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One of the most favored trends in modern agriculture is biological control. However, many reports show that survival of biocontrol bacteria is poor in host plants. Providing biocontrol agents with protection by encapsulation within external coatings has therefore become a popular idea. Various techniques, including extrusion, spray drying, and emulsion, have been introduced for encapsulation of biocontrol bacteria. One commonly used biopolymer for this type of microencapsulation is alginate, a biopolymer extracted from seaweed. Recent progress has resulted in the production of alginate-based microcapsules that meet key bacterial encapsulation requirements, including biocompatibility, biodegradability, and support of long-term survival and function. However, more studies are needed regarding the effect of encapsulation on protective bacteria and their targeted release in organic crop production systems. Most importantly, the efficacy of alginate use for the encapsulation of biocontrol bacteria in pest and disease management requires further verification. Achieving a new formulation based on biodegradable polymers can have significant effects on increasing the quantity and quality of agricultural products.

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Drought is a major abiotic stress imposed by climate change that affects crop production and soil microbial functions. Plants respond to water deficits at the morphological, biochemical, and physiological levels, and invoke different adaptation mechanisms to tolerate drought stress. Plant growth-promoting bacteria (PGPB) can help to alleviate drought stress in plants through various strategies, including phytohormone production, the solubilization of mineral nutrients, and the production of 1-aminocyclopropane-1-carboxylate deaminase and osmolytes. However, PGPB populations and functions are influenced by adverse soil factors, such as drought. Therefore, maintaining the viability and stability of PGPB applied to arid soils requires that the PGPB have to be protected by suitable coatings. The encapsulation of PGPB is one of the newest and most efficient techniques for protecting beneficial bacteria against unfavorable soil conditions. Coatings made from polysaccharides, such as sodium alginate, chitosan, starch, cellulose, and their derivatives, can absorb and retain substantial amounts of water in the interstitial sites of their structures, thereby promoting bacterial survival and better plant growth.

BACKGROUND Wheat is a valuable food source that is exposed to many diseases that reduce its quantity and quality. One of the most important diseases affecting wheat is take‐all, caused by Gaeumannomyces graminis var. tritici. The application of bacterial inoculants into the soil can increase plant nutrient absorption and enhance the efficiency of probiotic bacteria. For increased beneficial bacteria efficiency, the encapsulation technique has been used in agriculture. RESULTS The results of Fourier transform infrared (FTIR) and X‐ray diffraction analysis (XRD) indicated that the prepared formulation is a mixture of gellan and chitosan. Using SEM, the spherical structure of the microcapsules was confirmed. It was observed that the increase in bacterial release was gradual, and the highest amount of bacteria was released (109 CFU mL–1) on the 50th day. Greenhouse experiments showed that plants treated with S. fulvissimus Uts22 microcapsules had the highest efficiency with 90% disease control. Moreover, the highest fresh and dry weights of roots and shoots were observed in this treatment. CONCLUSION In this study, a new type of formulation aiming at controlling wheat take‐all disease was developed through bacterial and nanoparticles loaded chitosan‐ gellan gum microcapsules with spray drying method. This formulation has many advantages, such as a large surface area and high internal porosity and increased water‐holding capacity, while it also provides a proper habitat for bacteria to increase colonization rates and offers protection of the soil. © 2021 Society of Chemical Industry.