声明
ABSTRACT
摘要
Chapter 1 Review of Literature
1．1 Introduction
1．2 Effects of drought stress on plants and stress relief by potassium application
1．2．1 Leaf water relations and osmotic adjustment
1．2．2 Photosynthesis
1．2．3 Oxidative damage
1．2．4 Antioxidant defense system
1．2．5 Carbohydrate metabolism and dry matter partitioning
1．2．6 Nitrogen metabolism
1．3 Future Perspectives
1．4 Objectives
1．5 Technical route map of the experiment
References
Chapter 2 Potassium Improves Acclimation to and Recovery from Drought Stress in Functional Leaf Photo-Physiological Activities of Cotton
2．1 Introduction
2．2 Materials and methods
2．2．1 Plant materials and growth conditions
2．2．2 Experimental design
2．2．3 Sampling and processing
2．2．4 Leaf water potential measurement
2．2．5 Gas exchange parameters and chlorophyll fluorescence
2．2．6 MDA concentration and antioxidant enzymes activities
2．2．7 Leaf Proline and K contents assay
2．3 Statistical analysis
2．4 Results
2．4．1 Leaf K content
2．4．2 Changes in leaf water potential
2．4．3 Changes in leaf gas exchange parameters
2．4．4 Chlorophyll fluorescence parameters
2．4．5 Lipid peroxidation，proline content and enzymatic antioxidants activities
2．4．6 Fractional recovery of Pn and Fv／Fm in cotton cultivars after rewatering in relation to Ψw and varying rates of K fertilizer
2．5 Discussion
2．6 Conclusions
Reference
Chapter 3 Potassium Fertilizer Improves Drought Stress Alleviation Potential in Cotton by Enhancing Photosynthesis and Carbohydrate Metabolism
3．1 Introduction
3．2 Materials and methods
3．2．1 Plant materials and growth conditions
3．2．2 Experimental design and treatments
3．2．3 Plant sampling and measurements
3．2．4 Gas exchange parameters
3．2．5 Carbohydrate contents in leaves
3．2．6 Enzyme extraction and assay
3．2．7 Dry matter partitioning
3．3 Data analysis
3．4 Results
3．4．1 Effect of K application on photo-assimilates partitioning in response to drought
3．4．2 Gas exchange parameters
3．4．3 Effect of K on functional leaves carbohydrate content in response to drought stress
3．4．4 Effect of K on carbohydrate metabolism enzyme activities in response to drought stress
3．5 Discussion
3．6 Conclusions
References
Chapter 4 Potassium Regulates Nitrogen Metabolism and Osmotic Adjustment in Cotton(Gossypium hirsutum L．)Functional Leaf under Drought Stress
4．1 Introduction
4．2 Materials and methods
4．2．1 Plant material and Experimental design
4．2．2 Sampling and processing
4．2．3 Leaf relative water content and osmotic adjustment
4．2．5 Soluble sugars，amino acid and proline
4．2．6 N metabolizing enzymes and soluble protein
4．2．7 Leaf nitrate and K contents
4．3 Statistical analysis
4．4 Results
4．4．1 Changes in leaf water relations and osmotic adjustment
4．4．2 Leaf nitrate and K contents
4．4．3 Changes in leaf chlorophyll and sugar contents
4．4．4 Changes in soluble protein，free amino acids and proline contents
4．4．5 Changes in N metabolizing enzymes
4．5 Discussion
4．6 Conclusions
References
Chapter 5 Discussion and Conclusions
5．1 Potassium improves acclimation to and recovery from drought stress of photo-physiological activities in cotton leave
5．2 Potassium improved carbon assimilation and metabolism in drought stressed cotton plants
5．3 Potassium regulated Nitrogen metabolism and osmotic adjustment of drought stressed cotton leaves
5．4 Conclusions
Reference
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ACKNOWLEDGEMENTS
