【作者】 李朴芳；

【导师】 熊友才；

【作者基本信息】 兰州大学 ， 生态学， 2010， 硕士

【摘要】 以进化上具有亲缘关系的6个小麦品种作为实验材料,采用盆栽控水的方法,2008年和2009年测定了四个野生近缘种(二倍体MO1和M04、四倍体DM22和DM31)、两个六倍体包括古老六倍体品种和尚头(无麦芒)及1998年培育成的现代六倍体品种陇春8275(有麦芒)的株型和产量形成变化。利用灰色关联度分析法和异速生长关系等统计方法研究了不同供水条件下不同倍体小麦株型性状的演化特征(叶型、茎型)、籽粒产量形成和植株组件之间的几何关系,得出如下主要结论：1.旱地小麦的叶型演变强化了人工种群属性。随着小麦染色体倍数的增加,小麦植株上三片叶的叶夹角、叶开角、弯曲度及叶面积均呈逐渐增大的趋势,而叶片长／宽比却表现为逐渐变小,该现象在充分供水条件下更加明显。这些特征表明旱地小麦通过增大叶片角度、叶片演化向着短而宽的方向演化来规避种群内部竞争和增大群体水平上的光捕捉面积,这种进化策略有助于提高群体产量,验证了现代小麦的个体互利型属性和人工种群性质。2.旱地小麦茎型是以产量为目标进行演变。随着小麦倍体的增加,单株分蘖数逐渐减少,株高逐渐增加。充分供水条件下,二倍体和四倍体的分蘖数在7和4之间,显著高于六倍体的3个分蘖数,干旱条件下二倍体和四倍体的分蘖数在4到3之间同样显著高于六倍体的2个分蘖数,且充分供水条件下不同品种的分蘖数均高于干旱条件下的分蘖数,分蘖数的减少有利于资源更多地配置到主株的垂直分配上,从而提高植株高,不同倍体茎秆节数均出现四个节、五个节和六个节现象,且四个节的植株最接近株高构成指数的“黄金分割”—0.618,五个节的植株次之,六个节最差,该趋势在充分供水条件下更为明显。初步认为,在供水充足条件下小麦植株主要建立茎节间的理想黄金分割比例来获得较高的繁殖分配,进一步证明了以籽粒产量为目标的茎节间的黄金分割比例规律。3.株高的黄金分割比例关系是自然选择和人工选择的结果。充分供水条件现代品种茎节间的黄金分割出现偏离,偏离值在介于8.23%和-60.33%之间,干旱胁迫下不同品种的偏离值和调控能力有较大差异。现代品种的偏离值介于-5.48%和-19.09%之间,而野生近缘种则处于-32.91%和-12.34%(二倍体)与-26.05%和-53.47%(四倍体)之间。干旱胁迫下小麦株高随着小麦倍体的增加而增加,从二倍体到四倍体的株高的增加是对自然选择的适应性进化,而从四倍体到六倍体的株高增加则主要是以产量为目标的人工选择的结果。4.基茎横截面积与籽粒产量具有高度的关联性。无论是干旱胁迫组还是充分供水组,小麦植株分蘖数与产量的关联度均为最低,而株高与产量的关联度均较高,推测旱地小麦在从二倍体到六倍体的进化过程中朝向“低分蘖、高株型”的方向演变。三种主要光合叶片(旗叶、倒2叶和倒3叶)的“生物量”与产量的关联度均大于“叶位高度”的关联度,表明叶片的“质量效应”大于其“”空间着生效应。基茎横截面积在充分供水组中与产量的关联度最高,而在干旱胁迫组中则排倒数第二,表明该性状可能是干旱胁迫下产量形成的敏感指标,是作物产量形成的物质及结构基础。5.小麦植株各组件间的异速生长关系比较。除极个别品种外,不同倍体小麦籽粒产量与地上生物量,叶片重量与地上生物量,分蘖数与地上生物量均存在异速生长关系,这种异速生长关系可采用模型方程y=a+bx表示。充分供水条件下二倍体籽粒重量与地上生物量异速生长现象较干旱条件不不明显,六倍体则相反；充分供水条件下二四六倍体叶片重量与地上部分生物量的异速生长现象明显；二倍体品种的分蘖数与地上生物量在充分供水异速生长现象明显,其余各品种均不明显,趋于协调趋势。更多还原

