Changes of Fusarium oxysporum f.sp. lactucae levels and soil microbial community during soil biosolarization using chitin as soil amendment

• Published in: PloS one Vol. 15; no. 5; p. e0232662
• Main Authors: Randall, Tara E, Fernandez-Bayo, Jesus D, Harrold, Duff R, Achmon, Yigal, Hestmark, Kelley V, Gordon, Thomas R, Stapleton, James J, Simmons, Christopher W, VanderGheynst, Jean S
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 05.05.2020; Public Library of Science (PLoS)
• Subjects: Agricultural engineering; Agricultural production; Anaerobic conditions; Backup software; Bacteria; Biological activity; Biology and Life Sciences; Biomass; Chitin; Crop yield; Crustaceans; Deactivation; Environmental regulations; Fermentation; Field capacity; Food science; Fumigation; Fungi; Fusarium oxysporum; Greenhouse effect; Health; Inactivation; Lettuce; Medicine and Health Sciences; Microbial activity; Microbiomes; Microbiota; Microbiota (Symbiotic organisms); Microorganisms; Novels; Organic materials; Organic soils; Oxygen; Pathogens; Pests; Physical Sciences; Plant pathology; Plant protection; Research and Analysis Methods; Room temperature; Shellfish; Soil amendment; Soil layers; Soil microorganisms; Soil temperature; Soils; Studies; Temperature regime; Canada; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0232662

Regulatory pressure along with environmental and human health concerns drive the development of soil fumigation alternatives such as soil biosolarization (SBS). SBS involves tarping soil that is at field capacity with a transparent film following amendment with certain organic materials. Heating via the greenhouse effect results in an increase of the soil temperature. The organic amendments can promote microbial activity that can enhance pest inactivation by depleting oxygen, producing biopesticidal fermentation products, and competing with pests. The properties of the organic amendments can heavily influence the type and magnitude of these effects. This study evaluated the viability of chitin as a novel SBS soil amendment to influence soil fungal and bacterial microbial communities, including control of the plant pathogen Fusarium oxysporum f.sp. lactucae (FOL). Changes to FOL and the broader soil microbiota were monitored in response to biosolarization using 0.1% (by dry weight) amendment with chitin (Rootguard). FOL suppression was only observed in chitin amended soils that were incubated at room temperature, not under solarized conditions. Conversely, it decreased solarization efficacy in the upper (0-10 cm) soil layer. The presence of chitin also showed increase in FOL under anaerobic and fluctuating temperature regime conditions. Biosolarization with chitin amendment did exhibit an impact on the overall soil microbial community. The fungal genus Mortierella and the bacterial family Chitinophagaceae were consistently enriched in biosolarized soils with chitin amendment. This study showed low potential FOL suppression due chitin amendment at the studied levels. However, chitin amendment showed a higher impact on the fungal community than the bacterial community. The impact of these microbial changes on crop protection and yields need to be studied in the long-term.