干旱下氮素营养对不同穗型小麦苗期耐旱性的影响机制

ISWC OpenIR > 水保所2018--2022届毕业生论文(学位论文、期刊论文)

	干旱下氮素营养对不同穗型小麦苗期耐旱性的影响机制
其他题名	干旱下氮素营养对不同穗型小麦苗期耐旱性的影响机制
	王秀波
学位类型	博士
导师	上官周平
	2018-05-31
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位专业	生态学
关键词	小麦干旱胁迫氮素根系光合作用叶绿素荧光抗氧化系统
摘要	水分短缺和土壤贫瘠是限制我国北方植物生长和发育的两个重要的环境因素，水分和养分既有各自的特殊作用，又互相作用，影响着作物的产量和品质。本文以两种不同品系小麦（多穗型品种西农 979 和大穗型品种 2036））作为研究材料，采用人工控制实验方法，分别从小麦根系活力、叶片光合、叶绿素荧光、活性氧代谢以及抗氧化物质代谢调控等方面，研究了不同水分和养分处理下两个小麦品种的生理响应及其调控机制，揭示了小麦幼苗耐旱性机理及氮素对缓解干旱的生理调控机制，可为小麦利用自身的营养遗传特征挖掘其吸收、利用氮素的生理潜力提供理论依据。获得的主要研究结果如下：（1）水分与氮素存在着明显的互作效应，重度干旱胁迫和低氮处理都会降低小麦的生物量、根系总吸收面积、活跃吸收面积、根系活力、氮含量和植株的氮素积累量，且低氮处理增加了根长和根冠比。相比于低氮和中氮处理，高氮处理下西农 979 的根系总吸收面积、活跃吸收面积和根系活力显著提高，且分别比大穗小麦 2036 提高了 11%、14%和 27%。西农 979 植株氮素积累量在中氮和高氮处理之间无显著差异，但中氮处理下西农 979 的植株氮素积累量比大穗小麦 2036 提高了 13%~62%。低氮处理下，小麦根冠比（R/S）随干旱胁迫程度的增加而略有增加，其中在高氮处理和中度干旱胁迫下根-冠比表现为最小。相关分析结果表明，小麦根系的活跃吸收面积、根系活力与植株氮素积累量呈极显著的正相关关系（P<0.01），和根冠比呈极显著的负相关关系（P<0.01）。在轻度干旱胁迫下，增加氮素供给能有效提高西农 979 的根系吸收面积和根系活力，但是过量的氮素供给不利于大穗小麦 2036 根系的生长，表明不同穗型小麦的根系活力和生长对不同水氮耦合的响应是不同的。通过适宜的水氮耦合调控，有利于良好小麦根系形态的构建与根系活力的提高，从而提高小麦根系对水分和养分的吸收能力。（2）干旱胁迫显著降低了小麦的净光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Gs），但提高了瞬时水分利用效率（WUE）。此外，干旱胁迫同样导致了小麦叶片的光化学猝灭系数（QP）、最大光化学效率（Fv/Fm）、光系统Ⅱ（ΦPSⅡ）的量子产量和表观光合电子传递速率（ETR）的下降，但在氮素（N）的供给有效缓解了小麦因干旱胁迫导致的光合效率的下降。在干旱胁迫下，氮素供应的适度增加能够减轻光抑制作用从而提高小麦的光合效率，最终提高小麦的抗旱性；但过量的氮素供应对植物抗旱性的提高并没有显著性作用，甚至对植物的生长产生了不利的影响。在低氮处理下，西农 979 比大穗小麦 2036 具有更强的抗旱性。（3）在同样的干旱胁迫条件下，耐旱性品种西农 979 具有较高的抗氧化和活性氧调控能力。随着氮素浓度的提高，小麦体内活性氧表现出下降的趋势。干旱胁迫下大穗小麦 2036 根系中的活性氧和膜脂过氧化产物（MDA）都高于西农 979。此外，干旱胁迫下，氮素供应增加能够提高小麦植株中超氧化物歧化酶（SOD）和酚过氧化物酶（POD）的活性以及抗氧化剂抗坏血酸（ASA）和谷胱甘肽（GSH）的含量，尤其是在轻度干旱胁迫下，保护酶活性的显著升高有利于活性氧的清除。低氮处理下，西农 979 小麦的 POD 和过氧化氢酶（CAT）活性均高于大穗小麦 2036，抗氧化剂 GSH 的含量也较高，表明在相同的干旱胁迫条件下，耐旱性品种西农 979 具有较高的抗氧化和活性氧调控能力，此外，西农 979 在低氮处理下适应性也比大穗小麦 2036 更强。在没有受到干旱胁迫时，适量的氮素供给增加可以提高叶片中抗氧化酶的活性；而在遭受干旱胁迫时，适量氮素供给的增加能够提高酶活性，表明适当的增加氮素供给可以缓解干旱胁迫，减轻自由基对细胞的伤害。
其他摘要	Water shortage and soil barren are two important environmental factors restriciting plant growth and development factors in Northwest China. Water and nutrients not only have their own special effects, but also affect the yield and quality of crops. In this paper, two kinds of wheat with different panicle types (Xinong 979 and Large-spike 2036) were used as the research materials. We studied the root activity, leaf photosynthesis and chlorophyll fluorescence of wheat, active oxygen metabolism and metabolism regulation of antioxidants, respectively by artificial control method. The response, regulation and adaptation of two wheat varieties to different water and nutrients were studied to investage the difference between the two wheats. This study has great significance in revealing the drought tolerance mechanism of wheat seedlings and the regulation mechanism of nitrogen on drought. It provides theoretical basis and technical support for wheat to use its nutritional genetic characteristics to mine its absorption and to utilize the physiological potential of nitrogen. The main results are as follows: (1) The purposes of this study were to investigate the effects of water and N coupling on root vigor and uptake of nitrogen in Wheat. Two different cultivars of wheat Xinong 979 and Large-spike 2036 was planted in Hoagland nutrient solutions. Three treatments of different N levels, i.e. low N (0.5 mM NO3-) , normal N (8 mM NO3-) and high N (16 mM NO3-) and three water regimes, i.e. well-watered (no stress), moderate drying (8% PEG) and severe drying (15% PEG) were conducted. The results showed that there was a significant interaction between water regimes and N supply. Severe water stress could decrease the biomass, total absorbing surface, activity absorbing surface, root vigor, nitrogen content and nitrogen accumulation in wheat. Nitrogen deficiency increased the root length and root/shoot, decreased the biomass, total absorbing surface, activity absorbing surface, activity/total absorbing surface, root vigor, nitrogen content and nitrogen accumulation significantly. The root total absorbing surface, activity absorbing surface and root vigor of Xinong 979 increased significantly, and