BackgroundGlobally, salinity poses a threat to crop productivity by hindering plant growth and development via osmotic stress and ionic cytotoxicity. Plant extracts have lately been employed as exogenous adjuvants to improve endogenous plant defense mechanisms when grown under various environmental stresses, such as salinity. This study investigated the potential of melatonin (Mt; 0, 50, and 100 mM) as an antioxidant and licorice root extract (LRE; 0.0 and 3%) as an organic biostimulant applied sequentially as a foliar spray on faba bean (Vicia faba L.) grown in cadmium (Cd)-contaminated saline soil conditions [Cd = 4.71 (mg kg- 1 soil) and ECe = 7.84 (dS m- 1)]. Plants not receive any treatment and sprayed with H2O were considered controls. The experimental treatments were laid out in strip plot in a randomized complete block design replicated thrice, where the LRE and Mt were considered as vertical and horizontal strips, respectively. Growth characteristics, photosynthetic pigments, nutrient uptake, physiology and metabolic responses, anatomical features, and yield were assessed.ResultsCadmium (Cd) and salinity-induced stress significantly altered leaf integrity, photosynthetic efficiency, total soluble sugars (TSS), free proline (FPro), total phenolic, DPPH, and total soluble proteins (TSP), non-enzymatic and enzymatic antioxidants, growth characteristics and yield-related traits. However, the application of LRE + Mt considerably improved these negative effects, with higher improvements were observed due to application of LRE + Mt100. Application of LRE + Mt significantly reduced hydrogen peroxide (H2O2) accumulation, lipid peroxidation and Cd content in leaves and seeds, all of which had increased due to Cd stress. Application of LRE + Mt significantly mitigated the Cd-induced oxidative damage by increasing the activity of reactive oxygen species (ROS) scavenging enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase, in parallel with enhanced ascorbate and reducing glutathione content. Exogenous application of LRE + Mt significantly increased osmolyte content, including FPro, TSS, and total phenols and mitigated Cd-induced reduction to considerable levels.ConclusionsOur findings showed that LRE + Mt increased V. faba plants' morphological, physiological, and biochemical properties, reducing Cd stress toxicity, and promoting sustainable agricultural practices.Clinical trial numberNot applicable.

D ROUGHT is a highly damaging abiotic stress that affects crops' development, functioning, productivity, and quality. In contemporary farming, nanoparticles are advantageous because of their extensive surface area and enhanced ability to penetrate plant leaves when applied as a spray. Lately, nano-fertilizers have been employed in agriculture to help reduce the negative impacts of drought stress. This study aims to investigate the effects of different forms (nano and chelated) of iron (Fe), zinc (Zn), and manganese (Mn) foliar application, as well as their combinations, on the growth, yield, and water productivity of faba bean plants under different soil moisture levels (100, 80, and 60% of field capacity, FC). The results indicated the best readings of traits studied in the faba bean plant were observed under soil moisture at 100% of FC (control) compared to 60% of FC. On the other hand, results showed that the combined foliar application (FA) of FeZnMn-nanofertilizers (FeZnMn-NFs) to faba bean plants yielded the most favorable growth characteristics and chlorophyll content compared to the untreated plants (control). Also, the FA of FeZnMn-NFs treatment resulted in the highest seed yield and macronutrient (NPK) content in both straw and seed. The seed yield under FeZnMn-NFs treatment (21.24 g pot-1) was significantly more significant than the control (15.47 g pot-1). Regarding water use efficiency (WUE), the FeZnMn-NFs treatment achieved the highest WUE for the faba bean (2.44 kg m-3) compared to the control (1.60 kg m-3). Conversely, the amount of irrigation water applied (IWA) was lowest with the FeZnMn-NFs treatment (8.72 L pot-1) compared to the control (9.64 L pot-1). Concerning the interaction between irrigation levels and foliar spray treatments of faba bean plants, there were no significant differences in seed yield between the 100% irrigation level and the 80% level when foliar application of FeZnMn-NFs. Additionally, nano-fertilizers (NFs) demonstrate greater effectiveness than chelated fertilizers (EDTA), significantly enhancing yield and macronutrient content. Thus, the results highlight the crucial role of NFs in mitigating damage from drought stress, improving growth characteristics, and saving 20% of the amount of IWA for faba bean plants, allowing it to be used elsewhere in agriculture. Consequently, these findings suggest that using NFs of Fe, Zn, and Mn as foliar applications (FA) could be a promising approach to boost the growth parameters, seed yield, and WUE of faba bean plants in arid and semi-arid regions.

