| ABSTRACT | 第6-8页 |
| 摘要 | 第9-16页 |
| CHAPTER 1 REVIEW OF LITERATURE | 第16-44页 |
| 1.1 An introduction to global maize production and its importance | 第16-18页 |
| 1.2 Plant growth regulators (PGRs) | 第18-26页 |
| 1.2.1 Plant growth retardants and their mode of action | 第18-19页 |
| 1.2.2 Gibberellins | 第19-22页 |
| 1.2.3 Paclobutrazol (PBZ) | 第22-24页 |
| 1.2.4 Mepiquat chloride (MC) | 第24-26页 |
| 1.3 The application methods for growth regulators | 第26-29页 |
| 1.3.1 Soil Drenching | 第26-27页 |
| 1.3.2 Foliar Spray | 第27-28页 |
| 1.3.3 Seed Treatment | 第28-29页 |
| 1.4 Agricultural importance of PGRs | 第29-43页 |
| 1.4.1 Effect of PGRs on root growth characteristics | 第29-31页 |
| 1.4.2 Effect of PGRs on plant above ground morphological characteristics | 第31-33页 |
| 1.4.3 Effect of PGRs on chlorophyll pigments and photosynthesis | 第33-36页 |
| 1.4.4 Efficacy of PGRs in lodging resistance of crops | 第36-38页 |
| 1.4.5 Efficacy of PGRs on antioxidants and their role as stress protectants | 第38-40页 |
| 1.4.6 Effect of growth retardants on yield attributes | 第40-43页 |
| 1.5 Objectives of the Research | 第43-44页 |
| Chapter 2 Materials and Methods | 第44-55页 |
| 2.1 Site Description | 第44-45页 |
| 2.2 Experimental design and crop management | 第45-46页 |
| 2.3 Sampling and Measurement | 第46-54页 |
| 2.3.1 Root length, volume, area, and diameter | 第46页 |
| 2.3.2 Root length density (RLD) | 第46页 |
| 2.3.3 Root surface area density (RSD) | 第46-47页 |
| 2.3.4 Root dry biomass | 第47页 |
| 2.3.5 Root weight density (RWD) | 第47页 |
| 2.3.6 Determination of root activity | 第47页 |
| 2.3.7 Collection of root-bleeding sap | 第47-48页 |
| 2.3.8 Above ground dry biomass | 第48页 |
| 2.3.9 Plant height, ear height, and center of gravity height | 第48页 |
| 2.3.10 Internode length, diameter and wall thickness | 第48页 |
| 2.3.11 Stalk breaking strength (BS) and rind penetration strength (RPS) | 第48-49页 |
| 2.3.12 Dry weight per unit length (DWUL) | 第49页 |
| 2.3.13 Determination lignin content | 第49页 |
| 2.3.14 Lignin-related enzymatic activities | 第49-51页 |
| 2.3.15 Measurement of lodging rate | 第51页 |
| 2.3.16 Measurement of leaf area | 第51页 |
| 2.3.17 Determination of chlorophyll contents | 第51页 |
| 2.3.18 Leaf gas exchange parameters | 第51-52页 |
| 2.3.19 Chlorophyll fluorescence parameters | 第52页 |
| 2.3.20 Determination of antioxidants activities and soluble protein content | 第52-53页 |
| 2.3.21 Determination of malondialdehyde (MDA) | 第53页 |
| 2.3.22 Measurement of proline contents | 第53-54页 |
| 2.3.23 Ear characteristics and grain yield | 第54页 |
| 2.4 Statistical analysis | 第54-55页 |
| CHAPTER 3 EFFECT OF PACLOBUTRAZOL ON ROOT GROWTH CHARACTERISTICS AND GRAIN YIELD OF MAIZE UNDER A SEMI-ARID REGION | 第55-73页 |
| 3.1 Root activity and root-bleeding sap flow | 第55-58页 |
