【作者】 苗芳；

【导师】 张嵩午；

【作者基本信息】 西北农林科技大学 ， 作物栽培学与耕作学， 2003， 博士

【摘要】 冷型小麦的叶片功能期较长，根系发达，叶片的叶绿素含量、蒸腾速率和净光合速率均较高，且在阴雨和干旱天气下仍具有较好的生理特性。因此，冷型小麦是培育高产、稳产小麦品种的较为理想的种质资源。目前关于冷型小麦的研究多集中在生态生理方面，本研究的目的是从解剖学角度揭示冷型小麦和暖型小麦各器官在灌浆结实期(扬花～成熟)的结构差异，以及在干旱和淹水条件下冷、暖型小麦叶片结构的动态变化特征。 采用临时制片法和石蜡切片法研究了冷型小麦在扬花期叶片的结构特征及灌浆结实期叶片结构的动态变化。结果显示，冷型小麦叶肉细胞较短，细胞层数较多，单位叶面积叶肉细胞数目较多。叶片较薄，维管束横截面积较大，叶脉间的距离较小。在灌浆中、后期，冷型小麦叶肉细胞叶绿体解体较慢，叶肉细胞含有叶绿体的时间较长，但冷型小麦和暖型小麦在叶表皮气孔器大小和气孔密度上无显著差异；在电子显微镜下观察了冷型小麦扬花期叶片超微结构特征，结果表明，冷型小麦叶肉细胞中含有数量较多的形状奇特的叶绿体，叶绿体外膜向外突起形成尾尖，有的叶绿体在尾尖处形成囊泡，囊泡具有单层膜，泡内液体具有一定的电子密度，说明含有溶质，因此，囊泡的形成有利于叶绿体中光合产物向外运输。有的叶绿体尾形突起顶端膨大其中充满基质，形成叶绿体前质体，经生长发育形成叶绿体，从而增加叶绿体数目以及完成叶绿体的更新。冷型小麦叶片叶绿体中基粒片层小于10的低基粒片层数占统计基粒片层数的百分率较低(冷型小麦陕229旗叶、倒二叶和倒三叶分别为29.7％、21.1％和19.7％，暖型小麦NR9405分别为48.7％、32.1％和20.1％)，叶绿体内膜系统发达，叶片中组成维管束的细胞胞间连丝较发达。 应用石蜡切片的方法研究了冷型小麦茎在灌浆结实期的结构特征，结果表明，在穗粒数接近的小麦品种中，冷型小麦茎中的维管束数目较多。冷型小麦单位横截面积茎内维管束数目及维管束总面积占茎横截面积的百分率均较高(冷型小麦穗下节间平均值分别为22.7和8.5％，倒二节间平均值分别为14.3和6.8％。暖型小麦穗下节间平均值分别为20.0和7.4％，倒二节间平均值分别为11.0和5.9％)。在灌浆期，冷型小麦茎中的叶绿体解体缓慢，茎中含有叶绿体的时间较长。试验结果说明，冷型小麦茎中维管束较发达，在灌浆后期衰老较晚。 应用石蜡切片法和扫描电镜观察了冷型小麦胚乳细胞中淀粉粒的形态，用电子显微镜观察了灌浆后期冷型小麦颖果腹沟区的超微结构。结果表明，冷型小麦胚乳细胞中大型淀粉粒数量较多，且灌浆中期至后期，淀粉粒直径增加幅度大，说明冷型小麦灌浆后劲较足，胚乳细胞充实程度较好。在灌浆后期，冷型小麦籽粒腹沟区有色细胞衰老较晚，具体表现在，有色细胞中脂类物质和丹宁沉积较少，细胞质浓厚，细胞器数量较多，而且结构较完整，细胞壁增厚不明显，胞间连丝发达。 应用徒手切片法观察了冷型小麦种子根和次生根的显微结构，结果表明，冷型小麦种子根的皮层较厚，有利于根内贮藏营养物质，进而促进根系的生长和发育。种子根和次生根的中柱面积及导管横截面积较大，次生根导管总数较多。这说明冷型小麦根中的维管组织发达，有利于根对土壤水分和养分的吸收以及向茎中的运输。 应用光学显微镜和电子显微镜观察了干旱和淹水条件下冷型小麦叶片结构特征及叶片结构的动态变化过程，并统计了灌浆结实期叶片叶绿体基粒片层及基粒垛数，结果表明，在干旱和淹水条件下，冷型小麦灌浆结实期叶片叶绿体中基粒片层数大于20的基粒总片层数所占的百分率均较高(在干旱条件下陕229旗叶、倒二叶和倒三叶分别为35.3%、23.1%和43.3%，NR9405分别为17.8%、15.5%和39.4%。在淹水条件下陕229三片功能叶分别为23.2%、34.5%和25.9%，NR9405分别为17.7%、17.4%和18.6%)，而基粒片层数小于10的基粒总片层数所占的百分率均较低(在干旱条件下陕229旗叶、倒二叶和倒三叶分别为18.4%、26.5%和18.0%，NR94OS分别为44.6%、34.1%和13.3%。在淹水条件下陕229三片功能叶分别为29.7%、25.3%和27.6%，NR94OS分别为39.8%、45.0%和39.3%)，表明冷型小麦叶片叶绿体在不良环境下内膜系统仍较发达，这是其叶片在不良环境下仍具有较好的光合特性的结构基础。在干旱条件下，进入灌浆中期，冷、暖型小麦叶片结构开始出现明显差异，暖型小麦叶片结构衰老特征比冷型小麦出现早，具体表现在:叶肉细胞失水变小，细胞间隙增大，叶绿体解体，叶绿体数目减少。叶绿体基粒片层解体，基粒垛数减少，嗜饿颗粒数目增多，体积增大，淀粉粒消失，基质电子密度减少。线粒体基质透明度增加，峭变少，甚至消失。组成维管束的生活细胞壁增厚，胞间连丝减少。灌浆后期，暖型小麦叶片中的叶绿体全部解体，冷型小麦叶片中还含有一定数量的叶绿体，有的品种叶绿体结构完整。在淹水条件下，冷、暖型小麦叶片结构受到的伤害程度不同，暖型小麦在灌浆结实期叶片结构伤害程度较严重，叶绿体和线粒体解体的数量较多，特别是在灌浆后期叶片中大多数叶绿体基粒减少，基粒片层肿胀，宽?更多还原

