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The aim of the current study was to assess the potency of the exopolymeric substances (EPS)-secreting purple non-sulfur bacteria (PNSB) on rice plants on acidic salt-affected soil under greenhouse conditions. A two-factor experiment was conducted following a completely randomized block design. The first factor was the salinity of the irrigation, and the other factor was the application of the EPS producing PNSB (Luteovulum sphaeroides EPS18, EPS37, and EPS54), with four replicates. The result illustrated that irrigation of salt water at 3–4‰ resulted in an increase in the Na+ accumulation in soil, resulting in a lower rice grain yield by 12.9–22.2% in comparison with the 0‰ salinity case. Supplying the mixture of L. sphaeroides EPS18, EPS37, and EPS54 increased pH by 0.13, NH4+ by 2.30 mg NH4+ kg−1, and available P by 8.80 mg P kg−1, and decreased Na+ by 0.348 meq Na+ 100 g−1, resulting in improvements in N, P, and K uptake and reductions in Na uptake, in comparison with the treatment without bacteria. Thus, the treatments supplied with the mixture of L. sphaeroides EPS18, EPS37, and EPS54 resulted in greater yield by 27.7% than the control treatment. [ABSTRACT FROM AUTHOR]

Saline soils negatively affect and cause serious problems for rice cultivation. This study aimed to evaluate the efficacy of the purple nonsulfur bacteria (PNSB) capable of secreting 5-aminolevulinic acid (ALA) to reduce soil salinity, improve soil fertility, and enhance rice growth and yield. A two-factorial experiment was conducted in a randomized complete block design with four replications. Factor one was the salinity of the irrigated water, and factor two was the supplementation of the ALA-producing PNSB. The results indicated that watering with saline water above 3‰ led to decreases in plant growth and rice yield compared to the treatments watered with tap water. Application of either an individual strain or the mixture of W01, W14, and W22 ameliorated soil properties and increased total NPK uptake, whereas treatments supplied with the mixed strains reduced total Na uptake (9.50 mg Na pot−1). Supplying the W01, W14, and W22 strains individually or in a mixture enhanced the plant height by 3.51–5.45% and rice grain yield by 14.7–26.2%, compared with those of the control treatment. From the study, the combination of the L. sphaeroides W01, W14, and W22 strains is promising for application in saline or salt-contaminated regions to aid the damages caused by salinity on cultivars there, especially rice. Furthermore, this is a biological approach to ease an environmental problem and improve crop performance, which is supposed to be a trend in the sustainable agriculture. [ABSTRACT FROM AUTHOR]

In rice-shrimp farming systems, the high level of sodium that shrimps are able to grow in may create an adverse environment for rice. This research aimed to isolate purple nonsulfur bacteria (PNSB) from rice-shrimp fields and select strains that were resistant to H+, Al3+, Fe2+ and Mn2+, that can produce plant growth promoting substances such as 5-aminolevulinic acid, exopolymeric substances, indole-3-acetic acid and siderophores. The selected bacteria were applied in a soil pot experiment to determine their ability to enhance rice growth and yield. From 63 PNSB isolated from 21 paddy fields of rice-shrimp systems, four strains were selected for their properties as biofertilizers and plant growth promoters (PGP). They were all identified as strains of Luteovulum sphaeroides. A randomized complete block design incorporating six treatments was used to investigate the ability of the four PNSB strains to ameliorate rice growth and yield in saline acidic soil with saline water irrigation at 4‰. PNSB cultures at 1.90 × 105 CFU g−1 dry soil weight were applied three times, along with normal chemical fertilizers, and all monitored parameters of rice growth and grain yield significantly improved in soil with a toxic Al3+ content of 10.8 meq 100 g−1. A mixed four cultures most effectively increased grain yield (86.8%) compared with no applied PNSB. Remediation of the pot soil was exhibited in decreased exchangeable Na in soil and proline content in leaves. The four PNSB could act as biofertilizers, PGP and bioremediators with potential to enhance rice yield in rice-shrimp systems for sustainable rice cultivation. [ABSTRACT FROM AUTHOR]

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 4 × 3 factorial experiment consisting of different levels of the solid PNSB biofertilizer mixture at 0, 3, 4, and 5 t·ha -1 (0, 1.81 × 10 8 , 2.24 × 10 8 , and 2.68 × 10 8  cells pot -1 , respectively), and nitrogen (N) and phosphorus (P) inorganic fertilizer rates (100, 75, and 50 kg·N·ha -1 ; 60, 45, and 30 kg P 2 O 5 ·ha -1 , respectively) was performed in pots with the sesame variety of ADB1 in the dyked AS. The solid PNSB biofertilizer mixture at at least 3 t·ha -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., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Nguyen Quoc Khuong et al.)