No abstract

No abstract

Soil microorganisms play an important role in agricultural ecosystems, but their response to organic fertilizer application has not been thoroughly elucidated. Thus, high-throughput sequencing was used to investigate the responses of soil bacterial to organic fertilizer amendment (composted from pig manure) in the field during the entire growth cycle of maize plants. Four treatments were studied: treatment with 2 kg·m–2 organic fertilizer application (OF_2), treatment with 4 kg·m–2 organic fertilizer application (OF_4), treatment with 6 kg·m–2 organic fertilizer application (OF_6), and a controlled treatment (CK) without fertilization. The results revealed that the bacterial richness in OF_2 was significantly lower than that of CK (p < 0.05). Soil eutrophication bacteria Bacteroidetes increased effectively in all fertilized soils, relative abundance in OF_2, OF_4, and OF_6 for the entire maize growth cycle was 68.00%, 71.40%, and 77.93% higher than that in CK, respectively. In addition, soil nitrobacteria (Nitrospirae, Nitrospira), were markedly decreased (p < 0.05) with fertilization amount. The relative abundance of the nitrogen-fixing genus Adhaeribacter in OF_6 was 209.28%, 72.8% and 35.66% higher than that in CK, OF_2 and OF_4 at mature stage. The pathogenic genus Flavolibacterium was significantly increased (p < 0.05) in fertilized soil at the seeding stage. The driving factor governing the variations of bacterial community in CK, OF_2, OF_4 and OF_6 were pH value, available phosphorus, available phosphorus, and chromium, respectively. The findings highlight that part of the soil functional or pathogenic bacteria population was susceptible to organic fertilizer application; and the driving factor of bacterial composition change was associated with the rate of fertilization. More targeted experiments are needed to enhance the understanding of functional bacteria and the synergistic effect of soil physicochemical property physical on soil bacteria.

Sulfur dioxide (SO 2 ) is a major air pollutant and its concentration is increasing in many metropolitan and industrial areas. Identification of SO 2 tolerant species that can be used in wetland plantings in those areas is needed. We compared SO 2 toxicity and tolerance in 16 wetland herbaceous plants by examining SO 2 effects on their photosynthetic apparatus. After leaf sections had been immersed in 0, 10, 20, 30, 40, 50, and 100 mmol/L NaHSO 3 for 20 h, the maximum quantum yield and maximum electron transport rate of all 16 herbaceous plants decreased at different rates with increasing SO 2 concentrations, suggesting that photosystem reaction centers were damaged due to SO 2 stress, electron transport was inhibited, and photosynthetic efficiency decreased. Species were assigned to two groups, relatively resistant and sensitive, with dendrograms. The relatively resistant species were Typha angustifolia, Arundo donax, Echinochloa crusgalli var. mitis, different wetland herbaceous plants to SO 2 provides basic information for screening suitable species for wetland creation and restoration in urban areas.