【作者】 倪英丽；

【导师】 王振林；

【作者基本信息】 山东农业大学 ， 作物栽培学与耕作学， 2013， 博士

【摘要】 小麦是世界上重要的粮食作物之一，其产量水平的高低直接影响着全球粮食安全。提高穗粒数是小麦产量超高产栽培的重要途径之一。因此研究小麦小花发育及穗粒数的形成机理及栽培调控措施对提高小麦单产具有重要的理论和实践意义。本研究选用不同穗型小麦品种为试验材料，通过设置不同的种植密度、氮素水平和外源激素等栽培措施，系统研究不同穗型小麦品种小花发育过程中，穗花及其功能叶内源激素变化，探讨内源激素含量及其平衡状况与小花发育结实的关系，明确内源激素对小花发育的调控机制，阐明种植密度、氮素水平及外源化学调控措施对小麦小花生长发育的调节效应及机制，在理论和技术上探讨了增加小花结实率，提高结实整齐度的途径。主要研究结果如下：1不同穗型小麦品种小花发育差异性的生理基础的研究大穗型小麦品种小花分化速率较快，每穗总小花数多，形成的可孕小花数和结实粒数显著高于多穗型小麦品种。大穗型品种与多穗型品种在强势位小花的结实率差异较小，但大穗型品种弱势位小花的结实率显著高于多穗型品种。在小花分化后期，大穗型品种穗/茎干物重比值显著高于多穗型品种，相关分析表明，开花期穗干物重与结实粒数之间存在显著正相关关系。说明，大穗型品种有更多的同化物转运到穗中，为更多结实粒数的形成提供有利条件。大穗型小麦品种功能叶中蔗糖含量、穗内可溶性总糖含量、蔗糖含量以及可溶性蛋白质含量均显著高于多穗型小麦品种。在药隔形成期以后，大穗型品种穗内C/N比值显著高于多穗型品种。小麦穗内N代谢有利于小花原基分化，C代谢则促进小花发育，穗内较高的C/N比值有利于大穗的形成和小花的结实。随小花发育进程，大穗型和多穗型小麦品种穗内GA3含量均呈“W”曲线变化。与多穗型小麦品种相比，大穗型品种穗内GA3含量高峰期出现延迟；在药隔形成期，大穗型品种穗内GA3含量显著高于多穗型品种。穗内IAA含量随小花发育进程呈“S”型曲线变化；在药隔形成期，大穗型品种穗内IAA含量显著高于多穗型品种。大穗型品种穗内ZR含量随小花发育呈“W”型变化模式，而多穗型品种则呈“V”型变化；在药隔形成期，大穗型品种穗内ZR含量显著高于多穗型品种。这说明，药隔形成期穗内较高的GA3、IAA和ZR含量有利于大穗的形成。随小花发育进程，大穗型和多穗型小麦品种穗内ABA含量呈先升高后降低然后趋于平稳的变化趋势。药隔形成期，大穗型小麦穗内ABA含量迅速下降，而多穗型下降速度较为缓慢，这说明，药隔形成期至四分体形成期，穗内ABA含量的迅速下降，有利于大穗的形成。相关分析表明，结实粒数与药隔形成期穗内GA3含量和穗/叶GA3比值呈极显著正相关关系（P<0.01），与药隔形成期穗内IAA含量呈极显著正相关关系（P<0.01），与药隔形成期和四分体形成期穗内ABA含量呈极显著负相关关系（P<0.01），这表明，药隔形成期，穗内GA3和IAA含量越高，ABA含量越低，结实粒数越多。穗内较高的GA3、IAA和ZR含量是形成较多结实粒数的重要生理基础。小穗上各小花鲜重、可溶性糖含量、蔗糖含量、果聚糖含量、可溶性蛋白质含量均随小花位升高而降低，并且大穗型品种小花高于多穗型品种小花。在开花前18天开始，不结实小花鲜重、可溶性糖含量、蔗糖含量、果聚糖含量、可溶性蛋白质含量出现显著下降，表明不结实小花已经开始进入退化期。结实小花内源GA3和ABA含量随小花发育表现为先降低后升高的变化趋势，结实小花中IAA含量则保持相对较低的水平，并且保持相对稳定状态。而不结实小花中IAA含量在小花退化开始时就处于较高的水平，显著高于结实小花；不结实小花中ABA含量随小花退化出现大幅度上升。小花退化开始时，不结实小花中GA3/ABA、IAA/ABA和ZR/ABA比值均显著高于结实小花，随后出现大幅度下降。说明不结实小花中较高的IAA含量和GA3/ABA、IAA/ABA和ZR/ABA的快速下降可能是导致小花退化的原因。2栽培措施对小花生长发育及机理调控的研究2.1不同种植密度下，小花生长发育及机理的研究在小花发育过程中，功能叶蔗糖含量随种植密度增加而降低；穗内可溶性总糖含量、蔗糖含量和果聚糖含量随种植密度增加而降低，而穗内可溶性蛋白质含量则随种植密度增加而增加。这表明，低种植密度条件有利于穗内可溶性糖的合成，或者低种植密度条件有利于功能叶中蔗糖向穗内转运。穗内C/N比值随种植密度增加而降低，这说明，过高的种植密度有利于穗内氮代谢进程，不利于碳代谢进程，不利于大穗的形成。药隔形成期以后，随种植密度增加，两不同穗型小麦品种穗内GA3、IAA和ZR含量均表现为下降的趋势，而穗内ABA含量随种植密度增加而增加。功能叶中GA3、IAA和ABA含量均随种植密度增加而增加，但是功能叶中ZR含量在各种植密度处理之间无显著差异。这说明，低种植密度条件有利于小花发育后期穗内GA3、IAA和ZR的合成，但是不利于ABA的合成。随种植密度下降，穗部结实特性和粒重有优化的趋势，大穗型小麦品种对种植密度反应更为敏感，而多穗型小麦品种的小穗位和粒位对种植密度的调节效应较强。小麦穗的结实粒数、小穗重与单粒重在不同小穗位上均呈二次曲线分布，呈现籽粒的近中优势，主茎优于分蘖。随种植密度的增加，单穗结实小穗数、每小穗结实粒数和单粒重有降低的趋势，表明种植密度过大不利于产量的形成。2.2氮素水平对小花生长发育及机理的影响小花分化发育前期，总小花数随氮素水平增加而降低，这表明，低氮水平促进小花分化发育，高氮水平延缓小花发育进程。随氮素水平增加，穗粒数、小花分化数、可孕小花数目、分化速率和开花期穗干物重均表现为先升高后降低的变化趋势，在氮素水平240N kg·hm^-2处理条件下达到最大值。这表明，氮素水平240N kg·hm^-2栽培措施最有利于穗粒数的形成。在氮素水平低于240N kg·hm^-2时，穗内可溶性总糖含量和蔗糖含量随着氮素水平提高呈上升趋势，但氮素水平再提高，蔗糖含量又开始下降，表明施氮有利于穗内蔗糖的积累，但过量施氮不利于穗中蔗糖的形成，或者不利于叶中蔗糖向穗内转运。穗内可溶性蛋白质含量随氮素水平增加而增加，这表明增施氮肥有利于穗内可溶性蛋白质的合成。穗内C/N比值随氮肥增加呈上升趋势，在氮素水平240N kg·hm^-2处理条件下达到最大值，说明增施氮肥有利于穗内C/N比值的提高，但是过多施氮反而降低穗内C/N比值。药隔形成期以后，随氮素水平增加，穗内源激素GA3、IAA、ZR和ABA含量均表现为升高的趋势。穗内GA3/ABA、IAA/ABA和ZR/ABA比值均随氮素水平增加呈先上升后下降的趋势，在氮素水平240N kg·hm^-2条件下达到最大值。这说明，增施氮肥有利于穗内GA3/ABA、IAA/ABA和ZR/ABA比值的提高。增施氮肥显著提高小花发育后期大穗型品种穗/叶GA3、穗/叶IAA和穗/叶ABA比值。与不施氮肥相比，增施氮肥抑制了药隔形成期以后穗内细胞分裂素氧化酶活性的提高。穗内细胞分裂素氧化酶活性在氮素水平240N kg·hm^-2时达到最小值，氮素水平再提高(360N kg·hm^-2)，其活性与240Nkg·hm^-2条件下无显著差异。与不施氮处理相比，施氮处理(240N kg·hm^-2)显著提高了小麦穗内TaCKX3基因表达量，说明氮素可调控小花发育后期穗内细胞分裂素氧化酶基因的表达。2.3外源激素ZT或ABA对小花发育与结实的调控外源ZT和ABA对小花发育具有显著的调控效应。外源ZT主要通过增加弱势位小花结实率来提高穗粒数。外源ZT显著提高了穗内可溶性糖含量和C/N比值，从而为大穗的形成提供有利条件。外源ZT显著降低了穗内ABA含量，提高了穗内GA3、IAA和ZR含量，尤其以药隔形成期的外源ZT处理效果最为显著。外源ABA降低了弱势位小花结实率，显著降低了穗粒数。外源ABA降低了穗内可溶性糖含量和C/N比值，降低了穗内GA3、IAA和ZR含量，但增加了穗内ABA含量。更多还原

