Salma Latique

Soil salinity is a crucial factor that limits agricultural production, negatively impacting the growth and physiological functions of salt-sensitive crops, such as beans. The present study examined the efficiency of Ulva rigida seaweed extracts (URE) as biostimulants to enhance the growth and photosynthetic ability of bean plants (Phaseolus vulgaris L.) under saline conditions (51.33 mM NaCl). Seaweed extracts were obtained by maceration and ultrasonic assistance at two concentrations, 25% and 50% (v/v), and applied as a foliar spray or irrigation. The most significant improvement was observed following foliar sprays of 50% ultrasonic extract (UP-50), with an increase of 96% in CCI compared to salt-stressed controls and by 71% compared to non-stressed controls. Stomatal conductance (SC) was also significantly improved with UP-50, reaching levels that were 146% higher than those of salt-stressed plants and 53% higher than those of non-stressed plants. The OJIP transients under salinity were significantly improved by both ultrasonic-assisted and maceration extracts; especially, 50% maceration extracts (MP-50) restored PSII quantum efficiency (ΦPo) and total performance index (PItotal) of salinity-stressed seedlings to 107% and 255% of non-stressed control and 122% and 314% of salt-stressed control, respectively. Root length and indole acetic acid (IAA) levels in treated plants were also enhanced, particularly in response to higher concentrations of the extract, suggesting improved root growth as well as hormonal homeostasis in the presence of salt stress. According to these findings, U. rigida extracts, specifically those applied at high concentrations as a foliar spray, serve as biostimulants that mitigate the adverse effects of salt stress on beans by preventing chlorophyll degradation and enhancing photosynthesis, root development, and hormonal balance.

Salinity stress emerges as an important menace to global food security, particularly affecting susceptible crops such as common bean plants (Phaseolus vulgaris L.). The disruption of ion balances caused by salt stress within plant cells reduces water and nutrient absorption and hampers growth and productivity. Sacchorhiza polyschides, a brown macroalga rich in essential elements and macrominerals, has drawn attention as a natural biostimulant, being a potential remedy to bolster crop resilience against salt stress. This study delves into the effect of water extracts of Sacchorhiza polyschides (SPE) across varying concentrations (1%, 2%, and 5%) in common bean plants under salt stress (68.4 mM NaCl) conditions. Two different methods of application were used: by spraying the aerial part of the plant or by irrigation together with the watering solution. The effects of both systems of application were studied on the aerial parts of the plants. SPE exhibited significant enhancements in morphological parameters, chlorophyll content, carbon–nitrogen activities, and antioxidant enzymatic system activities, alongside increasing osmolyte accumulation, compared to salt-stressed plants without biostimulation. Moreover, SPE reduced reactive oxygen species (ROS) levels caused by salt stress, mitigating lipid peroxidation. The concentrations of 2% and 5% SPE applied by spraying showed the most significant results in most of the parameters analyzed. By shedding light on the underlying science behind this biostimulant effect, this research underscores the potential of SPE to enhance crop resilience and augment food production in salt-challenged environments.

Salinity stress emerges as an important menace to global food security, particularly affecting susceptible crops such as common bean plants (Phaseolus vulgaris L.). The disruption of ion balances caused by salt stress withing plants cells reduces water and nutrient absorption, and hampers growth and productivity. Sacchorhiza polyschides, a brown macroalga rich in essential elements, and macrominerals, has drawn attention as a natural biostimulant, being a potential remedy to bolster crop resilience against salt stress. This study delves into the effect of water extracts of Sacchorhiza polyschides (SPE) across varying concentrations (1%, 2%, and 5%) in common bean plants under salt stress (68.4 mM NaCl) conditions. Two different methods of application were used: by spraying the aerial part of the plant or by irrigation together with the watering solution. The effects of both systems of application were studied on the aerial parts of the plants. SPE exhibited significant enhancements in morphological parameters, chlorophyll content, carbon-nitrogen activities, and antioxidant enzymatic system activities, alongside increasing osmolyte accumulation, compared to salt-stressed plants without biostimulation. Moreover, SPE reduced reactive oxygen species (ROS) levels caused by salt stress, mitigating lipid peroxidation. The concentrations of 2% and 5% SPE applied by spraying showed the most significant results in most of the parameters analyzed. By shedding light on the underlying science behind this biostimulant effect, this research underscores the potential of SPE to enhance crop resilience and augment food production in salt-challenged environments.

Microalgae are widely exploited for numerous biotechnology applications, including biofuels. In this context, Chlamydomonas debaryana and Chlorococcum sp. were isolated from Fez freshwater (Morocco), and their growth and lipid and carbohydrate production were assessed at different concentrations of NaCl, NaNO₃, and K₂HPO₄. The results indicate a small positive variation in growth parameters linked to nutrient enrichment, with no considerable variation in carbohydrate and lipid levels in both algae. Moreover, a negative variation was recorded at increased salinity and nutrient limitation, accompanied by lipid and carbohydrate accumulation. Chlorococcum sp. showed better adaptation to salt stress below 200 mM NaCl. Furthermore, its growth and biomass productivity were strongly reduced by nitrogen depletion, and its lipid production reached 47.64% DW at 3.52 mM NaNO₃. As for Chlamydomonas debaryana, a substantial reduction in growth was induced by nutrient depletion, a maximal carbohydrate level was produced at less than 8.82 mM NaNO₃ (40.59% DW). The effect of phosphorus was less significant. However, a concentration of 0.115 mM K₂HPO₄ increased lipid and carbohydrate content without compromising biomass productivity. The results suggest that growing the two Chlorophyceae under these conditions seems interesting for biofuel production, but the loss of biomass requires a more efficient strategy to maximize lipid and carbohydrate accumulation without loss of productivity.

