【作者】 刘爱玉；

【导师】 陈金湘；

【作者基本信息】 湖南农业大学 ， 作物学， 2007， 博士

【摘要】 棉花是我国最重要的经济作物之一。在棉花生产中,棉花株高不仅是重要的农艺性状,而且还是大田群体构成和棉田生态结构的主要影响因子。通过对棉花株高的调控来塑造理想株型和构建合理的群体结构,是棉花栽培和品种改良的重要任务。但当前棉花生产中往往只注重通过化学调节剂和人工调节等栽培措施来控制棉花株高,而忽略了品种的改良,尤其忽略了矮秆品种的选育。随着社会和环境的和谐发展,对棉花无公害、高效、节本生产的要求越来越突出,因而在不借助化学或人工调控措施的前提下,通过品种改良,培育矮秆或半矮秆的棉花新品种以构建合理的群体结构,提高光热资源利用率和棉花生产潜力,达到既能节本省工,又避免因施用化学调节剂而引起的环境污染,还可防止对化学调控技术和品种特性缺乏正确认识,或人工调控措施不恰当而造成的减产和品质下降均具有十分重要的意义。本文通过对陆地棉矮秆品种陆矮1号（湖南农业大学棉花研究所选育）的形态特征、矮化机理、生理生化特点和遗传特性的比较研究,揭示了棉花株高的主要控制因素和形成的原因,可为棉花株型育种和栽培调控提供参考依据。主要研究结果如下:（1）陆矮1号是一个典型的矮秆品种,吐絮期株高比对照遗传标准系TM-1和（?）97004H分别矮91.0%和72.5%,矮秆性状稳定,且中上部叶片较小,果枝较短,纵横比例较为协调,成铃集中,单株成铃12-18个,表现早熟。（2）导致陆矮1号株高矮化的时期是生长的中后期。陆矮1号苗期主茎生长速度及节间分化速度与对照品种基本一致,现蕾后陆矮1号株高增长速度减慢,停止生长时间早。盛花期后伸长节间基本固定,表现为有限生长习性。（3）不同品种主茎形态比较研究发现,陆矮1号株高极显著低于对照是由节数减少和节间缩短共同引起,但以节间缩短影响更大,尤其是主茎中上部节间缩短特别明显。陆矮1号主茎节间总数比正常株高品种TM-1和97004H分别少21.2%和14.4%,而主茎节间的平均长度分别缩短57.6%和50.7%。（4）形态解剖和显微观察表明,陆矮1号主茎节间较短主要是由于细胞数量减少所引起的。陆矮1号花铃期主茎倒1-倒6各节间皮层及髓部薄壁细胞均较对照TM-1排列疏松,节间纵向总细胞数明显少于对照,而皮层和髓部细胞大小均无显著差异。（5）形态解剖和显微观察显示陆矮1号主茎次生生长开始早,次生木质部和次生韧皮部、木栓形成层的发生均比TM-1早,且节间维管系统发育进度较对照快,各节间皮层及髓部细胞开始快速伸长和停止伸长的部位也较对照离顶端更近。一般陆矮1号主茎节间发育进度约比对照TM-1早1-2个节间。说明次生生长的过早过快发育对主茎顶端分生组织的生长分化有显著的影响,而这种影响导致了陆矮1号节数的增多和各节内细胞数目的减少,进而使得株高的增长受到限制。（6）对陆矮1号顶芽激素含量分析表明,促进生长的激素含量较少,而抑制生长的激素含量相对较多,从而抑制了陆矮1号株高的增长。陆矮1号在株高建成的主要时期,同时也是陆矮1号株高与对照出现差异的时期,顶芽的GA₃和IAA含量均低于对照TM-1及（TM-1×陆矮1号）F₁,特别是株高增长最快的盛蕾期,分别只有TM-1和F₁顶芽GA₃含量的28.37%和31.04%,初蕾期也只有TM-1的68.4%。盛蕾期以后虽然陆矮1号项芽的ABA含量与其它品种一样急剧减少,但与TM-1和F₁相比仍相对较高,盛蕾期、初花期、盛花期分别比TM-1高26.7%、32.4%、132.5%,比F₁高129.1%、87.5%、37.4%。（7）以激素对株高增长的促进率[（激素处理株高增加量-对照株高增加量）/对照株高增加量×100%]为指标来判断陆矮1号对激素的敏感性。陆矮1号对外源赤霉素的反应敏感性显著强于高秆品种TM-1及其杂种F₁,在100mg/L浓度时,外源赤霉素对陆矮1号株高的促进率达到102.1%。ABA显著抑制陆矮1号、TM-1、F1株高的增长,尤其是较高浓度（40mg/L）ABA,抑制率（负向促进率）达到极显著水平。IAA和KT对陆矮1号和高秆对照及其杂种F₁的株高的增长表现为低浓度促进,高浓度抑制。几种外源激素混合使用时,ABA能大幅度抵消GA₃的促进作用,而IAA、KT的影响效果均不显著。从试验结果分析,可初步认为陆矮1号为GA₃敏感型。（8）陆矮1号功能叶总叶绿素含量与97004H及TM-1无显著差异,但其光合速率却显著低于97004H及TM-1;可溶性糖、淀含量都低于97004H及TM-1。陆矮1号叶片光合速率和可溶性糖及淀粉含量较低是矮秆基因作用使棉株体内激素失衡导致的结果,而不是导致矮秆的原因。（9）陆矮1号矮生性表现为数量性状遗传,从225对引物中筛选出1对与其矮生性连锁的SSR标记BNL3034,经单标记方差分析,该标记对矮秆的贡献率为17.11%。更多还原

【Abstract】 Cotton is one of the most important economic crops in China.Plant height is not only an important agronomic traits of cotton,but also a major factor for field population structure and ecological structure.It is a main task that making ideal shapes and designing rational population structure by adjusting cotton plant height.Up to now,it has been paid much attention to using plant growth regulators（PGRs）and/or pruning artificially to control plant height,but the varieties improving,especially the breeding of dwarf varieties was neglected in a long time.With the developing harmoniously between social and environment,it has been required urgently for cotton production without environment pollution,higher efficiency and cost-saving.Consequently,it is very important to breed dwarf or semi-dwarf cotton-varieties replacing chemical regulators or manpower to modulate plant growth and development,form ideal