【作者】 王娜；

【导师】 史振声；

【作者基本信息】 沈阳农业大学 ， 作物学， 2011， 博士

【摘要】 玉米维管束是植株机械支撑和物质运输的重要系统,在源库系统中承担“流”的作用,是玉米源库系统协调的重要组织。本文以2种不同耐密类型的4个玉米品种为试验材料,采用植物显微技术与生理生化相结给的方法,研究了不同耐密性玉米品种的维管束形态、发育特点和结构特性,并比较了类型间和品种间的差异；探讨了4个玉米品种维管束性状、“流”强度与流质、叶源和穗库对密度的响应,维管束在源库系统中的作用；分析了维管束特性与倒伏的关系和对水分胁迫的响应。试图进一步完善源库理论,了解玉米维管束输导系统的结构、功能及与源库的关系,为玉米高产栽培与种质创新提供理论依据和参考。试验主要研究结果如下：1不同耐密性玉米品种的维管束特性拔节期茎基部节间维管束在类型内和类型间差异均不显著；抽雄期在类型内、类型间各品种间的差异显著；抽雄期至乳熟期穗位节间维管束在类型间、类型内始终存在着明显差异；穗柄节间、穗轴维管束均表现为随发育进程在类型间和和类型内差异愈加明显。4个玉米品种维管束的差异在植株生长发育早期表现不突出,进入抽雄期后各类型品种间的差异开始完全表现。从不同耐密类型品种的不同植株部位情况来看,茎基部节间维管束发育是稀植型要优于密植型,其中东单60表现最佳；穗位节间、穗柄节间和穗轴的维管束发育则是密植型要优于稀植型,而且衰老进程也较慢,其中以郑单958表现最好。从植株不同部位维管束的内部结构来看,除穗位节外,茎基部节间、穗柄节间和穗轴维管束结构比例变化表现为密植型品种要比稀植型品种更符合植株的生长发育进程。2不同耐密性玉米品种维管束与源库系统对密度的响应稀植型品种植株茎基部节间维管束各密度处理均要大于密植型品种。在植株生长发育早期,密植型品种和东单60茎基部节间维管束对密度的反应较为敏感,至生长发育后期敏感程度降低,而辽单526表现相反。抽雄期和乳熟期,密植型品种的穗位节维管束对密度变化不敏感,而稀植则表现出较大敏感性。抽雄期穗柄维管束只有辽单565对密度响应敏感,至乳熟期两种类型品种穗柄维管束受密度影响均较大。增加密度对玉米植株维管束主要是负向影响。在本试验中将茎基部伤流视为研究“流”活性的一种方式。植株生育前期与中后期密植型品种茎基部节、穗位节的伤流量要大于稀植型品种,由此推断密植型品种维管束的输送能力要优于稀植型品种。4个品种茎基部节伤流量在各密度处理后期比前期有所下降,而穗位节伤流量则相反。郑单958茎基部节伤流对密度的响应在生育前期和后期表现出相同的规律,其它3个品种规律不明显。4个品种穗位节伤流类型内表现出相同的变化规律,且生育前期与后期规律相同。不同耐密性品种茎基部节伤流成分在生育后期与生育前期相比,可溶性糖、无机磷与硝态氮含量呈下降趋势,可溶性蛋白和氨基酸总量增加；各成分所占的比例,密植型品种,由以可溶性糖为主变为以氨基酸为主,稀植型品种除东单60在较高和最高密度处理外,则由以可溶性糖为主变为以无机磷为主。因此认为,不同耐密性品种可能存在着不同的维管束运输协调系统。生育前期,郑单958与其它3个品种相比,在各密度下各成份含量相对均衡,说明其在密度变化时单株的自我调节能力较强,可以推断生育早期郑单958根系的吸收、转化及维竹束的运输能力更强。而生育后期,4个品种各伤流成分在不同密度处理变化都较大,表现出对密度的高度敏感。密植型品种的源系统叶面积小,叶绿素含量低,但已达到光合作用所需水平,总体对密度的响应敏感性相对较差,LAI较高,叶面积与密度呈二次曲线关系,随密度增加有一定的缓冲；稀植型品种相对叶面积多,但对密度响应敏感,与密度呈线性相关,对于密度增加没有缓冲。密植型品种与辽单526的光合速率、蒸腾速率及气孔导度均表现出在对照密度下表现最佳,而东单60光合速率则随密度的增加持续下降。蜡熟期与灌浆期相比,稀植型品种光合速率的下降比例要大于密植型品种。密植型品种的光合速率较高,生育后期水分代谢仍相对旺盛,保证了光合作用的持续。4个品种的产量均在适宜密度时达到最大,且各密度处理下密植型的产量要高于稀植型品种；与密度的拟合均符合一元二次回归方程。不同耐密性玉米品种籽粒营养成分受密度影响不大。3不同耐密性玉米品种维管束与倒伏的关系穗位以下1～7节的抗压力,不同耐密性品种均对密度反应敏感；不同节位的茎粗,在灌浆期和乳熟期与抗压力的相关系数较大且均达极显著水平,且以第3节相关系数最大,这说明茎节的抗压力更主要取决于茎节的粗度。在这两个时期,密度与各节的抗压力呈高度负相关,达极显著水平,这表明密度越大茎秆的抗压力就越差,因此可以用茎秆的抗压力指标测定密度对茎秆强度的影响,并可以此推断田间倒伏情况。不同耐密性品种第3节茎长/茎粗变异系数最大,而穗位/株高比相对稳定,且表现出穗位系数与倒伏率成反比。通径分析结果表明,在茎秆农艺性状与倒伏关系中,第3节茎长/茎粗和株高/第3节茎粗与倒伏率的关系最为密切。茎基部1～3节维管束对密度响应的变化表现为维管束面积的变化与韧皮部面积的变化一致,木质部对密度响应变化相对平缓。茎基部1～2节间维管束对密度变化响应较差,而第3节间维管束对密度的响应更加敏感。这从茎节的生理结构角度显示了茎基部第3节易成为倒伏节的主要原因。不同耐密性品种茎基部第3节性状与倒伏率的关系上,密植型品种比稀植型品种关系更加密切。此外,本试验结果还表明,抗倒伏与株型之间无必然联系,而与品种茎秆性状对密度敏感程度关系更为密切。4不同耐密性玉米品种维管束与水分胁迫的关系生育前期的水分胁迫不仅对营养生长期植株的维管束产生影响,对于生殖生长期的植株维管束同样存在明显的延后效果。维管束大小对水分胁迫在拔节期反应更为敏感,4个品种均有较大程度的减少,但维管束内部结构相对稳定。抽雄期,穗位节维管束受水分胁迫的影响同样表现为逆向,维管束大小缩减,发育缓慢,而此时维管束内部结构调整却更加明显。散粉期各品种穗柄的维管束大小要比对照有所增加,维管束发育状况也优于对照,维管束内部结构调整不大,此期水分胁迫影响表现出积极的一面。水分胁迫品种间的差异要大于类型间的差异。同类型内并未表现出有相似规律的变化。郑单958、辽单565和东单60水分胁迫的敏感性和响应程度更为明显,生育前期水分胁迫的负效应明显,生育后期水分胁迫的正效应也表现明显,而辽526生育前、后期对水分胁迫反应均不敏感,可能缺乏适应外界环境变化的自身调节能力。更多还原

【Abstract】 The vascular bundles are the significant system for mechanical framework and matter transportation of maize, and playing an important role in the flow that harmonizes the source-sink system. Four maize varieties that belong to two different density-tolerant types were selected in this experiment. The shape, development and structure of the vascular bundles and the difference of vascular bundles between varieties were observed through optic microscope. Meanwhile the responses of flow intension and its components, leaf-source and ear-sink to densities were studied to analyze the function of vascular bundles in source-sink system and the relationship between vascular bundles and lodging. In addition the effects of water stress on vascular bundle characteristics were also studied in this experiment. The understanding of the structure and function of vascular bundles and its relationship to source-sink system could perfect the source-sink theory and provide an insight for high-yield cultivation and breeding for maize. The main results showed as follows:1 The vascular bundle characteristic of different density-tolerant maizeThere was no significant difference of basal stem vascular bundle within the same type and between the different types at jointing stage, but the significant difference was found at tasselling stage. From the tasselling stage to the milk maturity, the significant