【Abstract】 Wheat (Triticum aestivum L.) production is considered vital to ensure global food security.It has been recently agreed that the grain number per spike is still the main factor limitingwheat super high yield potential. Physiological basis of floret development and grain numberper spike and its regulation in wheat play a major role in the remarkable grain yield in wheat.In this study, wheat cultivars differing in spike-types were grown at Tai’an ExperimentalStation of Shandong Agricultural University during the2010-2011and2011-2012growingseasons. The studies were focused on the changes endogenous hormones in spike, floret andleaf. The result elucidated the relationship between endogenous hormones and floretdevelopment and grain set, discussed the regulatory mechanism of endogenous hormones onfloret development, and physiological and chemical mechanism of plant densities, nitrogenapplication rates and exogenous hormone effect on floret development in wheat. Informationobtained will help to provide a theoretical basis for obtaining higher floret setting rate andimproving floret setting uniformity. The main results were as follows.1Physiological Basis of Floret Development in different spike type wheatLarge-spike cultivars had the faster floret differentiation rate, more floret number, fertilefloret number and grain number per spike than medium-spike cultivars. There were littledifferences in superior floret setting rate between large-spike cultivars and medium-spikecultivars, but a large difference in inferior floret setting rate between them. Analyzing fromthe photosynthate, at the later floret development stage, the rates of photosynthate ofspike/culm in large-spike cultivars were significantly larger than that in medium-spikecultivars. Correlation analysis showed that there was a significantly positive relationshipbetween spike dry weight at anthesis and grain number per spike. It was showed that more photosynthate to spike was favored for more grain number.Sucrose content in leaves, total soluble sugar content, sucrose content and soluble proteincontent in spike were more in large-spike cultivars than in medium-spike cultivars. After theanther formation, the C/N ratio in spike in large-spike cultivars was larger than that inmedium-spike cultivars. It was showed that N metabolism in spike was advantageous to thefloret primordium differentiating, and C metabolism was in favour of floret development, andthe higher C/N ratio was beneficial to grain number per spike.During floret development stage, the changes of GA3content in spike showed the ‘W’model with the two lowest contents at stamen and pistil initiation and floret degeneration. AndIAA content in spike showed the ‘S’ model during floret development stage. Compared withthe medium-spike cultivars, the GA3and IAA peak levels of spike were delayed in thelarge-spike cultivars. Furthermore, the GA3and IAA content in spike of large-spike cultivarsat anther formation were much higher than that in the medium-spike cultivars. However, ZRcontent in spike of large-spike cultivars showed the ‘W’ model, but the ‘V’ model ofmedium-spike cultivars. And at anther formation, the ZR content in spike of the large-spikecultivars was much higher than that in the medium-spike cultivars. It was suggested thathigher GA3, IAA and ZR contents at anther formation were useful for the formation of lagerspike. At