population structure,enhance the utilizing efficiency of solar-thermal resources and potential productivity.On the other hand, the dwarf varieties with proper plant height had higher lodging resistance and a greater harvest index.This is also a new way for cost-saving in cotton production.So,it is important to exploit and investigate cotton dwarf traits for breeding cotton ideal plant type variety.A dwarf variety of cotton（Gossypium hirsutum L.）"Lu-ai 1" with better boiling and higher resistance to diseases,named temporarily,has been selected by Hunan Agricultural University from abroad cotton germplasm resources.In this study,dwarfing machnism of "Lu-ai 1" has been researched systematically from such respects as on morphology,anatomic structure,endogenous hormones content and the responses to exogenous hormones,the photosynthetical properties,genetic characters and molecular marking.The main results are as follows:（1）"Lu-ai 1" is a typical dwarf variety,which plant height is 91.0%and 72.5%shorter than that of TM-1 and 97004H（normal high statured varieties）respectively at boll opening stage.The dwarfing character of "Lu-ai 1" is stable,with the properties of smaller middle-upper leaves,shorter fruit-branches,harmonious ratio of vertical to horizontal, concentrative boiling（12-18 bolls per plant）and early maturing.（2）The key dwarfing period of "Lu-ai 1" comes into being in middle and late growth period.The elongation speed of intemodes and nodes differentiation speed in main stem of "Lu-ai 1" are similar to that of CK at seedling stage,however,the plant height of "Lu-ai 1" increases more slowly after squaring stage and stops increasing earlier.After full-flowering, the number of elongating internode increases no more,behaving determinate growth property,unlike indeterminate growth property of normal high-statured varieties.（3）The reason for that the plant height of "Lu-ai 1" is markedly lower than that of CK is caused by shorter internodes and less nodes together,of which the effect by shorter internodes,especially by shorter middle-upper internodes,is bigger.The total internode number of "Lu-ai 1" is 21.2%and 14.4%less than that of high-statured TM-1 and 97004H espectively,the average internode length of "Lu-ai 1" is 57.6%and 50.7%shorter than that of high-statured TM-1 and 97004H,respectively.（4）The shorter main stem internodes of "Lu-ai 1" is mainly due to its less cell number. The parenchyma cell of cortex and pith of 1^st～6^thinternode from top of main stem ranges more loosely in "Lu-ai 1" than in TM-1,and the total cell number in vertical of internodes is much less in "Lu-ai 1" than in TM-1.No significant difference of cell size is found in cortex and pith.