【作者】 黄玲；

【导师】 段爱旺；

【作者基本信息】 中国农业科学院 ， 农业水土工程， 2013， 博士

【摘要】 河南省是我国黄淮海地区冬小麦主要生产省份，2011年小麦种植面积532.3万hm2，总产量0.31亿t，分别占全国总量的21.9%和26.6%。水资源短缺是影响冬小麦高产稳产的重要因素，在河南中部地区冬小麦生育期降水无法满足正常生长发育需要，补充灌溉需求强烈。因此，培育和种植高产节水优质的冬小麦品种，并配合适宜的田间用水管理措施，是提高该区域冬小麦农田水分利用效率，缓解水资源供需矛盾，确保冬小麦生产持续稳定发展的重要途径。本文通过研究品种改良过程中，冬小麦需水特性、农艺性状、产量构成和根系特性的变化规律，以及对水分胁迫的响应，初步揭示了冬小麦品种更替过程中水分利用特性的变化规律及其生理机制，研究成果对于制定冬小麦抗旱节水育种目标和指导有限农业水资源的优化配置具有重要意义。本项研究选取河南省中部地区20世纪50年代初至2007年间大面积推广的6个主栽品种，在2010~2011和2011~2012年两个生长季，采用测坑与田间试验相结合的方法，系统的研究了不同水分处理下冬小麦品种的耗水特性、光合特性、农艺性状和根系特性的演变特征。测坑试验设置3个水分梯度：充分供水（CK，整个生育期充分供水，土壤含水量控制在田间持水量的75%~80%）、轻度水分亏缺（MD，田间持水量的60%~70%）；重度水分亏缺（SD，田间持水量的45%~55%）；田间试验设置3个灌水处理：W0，返青后不灌水，冬小麦生长完全依靠自然降水；W1，冬后拔节期灌一水；W2，冬后拔节期和灌浆期分别灌一次水。主要研究结果如下：1、在测坑条件下，各冬小麦品种耗水量为CK＞MD＞SD，籽粒产量在CK下最高，水分利用效率在SD下最高；在大田条件下，各冬小麦品种的耗水量为W2＞W1＞W0，籽粒产量在W2下最高，水分利用效率则在W0或W1下最高。发生水分胁迫时，冬小麦耗水量的降低幅度要高于籽粒产量的降低幅度，因此WUE得到提高。冬小麦品种的耗水量随着年代递增呈现了一定的降低趋势，但幅度不大；随品种更替籽粒产量潜力则呈现了明显的增加趋势；两者共同作用，使得冬小麦的WUE不断增加。数据显示，冬小麦WUE增加的主要贡献来自于产量潜力的增加。在水分胁迫条件下，现代品种的WUE普遍高于早期品种。2、冬小麦的日均耗水强度、阶段耗水量和耗水模系数在拔节至开花阶段最高，开花至成熟阶段次之，越冬至返青阶段最低。在测坑条件下，现代品种的日均耗水强度、阶段耗水量和耗水模系数在拔节至开花阶段和开花至成熟阶段均表现出低于早期品种的趋势。大田试验中，现代品种的阶段耗水量、日均耗水强度和耗水模系数在拔节至开花期阶段低于早期品种，而在开花至成熟阶段高于早期品种，测坑试验与田间试验结果的差异主要因为灌水时期和灌水量不同所致。3、品种更替过程中，冬小麦旗叶叶绿素含量呈现明显的增加趋势，但现代品种旗叶的光合速率（Pn）在各生育期并没有表现出明显的优势。在测坑条件下，随着年代的推移，冬小麦品种的旗叶蒸腾速率（Tr）在开花至灌浆中期表现为先增加后降低的趋势，20世纪70~80年代品种的平均Tr最高。现代品种的胞间二氧化碳浓度（Ci）和平均气孔导度（Gs）均高于50~60年代品种。现代品种的原初光能转换效率（Fv/Fm）在孕穗期和灌浆期相对较高，在花后防御光抑制能力相对较强。4、现代品种旗叶的丙二醛（MDA）含量降低，膜脂过氧化程度要轻于早期品种。现代品种旗叶可溶性蛋白在花后0~7天高于早期品种，且降解速度慢。现代品种的超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性在花后的测定中均明显增强，表明现代品种具有更强的活性氧清除能力，可减缓叶片衰老速度，有利于叶片维持较强的光合功能，更有利于叶片光合产物的合成与运输，为千粒重及最终籽粒产量的增加奠定了生理基础。5、随着品种的不断改良，冬小麦都表现了株高降低，节间距缩短，千粒重、产量和收获指数明显提高的趋势，而穗长、基部茎节直径、单位面积穗数和穗粒数并没有表现出明显的变化规律。田间试验测定结果显示，在不同水分处理下，冬小麦的株高由20世纪50年代的100~120cm降低到现代的54~80cm，降低幅度达到25.6%~49.3%；穗下节由50年代的34.8~40.4cm降低到22.4~25.3cm，降幅为35.5%~38.3%；千粒重由50年代的28.0~29.2g增加到现在的46.4~47.6g，增幅为63.0%~66.0%；籽粒产量由50年代的4069~5206kg·hm-2增加到现在的6443~6880kg·hm-2，增幅为44.4%~58.3%，平均每次品种更替产量增加279~395kg·hm-2；收获指数由50年代的0.27~0.32增加到2002年的0.35~0.37，增幅为17.9%~35.8%；WUE由50年代的1.15~1.42kg·m-3增加到2002年1.78~1.81kg·m-3，增幅为35.2%~55.3%。品种改良提高了花前和花后干物质转运量、花前干物质转运率及贡献率，现代品种叶片的物质积累和优化分配同化产物的能力强，是千粒重持续增长的基础，而产量的增加主要源自千粒重的增加和收获指数的提高。6、水分胁迫会降低冬小麦根系活力，但会增加冬小麦的根长密度和根尖数，尤其是0~0.05mm和0.5~2.0mm径级的根长密度，根长密度的增加主要来自于细根的增加。在水分胁迫下，现代品种土壤耕层的根系活力要明显高于早期品种，现代品种比早期品种表现的更为适应干旱。借助微根管技术进行的原位监测显示，现代冬小麦品种根系直径增加，大于0.45mm径级的根长密度所占比例明显增加，提高了植株对主要耕层土壤水分的利用，是其抗旱性提高的主要原因。更多还原

【Abstract】 Henan (HN) Province, located in southern part of the Yellow River, Huaihe River andHaihe River plain, is the most important winter wheat producer in China, with a yield of31million tons from an arable area of5.32million ha, occupied about21.9%and26.6%ofthe national total amount in2011. In central Henan province, water shortage is the mainfactor of limiting sustainable development of winter wheat production. Selecting cultivarswith high water use efficiency is an important way to relieve water competition and toensure the suistanable development of winter wheat production in the region. Theobjectives of this study were to analyze the changes of water requirement, agronomic traits,yield and its components and root features, to analyze the differences in water useefficiency and responses to different water stress conditions among winter wheat cultivarsreleased in defferent decades, and to understand the genetic and physiological mechanismsbehind these changes and differences. The results would