Poly-gamma-glutamic acid-containing vaccine(BL)

To investigate the effect of poly-γ-glutamic acid (γ-PGA) biopreparation on ameliorating coastal saline soil, three treatments were established: soil salt washed treatment (CK), soil salt washed with added γ-PGA (PGA), soil salt washed with added γ-PGA biopreparation (PGAB). This study determined the effects of γ-PGA on coastal saline soil by analyzing soil aggregate, soil evaporation, soil vertical water and salt distribution, and soil cation content, soil pH, soil nutrient content and soil microorganism quantity. Results showed that γ-PGA had an ameliorative effect on saline soil, with the PGAB treatment exhibiting the most pronounced ameliorative effect compared to CK. Adding PGAB reduced soil evaporation by 30.45 %, soil salt content by 27.91 %, meanwhile increasing plant height by 33.86 %, plant fresh weight by 98.54 %, soil aggregate diameter by 6.68 times, soil water content by 26.47 % (P < 0.05). Additionally, soil total nitrogen was increased by 50.0 % in PGAB treatment, and available nitrogen and phosphorus contents were increased by 1.68 times and 85.83 % (P < 0.05), respectively. Populations of soil-culturable bacteria and fungi of PGAB treatment increased by 65.96 % and 1.23 times, respectively (P < 0.05). After salt-washing process, adding PGAB improved soil physicochemical properties, which altered the ecological environment of rhizosphere soil and promoted plant growth. The results can provide a practical approach for ameliorating coastal saline soils.

Poly‐γ‐glutamic acid (γ‐PGA) is employed extensively in agriculture to enhance soil water retention; however, the underlying mechanism by which γ‐PGA improves soil structure and soybean productivity in arid regions remains poorly understood. A micro‐scale field experiment was conducted in the arid region of northwest China, employing five concentrations of γ‐PGA to investigate its impacts on soybean yield, photosynthesis, and water‐use efficiency, as well as soil aggregates and water distribution. The five levels of γ‐PGA were 0 (CK), 10 (P1), 20 (P2), 40 (P3), and 80 kg ha−1 (P4).

The results demonstrated that the application of γ‐PGA significantly improved soybean yield, photosynthesis, and chlorophyll content. It resulted in a decrease in soil aggregate content with a maximum diameter of less than 0.053 mm and an increase in the stability of soil aggregates in the uppermost layer of the soil (0–30 cm). The application of γ‐PGA significantly increased soil water content, particularly in the uppermost layer of the soil, and effectively reduced water consumption and improving water use efficiency in soybeans. Overall, the P3 treatment exhibited the most pronounced improvement of soybean yield, photosynthesis, water‐use efficiency, as well as distribution of soil aggregates and water. The correlation matrix heatmap also revealed a strong correlation between improvement of soybean yield or photosynthesis at various γ‐PGA application levels and the enhancement of soil stability or soil water content.

The multivariate regression analysis revealed that an optimal application level of 46 kg ha−1γ‐PGA could enhance effectively both yield and water use efficiency of soybean in the arid region of northwest China. © 2024 Society of Chemical Industry.