【作者】 钟雪梅；

【导师】 史振声；

【作者基本信息】 沈阳农业大学 ， 作物学， 2014， 博士

【摘要】 试验于2011年-2013年在沈阳农业大学南试验基地(北纬41。49’,东经123。34’)进行。以易空秆和不易空秆的成对近等基因系沈农98A和沈农98B,易空秆杂交种东单90、东单80,不易空秆杂交种郑单958为试材,在遮荫胁迫处理下,研究比较两种类型品种(系)对弱光胁迫的敏感性差异。明确引起玉米空秆的弱光胁迫时期,探讨不同遮荫胁迫及光照转换后光合速率及荧光特性的动态适应性变化,以期解释寡照天气引起弱光敏感型玉米发生异常性空秆的生理机制,为耐密植(耐荫)玉米新品种选育及对弱光敏感型品种鉴定技术体系的构建奠定基础。主要研究结果如下：1.沈农98A、东单80和东单90属于容易发生空秆的自交系和杂交种即这里所说的空秆型品种(系),其中沈农98A是与不空秆自交系沈农98B相对应的近等基因系。与不空秆品种(系)相比,空秆型品种(系)在三方面显示出明显差异：一是在相同的光胁迫强度下,发生空秆的比率大大高于不空秆型品种(系)；二是诱发空秆的光胁迫强度低于不空秆型品种(系)；三是诱发空秆的光胁迫强度范围清晰明显。进一步证实了玉米中遗传缺陷性空秆的存在。2.抽雄至吐丝末期是玉米遗传缺陷性空秆的弱光敏感时期。此期的弱光胁迫将产生大量不吐丝或吐丝严重不良而形成空秆,其中吐丝株数降低是弱光敏感品种(系)大量空秆的主要原因。诱发具有空秆遗传缺陷的自交系沈农98A空秆基因表达的遮荫胁迫强度为38%遮荫胁迫；诱发正常自交系沈农98B和昌7-2空秆的遮荫胁迫强度范围应为38%-60%遮荫,即遮荫38%以2上且接近38%的光照胁迫是区分沈农98B、昌7-2与沈农98A的光强界限。3个杂交种中,郑单958对弱光的适应性相对较强,特别是75%遮荫时东单90和东单80基本都空秆,而郑单958空秆率只有50%。3.遮荫使玉米雌穗幼穗发育迟缓、变短、变细,穗粒数减少、败育粒数增加；雄穗主轴长、第一分枝数、第一分枝长度和雄小穗总数大幅度下降,并随遮荫强度的增加而加重,易空秆品种(系)的反应更为强烈；株高对遮荫的反应较复杂,轻度遮荫(38%遮荫)可以促进株高的增加,但长时期重度遮荫(75%遮荫)却会降低株高。此外,遮荫胁迫还会使玉米叶面积、比叶重、叶片各部分干重降低,茎秆变细,茎秆强度下降。4.不同自交系对弱光的适应性差异较大,其表现由自交系对弱光的敏感性所决定。不论是在自然光照还是遮荫胁迫下,弱光敏感型自交系沈农98A的净光合速率均低于沈农98B。38%遮荫的光照胁迫是导致弱光敏感型自交系沈农98A与其近等基因系沈农98B产生明显差异的界限光强。此外,弱光敏感型品种(系)的叶绿素含量总体上也低于不敏感型品种(系)。5.遮荫及光照转换对玉米的叶绿素荧光参数有明显影响。遮荫处理后,弱光敏感型自交系沈农98A的最大光化学效率(Fv/Fm)、非循环光合电子传递速率(ETR)、实际光化学效率(φ)psn)和光化学猝灭系数(qP)始终低于沈农98B。恢复光照后,两个自交系的净光合速率(PN)能很快恢复到正常光照的水平,且除沈农98B的qP低于对照外,其余参数均高于对照。弱光敏感型自交系沈农98A的叶绿素荧光参数均低于不敏感型自交系沈农98B,表明沈农98B的对光照转换的适应能力要优于沈农98A。更多还原