be helpful for furtherimprovement of drought resistance and water saving capacity in breeding new winterwheat cultivars and improvement of optimal utilization of limited agricultural waterresources in central Henan.Six representative winter wheat cultivars released from early1950s to2007for centralpart of Hennan province were selected and tested during2010~2011and2011~2012growing seasons. With experiments carried out in leaching ponds under rain shelter andplots in field, water consumption features, photosynthetic characteristics, agronomic traitsand roots features under different water situations were studied. In leaching pondexperiment, three water situations were set as follows: control check (CK): Irrigating whensoil moisture was less than75%~85%of field capacity (FC); Mild water deficit (MD): lessthan60%~70%of FC; Serious water deficit (SD): less than45%~55%of FC. In fieldexperiment, three water situations were set as: W0: no irrigation after returning green stage;W1: only an irrigation at the jointing stage; W2: two irrigations at jointing stage and milkystage respectively. The main results were as followings:1. Water consumptions of winter wheat under different water situations can be ranked asCK＞MD＞SD. The highest grain yield for different winter wheat cultivars appeared inCK treatment, and the highest WUE occurred in SD treatment in pond experiment. Underfield experiment, water consumption can be ranked as W2＞W1＞W0, the highest grainyield was investigated in W2treatment, and the highest WUE in W0or W1treatment. Thepercentage of water consumption decreasing was obviously greater than that of grain yielddecreasing under water stress, which resulted in an increasing of WUE. There was a veryweak trend that water consumption decreased gradually, but an obvious trend that grainyield increased gradually with winter wheat cultivars changed, which resulted in aremarkable increasing thend for WUE of winter wheat. Data showed that the WUE increasing of winter wheat cultivars was mainly due to grain yield increasing. WUE ofmodern cultivars were generally higher than those of early cultivars under water stress.2. The greatest stage water consumption amount(CA), average daily water consumption(CD) and percentage of stage water consumption to total water consumption (CP) occurredin stage of jointing to flowering and stage of flowering to maturity, and the least valuesappeared in stage of overwintering to jointing. The CA, CD and CP of the modern cultivarswere less than those of the early cultivars in period of jointing to flowering and period offlowering to maturity in pond experment. The CA, CD and CP of early cultivars weregreater than those of the modern cultivars in period of jointing to flowering. Under fieldexperiment, the CA, CD and CP of early cultivars were less than those of modern cultivarsin period of flowering to maturity. The differences in CA, CD and CP between pondexperiement and field experiment were mainly caused by the differences in irrigation timeand irrigation quota for the two experiments.3. The chlorophyll content of flag leaf of winter wheat cultivar increased with itsreleased year, but the modern cultivars had no significant advantages in photosynthetic rateof flag leaf under all growing stages. In pond experiment, transpiration rate (Tr) of flag leafincreased at early and then decreased afterward during flowering to middle filling period.The winter wheat cultivars released