Effects of Continuous Cropping of Sweet Potato on the Fungal Community Structure in Rhizospheric Soil

Abstract

Soil microorganisms play an important role in the ecosystem, and have a certain relationship with the continuous cropping obstacles, which are common with sweet potato. However, there are few reports on the effects of continuous cropping of sweet potato on the microbial community structure in the rhizospheric soil. Here, we investigated the effects of continuous cropping of sweet potato on the fungal community structure in rhizospheric soil, in order to provide theoretical basis for prevention and control of continuous cropping obstacles. This study used X18 and Y138 varieties as experimental materials. Soil samples were collected during the early period of planting and harvest in two consecutive years, and fungi were analyzed using Illumina Miseq. Results showed that the fungi diversity and richness in rhizospheric soil of X18 and Y138 were significantly increased after continuous cropping; the most dominant fungi phylum was Ascomycota, which decreased significantly after continuous cropping. In addition, the content of beneficial fungi such as Chaetomium was reduced, while that of harmful fungi such as Verticillium, Fusarium, and Colletotrichum were increased. The composition of X18 and Y138 fungal community in the same sampling period after continuous cropping was similar, although that of the same sweet potato variety significantly differed with the sampling period. Overall, our results indicate that continuous cropping alters the fungal community structure of the sweet potato rhizospheric soil, such that the content of beneficial fungi decrease, while that of harmful fungi increase, thereby increasing soil-borne diseases and reducing the yield and quality of sweet potato. Furthermore, these effects are different for different sweet potato varieties. Thus, during actual production, attention should be paid to maintain the stability of sweet potato rhizospheric soil micro-ecology through rotation or application of microbial fertilizers and soil amendments to alleviate continuous cropping obstacles.

Effects of Continuous Cropping on Bacterial Community Structure in Rhizospheric Soil of Sweet Potato

“…The average temperature was 12.5 °C. The mean annual precipitation was 494 mm [7]. This region has a warm temperate sub -humid continental monsoon climate and the local soil type is Mottlic Hapli-Ustic Argosols (cinnamon soil).…”

“…A random block design was used, with three experimental repetitions. The ridge distance was 85 cm, seedling spacing was 25 cm for ve rows, length of the plot was 6 m, and the area of the plot was 25.5 m 2 [7]. The agronomic management was the same for all elds in two years.…”

“…The pooled DNA product was used to construct Illumina Pair-End library following Illumina's genomic DNA library preparation procedure. Then the amplicon library was paired-end sequenced (2 × 250) on an Illumina MiSeq platform (Shanghai BIOZERON Co., Ltd.) according to the standard protocols [7]. Complete data sets generated in this study were deposited in the NCBI Sequence Read Archive database under accession number SRP214716.…”

“…However, continuous cropping obstacles are common with sweet potato, which can lead to reduced yield and quality, severe plant death or even failure to harvest [5][6]. In recent years, the phenomenon of continuous cropping obstacles of sweet potato has become serious, and it has become a bottleneck problem that restricts the sustainable development of sweet potato industry in China [7].…”

“…These changes have further led to severe continuous cropping obstacles [9]. Therefore, the relationship between rhizospheric soil microbial community structure and continuous cropping obstacles has become one of the research hotspots [7].…”