Improvement of Nutrient Uptake, Yield of Black Sesame (Sesamum indicum L.), and Alluvial Soil Fertility in Dyke by Spent Rice Straw from Mushroom Cultivation as Biofertilizer Containing Potent Strains of Rhodopseudomonas palustris.

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 × 108, 2.24 × 108, and 2.68 × 108 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 P2O5·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.

Influence of purple non-sulfur bacterial augmentation on soil nutrient dynamics and rice (Oryza sativa) growth in acidic saline-stressed environments.

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.

Overexpression of the oil palm (Elaeis guineensis Jacq.) TAPETUM DEVELOPMENT1-like Eg707 in rice affects cell division and differentiation and reduces fertility.

The functional analysis of the TAPETUM DEVELOPMENT1-like analog Eg707 of oil palm was carried out in rice by over-expressing Eg707 under the control of a double cauliflower mosaic virus 35S promoter. Ectopic expression of Eg707 in rice induced dark green and matured compact brownish calli compared to pale wild type and negative control calli. Regenerated transgenic rice plants exhibited a reduction in organ size and plant height, rolled, erect leaves, less tillers, increased chlorophyll content, and reduced fertility with smaller green seeds. At the molecular level Eg707 overexpression caused an increase in the transcription of SAPK9, a SnRK2 protein kinase family member that is activated by ABA and hyperosmotic stress. Together, the results show that ectopic Eg707 expression influences cell division and differentiation, presumably via altered hormone homeostasis.

Isolation and characterization of novel potassium-solubilizing purple nonsulfur bacteria from acidic paddy soils using culture-dependent and culture-independent techniques.

The current research as aimed (i) to isolate and select the purple nonsulfur bacteria (PNSB) possessing the potassium-solubilizing ability from acid paddy fields and (ii) to evaluate the ability to release the plant growth-promoting substances (PGPS) of selected PNSB. A total of 35 acid sulfate (AS) soil samples were collected in An Giang province, Vietnam. Then, 70 PNSB strains were isolated from the AS soil samples. In the current study, the isolated strains were screened and selected according to their tolerability to acidic conditions, ability to solubilize potassium, and characteristics of a plant growth promoter on basic isolation media with various incubation conditions. Therein, three strains, TT07.4, AN05.1, and AC04.1, presented the highest potassium solubilization under the microaerobic light (11.8-17.7 mg L-1) and aerobic dark (16.4-24.7 mg L-1) conditions and stresses from Al3+, Fe2+, and Mn2+ toxicity. The selected strains were identified as Rhodopseudomonas pentothenatexigens by the 16S rDNA sequence, with 99% similarity. The selected acidic-resistant strains possessed the traits of biofertilizers under both microaerobic light and aerobic dark conditions, with abilities to fix nitrogen (0.17-6.24; 7.93-11.2 mg L-1); solubilize phosphorus from insoluble compounds with 3.22-49.9 and 9.49-11.2 mg L-1 for Al-P, 21.9-25.8 and 20.2-25.1 mg L-1 for Ca-P, and 10.1-29.8 and 18.9-23.2 mg L-1 for Fe-P; produce 5-aminolevulinic acid (0.63-3.01; 1.19-6.39 mg L-1), exopolymeric substances (0.14-0.76; 0.21-0.86 mg L-1), indole-3-acetic acid (12.9-32.6; 13.6-17.8 mg L-1), and siderophores (28.4-30.3; 6.15-10.3%). The selected potassium-solubilizing strains have a great potential to apply in liquid form into rice seed and solid form in AS soils to supply nutrients and PGPS for enhancing rice growth and grain yield.

Using Trichoderma asperellum to Antagonize Lasiodiplodia theobromae Causing Stem-End Rot Disease on Pomelo (Citrus maxima).

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.