This work aims to develop a multihole atmospheric pressure plasma jet (APPJ) device to increase the plasma area and apply it to a continuous seed treatment system. Broccoli seed was used to study the effects of an atmospheric pressure plasma jet on seed germination and growth rate. An argon flow rate of 4.2 lpm, a plasma power of 412 W, and discharge frequency of 76 kHz were used for seed treatment. The contact angle decreased strongly with the increase in treatment time from 20 s to 80 s. The broccoli seed’s outer surface morphology seemed to have been slightly modified to a smoother surface by the plasma treatment during the treatment time of 80 s. However, the cross-sectional images resulted from Synchrotron radiation X-ray tomographic microscopy (SRXTM) confirmed no significant difference between seeds untreated and treated by plasma for 80 s. This result indicates that plasma does not affect the bulk characteristics of the seed but does provide delicate changes to the top thin layer on the seed surface. After seven days of cultivation, the seed treated by plasma for 30 s achieved the highest germination and yield.

This study investigated the antibacterial properties of Pleurotus ostreatus (Jacq. Ex Fr.) P. Kumm. extracts against various pathogenic bacteria. The fruiting bodies of fresh oyster mushrooms were collected from Mae Phai Boon Mushroom Farm in Ban Thung Nang Rao, Mueang District, Mahasarakham Province, and subjected to extraction using 95% ethanol and 95% ethyl acetate solvents. The effectiveness of the extracts in suppressing the proliferation of pathogenic microorganisms, encompassing Bacillus cereus, Enterobacter cloacae, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, and Staphylococcus aureus, was assessed through the utilization of the paper disk diffusion technique. The results revealed that the crude extract obtained from the 95% ethanol solvent exhibited significant inhibitory effects against B. cereus, E. cloacae, P. aeruginosa, S. marcescens, and S. typhi, yielding inhibition zone diameters from 9.22 to 12.33 mm. In contrast, the crude extract from the 95% ethyl acetate solvent showed inhibitory activity only against E. coli, revealing an inhibition zone diameter of 12.00 mm. Additionally, the determination of the minimum inhibitory concentration (MIC) of the 95% ethanol crude extract against P. aeruginosa and S. marcescens established a value of 150 mg/ml, and concomitantly, the minimal bactericidal concentration (MBC) was also established at 150 mg/ml. However, it was observed that the 95% ethanol crude extract at a concentration of 15 mg/ml was incapable of suppressing the proliferation of E. coli in the MIC evaluations. These findings imply that the extracts originating from P. ostreatus possess inherent capacity as organic antibacterial agents targeting specific pathogenic bacteria. Therefore, these findings justify the necessity for additional scrutiny into their conceivable utilities within the domains of medicine and food preservation.

The efficacy of antagonistic microorganisms and secondary metabolites of entomopathogenic bacteria was evaluated in vitro and in vivo against Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of rice bacterial leaf blight. The effect of the culture filtrates of the microorganisms was tested against Xoo, using the agar well diffusion assay. Trichoderma sp. UB05/3 was the most effective against Xoo. However, the results were not statistically different from those of the entomopathogenic bacterium Serratia nematodiphila GCSR38 with a 22.97 mm and 19.15 mm zone of inhibition, respectively. The effect of the secondary metabolite crude extracts of antagonistic microorganisms (2,000 µg/ml) on Xoo inhibition was tested by the paper disc diffusion method. Only S. nematodiphila GCSR38 was able to control Xoo, with an inhibition zone of 17.60 mm. Minimum inhibitory concentration (MIC) was determined using a 96-well microtiter plate. The MIC of secondary metabolites crude extracts of S. nematodiphila GCSR38 was 1,000 µg/ml and the minimum bactericidal concentration (MBC) was 1,000 µg/ml. The efficacy of the secondary metabolite crude extract of S. nematodiphila GCSR38 against Xoo was tested using the detached leaf technique; the secondary metabolite crude extracts controlled the disease, with 24.45% and 15.56% disease severity when used before and after inoculation with Xoo, respectively. Inoculation with Xoo alone resulted in a disease severity of 44.45%. The secondary metabolite crude extracts of S. nematodiphila GCSR38 can reduce disease severity of bacterial leaf blight in rice by 28.89%, whereas zinc thiazole causes a disease severity of 22.22% and Xoo alone causes a disease severity of 66.67%.