【Abstract】 The cold type wheat (CTW) is idea germplasm resource because its leaf has a longer function period,higher chlorophyll content,higher transpiration rate and higher net photosynthesis rate,its root prospers,and meanwhile it has the good physiology characteristics under rainy and drought weather.At present,more studies on cold type wheat focus on the aspect of ecophysiology.The aim of this study is to open out the structure difference of different organ and leaf structure change under more water and drought conditions in grain-filling period between cold type wheat and warm type wheat (WTW) .The leaf structure characteristic in anthesis and dynamic change in grain-filling period were studied by means of temporarily preparing slice method and paraffin wax section method.The results reveal no significiant difference in size and density of leaf epidermis stomatal apparatus between CTW and WTW. Compared with WTW,CTW has shorter mesophyll cell,more cell layers, higher cell density,thinner leaf,larger vascular bundle transverse area and shorter interval between veins.In filling midterm and finalphase, chloroplasts disappearing rate in mesophyll cell is slower.In anthesis,more peculiar shape chloroplasts in mesophyll cell were observed under electron microscope ,ectoplast of which form outer cauda,some of which form vesiclewith monolayer membrane and solute and the other form chloroplast proplastid which develops new chloroplast at last.The percent of grana lamellae which is less than 10 is lower(CTW shan229 flagleaf,2nd leaf and 3rd leaf respectively is 29.7%,21.1 % and 19.7%.WTW NR9405 respectively is 48.7%,32.1% and 20.1 %),chloroplast inner membrane system is more complex,plasmodesma in vascula bundle cell is more.The stem structures of CTW in grain-filling period were studied with paraffin wax section method.The results indicate that vascula bundle number of CTW is more compared with near spike grains. The vascula bundle number in unit stem transverse area and the rate of the total area of vascula bundle and stem transverse area is higher(CTW 1st internode below the ear average respectively is 22.7and8.5%, 2nd internode below the ear average respectively is 14.3 and 6.8%. WTW 1st internode below the ear average respectively is 20.0 and 7.4%, 2nd internode below the ear average respectively is 11.0 and 5.9%). In grain-filling period,the chloroplast disintegrate rate is slower.The starch grain shape in endosperm cell and the ultrastructure of caryopsis ventral canal in grain-filling final period were studied with optics and electron microscope .The results are : the large size starch grain number is more in endosperm cell of CTW,and the starch grain diameter clearly magnify from filling midterm to finalphase.In grain-filling final period,compared with WTW,the CTW grain ventral canal pigment strand cells have more cell organs ,cytoplasm, plasmodesma and fewer lipoid and tannin deposition.Thecell wall thicken no clearly.The seminal root and secondary root micro structure of CTW were observed with barehanded section method,the results indicate:the CTW root have many characteristics contrasted with WTW,the cortex of seminal root is thicker,the stele and vessel transverse area is larger,the vessel total number of secondary root is more.The CTW leaf structure and structure change characteristics were studied under drought and more water conditions ,and grana lamellae and grana amount in leaf chloroplast were counted,the results are: under the drought and more water conditions,the percent of grana lamellae which is more than 20 in CTW leaf chloroplast is clearly higher(under drought condition,CTW shan229 flagleaf,2nd leaf and 3rd leaf respectively is 35.3 % ,23.1 % and 43.3 %. WTW NR9405 respectively is 17.8 % ,15.5 % and 39.4 %. under more water condition,CTW shan229 flagleaf,2nd leaf and 3rd leaf respectively is 23.2 %,34.5% and 25.9%.WTW NR9405 respectively is 17.7%,17.4% and 18.6 %),and the percent of grana lamellae which is less than 10 is clearly lower(under drought condition,CTW shan229 fl更多还原