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Microbial communities in paddy fields in the Mekong delta of Vietnam

functional and molecular diversity

Do, Thi Xuan (2012). Microbial communities in paddy fields in the Mekong delta of Vietnam. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2012:101
ISBN 978-91-576-7748-8
[Doctoral thesis]

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Rice paddy fields are considered to be unique ecosystems. Intensive rice cultivation was developed to increase yield and to meet the need of food security. This practice has many negative effects on the soil ecosystem, such as reduction of soil nutrients, soil and water pollution and increase in soil-borne plant pathogens and a possible reduction of soil microorganism diversity. Alternative management strategies are required to counteract these negative effects to maintain soil fertility. The aims of this thesis are to investigate the microbial community in the rice paddy field to assess the influence of microorganisms on the degree of crop residue degradation and in protecting the next crop against soil-borne plant pathogens, including Rhizoctonia solani, and to understand the relationship between microbial diversity and functional groups involved in straw degradation and the inhibition of R. solani growth. Furthermore, the effect of intensive rice cultivation on the yield, abundance and diversity of the total bacterial community and on the diazotrophic bacterial community compared with the rice crop rotation system is investigated.

Bacteria isolated from rice stubble with both cellulolytic and combined cellulolytic and chitinolytic activity were phylogenetically linked to distinct microbial groups. Selected bacterial isolates with these functions inhibited R. solani growth on agar plates; most of these isolates seemed to be neutral with respect to their effect on rice seed germination and radicle length. There was a positive relationship between straw weight loss and the number of isolates and functional groups. Fungal isolates were more important for straw degradation than the bacteria. The growth of R. solani was inhibited when it was inoculated on degraded straw. There was a negative relationship between straw weight loss and the growth of R. solani. Finally, crop management practices had a significant effect on both rice production and bacterial community structure. Rice yield from all the rice crop rotations that included maize and/or mungbean was significantly higher than that from the rice monoculture. Besides the yield effect, the structure and diversity of the total bacterial community and of the potential nitrogen-fixing bacterial community were significantly influenced by crop rotation when compared with that detected in the rice monoculture soil.

This thesis highlights that crop rotation systems had a positive impact on rice production and on soil microbial diversity in the rice field ecosystem. Results from this study can be applied in the future development of a sustainable rice management.

Authors/Creators:Do, Thi Xuan
Title:Microbial communities in paddy fields in the Mekong delta of Vietnam
Subtitle:functional and molecular diversity
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2012
Number of Pages:61
I.Do Thi Xuan, Sadhna Alström, Anna Rosling, Nils Högberg. Phylogenetic and functional characterization of cultured and cloned bacteria inhabiting rice stubble and their potential antifungal effect (manuscript).
II.Do Thi Xuan, Sadhna Alström, Anna Rosling, Ingvar Nilsson, Nils Högberg. Generalist microorganisms with combined cellulolytic and chitinolytic activities drive decomposition of rice straw and antagonism against Rhizoctonia solani (manuscript).
III.Do Thi Xuan, Vo Thi Guong, Anna Rosling, Sadhna Alström, Benli Chai, Nils Högberg (2012). Different crop rotation systems as drivers of change in soil bacterial community structure and yield of rice, Oryza sativa. Biol Fertil Soils 48(2), 217–225
IV.Do Thi Xuan, Qiong Wang, Sadhna Alström, Vo Thi Guong, Anna Rosling, Nils Högberg. Diazotrophic and total diversity of soil bacterial communities in a rice field rotated with mungbean and maize (submitted).
Place of Publication:Uppsala
Publisher:Dept. of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7748-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F01 Crop husbandry
F Plant production > F08 Cropping patterns and systems
P Natural resources > P34 Soil biology
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Agricultural Science
Agrovoc terms:oryza sativa, rice, crop rotation, rice fields, paddy soil, microbial flora, soil microorganisms, rhizoctonia solani, nitrogen fixing bacteria, genetic variation, isolation
Keywords:rice, crop rotation, N2-fixing bacteria, bacterial community, diversity, cellulolytic, chitinolytic, decomposition, Rhizoctonia solani, antagonistic effect
Permanent URL:
ID Code:9243
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
External funders:Swedish Institute
Deposited By: PhD Thi Xuan Do
Deposited On:19 Nov 2012 13:55
Metadata Last Modified:02 Dec 2014 10:53

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