This study aimed to (i) evaluate purple nonsulfur bacteria (PNSB) strains possessing the highest phosphorus (P) solubilizing capacity in field and (ii) determine the efficacy of PNSB biofertilizers in improving soil quality, P uptake, growth, and yield of pineapple cultivated in acid sulfate soil (ASS). A field experiment was conducted in a completely randomized block design with two factors, including the first factor as P fertilizer levels (0, 50, 75, and 100% P) based on recommended fertilizer formula (RFF) and the second factor as supplementation of biofertilizers containing P solubilizing PNSB (no inoculated PNSB, Rhodobacter sphaeroides W48, R. sphaeroides W42, and a mixture of R. sphaeroides W48 and W42). The results indicated that the supplementation of PNSB biofertilizers led to an increase of 25.3–33.9% in soluble P concentration in soil compared to control treatment. Among the selected PNSB strains, R. sphaeroides W42 and a mixture of the PNSB in biofertilizers solubilized all insoluble P fractions (Fe-P, Al-P, and Ca-P) and strain W48 in biofertilizers for Fe-P and Al-P. Furthermore, the supplementation of biofertilizers from R. sphaeroides W48 and W42 individually and their mixture raised plant height by 3.56–4.10% and available P concentration by 25.3–33.9%. Total P uptake in pineapple treatments with biofertilizers from mixed PNSB was 42.9% higher than that in the control treatment ( ). Application of mixed PNSB strains can reduce 25% P of chemical fertilizer, but the pineapple yield rose over 12.1%. Both R. sphaeroides W48 and W42 are potent for use as crop yield enhancers to obtain the sustainable pineapple cultivation under acidic stress.

Stem-end rot disease has been causing damage to the production of pomelos in Vietnam. The cur-rent study aimed to (i) isolate fungal pathogens causing pomelo stem-end rot disease (PSERD) and (ii) discover Trichoderma spp. that had an antagonistic ability against pathogens under in vitro conditions. Fungi causing PSERD were isolated from pomelo fruits with symptoms of stem-end rot disease and collected from pomelo farms in Ben Tre province, Vietnam. Moreover, 50 fungal strains of Trichoderma spp. also originated from soils of these pomelo farms in Ben Tre province and were dual-tested with the fungal pathogen on the PDA medium. The results demonstrated that 11 pathogenic fungi causing PSERD were isolated from the fruit and showed mycelial growth of roughly 5.33–8.77 cm diameter at 72 h after inoculation. The two fungi that exhibited the fast-est growth, namely, S-P06 and S-P07, were selected. ITS sequencing of the S-P06 and S-P07 fungi resulted in Lasiodiplodia theobromae. All the 50 Trichoderma spp. strains were allowed to antago-nize against the S-P06 and S-P07 strains under in vitro conditions. The greatest antagonistic effi-ciency was found in Trichoderma spp. T-SP19 at 85.4–86.2% and T-SP32 at 84.7–85.4%. The two antagonists were identified as Trichoderma asperellum T-SP19 and T-SP32. The selected strains of Trichoderma asperellum were potent as a biological control for fruit plants.

The present study aimed to identify the abilities of the δ-aminolevulinic acid (ALA) producing purple non-sulfur bacteria (PNSB), Luteovulum sphaeroides W22 and W47, to reduce the Na⁺ concentration, and to ameliorate the soil fertility, nutrients uptake, growth and yield of rice on the salt-contaminated soil. A two-factor experiment was conducted following a completely randomized block design. The factors were the frequency of applying saline irrigation (zero, one, two, three and four times) and the ALA-producing PNSB supplementation (applying only W22, only W47 and mixed W22 + W47). The results revealed that supplying the PNSB mixture not only reduced the proline content but also increased the plant height, number of panicles per pot, percentage of filled seeds, contents of NH₄⁺, PO₄³⁻, total N, P uptake and grain yield. The mixed PNSB application also reduced the Na content and the total Na uptake in plants. L. sphaeroides W22 and W47 decreased the proline content by 31.3% and increased the grain yield by 27.2% in the condition of applying 5‰ saline irrigation four times.

The aim of the current research was to evaluate the effects of members of purple nonsulfur bacteria (PNSB), Rhodopseudomonas palustris strains of VNW02, TLS06, VNW64, and VNS89, mixed with spent rice straw (SRS) from mushroom cultivation as a carrier on promoting sesame growth and yield, and ameliorating the alluvial soil (AS) fertility in dykes. A 43 factorial experiment consisting of different levels of the solid PNSB biofertilizer mixture at 0, 3, 4, and 5tha⁻¹ (0, 1.8110⁸, 2.2410⁸, and 2.6810⁸cells pot⁻¹, respectively), and nitrogen (N) and phosphorus (P) inorganic fertilizer rates (100, 75, and 50kgNha⁻¹; 60, 45, and 30kg P₂O₅ha⁻¹, respectively) was performed in pots with the sesame variety of ADB1 in the dyked AS. The solid PNSB biofertilizer mixture at at least 3tha⁻¹ significantly enhanced the sesame seed yield by providing higher macronutrients for plants by increasing available N and soluble P concentrations in the soil. The solid PNSB biofertilizer mixture in addition to 75 of the recommended N and P fertilizers produced an equivalent yield in comparison to the utilized 100 of N and P inorganic fertilizers. The solid PNSB biofertilizer mixture in the SRS from the mushroom production reduced at least 25 of N and P chemical fertilizers for gaining the maximal seed yield and enriched soil characteristics for the sustainable black sesame cultivation in the dyked AS.