| 3.2 Root diameter | 第58-59页 |
| 3.3 Root dry weight | 第59页 |
| 3.4 Root/shoot ratio | 第59-60页 |
| 3.5 Root weight density (RWD) | 第60-61页 |
| 3.6 Root length density (RLD) | 第61-64页 |
| 3.7 Root surface area density (RSD) | 第64页 |
| 3.8 Ear characteristics and grain yield | 第64-66页 |
| 3.9 Correlation analysis of root characteristics and grain yield | 第66-68页 |
| 3.10 Discussion | 第68-72页 |
| 3.10.1 Effect of paclobutrazol on root growth and distribution | 第68-71页 |
| 3.10.2 Effect of paclobutrazol on ear characteristics and grain yield of maize | 第71-72页 |
| 3.11 Conclusion | 第72-73页 |
| CHAPTER 4 EFFECT OF PACLOBUTRAZOL ON LODGING RESISTANCE OF MAIZE BY REGULATING STEM MECHANICAL STRENGTH, AND LIGNIN ACCUMULATION | 第73-92页 |
| 4.1 Morphological characteristics of the basal third internode | 第73-76页 |
| 4.2 Plant height, ear height, and center of gravity height | 第76页 |
| 4.3 Rind penetration strength, stalk breaking strength and dry weight per unit length | 第76-77页 |
| 4.4 Enzymes activities | 第77-83页 |
| 4.5 Lignin accumulation | 第83-84页 |
| 4.6 Lodging percentage and grain yield | 第84-85页 |
| 4.7 Correlation analysis of lignin, related enzymes, lodging rate, plant height, stalk breaking strength and various morphological characteristics of stem | 第85页 |
| 4.8 Discussion | 第85-90页 |
| 4.9 Conclusion | 第90-92页 |
| CHAPTER 5 PACLOBUTRAZOL IMPROVES MAIZE GRAIN YIELD BY REGULATING PHOTOSYNTHETIC CAPACITY AND ANTIOXIDANTS UNDER A SEMI-ARID REGION | 第92-115页 |
| 5.1 Photosynthetic pigments | 第92-93页 |
| 5.2 Gas exchange parameters | 第93页 |
| 5.3 Leaf chlorophyll fluorescence | 第93-101页 |
| 5.4 Leaf area | 第101-102页 |
| 5.5 Antioxidant enzyme activity | 第102-103页 |
| 5.6 Malondialdehyde (MDA) content | 第103-107页 |
| 5.7 Soluble protein and proline content | 第107页 |
| 5.8 Ear length and diameter | 第107页 |
| 5.9 Yield and yield components | 第107-110页 |
| 5.10 Discussion | 第110-114页 |
| 5.11 Conclusion | 第114-115页 |
| CHAPTER 6 MEPIQUAT CHLORIDE INCREASES LODGING RESISTANCE OF MAIZE BY ENHANCING STEM PHYSICAL STRENGTH AND LIGNIN BIOSYNTHESIS | 第115-133页 |
| 6.1 Grain yield and lodging rate | 第115页 |
| 6.2 Plant, ear and gravity center height | 第115-116页 |
| 6.3 Stalk morphological traits | 第116-119页 |
| 6.4 Stalk bending strength (BS) and rind puncture strength (RPS) | 第119-123页 |
| 6.5 Lignin-related enzymes activities | 第123-124页 |
| 6.6 Lignin accumulation | 第124-126页 |
| 6.7 Correlation analysis among physical strength of stem, lodging percentage, and lignin content | 第126-128页 |
| 6.8 Discussion | 第128-132页 |
| 6.9 Conclusion | 第132-133页 |
| CHAPTER 7 SUMMARY AND MAIN CONCLUSIONS | 第133-135页 |
| REFERENCES | 第135-152页 |
| ACKNOWLEDGEMENT | 第152-153页 |
| RESEARCH PUBLICATIONS | 第153-154页 |
