【作者】 段骅；

【导师】 杨建昌；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2013， 博士

【摘要】 温度和水分是影响水稻生长和发育最重要的生态因子。随着全球温室效应的增加,高温和干旱已成为危害水稻生产的主要逆境。研究水稻高温与干旱危害的机理与对策对稳定和促进粮食生产有重要意义。本研究分析了高温、干旱及高温干旱双重胁迫对水稻产量和品质的影响及其生理机制,探讨了减轻水稻高温危害的栽培技术。主要结果如下：1.抽穗灌浆期高温对水稻产量和品质的影响及其生理原因以常规中熟籼稻品种双桂1号(热敏感品种)和黄华占(耐热品种)为材料,分别于抽穗灌浆早期(始穗后0-10d)和灌浆中期(始穗后11-20d)进行高温(白天平均温度>33℃)处理,以同期自然温度(白天温度<30℃)为对照,研究高温对水稻产量和品质的影响。结果表明,与对照相比,高温处理显著降低两品种的结实率和粒重,导致产量下降；降低了精米率、整精米率、胶稠度及崩解值,增大垩白米率、垩白度和消减值,热敏感品种产量和品质降低的幅度大于耐热品种,且抽穗灌浆早期高温处理影响大于灌浆中期处理。高温胁迫显著增加了灌浆早期籽粒中淀粉合酶(StS)含量、乙烯释放速率和脱落酸(ABA)含量,明显降低了淀粉分支酶(SBE)、玉米素(Z)+玉米素核苷(ZR)和吲哚乙酸(IAA)含量,耐热品种增降的幅度小于热敏感品种。在高温胁迫下,StS和SBE活性、内源Z+ZR.IAA及ABA含量较高,乙烯释放速率较小是耐热型品种在高温胁迫下保持较高产量和较好品质的重要生理原因。2.土壤水分对水稻产量和品质的影响及其生理机制(1)减数分裂期土壤干旱对颖花结实的影响以旱A-3(HA-3,抗旱性品种)和武运粳7号(WY-7,干旱敏感品种)为材料,在减数分裂期(抽穗前15-2d)进行充分灌溉(WW)和土壤水分胁迫(WS)处理。结果表明,WS处理显著降低叶片水势,但穗水势无显著差异。WS处理的颖花不孕率,WY-7较WW增加58.5%-50.9%,HA-3仅较WW增加126%-12.8%。颖花中的玉米素+玉米素核苷(Z+ZR)、吲哚乙酸(IAA)和赤霉素(GA1+GA4)浓度在WW与WS处理间以及在两品种间无显著差异。WS显著增加颖花中脱落酸(ABA)、乙烯和1-氨基环丙烷-1-羧酸(ACC)浓度。WY-7乙烯的增加大于ABA的增加,而HA-3乙烯的增加等于ABA增加。在减数分裂早期对WS稻穗施用氨基-乙氧基乙烯基甘氨酸(AVG,乙烯合成抑制剂)和ABA,颖花的不孕率显著降低；施用乙烯利(乙烯释放促进物质)和氟草酮(ABA合成抑制物质),结果则相反。上述结果说明,在减数分裂期遭受水分胁迫,内源ABA和乙烯的相互拮抗作用调控颖花的育性,较高ABA与乙烯的比值是水稻适应水分逆境的一个生理特征。(2)水稻抽穗灌浆期土壤水分对产量和品质的影响以扬稻6号(籼稻)和武运粳7号(粳稻)为材料,研究了结实期土壤水分对产量、米质和籽粒中淀粉合成关键酶活性的影响及它们之间的关系。结果表明,与WW(保持水层,well-watered)相比,土壤轻度落干(MD,moderate soil-drying,土壤水势保持在-10～-30kPa)显著提高了千粒重、稻米的最高黏度和崩解值,显著降低了垩白度和消减值，土壤重度落干(SD, severe soil-drying,土壤水势保持在-40～-60kPa)则使稻米品质变劣。MD处理显著增加了灌浆中后期籽粒中蔗糖合酶(SuS)、腺苷二磷酸葡萄糖焦磷酸化酶(AGP)和淀粉合酶(StS)活性,SD处理则降低了上述各酶的活性。说明结实期土壤轻度落干通过增强籽粒SuS、AGP和StS活性,促进籽粒充实和提高稻米品质。3.高温与干旱胁迫对水稻产量和品质的影响及其生理基础以黄华占(籼稻,耐热型)、双桂1号(籼稻,热敏感型)、沪早15(籼稻,节水抗旱型)、扬稻6号(籼稻)、两优培九(两系杂交籼稻)、扬辐粳8号(粳稻)和扬粳4038(粳稻)为材料种植于盆钵,分别于减数分裂期(抽穗前15～2d)和抽穗和灌浆早期(始穗后0～10d)设置高温(日最高温度为37.5℃)、干旱(土壤水势保持在-30±10kPa)、高温+干旱3种处理,以同期自然温度且正常供水为对照。结果表明,与对照相比,减数分裂期高温、干旱和高温+干旱3种处理均显著降低了各品种的花粉可育率、受精率、开裂率、每穗粒数、结实率和产量；抽穗灌浆期高温、干旱和高温+干旱3种处理均显著降低了各品种的花粉可育率、受精率、结实率和产量：减数分裂期和抽穗灌浆期高温或干旱处理均降低了精米率、整精米率、胶稠度、崩解值和支链淀粉短链部分,增加了垩白米率、垩白度、消减值和支链淀粉中长链部分。无论是在减数分裂期还是在抽穗灌浆期,耐热品种和节水抗旱品种产量和品质下降的幅度均小于其他品种。在高温或干旱胁迫下,耐热品种和节水抗旱品种具有较高的叶片光合速率、抗氧化保护酶活性,根系氧化力、籽粒蔗糖-淀粉代谢途径关键酶活性及其基因表达量,使其保持了较高产量和较好品质。4.灌溉方式对减轻水稻高温危害的作用以常规中熟籼稻品种双桂1号(热敏感品种)和黄华占(耐热品种)为材料,在抽穗灌浆期进行高温(白天/夜间平均温度为351℃/20.8℃)和正常温度(白天/夜间平均温度为29.0℃/20.8℃)处理并设置轻干湿交替灌溉(土壤落干至土水势为-15kPa时复水)、重干湿交替灌溉(土壤落干至土水势为-30kPa时复水)和水层灌溉(对照)3种灌溉方式,观测产量和品质形成的特点。结果表明,在相同温度尤其是在高温胁迫下,与水层灌溉相比,轻干湿交替灌溉显著增加结实率、千粒重和产量,增加出糙率、精米率和整精米率,降低垩白米率和垩白度,增大崩解值,减小消减值,重干湿交替灌溉的结果则相反。两品种结果趋势基本一致。说明抽穗结实期遭受高温胁迫,采用轻干湿交替灌溉方式可以获得较高的产量和较好的稻米品质。轻干湿交替灌溉方式减轻水稻高温危害的重要生理机制是该灌溉方式可以降低冠层相对湿度、减小叶片活性氧生成速率、增加抗氧化物质抗坏血酸和还原型谷胱甘肽含量、提高内源细胞分裂素及亚精胺和精胺浓度。5.氮肥对减轻水稻高温危害的作用以中籼品种沪旱15和中粳品种扬粳4038为材料,于穗分化期进行低氮(每盆0.5g尿素)、中氮(每盆1.0g尿素)和高氮(每盆2.0g尿素)3种施氮量处理,在抽穗灌浆期进行高温(白天/夜间平均温度为35.1℃/20.8℃)和正常温度(白天/夜间平均温度为290℃/208℃)处理,观测产量和品质形成的特点。结果表明,在相同温度尤其是在高温胁迫下,与低氮相比,中氮和高氮显著增加每穗粒数、结实率、千粒重和产量,增加整精米率、崩解值和支链淀粉短B链,降低垩白米率,消减值和支链淀粉中长链,其中以中氮效果最明显。两品种结果趋势基本一致。说明抽穗结实期遭受高温胁迫,在穗分化期适当施用氮肥,可以获得较高的产量和较好的稻米品质。适量施用氮肥可以减轻高温危害与施氮后叶片光合速率、根系氧化力、籽粒蔗糖-淀粉代谢途径关键酶活性的提高有密切关系。更多还原

