Microencapsulation: Toward the Reduction of the Salinity Stress Effect on Wheat Plants Using NPK Rhizobacteria

Abstract

Salinity is one of the most vicious environmental factors controlling the productivity of crop plants as most of the crop plants are sensitive to salinity affected by high concentrations of salts in the soil. The objective of this study was to evaluate the influence of the inoculation with the encapsulated and liquid culture of three halo-tolerant plants growth-promoting rhizobacteria (PGPR) strains of Paenibacillus polymyxa MSRH5, Bacillus nakamurai MSRH1 and Bacillus pacificus MSR H3 on the growth and yield of wheat (Triticum aestivum L.). The three strains MSRH1, MSRH3 and MSR H5 were characterized as salt-tolerant bacteria. P. polymyxa MSRH5 had nitrogen fixation ability while B. nakamurai MSRH1 and B. pacificus MSRH3 were able to solubilize phosphate and K respectively. All strains can produce indole acidic acid (IAA) and exopolysaccharides (EPS) under saline conditions. Encapsulated beads were observed under Scanning Electron Microscope (SEM). Colonization of encapsulated bacteria on the root of the wheat plant was studied by Transmission Electron Microscopy (TEM). Under soil salinity conditions in two consecutive field tries, results cleared that strains in two forms succeed to colonize the plant root, the reduction in shoot proline was 35.8% with capsules inoculation as well as improved relative water content (%) to 60.57% and improved the electrolyte leakage recorded 18.1% respectively compared to control. Generally, halo-tolerant PGPR inoculation increased DHA (?), acidic and alkaline phosphatase activities compared to control, inoculation with capsules exhibited a reduction in catalase enzymes 46.00%, 37.5% in ascorbate peroxidase and 40% in superoxide dismutase respectively in shoots of the wheat plant. There is a significant increase in all yield parameters, the highest plant height 115.8 cm, spike length 21 cm and 1000 grains 71.3 g respectively recorded with capsules inoculation, it had considerable effects on the content of N, P, K and Na in shoots of wheat plants and reduced the value of Na/K ratio in all treatments inoculated compared to un-inoculated wheat plant.

Progress and Applications of Plant Growth-Promoting Bacteria in Salt Tolerance of Crops

“…Many bacterial endophytes can be cultured and can be directly applied to crops either by spraying, seed, or root inoculation [187]. A method for applying salt tolerant bacteria to agricultural production is to use bacterial capsules [188]. Bacterial capsules are polymer-coated outside of the bacteria, and the coating is positively charged and combines with a negatively charged cell wall to form a mixed capsule.…”

“…Bacterial capsules are polymer-coated outside of the bacteria, and the coating is positively charged and combines with a negatively charged cell wall to form a mixed capsule. It can be used to improve the survival and persistence of pathogenic bacteria on inoculated crops [188]. Bacterial capsules are non-toxic, durable, convenient, easy to store, and easy to apply.…”

“…Rainfall or irrigation dissolves the capsule to slowly release the bacteria. Additionally, capsules can include a variety of beneficial bacteria with complementary activities to improve plant salt tolerance and reduce application costs [188].…”

Health Hazards of Toxic and Essential Heavy Metals from the Poultry Waste on Human and Aquatic Organisms

“…Also of concern is the issue of air quality affected by dust particles, releases significant emissions of gases (methane, hydrogen sulfides, sulfur dioxide and ammonia) offensive odors and other pollutants such as volatile organic compounds (VOCs), particulate matter (PM), nitrogenous compounds during the decomposition of poultry waste that contributed to climate change which is a global concern and deleterious health effects (both chronic and acute) including respiratory conditions (i.e., bronchitis, asthma in children), heart disease, and lung cancer [85,86]. Poultry waste as an important source of nutrients for many edible crops, may also contain some biological hazards that can threaten human health [87]. Poultry waste could be a source of human pathogens such as Salmonella, Campylobacter and Listeria that can potentially contaminate both edible crops and environment, which consequently leads to food-borne diseases [88,89].…”

Beneficial microbes in agriculture under abiotic stress conditions: An overview

“…This strain not only helps to mitigate salt toxic effects but also increases plant growth and decreases crop losses due to salinity (Singh et al, 2020) [80] . (Saad et al, 2019) [67] reported that P. polymyxa, B. nakamurai and B. pacificus were effective in colonizing the wheat plant rhizosphere and in protecting wheat plants from destruction to salt stress. Such PGPRs also ameliorated the reduction of proline accumulation in shoots, increased RWC, electrolyte leakage and enzymatic activity, improved antioxidant enzymes, growth and wheat yield under saline stress.…”