查看更多>>摘要：ABSTR A C T The rhizosphere is of great interest to scholars as the main area where root-soil-microflora interactions occur. Studies on rhizosphere microorganisms have been mainly focused on medicinal plants, while little research has been done on ornamental plants. Paeonia lactiflora is a perennial herb peony, that belongs to Paeoniaceae and is widely used worldwide as an ornamental plant. To study the rhizosphere microbial communities of different cultivars of P. lactiflora, we analyzed the rhizosphere microbial communities of four cultivars of P. lactiflora using high-throughput sequencing technology. In our study, 62,139 to 65,634 high-quality sequences belonging to 9654 distinct Operational Taxonomic Units were obtained in each sample. Among all sequences, the dominant phyla with relative abundance greater than 1% were Proteobacteria, Acidobacteriota, Actinobacteriota, Myx-ococcota, Verrucomicrobiota, Bacteroidota, Crenarchaeota, Planctomycetota and Firmicutes. We found that the rhizosphere bacterial communities of four cultivars of P. lactiflora did not differ significantly in general, but there were some differences. The dominant rhizosphere microorganisms of P. lactiflora are Proteobacteria and Acid-obacteriota. The bacterial communities of the peony cultivars 'Zi Feng Yu' and 'Yang Fei Chu Yu' contained more bacteria that can promote plant growth under environmental stresses such as drought and high salinity compared to the other two cultivars. By analyzing the soil factors related with the P. lactiflora rhizosphere bacterial community, we found that different soil factors had effects on the abundance of the dominant bacterial genus in the rhizosphere soil of P. lactiflora. Among them, pH and alkaline phosphatase significantly affected the bacterial community, including Elusimicrobia, Gemmatimonadetes, Nitrospirota, Planctomycetota, etc. These results fill the gap in the study of rhizosphere microorganisms in P. lactiflora and provide a reference for future research on biofertilizers and the promotion of peony cultivation.
查看更多>>摘要：In a greenhouse experiment, we investigated the influence of leek (Allium porrum) intercropping, mycorrhizal fungi and earthworms on the root-knot nematode infection by Meloidogyne incognita (RKN) and the growth and development of tomato plants (Solanum lycopersicum). Tomato plants were grown in pots, intercropped with leeks or in monoculture, and earthworms and/or arbuscular mycorrhizal fungi (AMF) were introduced. The effects of these two treatments on root-knot nematode infection and tomato plant growth and development were assessed i) by counting the galls induced by the nematodes and the number of egg masses on their roots, and ii) by measuring their height increase, shoot and root dry biomasses and flowering time. Tomato growth was increased with leek compared to the monoculture (e.g., +82% shoot biomass), probably due to a lower plantplant competition, although a facilitation effect cannot be excluded. The presence of leeks did not reduce the number of galls (per g of root). The presence of AMF (Rhizophagus irregularis) increased the overall infection of M. incognita (e.g., +36% egg masses) and induced more galls with multiple egg masses in the leek-tomato association (+71%) but did not increase plant biomass. On the other hand, it increased plant height in presence of the compost earthworms (Eisenia andrei) compared to earthworms alone with RKN (+2%). It also delayed the flowering compared to RKN alone (+7.6 days in average). Competition between the two tomato plants in monoculture probably strongly impacted plant growth, flowering time and thereby the RKN infection, but leektomato interactions should be further examined. The overall increased number of multiple egg masses per gall in presence of AMF is contrary to its protective effect reported in the litterature.
查看更多>>摘要：Glyphosate is among the most used herbicides worldwide. However, both the active ingredient and additives of the commercial formulations may adversely affect chemical and biological processes in soil. Therefore, the aim of this work was to evaluate the effect of glyphosate and the commercial formulation (CH) on soil C, N and P dynamics, and microbial enzyme activity in two soil management conditions: a nopal plot (NP) with an history of 5 years of glyphosate application, and in an abandoned plot (AP) with a history of previous agricultural management without glyphosate applications. We performed three experiments: a) glyphosate and CH effects on phosphorus sorption by performing a non-biological P fixation experiment; b) glyphosate and CH effects on microbial activity, C, N and P dynamic, and the biodiversity of soil microorganisms in terms of biomarker fatty acids after a 27 day incubation experiment; and c) glyphosate and CH degradation was tested isolating bacteria from the incubated soil samples and growing in a defined media with potassium phosphate, glyphosate or CH as sole source of P. Our results suggested that other compounds from CH may be affecting P sorption, because when the herbicide was applied, P sorption was reduced in the NP, but in AP soil no significant effects were observed. In contrast, in the AP soil both glyphosate and the CH reduced C mineralization. Besides, CH application reduced Pmic concentration and laccase activity, but increased the specific activity of phosphonatase and phosphodiesterase in the AP soil. Additionally, the microbial community in NP soil revealed higher diversity index than the AP soil, but major changes in microbial groups were shown only when CH was applied. In vitro assay with native bacterial isolates confirmed their susceptibility to the commercial herbicide in both NP and AP soils. In conclusion, our results demonstrated changes on some processes related to soil C and P dynamics when pure glyphosate and a commercial glyphosate were applied, along with changes in microbial activity and community structure, being stronger the effects with the commercial formulation used. Further research should be done for test the effects of glyphosate on microbial stoichiometry and enzyme stoichiometry.
