【作者】 黄敏；

【导师】 崔克辉；

【作者基本信息】 华中农业大学 ， 植物生理学， 2016， 硕士

【摘要】 水分和氮素是水稻生产最重要的影响因素,两者存在互作效应。本试验选用两优培9、汕优63、旱优3号三个水稻品种,设置正常水分、轻度水分胁迫(质量体积比为7.5%的PEG6000溶液水势为-0.09 MPa)、重度水分胁迫(质量体积比为15%的PEG6000溶液水势为-0.3 MPa)三个水分处理,每个水分条件下设置低(20 ppm)、中(40 ppm)、高(80 ppm)三个氮水平,采用水培方式进行。探究不同水分和氮素处理对水稻根系解剖结构的影响,以及水分和氮素之间是否存在互作效应;明确水稻根系解剖结构的变化对水分、氮素吸收的影响。主要研究结果如下:1.在轻度干旱和重度干旱胁迫下,三个水稻品种苗期地上部生物量分别下降了11.9%-20.7%和20.1%-36.2%;与低氮处理相比,中氮和高氮水平下三个水稻品种苗期地上部生物量增加了11.2%-53.1%和35%-96.6%。在正常水分和高氮组合下三个水稻品种地上部生物量最大,在重度干旱胁迫和低氮组合下地上部生物量最小。轻度水分胁迫和重度干旱胁迫导致三个水稻品种的净光合速率分别减少了4.8%-13.1%和10.8%-24.8%;与低氮处理相比,中氮和高氮水平下三个水稻品种的净光合速率分别增加了14.7%-29.7%和40.4%-63.5%。在正常水分和高氮组合下三个水稻品种叶片净光合速率最大,在重度干旱胁迫和低氮组合下叶片净光合速率最小。以上研究结果表明,干旱胁迫抑制光合作用,降低水稻生物量积累;提高供氮浓度,植株光合能力增强,水稻生物量积累增加。2.水分亏缺胁迫和高氮条件下中柱直径与不定根直径比值增大,水分和氮素在皮层的运输距离减小;根系通气组织和厚壁细胞厚度在水分亏缺胁迫条件下显著增加,而在高氮处理下显著减少;水分亏缺胁迫降低内皮层通道细胞百分比,高氮处理促进内皮层通道细胞形成。根系解剖结构变化伴随着根系水分和氮素吸收能力的变化。水分亏缺胁迫抑制三个水稻品种各吸水途径吸水速率和植株总吸氮量;增大供氮浓度,三个水稻品种各吸水途径吸水速率和植株总吸氮量都增加。说明在干旱条件下,增大供氮浓度可以提高根系吸水能力。3.根系通气组织和厚壁细胞厚度都与总吸水速率、质外体途径吸水速率、细胞-细胞途径吸水速率、植株总吸氮量呈极显著负相关关系;水稻根系内皮层通道细胞百分比与根系总吸水速率、质外体途径吸水速率、细胞-细胞途径吸水速率、植株总吸氮量都呈极显著正相关关系。表明水稻根系通气组织、厚壁细胞形成不利于根系对水分和氮素的吸收,而内皮层通道细胞形成有利于根系对水分和氮素的吸收4.不定根直径、中柱直径、根系通气组织、厚壁细胞厚度、根系总吸水速率、质外体吸水速率、植株总吸氮量、根系吸氮能力等指标在水分和氮素之间存在互作效应,水分和氮素通过影响根系解剖结构来影响水分和氮素吸收,而且水分和氮素的这种影响是相互的,不是独立的。更多还原

【Abstract】 Water and nitrogen are the two main factors in rice growth and production; many studies have focused on the interaction of water and nitrogen applications and its effects on water and nitrogen absorption. In order to understand the responses of rice root anatomy to water and nitrogen application and its associations with water and nitrogen absorption, three rice genotypes, Liangyoupei 9, Shanyou 63, Hanyou 3, were grown hydroponically. We designed three water treatments: well watered condition, moderate water deficit condition(PEG6000, 7.5% w/v), severe water deficit condition(PEG6000, 15% w/v), and each water treatment contains three nitrogen conditions: low nitrogen(20 ppm), moderate nitrogen(40 mg·L-1) and high nitrogen(80 mg·L-1). Biomass, water and nitrogen absorption, root anatomy characteristics were measured. The main results are as follows:1. The shoot biomass deceased by 11.9%-20.7% under moderate water deficit conditions and decreased by 20.1%-36.2% under severe water deficit conditions. Compared with low nitrogen condition, moderate and high nitrogen increased the shoot biomass by 11.2%-53.1% and 35%-96.6%, respectively, in three rice genotypes. Under well watered condition, the shoot biomass was highest with high nitrogen supply; under severe water deficit condition, the shoot biomass was lowest with low nitrogen supply. Under moderate and severe water deficit conditions, photosynthetic rate decreased by 4.8%-13.1% and 10.8%-24.8%, respectively; under moderate and high nitrogen conditions, photosynthetic rate increased by 14.7%-29.7% and 40.4%-63.5%, respectively, in three rice genotypes. Under well watered condition, the photosynthetic rate was highest with high nitrogen supply; under severe water deficit condition, the photosynthetic rate was lowest with low nitrogen supply. Therefore, water deficit stress inhibits rice photosynthetic rate, reduce biomass accumulation; high nitrogen increases rice photosynthesis and biomass accumulation.2. Ratio of stele diameter to root diameter increased under both water deficit and high nitrogen conditions. Root aerenchyma and sclerenchyma cell diameter increased significantly under water deficit condition, but decreased significantly when expose to high nitrogen condition. Passage cell(%) decreased significantly under water deficit condition, but increased significantly when exposured to high nitrogen condition. These root anatomy characteristics diversifications were accompanied by the changes in root water and nitrogen absorption ability. There were a significant decrease in total water uptake rate, water uptake rate via apoplastic pathway, water uptake rate via cell-to-cell pathway and total nitrogen uptake under water deficit condition in three rice genotypes; but increased under high nitrogen condition. Suggest that nitrogen can enhance root water uptake capacity under water deficit condition.3. Root aerenchyma and sclerenchyma cell diameter were significantly and negative ly correlated with total water uptake rate, water uptake rate via apoplastic pathway, water uptake rate via cell- to-cell pathway and total nitrogen uptake. Passage cell(%) showed significantly positive correlation with total water uptake rate, water uptake rate via apoplastic pathway, water uptake rate via cell- to-cell pathway and total nitrogen uptake. Our results indicated that root aerenchyma and sclerenchyma cell formation impede water and nitrogen transport, passage cell formation enhances water and nitrogen transport.4. This study found the interactions between water and nitrogen application on root aerenchyma, sclerenchyma cell diameter, total water uptake rate, apoplastic water uptake rate and total nitrogen uptake, indicated that water application and nitrogen level affect root absorption ability by modifying rice roots anatomy traits.更多还原