Globally, the increasing demand for coal has led to a corresponding rise in the production of fly ash, a by-product of coal combustion. While fly ash has found significant applications in the construction industry due to its pozzolanic properties, its use in agriculture, particularly as a soil amendment or fertilizer, has raised environmental and health concerns. In greenhouse experiments, this study aimed to assess the effects of soils amended with fly ash (FA; 0, 5, 10, 20, 30, 40 and 50%) on Vicia faba L. (faba bean). The experiments were conducted to study the plant growth characteristics, photosynthesis variables, activity of nitrate reductase, damage indicators (reactive oxygen species, malondialdehyde, and cell viability), defense characteristics (proline and antioxidant enzyme activity) and yield parameters. Five replicates of each of the seven treatments were set up in a randomized block design. Among the FA-proportions tested, 40 and 50% caused significant decreases in plant growth characteristics, biochemical and yield attributes. Increases in reactive oxygen species (ROS) and malondialdehyde (MDA) contents corroborated these decreases in the mentioned parameters. However, in soils amended with 5% and 10% FA, plants exhibited significant (p <= 0.05) improvements in the mentioned parameters of growth, photosynthesis, stomata and cell viability, accompanied by the decreased contents of ROS and MDA, and coordinated increases in the activity of superoxide dismutase, catalase and peroxidases. Therefore, we concluded that 10% fly ash dose (lower doses) of FA might be considered an appropriate dose for faba bean cultivation in terms of safe FA utilization practices and sustainable maintenance of the biological and physicochemical health of the soil.

Salinity is a widespread environmental stress that severely impedes plant growth and development from seed germination to harvest. Thus, the development of suitable management practices to minimize the deleterious effects of salt stress has become necessary. Among these methods, seed priming is considered as one of the potential physiological approaches to enhance seed germination in salt-affected soils. In the present research, we investigated the potentiality of gallic acid (1 mM) and hydrogen peroxide (2 mM) as priming agents to alleviate the salinity-inhibited germination of three faba bean cvs. (Najeh, Chourouk and Bachaar). The seeds were soaked in distilled water (hydropriming) or pretreated with gallic acid and hydrogen peroxide, individually and simultaneously, and then subjected to 150 mM NaCl-salinity. Our results revealed that mean germination time was significantly increased; whereas final germination percentage and germination index as well as dry weight and water content of the embryonic axes were considerably lowered by salt stress in the unprimed seeds of the three faba bean cvs. This decrease was associated with inhibited starch degradation and increased malondialdehyde contents. Our results also indicated that although all germination traits as well as starch metabolism were enhanced following gallic acid, hydrogen peroxide and hydropriming treatments to varying degrees, priming-mitigating effects were agent-dependent with regard to salt-induced oxidative damage, and osmoprotectant accumulation (proline and glycine betaine) as well as non-enzymatic (total polyphenols and flavonoids) and enzymatic (superoxide dismutase, catalase and guaiacol peroxide) antioxidant defense system. Contrarily to hydropriming treatment for which no obvious effects were observed, gallic acid and hydrogen peroxide priming significantly decreased the malondialdehyde content, increased proline and glycine betaine accumulation and enhanced the non-enzymatic as well as the enzymatic defense system to varying degrees for the three faba cvs. When compared to other treatments, simultaneous priming with gallic acid and hydrogen peroxide was more efficient in mitigating the adverse effects of salt stress on faba bean at the germination stage and may be, therefore, suggested as a potential strategy to overcome the salinity-mediated impairment of faba bean, particularly salt-sensitive genotypes, at the germination stage.