This study aimed to develop and evaluate a bioformulation combining Trichoderma asperellum MSU007 and the plant growth-promoting rhizobacterium (PGPR) Bacillus velezensis MSU01 to enhance rice growth. Coexistence assays demonstrated that T. asperellum MSU007 and the PGPR B. velezensis MSU01 could grow concurrently without mutual inhibition. A powdered bio-formulation was created that showed effective water solubility and moisture content stability across the three formulations. Viability assessments indicated that T. asperellum MSU007 and the PGPR maintained high survival rates over a 60 day storage period, with formulation 3 (T. asperellum MSU007 and B. velezensis MSU01 at a 3:1 ratio) consistently exhibiting the highest viability. The effect of the bioformulation on rice growth was significant. Formulation 3 was the most effective in enhancing rice seed germination and seedling growth. It achieved 100% germination by the fourth day and consistently promoted improvements in shoot and root lengths, as well as in the fresh and dry weights of shoots and roots. Formulations 1 and 2 also showed positive effects but were less effective than formulation 3. In summary, the Trichoderma-PGPR bioformulations, particularly formulation 3, significantly enhanced rice growth, offering a promising solution for improving crop yield.

Damping-off disease represents a considerable hazard to the cultivation of Chinese kale (Brassica oleracea var. alboglabra), leading to seedling death and notable economic repercussions. This study explores the efficacy of guava leaf extracts, obtained through different extraction solvents, against Pythium aphanidermatum, a significant pathogen causing damping-off disease in Chinese kale (Pak Kha-naa) cultivation in Thailand. Guava leaf extract was obtained using different solvents: hexane, ethyl acetate and ethanol. Subsequently, the extract was diluted to concentrations of 1,000, 1,500 and 3,000 ppm to assessment the inhibitory effects on P. aphanidermatum utilizing the poisoned plate technique. Results revealed that only ethanol-extracted guava leaf extract at 3,000 ppm exhibited significant inhibition of P. aphanidermatum, achieving complete inhibition. At 1,500 ppm, ethanol-extracted guava leaf extract demonstrated inhibition comparable to carbendazim. Greenhouse trials further confirmed the efficacy of pre-planting seeds coating with ethanolic guava leaf extract at concentrations of 1,500 and 3,000 ppm in reducing damping-off disease incidence in Chinese kale. Chemical analysis of guava extract with GC-MS revealed the presence of 58 compounds in the hexane extract, with copaene, β-caryophyllene, calamenene and caryophyllene oxide being major constituents. The ethyl acetate extract contained 53 compounds, including β-caryophyllene and squalene, while caryophyllene was a predominant component among the 40 chemicals identified in the ethanol extract. Methylparaben was exclusively present in the ethanol extract, showcasing inhibitory effects on the fungus. This research sheds light on the potential of guava leaf extracts as a sustainable solution for disease management in Chinese kale cultivation. HIGHLIGHTSEthanolic extract of guava leaf at 3,000 ppm completely inhibits the pathogen Pythium aphanidermatum. Seed coated with ethanol-extracted guava leaf extract at concentrations of 1,500 and 3,000 ppm reduced damping-off disease incidence in Chinese kale in greenhouse trials. Chemical analysis via GC-MS revealed diverse compounds in guava leaf extracts, with notable constituents such as copaene, β-caryophyllene, calamenene and caryophyllene oxide in the hexane extract, β-caryophyllene and squalene in the ethyl acetate extract and caryophyllene predominance in the ethanol extract. Identification of methylparaben exclusively in the ethanol extract suggests its potential inhibitory effects on the fungus. This study underscores the promising potential of guava leaf extracts as a sustainable solution for disease management in Chinese kale cultivation, offering insights into alternative methods for controlling damping-off disease. GRAPHICAL ABSTRACT