For decades, conventional farming has played a vital role in producing food and reducing starvation in developed and developing countries. However, its negative impacts on human health, animals, plants, and the environment, especially soil, are becoming increasingly evident. Climate change is also exacerbating these impacts, including drought and soil salinity. Organic farming, on the other hand, seeks to address and mitigate these issues through various practices, particularly by maintaining the biodiversity of soil microorganisms and the addition of beneficial microorganisms such as arbuscular mycorrhizal fungi (AMF) in crop production. AMF are ubiquitous in the plant kingdom, with more than 80% of terrestrial plants forming symbiotic relationships with them. Known benefits include providing nutrition and protecting against biotic and abiotic stresses for the host plant. This research investigated the impact of conventional and organic farming practices on AMF biodiversity in both systems and isolated some quick-colonizing AMF species to test their effects on cucumber plants under salinity and drought stress. The overall research was divided into three parts: the first part’s objective was to investigate the impact of organic and conventional farming systems on the diversity of AMF in the rhizosphere soils of mango, citrus and cucumber. The objective of second part was to evaluate and compare the efficacy of native inoculation, obtained through a quick colonizing method, and a commercially available AMF product in enhancing the physiological responses of two cucumber varieties ‘Diva’ and ‘Safaa’ under four salinity stress conditions. The third study’s objective was to investigate the potential of enhancing drought tolerance in cucumber plants through a combination of a native quick root colonizer AMF, a commercial AMF, and potassium silicate (PS). The first study investigated the impact of organic and conventional farming practices on AMF diversity in the rhizosphere soils of mango, citrus, and cucumber from 16 sites. Spore morphological analysis and internal transcribed spacers (ITS) RNA analysis were employed for AMF identification. Additionally, some AMF species were isolated by using the quick colonizer method, and they were identified morphology and molecular techniques by using AMF primers. Spore morphological analysis identified 9 families, 20 genera, and 36 species, with higher diversity observed in samples from organic farming. ITS sequencing analysis detected 6 families and 12 genera, and, once again, greater diversity in terms of taxa and the Shannon H index was observed in organic farming samples. The families Diversisporaceae and Glomeraceae were found to be the most abundant across all treatments. A higher mycorrhizal inoculum potential for cucumber was observed in organic soils, and higher root colonization percentages were recorded for citrus in organic soils. Furthermore, two AMF species, Rhizoglomus intraradices and Septoglomus viscosum, were identified as quick colonizers with potential for cucumber production in Oman. These results contribute to the understanding of AMF diversity in different farming systems and support the development of sustainable agriculture in semi-arid and arid region. The second study compared the effects of native inoculation obtained through the quick colonizing method, a commercial AMF product, and control treatments on plant physiological response of two cucumber varieties; ‘Diva’ and ‘Safaa’. Salinity stress was induced by irrigating with saline water at various levels (0.64 dS m-1 as control, 2, 4, and 6 dS m-1 ). The mycorrhizae treatments included native AMF quick root colonizer and a commercial inoculum containing 5 species of Glomeraceae, Glomerales. The study found that salinity stress led to a significant reduction in plant growth, disrupted ion homeostasis (K/Na ratio), decreased mycorrhizal root colonization percentage, and increased levels of proline, chlorophyll content (SPAD), leaf chlorophyll fluorescence, Na concentration in leaves, and malondialdehyde (MDA) content. The two AMF inoculants improved plant growth, including plant height, biomass, potassium (K), and phosphorus (P) uptake. They also enhanced the K/Na ratio and optimized nutrient availability under saline conditions. AMF inoculation resulted in improved SPAD and photosynthetic efficiency, increased proline accumulation, and enhanced catalase activity. Notably, native AMF exhibited higher root colonization percentages compared to the commercial AMF product. These findings underscore the complex interplay between plant and fungal genotypes in regulating salinity tolerance. The study suggests that the use of native AMF species, better suited to the region's soil and climate, can partially benefit cucumber plants under salinity stress, offering potential integration into sustainable farming practices to improve vegetable production in high-salinity conditions. The third investigated the impact of combined AMF and potassium silicate on drought tolerance in cucumber plants in a greenhouse experiment. Cucumber plants were grown under two watering regimes: drought-stressed 60% water holding capacity (WHC)and unstressed 80%WHC, and three mycorrhizal inoculation treatments (control, native AMF: quick root colonizer species, and commercial AMF) with or without potassium silicate application. Drought stress significantly reduced plant height, biomass, and photosystem II efficiency, while it increased the content of leaf glycine betaine and catalase activity. Generally, AMF inoculation significantly improved plant growth, SPAD, photosystem II efficiency, concentration of proline, glycine betaine, and catalase activity, and the native species exhibited comparable effects to commercial species for most variables studied. Contrary to our expectations, PS application alone did not improve plant growth, except for increased photosystem II efficiency, but root fresh and dry weights were reduced. Under drought stress, combination of PS and AMF significantly improved plant height, shoot fresh weight, chlorophyll content (SPAD), glycine betaine, and catalase activity compared to PS alone. Our results highlight that the combined application of PS and AMF inoculants can protect cucumber seedlings from drought stress; however, further research is needed to optimize the PS application method and dosage and to investigate the long-term effects on plant growth and yield under field conditions.