Abiotic stress significantly limits plant growth and production. Drought, in particular, is a severe constraint that affects growth and limits agricultural productivity on a global scale. Water stress induces in plants a set of morpho-anatomical (modification of root and leaf structure), physiological, and biochemical (relative water content, membrane stability, photosynthesis, hormonal balance, antioxidant systems, and osmolyte accumulation) changes mainly employed to cope with the drought stress. These strategies allow the plant to overcome the unfavorable period of limited water availability. Currently, a promising alternative is available to improve plant growth and tolerance under drought conditions. The use of osmotolerant plant growth-promoting rhizobacteria (PGPR) as inoculants can alleviate water stress by increasing the water use efficiency of the plant. The PGPR improve the tolerance of plants to drought, through changes in the morphology and architecture of the root system, production of phytohormones, extracellular polysaccharides, ACC 1-(aminocyclopropane-1-carboxylate) deaminase, volatile chemicals, and osmolyte accumulation. They may also enhance the antioxidant defense system and induce transcriptional regulation of stress response genes. This review addresses the effects of stress on plant growth, adaptation, and response to drought conditions and discusses the significant potential of PGPR to modulate the physiological response against water scarcity, ensuring plant survival and improving the resistance and growth of agricultural crops.

In addition to changing global demography and global warming, agricultural production systems around the world are threatened by intensive agricultural practices (overuse of land and excessive use of chemical fertilizers and pesticides) that deplete soils by affecting their dynamics and their fertility, pollute the environment, lower production, and alter biodiversity on a large scale. The use of bioformulations based on PGPMs (plant growth-promoting microorganisms) seems to be a promising and sustainable strategy to overcome these threats, thanks to their tolerance to various biotic and abiotic stresses and via their beneficial effects in promising plant growth, pest protection, bioremediation, and restoration of degraded lands. In recent years, particular attention has been paid to encapsulated formulations because they offer several advantages over conventional bioformulation (liquid and solid) related to shelf life, problems of survival and viability in the environment, and the efficiency of rhizospheric colonization. This review focuses on the types of encapsulations and the different technologies used in this process as well as the most commonly used substrates and additives. It also provides an overview on the application of encapsulated bioformulations as biofertilizers, biopesticides, or other biostimulators and summarizes the knowledge of the scientific literature on the development of nanoencapsulation in this sector.

Cellulose represents the most abundant component of plant biomass on earth; it is degraded by cellulases, specific enzymes produced by microorganisms. However, cellulases of bacterial origin attract more interest due to their natural diversity and ability to inhabit a variety of niches, allowing the selection of cellulolytic strains resistant to environmental stresses. The screening of the cellulolytic activity of 398 bacteria isolated from various ecosystems in Algeria (cave, ruins, chott, thermal station, and rhizosphere of arid and semi-arid regions) was performed by the appearance of a hydrolysis zone on carboxymethylcellulose (CMC) medium. The cellulase activity on CMC (1%) broth allowed to select 26 strains among which 12 had the best activity (0.3 U/mL to 2.2 U/mL). Optimization of physicochemical parameters (salinity: 0–1 M NaCl; pH: 3, 4, 7, 9, and 11; temperature: 30, 45, and 50 °C; PEG₈₀₀₀: 0 and 30%) involved in growth and cellulose production showed that the majority of strains were mesophilic, neutrophilic, or alkali- tolerant and tolerant to 30% of PEG₈₀₀₀. The cellulase activity and stability under different stress allowed to retain five strains, which the most efficient. Based on the 16S-rRNA sequencing results, they belonged to the genus Bacillus. The physicochemical properties of cellulases (crude extract) showed a CMCase active over a wide range of pH (4 to 11), optimal at 50 °C and 60 °C. The inhibiting salinity effect on the activity was not detected and was negligible on the enzymatic stability. The residual CMCase activity remained between 40 and 70% in a temperature range between 40 and 70 °C, was stable over a wide range of saline concentrations (0–2000 mM), and was weakly affected at 30% of PEG₈₀₀₀. The crude enzyme extract was able to hydrolyze both soluble and insoluble cellulosic substrates. The evaluation of the hydrolysis capacity of lignocellulosic waste revealed the ability of tested strains to degrade wheat bran, barley bran, and corncob. In addition, the enzyme showed significant multi-stress resistance on solid and liquid media. By these characteristics, these cellulolytic bacteria could be attractive to be used in various industrial and biotechnology applications.