【Abstract】 Temperature and soil drying are the most important ecological factors to the rice growth. With the continuous increase of the greenhouse effect, high temperature and soil drying are becoming major harm to crop production. To understand the mechanism involved in the effect of high temperature and soil drying on rice(Oryza sativa L.) growth and to take counter measures to reduce damage of heat stress to rice would have great significance in promoting rice production and ensuring food security. In this study, the effects of high temperature, soil drying and high temperature plus soil drying on rice yield and quality and their physiological mechanisms were investigated. Cultivation techniques to reduce the injury of high temperature to rice growth and development were studied. The main results are as follows:1. Effect of high temperature during heading and grain filling on the yield quality and quantity of rice and its physiology reasonTwo mid-season indica cultivars, Huanghuazhan (a heat-tolerant rice cultivar) and Shuanggui1(a heat-sensitive rice cultivar), were pot-grown and subjected to high temperature treatments (mean temperature during the day/night at35.1℃/20.8℃) during early grain filling (0-10d after heading) and mid grain filling (11-20d after heading), and natural temperature (the mean temperature during the day/night at29.0℃/20.8℃) was taken as the control. The grain yield and quality of rice were investigated. The results showed that the high temperature treatment significantly reduced seed-setting rate, grain yield, milled rice, head rice, gel consistency and the break down viscosity of both cultivars. The high temperature also increased chalky kernel, chalkiness and the setback viscosity. The reduction rate was greater for the heat-sensitive cultivar than for the heat-tolerant cultivar, with a more reduction under the treatment during early grain filling than during mid grain filling. The high temperature obviously increased ethylene evolution rate, abscisic acid (ABA) contents and starch synthase (StS) activity, decreased contents of zeatin+zeatin riboside (Z+ZR), indole-3-acetic acid (IAA) and starch branching enzyme (SBE) activities in spikelets of Shuanggui1and Huanghuazhan during early grain-filling stage, but the increase or reduction was less for heat-tolerant cultivars than for heat-sensitive cultivars. These results suggested that higher concentrations of Z+ZR, IAA, ABA and activities of StS and SBE, lower ethylene evolution rate in spikelets were contributed to higher grain yield and better quality of rice for a heat-tolerant rice cultivar. 2. Effect of soil moisture on the yield quality and quantity of rice and its physiological mechanism(1) Hormones in rice spikelets in responses to water stress during meiosisTwo rice cultivars, Han A-3(HA-3, drought-resistant) and Wuyujing7(WY-7, drought-susceptible), were used and subjected to well-watered (WW) and water-stressed (WS) treatments during meiosis (15-2d before heading). Leaf water potentials of both cultivars markedly decreased during the period as a result of WS treatment, but panicle water potentials remained constant. The percentage of sterile spikelets in WS plants was increased by48.5to50.9%for WY-7, whereas only by12.6to12.8%for HA-3. Concentrations of Z+ZR, IAA and gibberellins (GAi+GA4) in spikelets showed no significant differences either between the WW and WS treatments or between the two cultivars. ABA, ethylene, and1-aminocylopropane-1-carboxylic acid (ACC) were all enhanced in spikelets by the water stress, with more enhanced for ethylene than for ABA in WY-7, whereas elevated ABA balanced ethylene production in HA-3. The spikelet sterility was significantly reduced when