Department of Biological and Agricultural Engineering, University of California, Davis, CA, United States of America.
Department of Food Science and Technology, University of California, Davis, CA, United States of America.
PLoS One. 2020 May 5;15(5):e0232662. doi: 10.1371/journal.pone.0232662. eCollection 2020.
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.
监管压力以及对环境和人类健康的关注推动了土壤熏蒸替代物的发展，例如土壤生物强化（SBS）。SBS 涉及在田间持水量下用透明薄膜覆盖土壤，然后用某些有机材料进行改良。通过温室效应加热会导致土壤温度升高。有机改良剂可以促进微生物活性，通过耗尽氧气、产生生物农药发酵产物和与害虫竞争来增强害虫失活。有机改良剂的特性会强烈影响这些效果的类型和幅度。本研究评估了壳聚糖作为新型 SBS 土壤改良剂的可行性，以影响土壤真菌和细菌微生物群落，包括控制植物病原体尖孢镰刀菌（FOL）。使用 0.1%（按干重计）的壳聚糖（Rootguard）进行生物强化后，监测了 FOL 和更广泛的土壤微生物群的变化。仅在室温下（不在太阳化条件下）用壳聚糖处理的土壤中观察到 FOL 抑制，而在太阳化条件下则没有。相反，它降低了上（0-10cm）土壤层的太阳化功效。壳聚糖的存在也显示出在厌氧和温度波动条件下 FOL 的增加。用壳聚糖进行生物强化确实对整体土壤微生物群落产生了影响。在添加壳聚糖的生物强化土壤中，真菌属 Mortierella 和细菌科 Chitinophagaceae 始终得到富集。在研究水平下，由于壳聚糖的添加，FOL 的抑制潜力较低。然而，壳聚糖添加对真菌群落的影响高于对细菌群落的影响。这些微生物变化对作物保护和产量的影响需要在长期内进行研究。
