Soil salinity is a major threat to modern agriculture, as it affects crop growth and development. The present study focuses on the integration of eco-friendly biostimulants in salinity stress as a strategy to achieve the alleviation of abiotic stress. Field experiments were conducted at two locations, consisting of saline and non-saline soil, to investigate the utilization of exopolysaccharide (EPS)-producing bacteria (Azotobacter chroococcum) and melatonin at different concentrations (0, 25, 50, and 100 µM) for alleviating the adverse effects of salinity on the growth and production of faba bean plants. Salinity stress caused a reduction in all measured parameters of the faba bean plants grown in the saline soil relative to the plants grown in the non-saline soil. The addition of bacteria and/or melatonin significantly increased the growth parameters and yield components under both soils compared to the respective control plants. Both bacteria inoculation and melatonin application enhanced N, P, and K concentrations; the proline content; RWC%; and the K⁺/Na⁺ ratio; however, Na⁺ and Cl⁻ concentrations were decreased significantly in salt-stressed faba beans. The combined use of bacteria and melatonin exhibited the highest stimulating effects. The present study recommends the combined use of EPS-producing bacteria and melatonin for the salinity stress management strategy of faba bean.

The extensive use of chemical fertilizers is responsible for numerous environmental problems including low food quality, soil degradation, and toxicity to beneficial living organisms in the soil. Nano-fertilizers (NFs) application may be a promising solution for combat these challenges. The current study focused on the efficiency of applying small amounts of NFs incorporated with conventional nitrogen, phosphorus, and potassium (NPK) fertilizers to reduce the quantities of conventional fertilizers (CFs) in lettuce cultivated in sandy soil. This study evaluated the effect of these incorporations on plant growth, yield, phytochemical accumulation, leaf nutrient, and leaf nitrate. A pot experiment was conducted during the winter seasons of 2020/2021 and 2021/2022 using the following treatments: CF100: 100% CFs, CF75NF25: 75% CFs + 25% NFs, CF50NF50: 50% CFs + 50% NFs, CF25NF75: 25% CFs + 75% NFs, and NF100: 100% NFs (=10% of CFs). Our findings displayed that the CF75NF25 and CF50NF50 treatments recorded the highest plant growth parameter values (plant length, root length, number of leaves, and fresh and dry biomass). The maximum of chlorophyll fluorescence measurements (photosystem II efficiency) were obtained in plants fertilized with CF75NF25, followed by CF50NF50 and CF100. The improvement ratios of photosynthetic pigments (Chlorophyll (Chl) a, b, and total) for CF75NF25 were 23.77, 50, and 23.72% in the first season and 10.10, 51.0, and 24.90% in the second season for Chl a, b, and total, respectively, as compared with the CF100 treatment. A similar tendency was observed for the CF50NF50 treatment. Generally, CF75NF25 significantly raised the content of total phenolic compounds (TPC), total flavonoid content (TFC), and antioxidant activity (AOA) in lettuce plants by 36.09, 47.82, and 40.16% in the first season and by 30.39, 37.53, and 32.43% in the second season, respectively, compared with CF100. In addition, the levels of leaf nutrient content and uptake of N, P, and K were significantly higher in plants fertilized with CF75NF25 compared to the other treatments, whereas CF25NF75 had the lowest values among the different treatments across both seasons for most of the tested traits. The nitrate content in lettuce leaves (NO₃⁻) for both seasons was lower than the acceptable level for human consumption. These results indicate that incorporating a low concentration of NFs into CFs could be a promising strategy to reduce the amount of CFs to 75% or 50% of lettuce NPK requirements without significant adverse effects on the growth and productivity of lettuce plants cultivated in sandy soil.

Recently, nanofertilizers are being tested as a new technology, either for soil or foliar applications, to improve food production and with a reduced environmental impact. Nano calcium phosphate (NCaP) was successfully synthesized, characterized and applied in this study. A pot experiment was carried out in two successive seasons in 2016 and 2017 on (Phaseolus vulgaris L.) plants to obtain the best phosphorus treatments. The results were applied in a field experiment during the 2018–2019 season. Single superphosphate (SSP) at 30 and 60 kg P₂O₅ fed⁻¹ and NCaP at 10%, 20% and 30% from the recommended dose were applied to the soil. Foliar application involved both monoammonium phosphate (MAP) at one rate of 2.5 g L⁻¹ and NCaP at 5% and 10% from the MAP rate. The results of all experiments showed that NCaP significantly increased the shoot and root dry weights, the nutrient content in the shoot and root, the yield components, the nutrient concentration and crude protein percentage in pods of the snap bean plants compared with traditional P. The greatest increase was obtained from a 20% NCaP soil application in combination with a 5% NCaP foliar application. The present study recommends using NCaP as an alternative source of P to mitigate the negative effects of traditional sources.

Salinity has become one of the most important challenges in agriculture. A pot experiment was conducted during 2017/2018 and 2018/2019 seasons at the greenhouse of Fac. Agric., Cairo Univ., Giza, Egypt, on Triticum aestivum L., var. Gemmiza 10. Plants irrigated with diluted seawater with tap water (control), 4.0 6.0, 8.0 and 10.0 dS m-1 to investigate the utilization of co-inoculation of plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) and the addition of compost individually or in combination as an environmentally sustainable tools to alleviate the effects of salinity on wheat plants at both 75 days after sowing (DAS) (elongation stage) and 150 DAS (maturity stage). Salinity stress caused significant reduction in shoot height, shoot fresh and dry weights, K+/Na+ ratio and nitrogen, phosphorous and potassium contents of shoot at 75 DAS, however, Na+ concentration increased significantly. At maturity yield and its attributes, nitrogen, phosphorous and potassium contents in grain and straw decreased significantly with increasing irrigation water salinity level. Co-inoculation and/or compost amendments increased significantly the growth parameters and yield components compared to untreated plants under all irrigation water salinity levels.

In modern agriculture, the nitrate accumulation in vegetables has become a serious threat to human health. That caused by an imbalance between nitrate absorption and assimilation in plants. Nitrogen fertilization and light intensity are the main factors affected nitrate accumulation. Therefore, a pot experiment was conducted during two successive summer and winter seasons of 2019/20 at the greenhouse of Fac. Agric., Cairo Univ., Giza, Egypt, on lettuce (Lactuca sativa L. var. longifolia Lam) plants to investigate the effect of growth seasons (summer and winter), different rates (0, 60, 90 and 120 Kg N fed-1) and sources (CO (NH2)2, NH4NO3 and (NH4)2SO4) of nitrogen fertilizers on lettuce growth and nitrate concentrations. The results showed that fresh and dry weight, yield and nutrient contents of lettuce plants increased gradually according to increasing dose of nitrogen, up to 90 Kg N fed-1 and the magnitude of increase, according to different N fertilizers used , was in the following order: CO (NH2)2 > NH4NO3 > (NH4)2SO4. The accumulation of nitrate was higher in winter compared to summer season for both inner and outer leaves.