This review delves into the role of plant growth-promoting microbes (PGPMs) in sustainable agriculture by enhancing soil health, improving plant stress tolerance, and controlling diseases. PGPMs, which include bacteria, fungi, and other microorganisms, are increasingly recognized as important contributors to promoting eco-friendly agricultural practices. Their ability to improve nutrient availability, stimulate plant growth, and protect crops from environmental stressors makes them a cornerstone for resilient and efficient farming systems. By reducing dependency on synthetic fertilizers and pesticides, PGPMs play a vital role in preserving environmental resources, minimizing greenhouse gas (GHG) emissions, and combating climate change’s negative impacts. This article thoroughly explores the complex interactions between PGPMs, soil nutrients, plant pathogens, and abiotic stressors. It also examines how these interactions influence phytohormone production and signaling pathways, ultimately impacting crop growth and development. Furthermore, this review discusses how PGPMs enhance nutrient uptake, modulate plant immune responses, and improve stress resilience, offering a holistic understanding of their multifaceted contributions to farming. By synthesizing current research and highlighting future directions, this review underscores the potential of PGPMs to revolutionize agricultural activities, ensuring food security and environmental sustainability in the face of global challenges.

Accumulation of high level of nitrate (NO₃⁻) in leaves is a serious issue for vegetable crops like lettuce (Lactuca sativa L.). Therefore, this study aimed to limit NO₃⁻ level by adjusting the balance between fertilization and irrigation program in lettuce. In a strip plot design with three replicates, lettuce plants were grown under four fertilizer treatments and three irrigation regimes. Three organic fertilizers (biochar, compost and vermicompost), in addition to mineral fertilizer, were used. The irrigation regimes were 60, 80 and 100% of crop evapotranspiration, ETc (ETc60, ETc80, and ETc100). Nitrogen (N), phosphorus (P) potassium (K) and organic matter (OM) in soil as well as yield, N, P, K and NO₃⁻ of lettuce were estimated. Findings showed that vermicompost or biochar (with any irrigation regime) as well as compost with irrigation by ETc60 were the effective combinations for increasing K content in soil after harvest. Under irrigation by ETc80 or ETc100, vermicompost or biochar were the efficient treatments for increasing lettuce yield equaling the farmer common practice (ETc100 x mineral fertilizer). Under irrigation by ETc60, mineral fertilizer or vermicompost showed the highest lettuce leaf content of K. Moreover, ETc60 or ETc80 x mineral fertilizer recorded the maximum NO₃⁻ content of lettuce leaves. The accumulation of nitrate in lettuce leaves owing to mineral fertilizer reached about 1.24 times than that of organic fertilizers. Compost x ETc80 or ETc100 showed the minimal NO₃–N accumulation, hence, high relative reductions in NO₃–N accumulation as compared to the common practice (ETc100 x mineral fertilizer) were observed. In conclusion, irrigation by 80% instead of 100% of crop evapotranspiration of organically fertilized lettuce (especially with vermicompost) could be adopted since such practice recorded high lettuce productivity with low NO₃⁻ content.

Reducing the water loss sources, i.e. soil evaporation and weeds presence, is an essential act for keeping well soil moisture to crop growth, especially under drought conditions. Therefore, two–year field trials were conducted for seeking the best compatible practice between irrigation regime and weed control method in onion onion. Three irrigation water regimes (60%, 80% and 100% of the crop water requirements, CWR) and seven weed control practices (rice, wheat and peanut straws as soil mulches as well as oxadiargyl, oxyfluorfen, weeding, and unweeded) were applied. Findings revealed that the application of 60% of CWR either with peanut straw mulch or weeding recorded the maximum reduction in weed biomass. In plots mulched by peanut straw irrigation with 80% of CWR produced acceptable marketable bulb yield, NPK contents, flavonoids content and economic returns closing irrigation by 100% of CWR. In conclusion, the rate of water loss from soil surface through evaporation was much lower in case of mulch treatment than non–mulched one. Thus, mulch not only keeps weeds out but also maintains soil moisture. This allows the opportunity to reduce irrigation water by 20% (80% of CWR) with gaining acceptable yield, saving water and raising benefit/cost ratio.

