La lecture à portée de main
Description
Informations
Publié par | universitat_hohenheim |
Publié le | 01 janvier 2009 |
Nombre de lectures | 31 |
Langue | English |
Poids de l'ouvrage | 1 Mo |
Extrait
Aus dem Institut für Pflanzenernährung,
der Universität Hohenheim
Prof. Dr. V. Römheld
Characterisation of natural and synthetic nitrification inhibitors and their
potential use in tomato cultivation
Dissertation
zur Erlangung des Grades eines Doktors
der Agrarwissenschaften
Vorgelegt der Fakultät Agrarwissenschaften
der Universität Hohenheim
Vorgelegt von
M. Sc. Mohammad Kazem Souri
aus Toyserkan, Iran
Stuttgart-Hohenheim
2008
Mohammad Kazem Souri:
Characterisation of natural and synthetic nitrification inhibitors and their potential use
in tomato cultivation
e-mail address: Kazem_sca@yahoo.ca
D100
Dissertation University of Hohenheim, Institute of Plant Nutrition, 2008
Dissertation thesis of the University of Hohenheim, Faculty of Agricultural Sciences,
for the acquisition of the degree of a”Doktor der Agrarwissenschaften” (Dr. sc. agr.)
(Ph. D. in Agricultural Sciences).
1. Supervisor and Review Prof. Dr. V. Römheld
2. Co-reviewer Prof. Dr. W. Claupein
3. Co-reviewer Prof. Dr. R. Blaich
4. Assistant Dean and Head of the Committee Prof. Dr. W. Bessei
Date of oral examination: 28. Aug. 2008
ii
List of Content
Chapter 1: Introduction ........................................................................................................... 1
1.1. Generals on nitrogen ....................................................................................................... 1
1.2. Forms of nitrogen:2
1.3. Nitrogen in the soil .......................................................................................................... 2
1.4. Nitrification ..................................................................................................................... 4
1.5. Nitrification inhibitors ..................................................................................................... 6
1.6. 3,4-Dimethylpyrazole phosphate (DMPP) ...................................................................... 8
1.7. Brachiaria as a source of natural nitrification inhibitor (NNI): ....................................... 9
1.8. Nitrogen uptake by plants ............................................................................................. 11
1.9. Why ammonium? .......................................................................................................... 13
1.10 Objectives of the research ............................................................................................ 15
Chapter 2: General Materials and Methods ........................................................................ 16
2.1 Plant cultivation ........................................................................................................ 16
2.1.1. Cultivation of Brachiaria humidicola .................................................................... 16
2.1.2. Cultivation of tomato plants ................................................................................... 17
2.2. Collection of root exudates: ..................................................................................... 18
2.3. Collection of xylem exudates18
2.4. Plant harvest and determination of growth parameters ............................................ 19
2.5. Plant mineral analysis: ............................................................................................. 19
2.6. Preparation of root exudates and tissue homogenates for characterization of
nitrification inhibiting compounds ........................................................................... 19
2.7. Bioassay for nitrification potentials ......................................................................... 20
2.7.2. Principle ........................................................................................................... 20
2.7.3. Application ....................................................................................................... 20
2.7.4. Chemicals ......................................................................................................... 20
2.7.5. Laboratory equipments ..................................................................................... 21
2.7.6. Procedure .......................................................................................................... 21
2.7.7. Test ................................................................................................................... 21
2.7.8. Spectrophotometric determination of nitrite .................................................... 21
2.7.9. Calculation22
2.8. Statistical analysis .................................................................................................... 22
Chapter 3: Efficiency of DMPP and chloride as microbial nitrification inhibitors in soil
.............................................................................................................................. 23
3. 1 Abstract .................................................................................................................... 23
3.2 Introduction .............................................................................................................. 23
3.3 Materials and Methods ............................................................................................. 25
3.3.1 Analysis ............................................................................................................ 26
3.4 Results ...................................................................................................................... 27
3.5 Discussion ................................................................................................................ 29
3.6 Conclusion35
Chapter 4: Effects of root exudates from Brachiaria humidicola on nitrification ........... 36
4.1. Abstract ......................................................................................................................... 36
4.2. Introduction ................................................................................................................... 36
4.3. Materials and Methods: ................................................................................................. 39
4.3.1. Soil incubation ........................................................................................................ 40
4.4. Results ........................................................................................................................... 40
4.4.1. Effects of DMPP concentrations ............................................................................ 40
4.4.2. Effects of N forms and pH of pre-culture solution ................................................. 41 4.4.3. Effects of plant age ................................................................................................. 42
4.4.4. Effects of collecting period .................................................................................... 42
4.4.5. Effects of N concentrations43
4.4.6. Effects of different light intensity .......................................................................... 44
4.4.7. Effect of freeze drying of root exudates ................................................................. 46
4.4.8. Effect of NH Cl in collection medium ................................................................... 46 4
4.5. Discussion ..................................................................................................................... 47
4.6. Conclusion51
Chpater 5: Effect of shoot and root homogenates and extracts from Brachiaria
humidicola on nitrification ................................................................................. 52
5.1 Abstract .................................................................................................................... 52
5.2 Introduction .............................................................................................................. 52
5.3 Materials and Methods ............................................................................................. 54
5.3.1 Plant culture ...................................................................................................... 54
5.3.2 Plant homogenates ............................................................................................ 54
5.3.3 Sequential extraction of plant material ............................................................. 55
5.3.4 Biotest for NI potential ..................................................................................... 55
5.4 Results ...................................................................................................................... 55
5.4.1 Plant growth and nutritional status ................................................................... 55
5.4.