不同氮源下镉胁迫对水稻生长和品质形成的影响

论文摘要

盆栽试验研究了四种不同氮源(尿素，硝酸钙，硫酸铵和有机氮)下两个镉水平(每千克土分别含镉0和100mg)对水稻生长和品质形成的影响。主要结果如下：(1)加入镉显著降低了水稻抽穗期和灌浆期的光合速率，且下降值随氮源不同而变化，以铵态氮和尿素处理下降较大。SPAD值显示，镉胁迫处理和对照在抽穗和灌浆期的叶绿素含量无显著差异，但是氮形态对SPAD值有影响显著，且这种影响与镉水平和生长期有关。四种氮源下旗叶和第二叶的大小差异显著，与对照相比，镉胁迫下旗叶叶面积显著变小，且不受氮形态影响；对于第二叶，只有有机氮处理的植株叶面积两个镉水平之间有差异。四种氮源下植株株高差异显著，铵态氮和硝态氮处理分别为最大和最小。加入镉显著降低株高，与其他两种氮源相比，尿素和铵态氮处理每株穗数明显较多。(2)镉胁迫下，不同氮源间植株对氮和镉的摄取差异显著，铵态氮处理植株氮含量最高，镉含量最低；硝态氮处理植株氮含量最低，镉含量最高。植株不同部位间镉含量高低顺序为茎＞穗＞叶。但叶、茎、穗对氮的积累受氮源影响更大。氮形态和镉胁迫在抽穗、灌浆两个时期都影响SOD的活性。与对照相比，硝态氮处理植株在两个时期活性分别有所下降或者无显著差异，而其它三种氮源处理抽穗期和灌浆期的SOD活性和过氧化物酶活性都显著增强。镉导致氧化损伤加剧，且损伤程度受氮源的影响。镉胁迫显著降低每穗籽粒数和植株总重，且下降值随氮源不同而变化，以有机氮处理的下降最大。结果表明，氮形态和镉胁迫均影响产量。正常情况下，与另外两个处理相比，尿素和铵态氮处理产量明显较高。铵态氮和有机氮处理下，镉胁迫导致产量显著降低，但在尿素和硝态氮处理下，两个镉水平间产量差异不显著。(3)在胁迫条件下氮形态影响糙米率。铵态氮和尿素处理糙米率分别为最高和最低。土壤中加入镉仅显著降低尿素氮源下籽粒的精米率。镉胁迫下，尿素和铵态氮处理植株的精米率(HMRR)明显下降。稻米的糊化温度，镉胁迫与对照之间差异显著。同时，四种氮形态之间对糊化温度的影响存在显著差异，且随镉处理而变化。无镉条件下，有机氮处理下植株糊化温度最高，与硝态氮处理下差异显著。在镉胁迫条件下，尿素处理下植株糊化温度最高，与铵态氮处理下差异显著。直链淀粉含量受镉胁迫影响不显著，但是值得关注的是它受氮形态的影响，硝态氮处理下植株直链淀粉含量最高。稻米的蛋白质含量，镉处理植株显著低于对照。四种氮形态之间植株蛋白质含量差异显著，铵态氮处理最高，尿素处理次之。17种氨基酸检测表明，有5种(天门冬氨酸，酪氨酸，苯丙氨酸，赖氨酸，精氨酸)受氮形态的显著影响，铵态氮和尿素处理它们的含量较高。

论文目录

• Dedication
• Declaration
• Acknowledgement
• Abstract
• Chinese Abstract
• Chapter 1 Literature Review
• 1.1 Cd chemistry and uptake by plants
• 1.2 Effects of Cadmium toxicity to humans
• 1.3 Effects of Cadmium toxicity on plants
• 1.3.1 Effects of Cadmium stress on plant growth
• 1.3.2 Effects of Cadmium stress on photosynthetic rate
• 1.3.3 The Cadmium-induced oxidative stress and anti oxidant capacity in plants
• 1.4 Cadmium accumulation in plant tissues
• 1.5 Strategies for alleviating Cadmium toxicity and accumulation in crops
• 1.5.1 Phytoremediation
• 1.5.2 Breeding for cultivars with high tolerant and low accumulation of Cadmium
• 1.5.3 Improving Nitrogen nutrition
• 1.5.4 Regulation of pH
• Chapter 2 Effect of Cd on different N fertilizer forms on growth,photosynthesis and yield of rice
• 2.2 Materials and methods
• 2.2.1 Experimental design
• 2.2.2 Sampling and measurements
• 2.2.3 Statistic method
• 2.3 Results and analysis
• 2.3.1 Effect of N forms on SPAD value,photosynthetic rate and leaf size under two Cd levels
• 2.3.2 Effect of N forms on plant height and yield under two Cd levels
• 2.3.3 Effect of N form on dry matter accumulation under two Cd levels
• 2.4 Discussions
• Chapter 3 Effect of different N fertilizer forms on oxidative stress and activities of antioxidant enzymes and grain yield of rice growing under Cd stress
• 3.1 Materials and methods
• 3.1.1 Experimental design
• 3.1.2 Sampling and measurements
• 3.1.3 Statistic method
• 3.2 Results and analysis
• 3.2.1 Grain yield
• 3.2.2 Effect of Cd level and N form on Cd concentration and N accumulation in rice plants
• 3.2.3 SOD activity
• 3.2.4 POD Activity
• 3.2.5 NDA Activity
• 3.4 Discussions
• Chapter 4 Rice grain quality under cadmium stress as affected by Nitrogen forms
• 4.1 Materials and methods
• 4.1.1 Experimental design
• 4.1.2.Sampling and measurements
• 4.1.3 Statistic method
• 4.2 Results and analysis
• 4.2.1 Effect of N forms on milling quality of rice under two Cd levels
• 4.2.2 Effect of N forms on gelatinization temperature,amylose content and protein content of rice under two Cd levels
• 4.2.3 Effect of N form on amino acid content in rice grains under two Cd Levels
• 4.3 Discussions
• References
• Publications