Cyanobacteria can play an important role in sustainable agriculture by improving crop growth and production, as well as environmental quality. The current study was conducted to evaluate the role of Spirulina platensis extract in the improvement of growth, photosynthetic capacity and yield of Lupinus luteus. Different concentrations (0.25, 0.5 and 1.0%) of S. platensis methanolic extract were used for priming seeds and foliar spraying applications. Growth, photosynthetic pigment content and activity were recorded at 35 days of cultivation. The yield measurements and protein profile of seeds were performed at 60 days. For both treatments, the lower concentration (0.25%) of the extract was the most successful in improving all growth metrics and the phytohormonal level of L. luteus. Photosynthetic pigment and capacity, nutrient content and yield components of L. luteus were improved with the extract of 0.25% concentration. However, the growth was significantly inhibited at the higher concentration (1.0%), recording lower values of the measured characters than the control. A positive correlation was observed between the total chlorophyll, photosynthetic rate, yield parameters and carbohydrate accumulation by the application of the S. platensis extracts. The protein profile of seeds revealed that spraying treatment triggered the appearance of a new band of 30.56 KDa. The promotion of growth could be attributed to the nutrients, bioactive molecules and phytohormones in the extract. The use of Spirulina-based stimulators is reliable with the concept of sustainable agriculture by enhancing photosynthetic pigment content and rate ensuring the correlation between the yield and those measured parameters of L. luteus.

One of the most significant environmental challenges in the twenty-first century is heavy metal pollution. The potential use of fresh Azolla pinnata to alleviate the toxic effects of Cd and Co on the germination measurements of wheat seeds (Triticum aestivum L.) and the biochemistry of seedlings was studied. Two concentrations (80 and 100 mg L⁻¹ solutions) of CdNO₃ and CoCl₂ were used before and after treatment with A. pinnata. The highest removal efficiency (RE) by A. pinnata was obtained on the fifth day, with a Cd RE = 55.9 and 49.9% at 80 and 100 mg L⁻¹, respectively. Cadmium and cobalt solutions reduced the germination percentage, and the measured variables of wheat seeds meanwhile increased the radicle phytotoxicity. In contrast, the presence of A. pinnata in the germination medium increased all the measured variables and decreased radicle phytotoxicity. At 80 and 100 mg L⁻¹, Cd significantly reduced the fresh and dry biomass, and height of wheat seedlings after 21 days of cultivation compared to Co. Cadmium and high concentrations of cobalt increased the contents of H₂O₂, proline, MDA, phenolic, and flavonoid compounds. The application of treated Cd and Co solutions by A. pinnata showed a decrease in H₂O₂, proline, phenolic, and flavonoid compounds levels accompanied by a reduction in catalase and peroxidase activities compared to the control. This study showed the positive role of A. pinnata in alleviating the metal impacts, particularly Cd, on the seedling growth of wheat and its germination.

Human risks increase by consuming plants growing in trace/heavy metals contaminated soil irrigated with polluted water. The present study aims to assess the ability of common mallow to accumulate trace/heavy metals from polluted soils at South Greater Cairo, Egypt; and their hazardous effects on consumer's health. Five quadrats were used to collect soil and plant samples from three sites of un-polluted and polluted fields for chemical analysis and measurement of growth variables, as well as for assessing the daily intake of metals (DIM) and hazard quotient (HQ). Irrigation water analysis showed elevated concentrations of the investigated metals and mineral salts in the polluted area compared with the un-polluted one. Plant samples showed reduction in their growth parameters; as well as pigments and nutrient content in the metal-contaminated soil. In addition, Pb, Cd, Cu, Ni, Fe, Mn, Zn, and Co concentrations in the shoots and roots of plants grown in polluted fields were higher compared with plants grown in un-polluted site. The bioaccumulation and translocation factors of most investigated metals indicated the great ability of common mallow to accumulate such metals, which would increase the human intake of metals in their daily diets compared to their reference values (RfD). The hazard quotient (HQ) of Pb, Cr, Fe, Mn and Zn for children and Pb, Cd, Fe and Mn for adults was >1, indicating health hazards for the consumers of common mallow cultivated in the polluted area.

The removal of pollutants from the environment has become a global demand. The current study aimed to relieve the Ni toxicity effect on the germination, growth, and grain yield of maize by using Azolla pinnata as a phytoremediator. Azolla-treated and untreated nickel solutions [0 (control), 24, 70, 140 and 190 ppm] were applied for germination and pot experiments. Electron microscope examination cleared the Ni accumulation in Azolla’s cell vacuole and its adsorption on the cell wall. The inhibition of the hydrolytic enzyme activity reduces maize germination; maximal inhibition was 57.1% at 190 ppm of Ni compared to the control (100%). During vegetative growth, Ni stimulated the generation of H₂O₂ (0.387 mM g⁻¹ F Wt at 190 ppm of Ni), which induced maximal lipid peroxidation (3.913 µMDA g⁻¹ F Wt) and ion leakage (74.456%) compared to control. Chlorophyll content and carbon fixation also showed significant reductions at all Ni concentrations; at 190 ppm, they showed maximum reductions of 56.2 and 63%, respectively. However, detoxification enzymes’ activity such as catalase and antioxidant substances (phenolics) increased. The highest concentration of Ni (190 ppm) had the most effect on constraining yield, reaching zero for the weight of 100 grains at 190 ppm of Ni. Azolla-treated Ni solutions amended all determinant parameters, indicating a high percentage of changes in hydrolytic enzyme activity (125.2%) during germination, chlorophyll content (77.6%) and photosynthetic rate (120.1%). Growth measurements, carbon fixation, and yield components showed a positive association. Thus, we recommended using Azolla as a cost-effective and eco-friendly strategy to recover Ni-polluted water.

Salinity is a serious and increasing problem for the agriculture sector in the world due to the expected climate change and water scarcity. This study aimed to screen the tolerance of eleven Egyptian genotypes/ cultivars (Giza716, Giza843, Masr 1, Nubaria 1, 3, 4, and 5, Sakha 1, 3, and 4, and Wadi 1) to salinity stress. The plants were grown under three salinity treatments in addition, to control (T1= 50 mM, T2= 75 mM, and T3= 100 mM NaCl). Biomass, biochemical, and leaf photosynthetic parameters were measured. The results revealed that increasing salinity stress led to a significant increase in soluble proteins, sugars, and phenolic compounds in the leaves of all genotypes compared to the control. Maximum transpiration rate and stomatal conductance values were under control conditions, while the minimum values were under T3 salinity treatment. The photosynthetic rates were generally decreased by increasing salinity stress except for Nubaria 3. The photosynthetic rates of Masr 1, Nubaria 1, and Nubaria 5 genotypes decreased by > 50% of their photosynthetic rate (A) values at T3 compared to their control. The Intrinsic water-use efficiency (iWUE) was remarkably high at T3 salinity treatment for all genotypes. The maximum increment of the antioxidant enzyme CAT activity under salinity stress was recorded in Nubaria 3. We can conclude that the Nubaria 3 genotype was considered the most tolerant genotype to salinity in terms of having better photosynthesis performance and antioxidant activity under salinity stress.