【Abstract】 The experiment was conducted on the south farm of Shenyang Agricultural University (41°49’N,123°34’E) from2011-2013, which is classified as a north temperate climate. The experiment applied a split-plot experimental design with inbred lines as the main plots and shading intensities as subplots. Low-light sensitivity differences of different types of varities and lines to shade stresses were compared by using paired near-isogenic line of vulnerable and invulnerable barren stalk inbred lines of Shennong98A and Shennong98B, vulnerable barren stalk hybrids of Dongdan90and Dongdan80, and invulnerable barren stalk hybrid Zhengdan958, to make explicit the key stress period inducing barren stalks, to explore dynamic adaptive changes in the photosynthetic rate and also fluorescence characteristics to different shade stresses and after light intensity transfer. The experiment also aimed to explain the photosynthetic characteristics of barren stalk of low-light-sensitive inbred lines when exposed to limited light conditions. The main results are followed:1. Pairs of near-isogenic line Shennong98A and Shennong98B are developed by the Institute of Specialty Corn of Shenyang Agricultural University. Shennong98A is a barren-stalk defective inbred line, and Dongdan80and Dongdan90are barren-stalk defective hybrids with barren stalk under weak light conditions. They are prone to barren stalks under weak light conditions. Compared with nonbarren-stalk varieties (or lines), barren-stalk varieties (or lines) show significant differences in three aspects:the ratio of barren-stalk is much higher than the barren-stalk varieties (or lines) under the same light intensity, light intensities induced barren-stalks are lower than the light of nonbarren-stalks, critical light intensity induced barren-stalks are clear. It further confirme the existence of genetic defect barren stalk of maize.2. The low-light-sensitive stage inducing genetic defect barren stalk of maize is from tasseling to the end of silking stage. At this stage, weak light stress will generate a large number of barren stalks because of non-silking. The shade stress inducing gene expression of the genetic defect barren stalks of Shennong98A is38%. Shade tolerance of Shennong98B and Chang7-2are similar, whose stress intensities should be between38%and60%. That is to say, more than38%shade or close to38%shade is the light intensity limit to distinguish Shennong98B, Changqi-2and Shennong98A. Zhendan958has the better adaptation ability to weak light condition in three hybrids. There are significant differences in three hybrids under the75%shade. Dongdan90and Dongdan80are basically barren stalks under the75%shade, but Zhengdan958is only50%.3. Shade stresses could make young female ear shorter and thinner, decrease grains per ear, and increase the number of abortive grains. The spindle length of tassel, the first branch numbers, the first branch lengh, and total of male floret numbers decreased with the increase of shade intensity and the reactions of easy barren stalk varieties were much more obvious, even caused100%barren stalk led by female ear agenesis. The reaction of plant height to shade was more complexed.38%shade could promote the increase of plant height, but75%shade for a long period would reduce plant height. In addition, shade stresses also can reduce leaf area, specific leaf weight, straw stiffness and the dry matter of stem, leaf, sheath.4. There were large differences in the weak-light adaptation of different inbred lines, and its performance was determined by the weak-light sensitivety of inbred lines. Whether in natural light or under shade stresses, the net photosynthetic rate of low-light sensitive inbred line Shennong98A was lower than Shennong98B.38%shade is the light intensity limit to distinguish the differences of Shennong98A and Shennong98B. In addition, chlorophyll content of weak-light sensitive varieties (or lines) was lower than insensitive varieties (or lines).5. The effects of shading on the fluorescence parameters of maize were obvious. The noncyclic photosynthetic electron transport rate (ETR) and nonphotochemical quenching (NPQ) of maize were significantly reduced while maximum photochemical conversion efficiency (Fv/Fm), actual photochemical efficiency (φpsn) and photochemical quenching (qP) increased after shading, with effective degrees exacerbated with increases in shade intensity. Upon removal of the shading treatment, NPQ increased and Fv/Fm,φpsu, qP and ETR were restored. Photosynthetic characteristics and their differences are important photosynthetic physiological indexes for identifying barren stalk and nonbarren stalk lines. The PN and fluorescence parameters of the barren-stalk line Shennong98A were lower than that of the nonbarren stalk line Shennong98B, both under a shade and nonshade environment, indicating that the light adaptability of Shennong98B is better than Shennong98A.更多还原