anther formation, ABA content in spike was dropped rapidly in large-spike cultivars,but slowly in medium-spike cultivars. It indicated that ABA content from anther formation tomeiosis dropped rapidly was beneficial for the formation of lager spike. The grain number perspike was highly positively correlated with GA3in spike and in spike/leaf at anther formation,and the IAA content in spike anther formation (P<0.01). There was a negative relationshipbetween grain number per spike and ABA content at anther formation and meiosis (P<0.01).During the floret development and degeneration stage, GA3and ABA in fertile floretsshowed ‘V’ model, but IAA content in fertile florets remained a relative stable and low level.But there was a much higher IAA content in stertile florets at the beginning of the floretdevelopment and degeneration stage. ABA content in stertile florets was significantlyincreased during the floret development and degeneration stage. However, GA3/ABA,IAA/ABA and ZR/ABA in stertile florets was much higher than that in fertile florets, but thendecimated. It was showed that the higher IAA content and the decimated of GA3/ABA,IAA/ABA, ZR/ABA in stertile florets may be one of the cases of floret degeneration.2The study of regulation of cultivation measures on floret development and mechanism2.1The study of floret development and mechanism under different plant densities During floret development stage, the sucrose content in leaves, the total soluble sugarcontent and the sucrose content in spike was decreased as increased plant densities. Butsoluble protein content in spike was increased with the increasing plant densities. The resultsuggested that low plant density was in favor of the accumulation of total soluble sugar inspike, or low plant density was beneficial to sucrose to spike within the leaf. The C/N ratio inspike was decreased as increased plant densities, and it was showed that higher plant densitywas not conducive to carbon metabolism, then to large spike formation.After anther formation, the GA3, IAA and ZR contents in spike were decreased with theincreasing plant densities, but ABA content in spike was increased. The result suggested thatlow plant density was in favor of the accumulation of GA3, IAA and ZR in spike at later floretdevelopment stage, but high plant density was in favor of the accumulation of ABA.The results showed that the grain number, spikelet weight, and grain weight with thespikelet positions from the bottom to the top increased first and then decreased, showedparabolic change. Meanwhile, grain setting traits of main spike were superior to that oftillering spike. Under low plant density, the grain setting characteristics and grain weight inlarge-spike cultivars were more superior to those in medium-spike cultivars, and those ofmain stem spike were more superior to those of tillering spike. In fact, high plant density isnot conducive to high yield.2.2Effect of nitrogen application rate on floret development and mechanismAt the early floret development stage, total floret number was decreased with increasingnitrogen (N) levels. The result suggested that low N level promoted the floret development,but the floret development was delayed under high N level. With the increaseing N levels, thegrain number per spike, total floret number, fertile floret, differentiation rate and