difference always existed in vascular bundle of ear-located stem in all four varieties. The difference of vascular bundle in the ear first stalk and ear cob among varieties was clearer with the developmental process of maize. Namely, there was no difference in vascular bundle of four maize varieties until tasselling stage.From the aspect of different plant parts of different density-tolerant maize varieties, the vascular bundle development in basal stem of the thin density varieties was better than that of the density-tolerant varieties, especially in Dongdan60. The vascular bundle development in ear first stalk and ear cob of the density-tolerant varieties was better than that of thin-density varieties, especially in Zhengdan958. From the aspect of vascular bundle structure in different plant parts, the vascular bundle structure of the basal stem, ear first stalk and ear cob except ear-located ear of the density-tolerant varieties was up to the plant development.2 The responses of vascular bundle and source-sink system of different density-tolerant maize to densitiesThe vascular bundle areas of the thin-density varieties at all density treatments were bigger than that of the density-tolerant varieties. The basal stem vascular bundles of density-tolerant varieties and Dongdan60 at early growing stage were sensitive to the change of density, and became insensitive at later growing stage. However, Liaodan565 was opposite. The ear-located vascular bundles of the density-tolerant varieties were not sensitive at the change of the density at tasselling and milk maturity stage, but it appeared more sensitive in the thin-density varieties. Ear stalk vascular bundle in Liaodan565 was sensitive at density at tasselling. Till milk maturity effects of density on ear stalk vascular bundle of both types were great. Increasing of density had mainly negative impacts on the vascular bundle of maize plant.The sap of the basal stem was considered as a flow to study its activities in this research. The sap content of basal and ear-located stem in density-tolerant varieties were more than that of the thin-density varieties, thus, it could be deduced that the transportation capacity of density-tolerant were better than that of the thin density varieties. The sap content of four varieties basal stem at all density treatments declined from the early growing period to the later growing period, however it acted on opposition in the ear located. The response of the basal stem sap content in Zhengdan958 to densities showed the same way at early and later growing stage, and there was no apparent rule in the other three varieties. The ear-located stem sap content within the same types showed the same change rule at both early and later growing stage.The contents of soluble sugar, inorganic phosphates and nitrate nitrogen in the basal stem sap decreased with the development, and yet the soluble protein and total amino acid content increased. The main component in basal stem sap of density-tolerant maize changed from soluble sugar to amino acid and inorganic phosphates became the main component in basal stem sap in thin-density maize varieties from soluble sugar except Dongdan60 at the top and higher density. Consequently the different density-tolerant maize varieties had their own adjusted vascular bundle transportation system. At early stage, the components of sap in Zhengdan958 were balanced compared with the other three varieties; thus, it was considered that zhengdan958 had strong self-adjustment ability and its ability of absorbing and transporting in root was better. At later stage, the components of sap in basal stem of all varieties were more sensitive to the density.Though the relative single leaf area of density-tolerant maize varieties was small and its chlorophyll content was low, LAI was higher and the photosynthesis demands were met. The relationship of leaf area with densities in density-tolerant maize was second-degree curve which helped to release the density press. However, the relationship of leaf area with densities in density-tolerant