【作者】 李万春；

【导师】 姚雅琴；

【作者基本信息】 西北农林科技大学 ， 植物学， 2012， 硕士

【摘要】 本研究以小偃22为材料，通过盆栽调亏灌溉的方法，运用分光光度计法、荧光标记、显微形态观察和细胞化学定位等相结合的手段，从形态学、生理学、解剖学和细胞化学角度，对比研究了不同生育阶段（返青期和拔节期）、不同氮磷肥水平[低肥N₁P₁（纯氮0.1g/kg、P₂O₅0.05g/kg）和高肥N₂P₂（纯氮0.3g/kg、P₂O₅0.15g/kg）]和不同水分亏缺[田间最大持水量的70%⁸5%（正常供水，CK）、55%⁷0%（轻度亏缺，LS）、40%⁵5%（重度亏缺，SS）]对冬小麦根系生长、过氧化氢（H）₂O₂)代谢和水分调节特性的影响。为认识冬小麦根系形态、生理和细胞结构变化与功能的关系，以及水分胁迫条件下作物的水肥高效利用和最优调控提供理论依据。研究结果如下：（1）水氮磷耦合对根形态指标的影响：在相同氮磷营养条件下，返青期和拔节期水分胁迫抑制了冬小麦的生长，干物质量的累积降低，抑制程度与水分胁迫程度呈正相关。返青期根冠比LS>CK>SS，且N₂P₂> N₁P₁；拔节期组根冠比LS> SS> CK，且N₂P₂<N₁P₁。同时，返青和拔节期水分亏缺均可促进根毛的生长发育，扩大其吸收水分和养分的有效面积。（2）水氮磷耦合对根渗透调节的影响：在相同氮磷营养条件下，返青期和拔节期随着水分亏缺程度的加剧，根系中游离脯氨酸、可溶性糖和可溶性蛋白含量上升。同一水分条件下，其含量N₂P₂＞N₁P₁。表明在受到胁迫后冬小麦会通过将光合产物向根系运输和根系自身合成渗透调节物质来维持细胞渗透压，提高其水分调节特性。并且，渗透调节能力高营养条件较低营养条件强。亏缺后复水根系中渗透调节物质仍继续维持较高值，尤其是拔节期亏水后复水，以此来缓减前期产生的伤害。（3）水氮磷耦合对根中H)₂O₂代谢的影响：相同氮磷营养条件下，返青期和拔节期根系H)₂O₂含量随水分亏缺程度的加剧而增加，并在SS达到最大。SOD、POD、CAT活性在LS达最高，维持细胞内H)₂O₂动态平衡。因此，细胞内MDA含量LS与CK接近，在SS显著增加。亏缺后复水SOD、POD、CAT活性仍持续保持较高值，以清除过量的H)₂O₂，修复前期亏水可能造成的伤害。同一水分条件下，虽然高肥条件下冬小麦生长更加旺盛，产生了相对多的H)₂O₂，但其清除酶活性也更强，所以在复水后得到更好恢复，各处理MDA含量低于低肥处理。（4）水氮磷耦合对根H)₂O₂分布的影响：返青期和拔节期随着水分亏缺程度的加剧，H)₂O₂的分布从根冠和成熟区逐渐延伸到分生区、伸长区，荧光强度也逐渐加强。表明水分亏缺下，冬小麦根尖是H)₂O₂产生的主要部位。进一步利用CeCl₃标记技术，对拔节期水分亏缺冬小麦根冠细胞中H)₂O₂在超微水平上的分布进行了定位，结果显示H)₂O₂主要分布于细胞膜上，同一水分条件下高肥处理高于低肥处理。随水分胁迫的加重，细胞间隙、细胞壁和液泡膜周围也出现了H)₂O₂标记，并在量上明显增多。（5）水氮磷耦合对根解剖结构的影响：返青期和拔节期随水分亏缺的加剧，冬小麦根尖皮层薄壁细胞体积变大，形状由近椭圆形变得不规则，排列也不再规则有序。导致皮层厚度增加和皮层占根系直径的比例增大，从而减小了根系水流导度，增加了水分向中柱运输的相对距离。中柱的有序性被打破，木质部导管的横截面积变小，从而使驱动水分流动的气压变化率减低，增大水分疏导阻力。这些变化有利于增加根系径向和轴向水分运输的阻力，从而提高根系的保水能力。同时，根解剖结构的此类变化主要是针对水分胁迫的一种响应。综上所述，高氮磷营养条件下返青期轻度亏水处理后复水的施肥和控水方式最有利于冬小麦生长，且产量最高，可以达到节水高产的目的。更多还原

