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Abstract In plant production, evaluation of salt stress protectants concerning their potential to improve growth and productivity under saline stress is critical. Bacillus subtilis (Bs) and cobalt (Co) have been proposed to optimize salt stress tolerance in coriander (Coriandrum sativum L. cv. Balady) plants by influencing some physiological activities. The main aim of this work is to investigate the response of (Bs) and (Co) as eco-safe salt stress protectants to resist the effect of salinity, on growth, seed, and essential oil yield, and the most important biochemical constituents of coriander produced under salt stress condition. Therefore, in a split-plot factorial experiment design in the RCBD (randomized complete block design), four levels of salinity of NaCl irrigation water (SA) were assigned to the main plots; (0.5, 1.5, 4, and 6 dS m−1); and six salt stress protectants (SP) were randomly assigned to the subplots: distilled water; 15 ppm (Co1); 30 ppm (Co2); (Bs); (Co1 + Bs); (Co2 + Bs). The study concluded that increasing SA significantly reduced coriander growth and yield by 42.6%, which could be attributed to ion toxicity, oxidative stress, or decreased vital element content. From the results, we recommend that applying Bs with Co (30 ppm) was critical for significantly improving overall growth parameters. This was determined by the significant reduction in the activity of reactive oxygen species scavenging enzymes: superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) and non-enzyme: proline by 5, 11.3, 14.7, and 13.8% respectively, while increasing ascorbic acid by 8% and preserving vital nutrient levels and enhancing plant osmotic potential to buffer salt stress, seed yield per plant, and essential oil yield increased by 12.6 and 18.8% respectively. The quality of essential oil was indicated by highly significant quantities of vital biological phytochemicals such as linalool, camphor, and protein which increased by 10.3, 3.6, and 9.39% respectively. Additional research is suggested to determine the precise mechanism of action of Bs and Co's dual impact on medicinal and aromatic plant salt stress tolerance.

The comparison between salt stress protectants in terms of their ability to increase growth and yield under salinity is of great importance in crop production. Melatonin (MT) and cobalt (Co) have been suggested to promote the plant's salt tolerance by mediating physiological mechanisms. To explore the difference between these protectants in increasing salt tolerance, cucumber plants (Cucumis sativus L., cv. Barracuda F1) were submitted to different levels of salt stress (control = 0.25, 2, 3 and 4 dS m−1) with pretreatment of MT (100 and 200 μM) or Co (15 and 20 mg L−1). The results indicated that the increasing level of salt reduced the growth and productivity of cucumber plants, which may result from ions toxicity (Na+ and Cl− accumulation), oxidative stress (hydrogen peroxide, H2O2 and malondialdehyde, MDA accumulation), and the reduction of essential nutrients content. The concentration used, whether from MT or Co, was instrumental in determining the level of salt tolerance in the cucumber plants. Foliar application with 15 mg L−1 Co and 100 μM MT mitigated, at a similar level, the NaCl- induced inhibition of cucumber growth, fruit number and weight. At the physiological levels, both treatments increased protein content, essential nutrients (N, P, K+, and Ca2+) content, and catalase (CAT) activity of stressed plants. The mitigation was also observed in the reduced levels of H2O2 and MDA. However, Co (15 mg L−1) showed superiority compared to MT in reducing the content of toxic ions (Na+ and Cl−) and increasing the total yield, especially under the high salt stress (4 dS m−1). These results suggest that Co and MT can improve the salt tolerance of the cucumber plants, but the level of improvement may differ in some aspects, and this may be due to the difference in salt tolerance mechanisms among those protectants.

Potato (Solanum tuberosum L.) is an important crop in Egypt with great trade value for the export market. The addition of agrochemicals with possibly containing heavy metals, such as cadmium (Cd), decreases the quality of the final product. Generally, little is known about the factors that influence Cd content in this crop. The current study estimated the Cd levels in different organs of three potato cultivars grown in four commercial regions across Egypt. Further, we investigated the soil properties that affected Cd uptake during two growing seasons. With the exception of the Cd content of the soils, no relationships were detected between the tested soil properties (i.e., pH, conductivity, organic matter, and clay content) and Cd content in potato organs, because the soil from different regions showed comparable levels for these parameters. The average Cd content in the peeled tubers among different cultivars (0.145 mg Kg−1 DW) was below the maximum limit (0.5 mg Kg−1 DW). The patterns of Cd accumulation in potato organs were constant among cultivars, with the highest levels detected in leaves (~82%), followed by stems (~16.5%), and the lowest content observed in tubers (~1.5%). The study showed that the tested potato cultivars exhibited diversity in the accumulation levels of Cd in the tubers (~2.6-fold). The cultivar Suntana displayed the lowest Cd levels among different field sites for the two growing seasons, suggesting the potential involvement of genetic factors.