amino-ethoxyvinylglycine (an inhibitor of ethylene synthesis) or ABA was applied to the panicles of WS plants at the early meiosis stage. Application of ethephon (an ethylene-releasing agent) or fluridone (an inhibitor of ABA synthesis) had the opposite effect. The results suggest that antagonistic interactions between ABA and ethylene may be involved in mediating the effect of water stress that affects spikelet fertility. A higher ratio of ABA to ethylene would be a physiological trait of rice adaptation to water stress.(2) Effect of soil moisture during heading and grain filling on the yield and quality of riceTwo rice cultivars, Wuyujing3(japonica) and Yangdao6(indica), were grown in pots. Three soil moisture treatments, well-watered (WW, well-watered), moderate soil-drying (MD, soil water potential at-10～-30kPa), and severe soil-drying (SD, soil water potential at-40～-60kPa), were imposed during grain-filing. Compared with WW, grain weight, peak viscosity and breakdown values were significantly increased, as well as chalkiness and setback values were reduced under MD. The results were reversed for SD treatments. Activities of sucrose synthase (SuS), adenine diphosphoglucose pyrophosphorylase (AGP) and starch synthase (StS) in grains in the middle and late grain-filling stages were significantly enhanced, whereas ethylene revolution rate of grains were decreased, under MD. The SD had the opposite effects. The results indicate that MD can improve rice quality, resulting from the physiological mechanism of enhancing activities of SuS, AGP and StS in grains.3. Effect of high temperature and soil drying on the yield and quality of rice and its physiological basesSeven rice cultivars, Huanghuazhan (an indica heat-tolerant cultivar), Shuanggui1(an indica heat-sensitive cultivar), Huhan15(an indica drought-resistant cultivar), Yangdao6(an indica inbred), Liangyoupeijiu (a two-line indica hybrid cultivar), Yangfujing8and Yangjing4038(japonica inbreds), were grown in pots and subjected to high temperature treatments (HT, maximum temperature during the day at37.5℃), soil drying treatments (SD, soil water potential at-30±10kPa) and high temperature plus soil drying treatments (HT+SD) during meiosis (15-2d before heading), heading, and early grain filling (0-10d after heading), and the natural temperature plus well-watered treatment was taken as the control (CK). The results showed that high temperature, soil drying or high temperature plus soil drying treatments during meiosis and during heading significantly reduced pollen fertility rate, fertilization rate, anther dehiscence rate, spikelets per panicle, seed-setting rate and grain yield of all the cultivars. High temperature or soil drying treatment during meiosis or grain filling stage significantly reduced milled rice rate, head rice rate, gel consistency, break down value and short chain in debranched amylopectin, whereas increased chalky grains, chalkiness and setback values. The increase or reduction was less for heat-tolerant cultivars and drought-resistant cultivars than for other kinds of cultivars. Both heat-tolerant cultivars and drought-resistant cultivars showed stronger root activity and antioxidative defense system, greater net photosynthetic rate of the flag leaf, higher activities of the key enzymes involved in sucrose-to-starch