In salt-affected soils, more than one approach should be adopted for minimizing the salinity impacts and enhancing the land productivity. The most effective practices in crop management under saline soil are choosing the plant type and variety and exploiting the best nutrient tactics. Under two soil salinity levels (3.54 and 9.28 dS m⁻¹), representing low and high salinity, respectively), two sugar beet cultivars (Romulus and Francesca) were fertilized with three potassium (K) rates (48, 96, and 144 kg K ha⁻¹), in addition to the check treatment (0 kg K ha⁻¹). During two seasons of 2018/2019 and 2019/2020, treatments were distributed in a split-split plot design based on a randomized complete block arrangement with three replicates. Several physio-biochemical and agronomic traits, as well as leaf mineral contents and juice quality, were assessed. Briefly, findings illustrated that K at a rate of 144 kg ha⁻¹ enhanced cell membrane stability, relative water content, and performance index by 1.17, 1.01, and 2.73 times, respectively, in high salinity soil, compared to low salinity × no K addition. Under high salinity, the addition of 48 and 144 kg K ha⁻¹ recorded the highest values of total phenolic content and total antioxidant activity, respectively. In high salinity soil, K supplying (144 kg ha⁻¹) caused the maximum improvements in gross and white sugar content with a decrease of 42.0% in sodium content and an increase of 35.9% in root yield ha⁻¹. Romulus cultivar fertilized with 144 kg K ha⁻¹ had the maximum relative water content, F_v/F_m, and performance index. Francesca cultivar with 144 kg K ha⁻¹ was the potent combination for increasing total soluble sugars, total phenolic content, total flavonoid content, and total antioxidant activity. Romulus cultivar fertilized with 144 kg K ha⁻¹ was the best practice for improving all agronomic traits of sugar beet. It could be concluded that a high potassium rate, i.e., 144 kg K ha⁻¹, reduced the injury ionic impacts of saline soils along with improving the genetic makeup of sugar beet cultivars, expressed in sugar yield and quality. However, all other attempts for reclamation of the saline soil should be adopted for increasing the potentiality of K fertilizer and enhancing gene expressions of different sugar beet varieties.

Plants are subjected to low use efficiency of water and nutrients in marginal lands such as calcareous soils. Moreover, plant wastes are not utilized optimally by the farmers. Hence, field trials were carried out in 2018 and 2019 summer seasons to find the practicable model which can be emerged through addition of sugar beet residues as mulching material and irrigation treatments in maize field. The amount of these residues were 0, 2.4, 7.2 and 12.0 ton ha⁻¹ (denoted ‎ M₀ M₁ M₂ and M₃, respectively). Irrigation treatments were 60%, 80% and 100% of crop evapotranspiration (signed as W₆₀, W₈₀ and W₁₀₀, respectively). The study was established in a strip plots design with three replications. Findings exhibited that W₈₀ x M₃ or M₂ were as similar as W₁₀₀ x M₂ in improving biological, straw and grain yields ha⁻¹. Similar beneficial effect of W₁₀₀ or W₈₀ on nutrient uptake was obtained under mulching soil with M₃ or M₂. Moreover, M₁ x W₈₀ or W₁₀₀ achieved the maximally available phosphorus (P) in soil. As well, M₃ x W₈₀ showed stable improvement in water use efficiency during the two studied seasons. Due to irrigation and soil mulching combinations, calcium carbonate (CaCO₃) was reduced by 5.6.1–32.6% compared to the initial CaCO₃ in soil (25.42%). Generally, application of sugar beet residues at a rate of 7.2 ton ha⁻¹ and moderate irrigation water supply, that is 80% of crop evapotranspiration may be considered a promising quixotic practice for regulating deficit irrigation in maize grown in calcareous soils. Continuous application of compatible irrigation regime and soil mulching, for example, 80% of crop evapotranspiration plus soil mulching could have the potentiality to improve calcareous soil properties year after year.