【作者】 孙骏威；

【导师】 蒋德安；

【作者基本信息】 浙江大学 ， 植物学， 2004， 硕士

【摘要】 干旱缺水是世界农业面临的最大问题之一，据估计干旱造成的农业损失可与其它所有胁迫导致的损失的总额相当。因此抗旱早的生理机制和适应性正日益引起人们的兴趣。本研究以Azucena陆生水稻和IR 1552水生水稻为试验材料，通过土培、砂培控制地下水位、撇水和复水处理或PEG-6000模拟干旱等，研究了不同水稻品种产量、养分含量、根系生长情况、光合速率、叶绿素荧光参数和抗氧化酶系统活性等，目的在于阐明水分胁迫对根系和地上部分的协同影响，比较不同品种间耐旱能力的差异及导致这种差异的可能的生理生化原因，为水稻抗旱栽培和育种提供理论依据。 十培结果表明，随着地下水位的不断下降，两水稻品种的单株谷粒产量、干粒重、结实率、总干重均有不同程度的下降，但下降幅度有所不同。品种Azucena在地下水位为80cm时生育严重延迟，不能在冬天来临前结实，而品种IR 1552仍表现出了较好的结实率和总干重；品种Azucena植株的氮磷钾含量随着地下水位的下降而下降，而品种IR 1552却呈增加趋势。沙培的研究结果表明，随着地下水位的下降，两个品种根系参数表现各异。品种Azucena的不定根数比灌水对照下降明显，而品种IR1552与灌水对照相差很小；品种Azucena的最大根长、根冠比、三条最长根的总根长、根尖数、根表面积和根体积均在25cm地下水位时表现最大；而品种IR1552在50cm地下水位时表现最大。 撤水处理的结果表明，随着时间的延续，净光合速率（Pn）逐渐下降，但最大光化学效率（Fv／Fm）并不随着胁迫的变化而变化。两品种的初始荧光（Fo）、PS Ⅱ有效光化学量子产量（F’v／F’m）、PSⅡ实际光化学量子产量((Φ_PSⅡ刚)和光化学猝灭（qP）均下降，但下降的幅度不一，品种IR 1552的下降幅度要低于Azucena。在干旱条件下，其SOD、CAT和POD活性逐渐上升，但上升的幅度上，品种IR 1552要胜于Azucena。土培、砂培和撤水处理的结果均表明，在严重干旱逆境下，品种IR 1552比Azucena更具抗旱性。 用PEG-6000模拟水分胁迫处理干旱敏感品种Azucena的结果表明，随着PEG处理浓度提高，Pn呈下降趋势，但各阶段起主导作用的因素不同。第一阶段，在10％PEG处理下Pn显著下降，色素和叶绿素荧光保持不变，气孔导度（Gs）和胞间CO₂浓度（Ci）反而上升，表明为非气孔因子限制光合速率；第二阶段，在15％PEG处理下色素和叶绿素荧光虽开始变化，Pn继续降低，并伴随Gs和Ci的下降而下降，因此气孔导度成为光合速率的主要限制因子；第三阶段，在20％PEG处理下Pn继续降低，Gs虽下降，但Ci并没有进一步下降，而色素和荧光参数均进一步变劣，此时光合膜的损伤成为限制光合的主导因子。上述结果表明，严重水分胁迫虽使光合机构吸收和传递光能效率下降，但过剩的激发能仍可能导致活性氧积累：尽管水稻叶内启动了超氧物防御系统，但仍能导致光合器官受损及PS Ⅱ光化学活性降低。更多还原

【Abstract】 Drought, with no-efficient water, is one of the most serious problems confronted with in the word agriculture. It is estimated that the loss in world agriculture caused by drought is nearly same as that by the other stresses. Therefore, it is increasingly interested in the physiological response and adaptation. In order to elucidate the synergic interactions between the roots and the shoots, genotypic difference and possible mechanism in response to water stress, Azucena, an upland rice cultivar and IR1552, a lowland rice cultivar, were used to investigate the variation of the yield, nutrients contents, root system, photosynthetic and chlorophyll fluorescence parameters, and anti-oxidative enzymes activities with soil, sand or PEG-6000 treatments resulting in the different water stress conditions. The results may provide the theoretical and practical information for understanding of anti-drought mechanism and rice upland culture.The results in soil cultured rice showed that the grain yield per plant, one-thousand-grain weight, setting rate, and total dry matter of the both cultivars were lowered with the dropping of underground water. In comparison with the control rice plant grown in soil surface submerging condition, all above mentioned index in IR1552 is less decrease than those in Azucena. Under the condition of 80cm of underground water level, Azucena was infertile owing to so late development that could not head before winter, while cultivar IR1552 ripened with higher total dry matter. The nitrogen, phosphorous and potassium contents in Azucena were decreased, while those in IR1552 were increased as the lowering of underground water levels. The results in sand cultured rice exhibited the different response to the falling in underground water levels in root parameters. The number of adventitious roots per plant was significantly inhibited at low levels of underground water in Azucena but it was not in IR1552. The root/shoot ratio and maximum root length per plant, and the length, root tip, root surface area and volume of the three longest roots, reached the peak at 25 cm of underground water level in Azucena, but those did the largest at 50 cm of underground water level in IR1552.Our experiment show that, as the days of withholding water progressed, net photosynthetic rate (Pn) became lower, but PS maximum photochemical efficiency (Fv/Fm) kept stable. Although the initial fluorescence(Fo), PS II available photochemical efficiency (F’v/F’m), PS II actual photochemical efficiency and photochemical quenching (qP) declined, the decrease was less in cultivar IR 1552than in cultivar Azucena. Under drought stress, the activities of three antioxidant enzymes (SOD, POD and CAT) increased, but the increase in cultivar IR 1552 was more than in cultivar Azucena. When soil became drier and drier, pigment contents, gas exchange and fluorescence parameters became worse and worse in both cultivars, the activities of three antioxidant enzymes (SOD, POD and CAT) decreased initially, and then increased, while the content of MDA became higher. However, by comparing the cultivar Azucena with IR 1552, the higher activity of the antioxidant emzymes in the latter seemed to removing of greater ROS and lowering the levels of MDA under water deficit stress. Therefore, the biomembrane in IR1552 can be protected from peroxidation. After rewatering for 2d, all parameter in IR1552 recovered to near the level of watering control plant. These results showed that the ability of the antioxidant enzymes system to avoid cellular damages may be an important attribute linked to the drought tolerance in cultivar IR 1552. All above reflects IR1552 a lowland rice cultivar is more resistant to serious drought than Azucena, an upland rice cultivar.After rice plants were treated with various concentrations of PEG (0, 10, 15 and 20% w/v) for 16d, characteristics of gas exchange, chlorophyll fluorescence, MDA content and activities of antioxidant enzymes (SOD, POD and CAT) were measured in the leaves. The results indicated that the reason for pho更多还原