metabolic pathway, and more gene expressions in grains, which contributed to maintaining a higher grain yield under the high temperature or drought stress.4. Role of irrigation patterns in reducing harms of high temperature to riceTwo mid-season indica cultivars, Huanghuazhan (a heat-tolerant rice cultivar) and Shuanggui1(a heat-sensitive rice cultivar), were grown in pots. Both high temperature (mean temperature during the day/night at35.1℃/20.8℃) and normal temperature (mean temperature during the day/night at29.0℃/20.8℃) treatments and three irrigation patterns, alternate wetting and moderate soil drying (MD, plants were re-watered when soil water potential reached15kPa), alternate wetting and severe soil drying (SD, plants were re-watered when soil water potential reached30kPa), and well-watered (control, continuously flooded), were conducted during heading and grain filling. The grain yield and quality of rice were investigated under these treatments. The results showed that under either normal or high temperature, compared with the control, the MD significantly increased seed-setting rate,1000-grain weight, grain yield, brown rice, milled rice and head rice, and reduced chalky grains and chalkiness degree. The MD also increased the break down viscosity and decreased the setback viscosity. The SD showed the opposite effects. The two cultivars behaved the same. These results indicate that the MD could maintain a higher grain yield and better quality of rice when subjected to high temperature. The reduction of relative humidity in the panicle canopy, decreased reactive oxygen production rate, elevated contents of ascorbic acid and reduced glutathione, and increased concentrations of cytokinins in leaves and spermidine and spermine in grains account for the reducing harms of high temperature to rice under the MD regime.5. Role of nitrogen fertilizer in reducing harms of high temperature to riceTwo rice cultivars, Huhan15(indica) and Yangjing4038(japonica), were grown in pots. Three nitrogen fertilizer rate, low nitrogen (LN,0.5g N per pot), middle nitrogen (MN,1.0gN per pot), and high nitrogen (HN,2.0g N per pot), were conducted during panicle initiation stage. Both high temperature (mean temperature during the day/night at35.1℃/20.8℃) and normal temperature (mean temperature during the day/night at29.0℃/20.8℃) treatments were conducted during heading and grain filling. The grain yield and quality of rice were investigated under these treatments. The results showed that under the same temperature, especially under high temperature, compared with the LN, the MN and HN significantly increased spikelets per panicle, seed-setting rate,1000-grain weight, grain yield, head rice, break down viscosity and short chain in debranched amylopectin, and reduced chalky grains and setback viscosity, and the effect was the most significant at MN. The two cultivars behaved the same. These results indicate that a proper nitrogen fertilizer rate could maintain a higher grain yield and better quality of rice when subjected to high temperature. Increases in photosynthetic rate of the flag leaf, root activity, and activities of the key enzymes involved in sucrose-to-starch metabolic pathway in grains were closely associated with the reducing harms of high temperature to rice under higher nitrogen rate.更多还原