it was also 11%, 14%, 27% higher than Large-spike2036 respectively at a high N level compared with low N and normal N levels. Root N accumulation and shoot N accumulation in Xinong 979 had no significant difference between normal N and high N levels. And the plant N accumulation of Xinong 979 was 13%~62% higher than Large-spike 2036 at normal N level. The root–shoot ratio (R/S) increased slightly with water stress at a low N level; the smallest root–shoot ratio was found at a high N level and moderate drought stress treatment. Correlation analysis showed that activity absorbing surface, root vigor was positively correlated to plant N accumulation (P<0.01), while there was extremely significant negative correlation between activity absorbing surface, root vigor and root/shoot (P<0.01). A negative correlation was observed between root/shoot and plant N accumulation (P<0.01). The increase of nitrogen supply can improve the absorbing surface and root vigor of Xinong 979 effectively, but excessive nitrogen supply was not conductive to the root growth of large-spike wheat. These results suggested that the root vigor and growth of wheat with different genotypes respond differently to water and nitrogen coupling. Optimal regulations of water and N supply are beneficial to the formation of good root morphology and increased root vigor, therefore leading to the enhanced ability of absorbing moisture and nutrients. (2) In our study, two winter wheat varieties, Xinong 979 and Large-spike wheat, were evaluated for their physiological responses to different levels of nitrogen and water status during their seedling stage grown in a phytotron. Our results indicated that drought stress greatly reduced the net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs), but with a greater increase in instantaneous water use efficiency (WUE). At the meantime, the nitrogen (N) supply improved photosynthetic efficiency under water deficit. Parameters inferred from chlorophyll ameasurements, i.e., photochemical quenching coefficient (qP), the maximum photochemical efficiency (Fv/Fm), the quantum yield of photosystemⅡ(ΦPSⅡ), and the apparent photosynthetic electron transport rate (ETR) decreased under water stress at all nitrogen levels and declined in N-deficient plants. These results suggest that an appropriate nitrogen supply may be necessary to enhance drought resistance in wheat by improving photosynthetic efficiency and relieving photoinhibition under drought stress. However, an excessive N supply had no effect on drought resistance, which even showed an adverse effect on plant growth. Comparing the two cultivars, Xinong 979 has a stronger drought resistance compared with Large-spike 2036 under N deficiency. （3）The ROS accumulated in the wheat under ow nitrogen concentration. MDA decreased with the increase of nitrogen content. The concentrations of ROS and MDA in the root of large-spike wheat were higer than those of Xinong 979 under drought stress. Underthe drought stress, the concentrations of ROS, POD, ASA, and GSH increased with nitrogen addition. Especially, the protective enzyme activity increased under mild drought stress. The POD and CAT activity and the GSH concentration of Xinong 979 were higher than those of Large-spike wheat under low nitrogen. It indicates that the oxidation resistance and active oxygen control ability of Xinong 979 is stronger than Large-spike wheat under drought stress, nitrogen addition can increase the antioxidant enzyme activity under the absent of drought stress, and only the suitable nitrogen addition could increase the enzyme activity of leaves under water stress. Moderate nitrogen addition could increase the drought resistance of wheat and mitigate the damage of ROS to wheat cells.
学科领域	第一研究方向
语种	中文
文献类型	学位论文
条目标识符	sbir.nwafu.edu.cn/handle/361005/8161
专题	水保所2018--2022届毕业生论文(学位论文、期刊论文)
作者单位	中国科学院教育部水土保持与生态环境研究中心
推荐引用方式 GB/T 7714	王秀波. 干旱下氮素营养对不同穗型小麦苗期耐旱性的影响机制[D]. 北京. 中国科学院研究生院,2018.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
王秀波博士学位论文提交版-2018060（1673KB）			开放获取	--	请求全文