maize was linear; the leaf areas of thin-density varieties were relatively higher and sensitive to densities. Photosynthetic rate, transpiration rate and stomatal conductance of density-tolerant varieties and Liaodan526 were at the highest level at the contrast density, but photosynthetic rate of Dongdan60 continuously declined with the density increased. Form the filling stage to wax ripeness stage, the decrease rate of photosynthetic rate of density-thin varieties was larger than that of density-tolerant varieties. The high rate of photosynthesis and water metabolism in density-tolerant varieties remained function of photosynthesis for a relative long time. The highest yield was gained at the proper density, and the yield of the density-tolerant varieties was higher than that of thin-density varieties. One-dimensional quadratic regression equation was build between the yield and the density in all varieties. There were no significant effects on grain nutrition by densities in all varieties.3 The relationship between the vascular bundle characteristic and lodgingThe response of stalk anti-press from the first stem to the seventh stem in different density-tolerant maize varieties to densities was sensitive. Correlation coefficient between diameter and anti-press of different stems was significant at 0.01 level at filling and milk maturity stage, in particular the third stem had the largest correlation coefficient. So the analysis of correlation suggested that the stem anti-press demanded on the stem diameter. The densities and stem anti-press were negative correlated which indicated higher density induced lower stem anti-press. Therefore the stem anti-press could be an index to determine the effect of density on stem intension to anticipate the lodging. The coefficient of variation of stem length/diameter of the third stem was the largest but the ear-located height/plant height was relatively stable. And the ear-located height/plant height was inversely proportional to the lodging rate. The relationship of lodging with stem length/diameter and plant/stem diameter in the third stem was closest through the path analysis.The responses of the basal 1-3 stem internodes vascular bundle to the densities showed the vascular areas change was similar with the phloem area and xylem area changed smoothly. The vascular bundle of the third stem was the most sensitive to the densities which explained the main reason for the lodging often caused by the third stem. The relationship of the lodging with third stem traits in the density-tolerant varieties was closer than that in the thin-density varieties. In addition the lodging was no necessary connected with the plant type but sensitive to the stem traits.4 The relationship between the vascular bundle characteristic and water stressWater stress occurred in early stage not only affected the development of vascular bundle in the nutrient period but also produced laggard effects on vascular bundle in generative period. The vascular bundle size at jointing stage was more sensitive to the water stress occurred at seedling stage with the evident decrease in vascular bundle size of all maize varieties, but the vascular bundle structure was stable. The effects of water stress on vascular bundle of ear-located stem at tasselling stage was negative which reduced the vascular bundle area and slow down the development, but the changes of vascular bundle structure were patent. At anthesis vascular bundle area in the ear stalk was increased and its development was facilitated under the water stress.The difference of vascular bundle induced by water stress in varieties was larger than that in types. The similar changes were not found in the same types. Zhengdan958, Liaodan565 and Dongdan60 were more sensitive to the water stress, and negative impacts by water stress were apparently observed at early growing stage and positive impacts at later growing stage. Liaodan526 was not sensitive to the water stress at all growing stage, maybe it was absent in self-adjustment for the change of the environment.更多还原