声明
Acknowledgements
Contents
Abbreviations
Abstract
摘要
Chapter 1 Introduction
1．1 Background
1．2 The Novelty of the current work
Chapter 2 Literature Review
2．1 Rice
2．3 Global water scarcity and water-saving strategies in rice paddies
2．4 Need of fertilizer in a rice paddy
2．5 Nitrous oxide production in paddy soils
2．6 Dominant processes of N2O production in paddy soil
2．7 Nitrification
2．8 Denitrification
2．9 Measurement of nitrification and denitrification
2．10 Factors affecting nitrification and denitrification
2．11 Mitigation strategies to enhance rice yield and reduce N2O emissions
2．12 Motivations
2．13 Objectives and hypothesis
Chapter 3 Nitrous oxide fluxes and nitrifier and denitrifier communities as affected by dry-wet cycles in long-term fertilized paddy soils
3．1 Introduction
3．2 Materials and methods
3．2．2 Soil chemical properties
3．2．3 Incubation experiments
3．2．4 Quantitative real-time PCR
3．3 Results
3．3．1 Chemical pmperties of the soil
3．3．2 N2O flux at instant flooding (IF) and air drying (AD) moments
3．3．3 N2O fluxes during drying-rewetting periods
3．3．4 Abundance of nitrifiers and denitrifier
3．3．5 Relationships between N2O emissions and soil microbial abundance and mineral N concentrations
3．4 Discussion
3．4．2 The role of soil microbe in different drying-rewetting events
3．5 Conclusion
Chapter 4 Change in nitrifiers and denitrifiers abundance and diversity under alternate wetting and drying conditions in paddy soils
4．1 Introduction
4．2 Materials and methods
4．2．3 q-PCR to determine the abundance of nitrifiers and denitrifiers
4．2．4 Illumina-based 16S rRNA gene sequencing
4．2．5 Statistical analysis
4．3 Results
4．3．2 N2O gas emission
4．3．3 Abundance of nitrifier and denitrifier
4．3．4 Proportion of greenhouse gases emission associated with micmbial biomass and water condition
4．3．5 Nitrifying and denitrifying bacterial community structure
4．4 Discussion
4．4．2 Effect of water conditions on nitrifier and denitrifier abundance based on long term fertilization
4．4．3 Effects of water conditions on the abundance of nitrifying and denitrifying microbial communities based on long-term fertilization
4．5 Conclusions
Chapter 5 Identification of N2O production pathways using 15N stable isotope under alternate wetting-drying events of paddy soils
5．1 Introduction
5．2 Materials and methods
5．2．2 Statistical analysis
5．3 Results
5．3．3 Proportion of greenhouse gas emissions associated with different micmbial processes under different water events
5．4 Discussion
5．4．1 Contribution of nitrification and denitrification processes on N2O emissions with respect to water conditions
5．5 Conclusions
Chapter 6 Combined effects of water and site-specific nitrogen management on rice yield，NUE，photosynthetic parameters，and rhizospheric nitrifier and denitrifier abundance
6．1 Intmduction
6．2 Materials and methods
6．2．1 Site description
6．2．2 Experiment design
6．2．3 Detemination of growth parameters
6．2．4 Dry matter accumulation，N uptake，yield，and yield components
6．2．6 N use efficiency
6．2．7 Soil samples collection
6．3．2 Grain yield and yield components
6．3．3 Nitrogen use efficiency
6．3．4 N uptake and other elements concentration in root and shoot
6．3．5 Photosynthesis parameters and SPAD value
6．3．6 Abundance of nitrifier and denitrifier
6．4 Discussion
6．4．2 Effects of water events and fertilizers on yield formation factors
6．4．3 Effects of water events and fertilizers on photosynthetic parameters
6．4．4 Effects of water events and fertilizers on inorganic nutrients concentration
6．4．5 Nitrifiers and denitrifier abundance based on N fertilizer management
6．4．6 Effects of water events and fertilizers on dry matter accumulation
6．5 Conclusions
Chapter 7 HighUghts and Summary
7．1 Highlights
7．2 Summary of the major findings
7．3 The inadequacies and future perspectives
References
浙江大学;
