The impact of salt stress on the growth and phosphorus utilization efficiency (PUE) of two leguminous species: Retama monosperma and Acacia gummifera was studied. The effectiveness of arbuscular mycorrhizal fungi (AMF) to mitigate salt stress was furthermore assessed. Growth, N and P tissue concentrations, mycorrhizal root colonization frequency and intensity, and P utilization efficiency (PUE) in the absence or presence of AMF were evaluated under no salt (0 mM L⁻¹) and three salt (NaCl) concentrations of (25, 50 and 100 mM L⁻¹) using a natural sterilized soil. A significant difference in mycorrhizal colonization intensity, root-to-shoot ratio, P uptake, PUE, and N uptake was observed between the legume species. Salt stress inhibited the shoot and root growth, and reduced P and N uptake by the legume species. Mycorrhizal inoculation aided to mitigate the effects of salt stress with an average increase of shoot and root growth responses by 35% and 32% in the inoculated than in the non-inoculated A. gummifera treatments. The average shoot and root growth responses were 37% and 45% higher in the inoculated compared to the non-inoculated treatments of R. monosperma. Average mycorrhizal shoot and root P uptake responses were 66% and 68% under A. gummifera, and 40% and 95% under R. monosperma, respectively. Mycorrhizal inoculated treatments consistently maintained lower PUE in the roots. The results provide insights for further investigations on the AMF conferred mechanisms to salt stress tolerance response by A. gummifera and R. monosperma, to enable the development of effective technologies for sustainable afforestation and reforestation programs in the Atlantic coast of Morocco.

The use of biostimulants has emerged as a promising strategy for enhancing seed vigor, germination, and seedling growth. This is due to the composition of beneficial substances considered as biostimulants that modulate plant physiology and metabolism. In this context, the interest in biostimulants is growing and the use of microalgal extracts is becoming more widespread. This study aims to assess the effect of Chlorococcum sp. aqueous extracts on the germination indices and the biometric and biochemical parameters of sesame (Sesamum indicum L.). Chlorococcum sp. culture exhibited favorable growth characteristics, including high productivity, specific growth rate, and short generation time. Furthermore, analysis of the extract demonstrated that it contains a high concentration of biomolecules, which suggests significant biostimulant potential. Importantly, the results also showed a significant improvement in germination indices as well as in biochemical parameters and photosynthetic pigments in seeds treated with the highest extract concentration (2 g/L). Furthermore, improvement in biometric parameters, including radicle length as well as fresh and dry weight, was observed at low extract concentration (0.1 and 0.5 g/L). Additionally, no phytoinhibitory effects were detected. Overall, the application of microalgal aqueous extract highlights a strong potential as a sustainable and cost-effective alternative to conventional synthetic chemical fertilizers, thereby promoting the development of an environmentally friendly agricultural practice of sesame cultivation.

Onion peel waste was tested to explore its anti-cyanobacterial activity on the growth of Microcystis aeruginosa. First, the onion peel was extracted by maceration using three different solvents: aqueous water, ethanol, and ethyl acetate. The efficacy of the aqueous, ethanol, and ethyl acetate extracts of onion peel against M. aeruginosa was assessed using both microdilution and paper disc diffusion techniques. Secondly, in a batch bioassay, the anti-cyanobacterial effect of the ethyl acetate extract, as the most active extract, on M. aeruginosa growth and pigment production was evaluated. To identify the potential allelochemicals, total phenolic and total flavonoid contents were analyzed in the different extracts. The obtained results demonstrated the ability of the ethyl acetate extract of onion peel to inhibit M. aeruginosa growth. This effect was dose-dependent. The highest inhibitory rate (99%) was achieved on day 8 under the highest concentration (100 mg/L). Consequently, all treatment groups exhibited a significant reduction in chlorophyll-a and carotenoid contents compared to the control group. The preliminary results demonstrated the anti-cyanobacterial effect of the ethyl acetate extract of onion peel on Microcystis growth and suggest it as a potential eco-friendly solution for controlling Microcystis blooms in eutrophic water bodies.

Fruits and vegetables are among the most widely consumed products; however, their processing by both industry and households generates substantial peel waste, leading to significant environmental concerns. This study aimed to assess fruit and vegetable peels as an eco-friendly source of natural cyanbactericidal compounds for controlling toxic algal blooms. Aqueous Extract (AE), Ethyl Acetate Extract (EAE), and Ethanol Extract (EE) of five fruit and vegetable peels (Avocado, tomato, mango, eggplant, and potato) were screened for their inhibitory effects on Microcystis aeruginosa using both paper disc diffusion and microdilution techniques. Therefore, the extracts of avocado peel, the most bioactive of the five peels, were selected for further testing in a batch bioassay. The inhibitory effect appeared to be dose-dependent. The maximum inhibition rate (98%) was recorded following an 8-day exposure period at the dose (MIC = 0.8 mg/mL) for both the AE and EAE. Thus, the EE showed significant potential, particularly at the highest concentration (MIC = 0.2 mg/mL), where inhibition peaked at 92% on day 8. Accordingly, all treated groups demonstrated a significant decrease in primary photosynthetic pigments and phycobiliproteins in comparison to the control groups. In conclusion, avocado peel extracts show the most potent inhibition in batch bioassay. These extracts could constitute a promising strategy to valorize avocado peel waste as a sustainable cyanobactericidal agent to suppress the proliferation of M. aeruginosa blooms in eutrophic aquatic ecosystems.