in1970s and1980s had higher transpiration rates. Theintracellular CO2concentration (Ci) and stomatal conductance (Gs) of winter wheatcultivars tended to increase with released year. PSII maximum photochemical efficiency(Fv/Fm) of the modern cultivars was relatively greater than those of the early cultivars,which was related to a stronger ability of avoiding photoinhibition after flowering.4. The malondialdehyde (MDA) concentrations of the modern cultivars weresignificantly lower than those of the early cultivars under all water treatments. Themembrane lipid peroxidation was remarkably serious in the early cultivars. Soluble proteincontent in flag leaves of modern cultivars was higher in period of0to7days after anthesisand with a slower degradation afterward. Activities of superoxide dismutase (SOD),peroxidase (POD), and catalase (CAT) of the modern cultivars increased more quicklythan those of the early cultivars after flowering, which shown that the modern cultivars hadstronger capacity of scavenging oxygen free radical. This characteristic was helpful for themaintenance of stronger photosynthetic capability, and was beneficial to the compositionand transportation of arbohydrated, and laid a good physiological foundation for high1000-grain weight and grain yield.5. Under all water treatments, It were shown clearly that plant height was reduced,internode length shorten, and1000-grain weight, grain yield and harvest index improvedremarkably with the cultivar changed, but there were no significant differences in spikelength, diameter of low internodes, spike number per unit land, and grain number per spike.The plant height was decreased from100~120cm for early cultivars to50~70cm for modern cultivars, percentage of reduction was from25.6%to49.3%. The spike internodelength decreased from34.8~40.4cm to22.4~25.3cm, a reduction by35.5%~38.3%percent; The1000-grain weight increased from28.0~29.2g to46.4~47.6g, a63.0%~66.0%improvement, or a3.06~3.29g increment for each generation; The grain yield increasedfrom4069~5206kg·hm-2to6443~6880kg·hm-2, a44.4%~58.3%improvement, or a279~395kg·hm-2increment for each generation; The HI increased from0.27~0.32to0.35~0.37, a17.9%~35.8%increase; The WUE increased from1.15~1.42kg·m-3to1.78~1.81kg·m-3, a35.2%~55.3%improvement. The significant genetic improvement wasbenifitial to dry matter accumulation and translocation before and after anthesis. Themodern cultivars demonstrated a stronger ability for dry matter accumulation and optimaldistribution, which was a very important foundation of the increasing of1000-grain weight.The1000-grain weight and harvest index have a significant positive relationship with yieldimprovement.6. Root vigor was decreased, but root length density, especially for the roots rangingfrom0~0.05mm and0.5~2.0mm in diameter, and root tip number was increased underwater stress. The root vigor of the modern cultivars was higher than that of the earlycultivars in cultivating layer under water stress, which made modern cultivars with bettertolerance to soil drought. By fine root measurement, it was shown that modern cultivarshad greater average root diameter, and the percentage of length density of roots withdiameter more than0.45mm increased significantly under water stress, which was helpfulfor improving water uptake and utilization in cultivating layer and maybe the main reasonsof the drought tolerance improvement for the modern cultivars更多还原