（5）The secondary growth of main stem,the occurrence of secondary xylem and phloem and phellogen are all earlier and vascular bundle of main stem internodes develop faster in "Lu-ai 1" than in TM-1,the sites of cell fast elongation and stagnant elongation in cortex and pith of internodes are closer to apex in "Lu-ai 1" than in TM-1. The development process of "Lu-ai 1" is about 2 internodes development process earlier than that of TM-1.It suggests that too early and too fast secondary growth may affect the growth and differentiation of apex meristem significantly,and this effect results in more internode number,less cell number and the inhibition of plant height increasing.（6）The less promoting hormones and more inhibiting hormones in apical buds restrain the plant height increasing in "Lu-ai 1".During the key period for plant height formation while the plant height difference between "Lu-ai 1" and CK becoming more obvious,the GA₃ and IAA contents in apical buds are lower in "Lu-ai 1" than in TM-1 and in F₁, especially at full squaring stage when plant height increase fastest,the GA3 content in apical buds of "Lu-ai 1" is only about 28.37%and 31.04%of TM-1 and F1 respectively,at first squaring stage,the GA₃ content in apical buds of "Lu-ai 1" is only 68.4%of TM-1. Although the ABA content in "Lu-ai 1" decreases rapidly after full- squaring stage,still keep higher level compared with that of TM-1 and F₁,with 26.1%、32.4%、132.5%higher than that of TM-1,and with 129.1%、87.5%、37.4%higher than that of F₁ at full- squaring stage,first-flowering stage and full-flowering stage respectively.（7）The index of "plant height promoting rate by hormones"[（increased plant height by hormones - increased plant height of CK）/increased plant height of CK×100%]is used to estimate the sensitivity of "Lu-ai 1" to hormones.The sensibility of "Lu-ai 1" to exogenous GA₃ is higher than that of TM-1 and F₁,the GA3 promoting rate to plant height of "Lu-ai 1" reach up to 102.1%under 100mg/L GA3 concentration.ABA inhibit the plant height of all tested varieties significantly,especially under higher concentration（40mg/L）, the inhibiting effect is extremely significant.The effect of IAA and KT to plant height of all tested varieties behaves promoting under lower concentration and inhibiting under higher concentration.When exogenous hormones are mixed to apply,ABA can counteract the promoting effect of GA₃ to a large extent,no significant effects by IAA and KT.From the results above,it can be considered that "Lu-ai 1" is sensible to GA₃.（8）There is no significant difference in total chlorophyll content among tested varieties, but,the photosynthesis rate" of "Lu-ai 1" is significantly lower than that of 97004H and TM-1,soluble sugar and starch content in "Lu-ai 1" are also lower than in 97004H and TM-1.The lower photosynthesis rate and soluble sugar and starch content in functional leaves is the result of hormones imbalance in "Lu-ai 1" and not the reason of dwarfing.（9）The dwarfing of "Lu-ai 1" behaves as quantitative genetic character.An SSR marker "BNL3034" which link with dwarfing is selected from 225 primers.Variance analysis indicates that the contribution rate of this mark to dwarfing is 17.11%.更多还原