【Abstract】 In order to do some contrast studies to root growth, metabolism of hydrogen peroxide（H）₂O₂) and water regulation characteristics of winter wheat, we use spectrophotometer,fluorescent staining, scanning electron microscope and cell chemistry positioning methods atthe regreening and jointing stage of winter wheat growth. Such studies also had been done atdifferent nitrogen phosphate levels from low fertilizer level of N₁P₁（Nitrogen0.1g/kg, P₂O₅0.05g/kg） to the high fertilizer level of N₂P₂（pure nitrogen0.3g/kg, P₂O₅0.15g/kg） treatingwith winter wheat, and at different water deficit levels （the proportion of soil moisturecontent to field moisture is70%⁸5%（CK）,55%⁷0%（LS）, and40%⁵5%（SS））.Theexperiment provides a theoretical basis for people to understand the root morphology and therelationship between physiological changes and cell functions of winter wheat and also give away to achieve an optimal control that promote the utilization of water and fertilizer whenwinter wheat grow at the water deficit conditions. The results were shown follows:（1） Effects of water-nitrate combination on root morphology indicate that under thesame N\P conditions, water stress in regreening and jointing stage inhibited the growth ofwinter wheat, which reduced the accumulation of dry matter. The relationship between thedegree of inhibition and the water stress were positively correlated. At the regreening stage,the root-top ratio was LS>CK>SS with N₂P₂> N₁P₁; At the jointing stage, the root-top ratiowas LS>SS>CK with N₂P₂<N₁P₁. When water stress at regreening and jointing stage, winterwheat can promote the growth and development of root hairs, enlarging the effective area toabsorb water and nutrients.（2） Effects of water-nitrate combination on root osmotic regulation show that under thesame N\P conditions, with water deficit intensified in regreening and jointing period, freepraline, soluble sugar and solubility protein were rising. At the same water defict level, thecontent of soil water performed to N₂P₂＞N₁P₁, which showed that after suffering from stressconditions, wheat can maintain its cell osmotic pressure through transmitting photosynthetic production to root for self-root synthesizing. Osmotic regulation matter finally improved itswater regulation features and this ability with higher nutrition more strength than that withlower nutrition. Osmotic regulation matter still maintain higher level in re-watering conditionafter root under water deficit conditions; especially after jointing stage, it can relieve hurtfrom earlier stage of cell.（3） Effects of water-nitrate combination on root H)₂O₂consumption indicate that underthe same N\P conditions, with water deficit intensified in returning green and jointing period,content of H)₂O₂was increased to the highest level in SS. The activity of SOD, POD and CATwere the highest level in LS to maintain the H)₂O₂dynamic balance. When the content ofMDA in cell was closed to CK, the level increased significantly in SS. After re-wateringtreaments, the activity of SOD, POD and CAT still keep intensified for eliminating excessH)₂O₂to restore the hurt in earlier water deficit stage. Under the same water level, althoughtreat wheat with high nutrition, its still grew vigorously, producing more H)₂O₂. But theenzyme to eliminate H)₂O₂active; therefore, after re-watering stage of growth, the MDAcontent of each treatment were lower than those with lower nutriments.（4） Effects of water-nitrate combination on H)₂O₂distribution of roots show thatfollowing the water deficit intensified in returning green and jointing period of wheat, H)₂O₂distribution area extended meristematic zone and elongation zone from root-shoot andmaturation region with fluorescence strength intensified slowly, which showed that underwater deficit condition, the root tip of winter wheat was the main area for producing H)₂O₂.Furthermore, H)₂O₂in the root-shoot cell of winter wheat with water deficit in jointing stagewere signed by CeCl₃and the results told us that H)₂O₂mainly located on the cell membraneat the same water level; H)₂O₂content under higher fertilizer level higher than those withlower fertilizer treatments. With water stress intensified, there H)₂O₂mark appeared inintercellular space、cell wall、and vacuole membrane, which increased significantly.（5） Effects of water-nitrate combination on root anatomical structure illustrate that withwater deficit intensified in returning green and jointing period, the thin-wall cell of winterwheat root-tip cortex, whose shape changed from oval to no rules with new arrangement indisorder. Leading to increase the thickness of cortex and the ratio of cortex-root diameter. soit decreased the flow conductance of root, and enlarged the relative distant of watertransmitting to central-pillar. The order of central pillar was ruined and the ratio of drivingwater flowing air pressure decreased, improving the water dredge resistance. These changeswere helpfully to increase the resistance in root radial and axial flowing, which can improvethe ability for roots to keep water. Meanwhile, those changes of root anatomical structurewere regarded as a response to water stress. In conclusion, under the higher N\P nutrients treaments, applying fertilizer and watercontrol in re-watering stage after lighter water deficit in returning green period were usefulfor winter wheat growing and having higher yield, which can promote water efficience andincrease crop yield.更多还原