spike dryweight was increased first, then decreased, and showed the largest increased at N level of240kg N ha-1. It was indicated that N level of240kg N ha-1was in favor of grain number.Nitrogen increased the sucrose content and the total soluble sugar content in spike of wheat.Sucrose content in wheat spike under240kg N ha-1treatments were significantly higher thanthat under N0treatment. However, the excess360kg N ha-1treatment led to a significantdecline in sucrose content in spike of the cultivars. These indicated that appropriate nitrogencould increase the sucrose, and excess nitrogen could decrease the transfer of the sucrose fromleaves to spike. The soluble protein content in spike was increased with the increasing Napplications, and it was suggested that N fertilizer was in favor of the accumulation of solubleprotein. N fertilizer generally increased the C/N ratio in spike as N rate was increased from0 to240kg N ha-1, and then decreased the C/N ratio in spike as N rate was further increased to360kg N ha-1. This indicated that N generally favored C/N in spike up to the N level of240kg N ha-1, while excessive N (360kg N ha-1) decreased the C/N ratio in spike.After anther formation, the GA3, IAA and ZR contents in spike were increased with theincreasing nitrogen applications, but the ABA content in spike was increased. The resultsuggested that low plant density was in favor of the accumulation of GA3, IAA and ZR inspike at later floret development stage, but high plant density was in favor of theaccumulation of ABA. GA3/ABA, IAA/ABA and ZR/ABA in spike were increased withincreasing0-240kg N ha-1levels, but decreased at360kg N ha-1level. It was showed thatnitrogen application was in favor in increasing GA3/ABA, IAA/ABA and ZR/ABA. Nitrogenapplication increased spike/leaf GA3, IAA and ABA during the later floret development stage.Cytokinin oxidase activity in spike was decreased with the increasing nitrogen treatment, andthe least level was under the240kg N ha-1treatment. However, there was no significantdifference of Cytokinin oxidase activity between the240kg N ha-1treatment and the360kg Nha-1treatment. Transcript levels for TaCKX3in spike under nitrogen treatment (240kg N ha-1)were significantly higher than that under nitrogen treatment (0kg N ha-1) from meiosis toanthesis, which indicating that nitrogen could increase the expression of TaCKX3genes inspike, and it is possible that nitrogen could regulate Cytokinin oxidase expression in transcriptlevels.2.3Effect of exogenous ZT or ABA on the floret development and the grain in wheatFloret development was obviously effected by exogenous hormone ZT and ABA.Exogenous hormone ZT increased the grain number by increasing the setting rate of inferiorfloret, especially for ZT application at anther formation. Exogenous ZT significantlyincreased sucrose content and C/N in spike, that provide much more photosynthate forlarge–spike cultivars. But Exogenous ZT increased the GA3, IAA and ZR content in spike,especially for ZT application at anther formation. Exogenous hormone ABA inhibited floretdevelopment, and decreased the fertile florets and grain set almost at all floret developmentstage. But at anther formation, the spike was more tolerant to ABA without significant lose offertile florets. The inhibition effect of ABA was mainly on inferior floret on a spikelet.更多还原