scholarly journals Dynamic changes in bacterial communities in the recirculating nutrient solution of cucumber plug seedlings cultivated in an ebb-and-flow subirrigation system

PLoS ONE ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. e0232446
Author(s):  
Chun-Juan Dong ◽  
Qian Li ◽  
Ling-Ling Wang ◽  
Qing-Mao Shang
2020 ◽  
Vol 96 (5) ◽  
Author(s):  
Tong-tong Liu ◽  
Hong Yang

ABSTRACT Bacterial communities play crucial roles in the biogeochemical cycle of the surface sediments of freshwater lakes, but previous studies on bacterial community changes in this habitat have mostly been based on the total bacterial community (DNA level), while an exploration of the active microbiota at the RNA level has been lacking. Herein, we analysed the bacterial communities in the surface sediments of Lake Taihu at the DNA and RNA levels. Using MiSeq sequencing and real-time quantification, we found that the sequencing and quantitative results obtained at the RNA level compared with the DNA level were more accurate in responding to the spatiotemporal dynamic changes of the bacterial community. Although both sequencing methods indicated that Proteobacteria, Chloroflexi, Acidobacteria, Nitrospirae, Bacteroidetes and Actinobacteria were the dominant phyla, the co-occurrence network at the RNA level could better reflect the close relationship between microorganisms in the surface sediment. Additionally, further analysis showed that Prochlorococcus and Microcystis were the most relevant and dominant genera of Cyanobacteria in the total and active bacterial communities, respectively; our results also demonstrated that the analysis of Cyanobacteria-related groups at the RNA level was more ‘informative’.


2020 ◽  
Vol 43 ◽  
pp. 23-31 ◽  
Author(s):  
Zhangcheng Liang ◽  
Xiaozi Lin ◽  
Zhigang He ◽  
Weixin Li ◽  
Xiangyun Ren ◽  
...  

Plant Disease ◽  
2000 ◽  
Vol 84 (10) ◽  
pp. 1147-1150 ◽  
Author(s):  
M. E. Stanghellini ◽  
C. J. Nielsen ◽  
D. H. Kim ◽  
S. L. Rasmussen ◽  
P. A. Rorbaugh

Zoospores of Phytophthora capsici spread from inoculated source plants to healthy potted pepper plants located on separate ebb-and-flow benches when the recycled nutrient solution originated from a common reservoir. Amending the recirculating nutrient solution with a surfactant, which selectively kills zoospores, resulted in 100% control of the spread of the pathogen in an ebb-and-flow and a top-irrigated cultural system. Without a surfactant in the recirculating nutrient solution, all plants in an ebb-and-flow cultural system died within 6 weeks. In contrast, all plants in a top-irrigated cultural system died within 2 weeks after inoculation of source plants. These results suggest that the use of recycled irrigation water in an ebb-and-flow cultural system is less conducive to pathogen spread than its use in a top-irrigated cultural system, but may still serve as efficient means of inoculum movement in the absence of control measures.


2002 ◽  
Vol 68 (12) ◽  
pp. 6094-6105 ◽  
Author(s):  
Regin Rønn ◽  
Allison E. McCaig ◽  
Bryan S. Griffiths ◽  
James I. Prosser

ABSTRACT The influence of grazing by a mixed assemblage of soil protozoa (seven flagellates and one amoeba) on bacterial community structure was studied in soil microcosms amended with a particulate resource (sterile wheat roots) or a soluble resource (a solution of various organic compounds). Sterilized soil was reinoculated with mixed soil bacteria (obtained by filtering and dilution) or with bacteria and protozoa. Denaturing gradient gel electrophoresis (DGGE) of PCR amplifications of 16S rRNA gene fragments, as well as community level physiological profiling (Biolog plates), suggested that the mixed protozoan community had significant effects on the bacterial community structure. Excising and sequencing of bands from the DGGE gels indicated that high-G+C gram-positive bacteria closely related to Arthrobacter spp. were favored by grazing, whereas the excised bands that decreased in intensity were related to gram-negative bacteria. The percentages of intensity found in bands related to high G+C gram positives increased from 4.5 and 12.6% in the ungrazed microcosms amended with roots and nutrient solution, respectively, to 19.3 and 32.9% in the grazed microcosms. Protozoa reduced the average bacterial cell size in microcosms amended with nutrient solution but not in the treatment amended with roots. Hence, size-selective feeding may explain some but not all of the changes in bacterial community structure. Five different protozoan isolates (Acanthamoeba sp., two species of Cercomonas, Thaumatomonas sp., and Spumella sp.) had different effects on the bacterial communities. This suggests that the composition of protozoan communities is important for the effect of protozoan grazing on bacterial communities.


Author(s):  
Guilherme S. Avellar ◽  
Wellington G. Campos ◽  
Livia M. Carvalho ◽  
Elka F. A. Almeida ◽  
Márcia N. O. Ribeiro

Fertilization is a limiting factor in plant development and indirectly affects the population density of phytophagous insects. This study tested the performance of the aphid Rhodobium porosum (Hemiptera: Aphididae) on three rose cultivars exposed to two nutrient solutions in subsurface 'ebb and flow' irrigation systems in greenhouse. The performance of R. porosum was determined by means of the life table and fertility. Both cultivar and fertilization affected many life history and population traits of the aphid. The lower insect fertility and survival were observed in the nutrient solution usually recommended for fruit-type vegetables and on the 'Tineke' rose cultivar, because this combination caused lower net reproductive rate R0 (0.52 female), finite rate of increase λ (0.9469 female/day), innate capacity to increase in number rm (-0.0516 female/female/day), as well as longer time interval between each generation T (16.62 days). The lowest performance of the R. porosum on 'Tineke' rose cultivated in the nutrient solution 1 suggests that this seems to be the best combination to reduce problems with aphid attack in soilless rose cultivation.


2001 ◽  
Vol 34 (11) ◽  
pp. 87-90 ◽  
Author(s):  
Herry Suhardiyanto ◽  
Kudang B. Seminar ◽  
Yudi Chadirin ◽  
Budi I. Setiawan

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