查看更多>>摘要：Enhanced anthropogenic nitrogen (N) addition has not been matched by increased phosphorus (P) inputs, leading to widespread P limitation of net primary productivity (NPP). Will ecosystems increasingly be limited by P with continued N addition? No consensus has been reached. Using soil phosphatase activity as an indicator of P limitation, Chen et al. (2020) provided a conceptual framework indicating that N-induced P limitation of NPP acclimates to long-term N addition. Thus, P limitation of NPP with long-term N addition may not be as strong as observed in short-term studies. We are writing this letter to recognize the recent relevant work by Vourlitis et al. (2021a) in Applied Soil Ecology. Their long-term continuous observations provide the first direct evidence supporting this framework. Without this framework, Earth System Models may underestimate ecosystem CO2 sequestration capacity with ongoing enhanced N addition. This framework may also be useful to optimize P management in agroecosystems.
查看更多>>摘要：Peatlands in anthropogenically transformed landscapes play an important role in biodiversity conservation. Most Baltic raised bogs have been completely destroyed by drainage and peat extraction. Collembolan and plant as-semblages from an old peat mine (post-excavation pits and dykes overgrown by pine trees) were compared to those of intact ombrotrophic raised bog habitats (open bog and bog-pine forest) 70 years after excavation cessation. The plant cover and collembolan structure in regenerating pits were similar to those of the assemblages in natural open raised bogs. Rare tyrphobiont and tyrphofilous Collembola species occurred in both habitats. The assemblages in open bog habitats differed significantly from those in natural pine bog forest and dykes over-grown by pine trees. The assemblages of the natural open raised bog and pine bog forest were the most diverse and included numerous highly specialized Collembola species. The assemblages occurring on wooded dykes were significantly different from those at other peatland sites and were more similar to those of upland pine forests. The analysis of environmental factors (determined by moss Ellenberg numbers) showed that moisture was the most important factor affecting Collembola occurrence in natural and disturbed habitats. The occurrence of moss species also had a significant influence on the species composition of the collembolan assemblages. Our study revealed that seventy years of spontaneous ecosystem regeneration after peat excavation have led to habitat restoration for peat bog mesofauna. These results have important implications for conservation and restoration planning in disturbed peatlands.
查看更多>>摘要：Given the conditions of scarce soil water availability, high UV exposure and huge temperature fluctuation, plant growth in desert is extremely limited. In the last three decades, reclaiming desertified land for agricultural use via the application of solar greenhouse has been developing in the arid regions, northwestern China. However, the soil microbiome shift driven by the transformation of land use remains largely unexplored. To this end, we examined the diversity and composition of the bacterial community in the vineyard soil at the edge of Tengger desert, using the high-throughput quantitative 16S rRNA gene sequencing. Two types of agricultural managed soils, including those near the plant (PLT) and the others on the fertilization furrow (FTL), were collected. Soils from the open desert land without agricultural practices were used as the control (CON). The results showed that agricultural reclamation significantly (p < 0.05) reduced the desert soil bacterial diversity while promoted the total bacterial abundance from 106 copies up to 108 per ng of DNA, which increased up to 90 folds. Among the dominant bacteria Firmicutes, Proteobacteria, Actinobacteria, and Acidobacteria, Bacilli and Actinobacteria were found to be the keystone taxa responding to the agricultural practices especially to the nutrient inputs from fertilization. The functional prediction of the microbiome suggested that amino acid and carbohydrate transport and metabolism were the most important metabolic pathways differed between the three types of soils. Overall, our findings provide deep insights into the understanding of desert soil microbial responses to agricultural reclamation on the processes of human urbanization and reversion of desertification.
NSTL
Elsevier