Dynamics of soil nematode communities revealed significant variation in greenhouse with different continuous cropping years

Abstract

Continuous cropping usually resulted in a series of soil problems, especially root knot nematode disaster in greenhouse because of imbalance in soil nematode community. However, the dynamic change in soil nematode community in greenhouse with various continuous cropping years during plant growing season is unclear. Here, soil nematode communities in greenhouse after 2 and 10 years of continuous cropping were comparatively analyzed using 18S rDNA high-throughput sequencing to reveal the changing processes in soil nematode communities. Compared to the 2-year greenhouse, soil in the 10-year greenhouse showed soil acidification, nutrients accumulation, salinization. In term of -diversity, Bacterial-feeding nematodes (BF) were dominant in the 2-year greenhouse over the whole growing season, but plant-parasitic nematodes (PP) became the dominant group in the 10-year greenhouse in the late growing season. Meloidogyne gradually became the dominant group (Relative abundance 70.9%) in the 10-year greenhouse, while Rhabditidae (Relative abundance from 99.8% to 26.8%) was the predominant members in the 2-year greenhouse. For {beta}-diversity, hierarchical clustering analysis, unWeighted UniFrac principal component analysis (PCA) and principal co-ordinates analysis (PCoA) all revealed that soil nematode communities in the two types of greenhouses exhibited significant differences. Redundancy analysis (RDA) showed that soil nematode communities in the 10-year greenhouse were related to high soil organic material, total nitrogen, electrical conductivity and disease index of root knot nematode. Fisher exact test and Pearson correlation coefficients revealed that Meloidogyne caused main differences in soil nematode communities between the two types of greenhouses. Meanwhile, population dynamics of Meloidogyne were divided into dormant phase, low-level increasing phase and exponential phase during the whole season. In total, the significant variation led different dynamics of soil nematode communities in the 2-year and 10-year greenhouse.