【Abstract】 Pot-culture and water-control experiments were conducted to determine the changes in plant type and yield formation using six wheat varieties with evolutionally genetic relationship as experimental materials including four wild relatives (Diploid wheat MO1 and MO4, Tetraploid wheat DM22 and DM31), and two hexaploid wheat including old hexaploid Monkhead and modern hexaploid Longchun 8275 which was released in 1998 under the conditions of rain shelter. By analysing the plant type evolution and its relationship with yield formation in different-ploidy wheats under drought stress and sufficient water supply. A few major conclusions were made as follows:1. The data indicated that the leaf angle against stem, the leaf opening angle, the leaf camber and the leaf area tended to increase with the multiplication of chromosome sets, while the length-to-width ratio of leaf was found to decrease. This trend was more distinct under well watered condition. The yield per pot and the yield stability were increased along with the evolvement of wheat varieties. The results showed that dryland wheat was developed to avoid intraspecific competition and enlarge the leaf area to capture sunlight at the level of population by way of increasing blade angle, broadening and shortening blade dimension, which would help improve the population yield as an evolutionary strategy. Experimental results demonstrate the mutually beneficial nature of modern wheat at the individual level and the property of artificial populations.2.Along with the growth of chromosome complement, wheat plant showed decreased branch number、increased stem length. The stem length increases in two ways, one is to increase the length of internode, and the other is to add pitch number. All different-ploidy wheats emerged tillers that have four internodes、five internodes、six internodes, and wheat plant with four internodes is nearest the Golden section index of plant height-0.618, followed by type of five internodes and then type of six internodes. To drought stress group, this kind of effects is sharper. It is believed that wheat plant build ideal Golden section to fulfill its high yield under sufficient water supply, this proportion is broken down under drought stress, whereas wheat with different diploid have different ability to recover and rebuild this proportion. It is obvious that modern wheat plants are superior to wild wheat plants in this direction. Wheat height evolution is not only an active way to adapt to natural selection, but also the result of artificvial selections with a view to increasing crop yields.3. Tactic difference of the golden proportion. The Golden proportion of modern varieties’internodes appear deviate under sufficient water supply, deviation value is between 8.23% and -60.33%, but to varieties under drought stress, there is a big gap between their deviation value and steering capacity. The research shows deviation value of modern varieties is between-5.48% and -19.09%, the value of wild species fall in between -32.91% and -12.34%(diploid) or between -26.05% and -53.47% (tetraploid). Plant height of wheat is increasing as its multiple increase under drought stress, stem height increasing from diploid plant to tetraploid plant is adaptive evolution of natural selection, nevertheless, stem height increasing from tetraploid plant to hexaploid plant is the result of artificial selection aimed volume of production.4. Grey analysis results indicated that the correlation of tillering number to yield was the lowest, but that of plant height to yield relatively high both in CK and S groups, suggesting that dryland wheat was evolved following the tendency of "lower tillering rate, higher plant height" along with the progress from diploid to hexaploid. Biomass of three kinds of main photosynthetic leaves (flag leaf, top 2nd leaf and top 3rd leaf) were observed to wholly share higher correlation to yield than their location height, showing that the effect of leaf biomass was superior to its spatial location effect. Specially, it was first found that the cross sectional area of bottom stem had the highest correlation rate to yield in CK group, but it was ranked last but one in S group. The evidence showed that this trait was likely to be a sensitive indicator of yield formation as a result of drought stress, which was substantial and structural basis of yield formation.5. The comparation of wheat plant pieces between different speed growth:Except very few pieces, different wheat grain yield and the biomass above-ground, leaf weight and ground biomass, the biomasses and tiller development exist allometry-relationship, the allometry-relationship can be showed with y=a+bx Compared with wheat under dronght stress, the grain weight and biomass growth rate of diploid wheat is not obvious under sufficient water supply, as it is not to hexaploid. For all three ploidy types, regulation of allometric growth between leaves weight and the biomass above-ground is obvious; Diploid tillering and the biomass above-ground is more noticeable under sufficient water supply, the others breed is not distinct, and tends to coordinate.更多还原