity, soil quality, and local livelihoods, yet they face challenges like overgrazing and climate change. Sustainable management practices, including reforestation and community engagement, are vital for mitigating degradation. Similarly, exploiting the argan tree’s rhizosphere can enhance soil quality by leveraging its rich microbial diversity. This approach not only improves crop growth but also maintains ecosystem balance, ultimately benefiting both agriculture and the environment. This enrichment can be achieved by different factors: mycorrhizae, plant extracts, algae extracts, and plant growth-promoting rhizobacteria (PGPR). The benefits provided by PGPR may include increased nutrient availability, phytohormone production, shoot, root development, protection against several plant pathogens, and disease reduction. In this study, the effect of rhizobacteria isolated from the Agran rhizosphere was evaluated on germination percentage and radicle length for Argania spinosa in vitro tests, growth, collar diameter, and branching number under greenhouse conditions. One hundred and twenty (120) bacteria were isolated from the argan rhizosphere and evaluated for their capacity for phosphate solubilization and indole acetic acid production. The results showed that 52 isolates could solubilize phosphorus, with the diameters of the solubilization halos varying from 0.56 ± 0.14 to 2.9 ± 0.08 cm. Among 52 isolates, 25 were found to be positive for indole acetic acid production. These 25 isolates were first tested on maize growth to select the most performant ones. The results showed that 14 isolates from 25 tested stimulated maize growth significantly, and 3 of them by 28% (CN005, CN006, and CN009) compared to the control. Eight isolates (CN005, CN006, CN004, CN007, CN008, CN009, CN010, and CN011) that showed plant growth of more than 19% were selected to evaluate their effect on argan germination rate and radicle length and were subjected to DNA extraction and conventional Sanger sequencing. The 8 selected isolates were identified as: Brevundimonas naejangsanensis sp2, Alcaligenes faecalis, Brevundimonas naejangsanensis sp3, Brevundimonas naejangsanensis sp4, Leucobacter aridicollis sp1, Leucobacter aridicollis sp2, Brevundimonas naejangsanensis sp1, and Staphylococcus saprophyticus. The results showed that Leucobacter aridicollis sp2 significantly increased the germination rate by 95.83%, and the radicle length with a value of 2.71 cm compared to the control (1.60 cm), followed by Brevundimonas naejangsanensis sp3 and Leucobacter aridicollis sp1 (2.42 cm and 2.11 cm, respectively). Under greenhouse conditions, the results showed that the height growth increased significantly for Leucobacter aridicollis sp1 (42.07%) and Leucobacter aridicollis sp2 (39.99%). The isolates Brevundimonas naejangsanensis sp3 and Leucobacter aridicollis sp1 increased the gain of collar diameter by 41.56 and 41.21%, respectively, followed by Leucobacter aridicollis sp2 and Staphyloccocus saprophyticus (38.68 and 22.79%). Leucobacter aridicollis sp1 increased the ramification number per plant to 12 compared to the control, which had 6 ramifications per plant. The use of these isolates represents a viable alternative in sustainable agriculture by improving the germination rate and root development of the argan tree, as well as its development, while increasing the availability of nutrients in the soil and consequently improving fertilization.

Climate change, through increased aridity, threatens ecosystems, including Morocco’s endemic Argania Spinosa L. Skeels. This study assesses the impact of aridity on argan trees by analyzing morphological, ecophysiological, and biochemical parameters across various regions and comparing them with historical data. Significant variations were observed in leaf area, leaf length, chlorophyll content, relative water content, polyphenols, flavonoids, soluble sugars, and antioxidant activity, while leaf width ratio and chlorophyll ratio remained stable. Tioughza exhibited the largest leaf area (136.07 mm²), the highest chlorophyll content (436.76 mg/m²), and superior water retention (52.27%). Conversely, Ezzaouite showed the smallest leaf area (85.76 mm²) and lowest water content (37.68%). Increased aridity has intensified these differences, revealing the argan tree’s vulnerability to climate change. The findings underscore the need for targeted conservation efforts, including reforestation, strengthened legislation, and enhanced genetic research, to sustain this vital species.

The argane tree (Argania spinosa L.) is a mostly self-incompatible species that must be cross-pollination. However, the cross-pollination is often insufficient to obtain a desirable fruit yield in the absence of compatibility between the orchard’s argane trees. Proper pollination design is therefore essential to ensure a supply of compatible pollen. In this study, pollen germination and pollen development following cross- and self-pollination were investigated in A. spinosa. The choice of compatible parents or a pollinizer is currently a new research topic for the production of argane fruits in the framework of argane farming programs. Different pollination experiments were designed with two main objectives: (i) to study cross/self-(in)compatibility in the argane tree, and (ii) to determine the degree of compatibility between selected superior genotypes for pollination strategies to improve fruit set in argane orchards. Thus, to determine if a pollination deficit exists, experiments were carried out on 14 genotypes, and 5421 flowers served as sampling. The germination rate of pollen was lower than 50% for three genotypes, and only four genotypes bloom twice a year. From cross-pollination trials, traits related to the mother trees, such as the shape of the fruit and fruit ripening duration, are not influenced by the gene flow transmitted by pollens. Self-pollination was very low (0.2%) for both hand- and free self-pollination but the highest fruit set rate observed was 5.3%. Based on the pollen effect study results, it can be concluded that different pollen sources affected the fruit set. Thus, the choice of an efficient pollinizer genotype must be inter-compatible with the main variety, bloom at the same time, and be regular (no alternation). This is the first time that a pollinizer tree was reported and studied for argane. To meet future argane farming requirements, the number and location of compatible pollinizers is very important in the argane orchard design. This design of pollination remains to be checked by alternately planting a row of pollinizer trees or inter-rows with main varieties.

The aim of this study is to examine the variability of yield and fatty acid composition of argan seed oil (Argania spinosa L.) in four provenances, and to find the relationship between fatty acid composition and environmental conditions. Twenty genotypes were preselected and evaluated for fatty acids composition during 3 years (2008–2010). The oil was extracted by a Soxhlet and the fatty acids composition was determined using gas chromatography. The results revealed a variation in seed oil content (51.83–57.50 %). Total saturated fatty acids content (C14:0; C16:0; C18:0; C20:0) ranged from 19.53 to 20.29 %, with lower content in Had Dra and Biougra than other provenances. However, the concentration of total unsaturated fatty acids ranged from 79.56 to 80.29 %, with a higher percentage of monounsaturated fatty acid (C16:1; C18:1; C20:1) (47.60 %) in Aoulouz and a higher percentage of polyunsaturated fatty acid (C18:2; C18:3) (35.53 %) in Biougra provenance. No correlation between oil content and fatty acid compositions with the morphological data (mother tree, fruit and seed forms) was found. The geographical localization and fatty acid content were not correlated with oil content. The study proved a significant contribution of environmental conditions to the variation in fatty acid composition. We conclude that there is a highly significant variation both in oil content and fatty acid composition in the argan provenances that can be used for its improvement.