Among plant disease management strategies, biological control is a sustainable alternative to the use of chemicals for the control of vascular wilt caused by Fusarium oxysporum. Fusarium wilt is the most devastating disease affecting a wide variety of plants. Bacillus species are the most widely used biological control candidates for the control of these fungal diseases. This review describes the pathogenicity of F. oxysporum, its virulence mechanisms, and host plant–pathogen interactions. The control means deployed by Bacillus species inhibit or kill these phytopathogens. Bacillus spp. produce a wide range of secondary metabolites, including volatile and non-volatile organic compounds. Biocontrol potential is achieved through direct antimicrobial activity, the induction of the host plant’s immune response (Induced Systemic Resistance), and competition for nutrients and space. In addition, parameters governing the selection of effective biocontrol agents and their survival in plant microbial communities are discussed. The influence of the microbiota on the establishment and development of biocontrol agents can assess the potential of these treatments and facilitate the development of effective biopesticides during their field application.

Biochar is known as a well-developed porous carbonaceous material with multifunctional abilities that can enhance the physical properties of soils. However, the lack of certainty about the consequences of biochar application to soils has limited its acceptability. Application of biochar can lead to a series of changes in the physical functions of soil, which are crucial in both agricultural and environmental management. The type of feedstock, pyrolysis conditions, size of particles, and rate of amendments are responsible for biochar effectiveness. Concurrently, the physical characteristics of soil, such as particle-size distribution, can intensify the impacts. Beside the physical attributes, the chemical components and interactions between biochar and the soil interface may play an important role. The chemical properties, such as the value of electrical conductivity, pH and zeta potential, are the remarkable parameters in the hydrophysical behavior. The summary proposes that biochar has a great contribution In enhancing the definite range of aggregation formation, reduction of compaction and shear strength frequency and/or intensity, improvement of microorganisms activity, and abundance. Simultaneously, biochar plays a devastating role by filling the pores, blocking the water flow pathways, and inhibiting macro fauna growth. Particle size of biochar as a major factor, and surface functional groups as a minor factor, affect the performance of biochar in improving the hydrophysical properties of amended soils. The increment in the dosage of biochar application is not promising to enhance the physical properties of soils. Therefore, it is necessary to find a balance between the consumption of biochar and promotion of the soil-water dynamic. This review provides an overview of fastidious perspectives on how to achieve an efficient and sustainable use of biochar in hydrophysical properties.

Halotolerant plant-growth-promoting rhizobacteria (PGPR) could not only promote plant growth, but also help in counteracting the detrimental effects of salt stress. In the present study, a total of 76 bacteria were isolated from the rhizosphere, non-rhizospheric soil and endophytes of the halophyte Salsola tetrandra, collected from natural saline soils in Algeria. Phylogenetic analysis based on the 16S rDNA sequence of Gram-negative bacteria (n = 51) identified, showed seventeen representative isolates grouped into four genera (Pseudomonas, Acinetobacter, Enterobacter, and Providencia). These bacterial isolates that exhibited different PGPR traits were selected and tested for their ability to tolerate different abiotic stress (NaCl, PEG8000, and pH). The majority of isolates were drought tolerant (60% of PEG8000) and had an optimal growth at high pH values (pH 9 and 11) and some strains tolerated 2 M of NaCl. Strains identified as Enterobacter xiangfangensis BE1, Providencia rettgeri BR5 and Pseudomonas stutzeri MLR6 showed high capacity of adaptation on their PGP traits. The salt-tolerant isolates were finally chosen to promote growth and enhance salt tolerance, separately or combined, of Arabidopsis thaliana (Col-0) exposed or not to 0.1 M NaCl, by following fresh and root weight, primary root elongation and lateral root number. The best bacterial effect was recorded for the MLR6 strain in increasing shoot fresh weight and for BE1 in terms of root fresh weight in the absence of salt stress. At stressed conditions, all growth parameters declined. However, inoculation of Arabidopsis thaliana with the three bacterial strains (MLR6, BE1 and BR5), single or in co-culture, conferred an increase in the shoot weight, primary root length and lateral root number. The use of these strains separately or combined as biofertilizers seems to be a powerful tool in the development of sustainable agriculture in saline soils.