Soil Microbial Ecology Associated with Disease Control of Fusarium oxysporum f. sp. Cucumerinum in Cucumis sativus Cultivation.

摘要

Fusarium oxysporum f. sp. Cucumerinum is a pathogen affecting continuous crop monoculture cucumber (Cucumis sativus) production. Soil fumigation and rotation of cucumber with other crops are two methods control the disease. Disease control is when yield is increased and disease incidence is reduce after treatment. Fumigation of soil with anhydrous ammonia and rotation of cucumber with other crops were investigated as disease management methods in continuous crop monoculture cucumber fields with high disease incidence and reduced yield. In 2013 at a continuous crop monoculture cucumber field near Jinhua, Zhejiang, China, three soil samples were collected from seven growing season time points from two soil treatments: 1) fumigated with anhydrous ammonia; or 2) not-fumigated. A total of forty-two samples. In 2014 at the same field above, eight soil samples were collected from one growing season time point from three soil treatments: 1) fumigated with anhydrous ammonia the year prior; 2) cucumber-tomato-celery crop rotation; or 3) not-fumigated in continuous crop monoculture cucumber. A total of 24 samples. Soil was analyzed for chemical properties. Soil microbial communities were profiled using bioinformatics software tools by analyzing sequenced amplicons of bacterial and archaeal 16s and fungal ITS1 rDNA from extracted soil sample DNA. Yield was increased and disease incidence was reduced by soil fumigation with anhydrous ammonia and crop rotation.;In 2013, soil fumigation significantly affected 116 unique fungal species and 28 unique bacterial genera relative abundances (P < 0.10). Following fumigation, 55 fungal species relative abundances were significantly enriched (P < 0.10) in fumigated compared to not-fumigated treatment soil. This was an r-selected fungal species succession to be later dominated by a smaller k-selected community of late successional saprophytic fungal species. Bacterial genus relative abundances were generally affected more by plant growth with 10 unique species relative abundances significantly enriched when cucumber was planted in fumigated compared to not fumigated treatment soil. Later, 11 unique genera relative abundances were reduced when cucumber was harvested in fumigated compared to not-fumigated treatment soil. Disease control in fumigated soil may be related to the competition of the late successional saprophytic community with the pathogen for similar niche space. The enrichment of potentially plant beneficial bacterial genera relative abundances at cucumber planting may also have contributed to disease control.;In 2014, the relative abundance of the cucumber pathogen, Fusarium oxysporum, was significantly reduced in both fumigated and rotation treatment soil when both were compared to not-fumigated (P < 0.10). Categorization of samples based on soil ammonium nitrogen concentration showed that communities with potential fitness for nitrogen cycling were selected while other communities potentially beneficial for plants were reduced when high ammonium nitrogen concentration samples were compared to low ammonium nitrogen concentration samples. Fumigated and rotation treatment soil microbial communities were different when compared to not fumigated soil. Fumigated soil had less enriched bacterial genera, fewer potentially plant beneficial genera, and was enriched in potentially pathogenic fungal species relative abundances than rotation soil when both were compared to not-fumigated soil. While both fumigated and rotation soil controlled the pathogen, each had different microbial communities. The difference in microbial communities could guide management decisions to help build the soil microbial resource functional redundancy and capacity.