By 2050, the predicted global population is set to reach 9.6 billion highlighting the urgent need to increase crop productivity to meet the growing demand for food. This is becoming increasingly challenging when soils are saline and/or deficient in phosphorus (P). The synergic effect of P deficiency and salinity causes a series of secondary stresses including oxidative stress. Reactive Oxygen Species (ROS) production and oxidative damage in plants caused either by P limitation or by salt stress may restrict the overall plant performances leading to a decline in crop yield. However, the P application in adequate forms and doses could positively impact the growth of plants and enhances their tolerance to salinity. In our investigation, we evaluated the effect of different P fertilizers forms (Ortho-A, Ortho-B and Poly-B) and increasing P rates (0, 30 and 45 ppm) on the plant's antioxidant system and P uptake of durum wheat (Karim cultivar) grown under salinity (EC = 3.003 dS/m). Our results demonstrated that salinity caused a series of variations in the antioxidant capacity of wheat plants, at both, enzymatic and non-enzymatic levels. Remarkably, a strong correlation was observed between P uptake, biomass, various antioxidant system parameters and P rates and sources. Soluble P fertilizers considerably enhanced the total plant performances under salt stress compared with control plants grown under salinity and P deficiency (C+). Indeed, salt-stressed and fertilized plants exhibited a robust antioxidant system revealed by the increase in enzymatic activities of Catalase (CAT) and Ascorbate peroxidase (APX) and a significant accumulation of Proline, total polyphenols content (TPC) and soluble sugars (SS) as well as increased biomass, Chlorophyll content (CCI), leaf protein content and P uptake compared to unfertilized plants. Compared to OrthoP fertilizers at 45 ppm P, Poly-B fertilizer showed significant positive responses at 30 ppm P where the increase reached + 18.2% in protein content, + 156.8% in shoot biomass, + 93% in CCI, + 84% in shoot P content, + 51% in CAT activity, + 79% in APX activity, + 93% in TPC and + 40% in SS compared to C+. This implies that PolyP fertilizers might be an alternative for the suitable management of phosphorus fertilization under salinity.

Many research studies have shown the importance of seaweed extract in agriculture. Marine macroalgae are rich in diverse compounds like lipids, proteins, carbohydrates, phytohormones, amino acids, osmoprotectants and minerals. In this study, we have tried to characterize Moroccan macroalgae species Ulva rigida collected from the coastal area of Akhfenir in order to evaluate their potential to improve growth plant. The proximate composition, mineral element (Ca, K, Mg, Na and Cl), pigments, amino acid, proteins, lipids, polyphenol contents were determined in liquid extract obtained from green seaweed (SWE) Ulva rigida. Results show that the application of SWE at different concentrations (0,12.5, 25, 50%) significantly enhanced growth parameters, especially with 25% of seaweed liquid extract. Therefore, algal treatment by foliar application is proved to be an effective technique to improve the growth of wheat plants. This study provides important information on the characterization, identification and utilization of seaweed resources for agriculture as biostimulants.

This study investigated the effect of seaweed extract (SWE) sprays obtained from Ulva rigida on wheat plants (Triticum durum L., variety Karim) grown under salt stress conditions for six weeks. Three levels of NaCl (0, 34.22, 68.44 mM) and four different concentrations (0, 12.5, 25 and 50%) of Ulva rigida as a water extract were applied. The obtained results indicated that seaweed treated plants showed higher ability to tolerate salt stress (34.22 or 68.44 mM of NaCl) by a significant (p < 0.05) increase of plant growth and the photosynthetic pigment contents, compared to those of control (non-treated plants). Furthermore, there was a significant improvement in antioxidant enzyme activity, such as superoxide dismutase (SOD), isocitrate dehydrogenase (ICDH), glutathione peroxidase (GPx), glutathione reductase (GR) activities in the stressed plants, especially in those treated with 12.5% of SWE. Overall, our results suggest that the application of the Ulva rigida water extract could be used as a promising plant growth biostimulant for treating wheat plants under salinity stress.

Many research studies have shown the importance of seaweed extract (SWE) in alleviating stress damage to plants. In this study, we examined the effect of liquid SWEs made from brown seaweed, Fucus spiralis, on germination, growth, antioxidant enzymes and some biochemical attributes of durum wheat under different levels of NaCl concentrations. Application of SWE at different concentrations (5, 10, 25, and 50%) significantly enhanced seed germination and growth parameters under salt stress, especially with 25% of seaweed liquid extract. Results show that the activity of antioxidant enzymes increased with increasing the algal extract concentration to 50%. Therefore, algal treatment is proved to be an effective technique to improve the growth of wheat seedlings under salt stress conditions. This study provides important information on the identification and utilization of seaweed resources for agriculture and it is the first study to report on the uses of this macroalgae as biostimulants in agriculture. Abbreviations TG: total germination (%); SL: shoot length (cm); SFW: seedling fresh weight (g); SDW: seedling dry weight (g); TC: total carotenoids (mg/g.FW); TSP: total soluble proteins (mg/g.FW); SSC: soluble sugars content (mg/g.FW); TPC: (µg equivalent AG/mg DW); CAT: catalase (U mg⁻¹ protein); SOD: superoxide dismutase (U mg⁻¹ protein); APX: ascorbate peroxydase (U mg⁻¹ protein).