【作者】 欧阳由男；

【导师】 张国平；

【作者基本信息】 浙江大学 ， 作物学， 2008， 博士

【摘要】 分蘖是水稻等禾本科作物在生长发育过程中形成的一种特殊的分枝，是十分重要的株型指标，与籽粒产量密切相关。分蘖及其叶片着生姿态是分蘖性状研究中的核心内容，而分蘖角度控制分蘖和叶片的着生姿态，进而影响植株光能利用和群体内个体间竞争。水稻前期分蘖散生可增加植株截光面积、提早封行和抑制杂草发生，后期分蘖直立则改善群体通风透光、提高抵御病害和倒伏能力。作者及所在课题组在前期研究工作中发现了前期分蘖散生、拔节后分蘖渐趋直立的水稻基因型DI508，经初步研究，表明其分蘖角度的变化与光周期相关。在此基础上，本文以分蘖角度动态型水稻基因型DI508和全生育期分蘖直立型基因型（协优9308或9308）、半散生基因型（M09或DI444）为材料，分析比较它们的形态特征和生长发育特性、光能和养分吸收利用上的差异，利用大田分期播种试验和可控环境条件研究水稻分蘖角度的光周期和温度效应，利用2个重组自交系群体进行分蘖角度的QTL分析，以阐明分蘖角度动态变化的生理生态和遗传机理。主要结果如下：1、分蘖角度动态型水稻DI508表现为分蘖期散生快长、拔节后趋于直立的生长特性，其主茎第1、第2和第3分蘖在始蘖期与水平地面夹角平均分别为59．74°、62．94°和68．54°，与半散生型基因型M09相似，抽穗后分蘖角度几近90°，与直立型基因型9308相似。DI508的分蘖成穗率为68．35％，高于M09；成熟期单株干重达155．54 g，比M09和9308分别高15．84％和64．09％；单蘖干量9．15g，比M09和9308分别高63．69％和44．78％；生育后期上三叶净光合速率值为26．89μmol．m^-2．s^-1、25．69μmol．m^-2．s^-1和24．83μmol．m-²．s^-1，下降幅度明显小于M09和9308。2、DI508对光环境适应性较强，分蘖盛期和灌浆期的最大净光合速率和光饱和点介于协优9308（分蘖直立型）和DI444（分蘖半散生型）之间。DI508在弱光下光合速率和表观量子效率均要高于其它两个基因型，且光补偿点较低。在各种光强下，DI508的羧化效率在分蘖盛期与另外两个基因型相近，但在灌浆期明显高于DI444；同时，该材料有较高的水分利用效率。3、DI508的分蘖角度在不同施氮条件下均呈动态变化，且植株收敛指数在分蘖盛期后逐渐增大，但施氮水平对分蘖角度和植株收敛指数有明显的影响：200 kg／ha和400 kg／ha施氮水平下，DI508分蘖角度和植株收敛指数明显大于不施氮或100 kg／ha施氮处理。同样，在不同氮-磷-钾施用配比条件下，DI508的分蘖角度亦呈动态变化，但分蘖角度和植株收敛指数在不同养分配比下差异显著，表现为随磷钾施用比例的增加而减小。DI508从植株形态和产量上显示较高的氮利用效率，株高、冠层高度、茎蘖数、成穗率、净光合速率、比叶重、单株叶面积、叶面积指数、干物质和产量等均随着施氮水平和磷、钾肥比例的提高而增加。4、在田间不同播期条件下，DI508分蘖角度从半散生渐趋直立的变化均发生在自然光周期变短（6月21日夏日至）后10-15 d。人工光周期处理条件下，DI508的分蘖角度同样表现出动态变化，短日照（10 h光期）处理促使分蘖角度转变提前，而长日照（14 h光期）处理则延缓转变。结果显示，DI508分蘖角度发生变化的临界光照时数在10 h左右，而温度对分蘖角度的变化无显著影响。5、利用珍汕97B／密阳46杂交后代构建的重组自交系（RIL）群体和协青早B／密阳46杂交后代构建的重组自交系（RIL）群体，对分蘖角度进行QTLs分析。结果表明，在始蘖期2个遗传群体的第1和9染色体上均检测到控制主茎分蘖角度的QTLs；在齐穗期，控制主茎分蘖角度的QTLs较为分散。运用条件变量分析方法和条件QTLs的复合区间作图法，在2个遗传群体中均检测到显著影响主茎分蘖角度的条件QTLs。在珍汕97B／密阳46的RIL群体中，检测到的条件QTLs主要分布在第5和第9染色体上，而在协青早B／密阳46的重组自交系（RIL）群体中，检测到的条件QTLs主要分布于第6、8、9和11染色体上。更多还原

【Abstract】 Tiller belongs to a special kind of branch in cereal crops,an important trait related closelyto grain yield.The stature of tillers and their leaves has been intensively studied as a key issuein the field of tiller trait,and tiller angle determines the stature of tillers and their leaves onthem,which in turn affect light utilization and competition among plant individuals.Semi-scattered tiller growth could be favorable for rapid formation of leaf area for lightinterception,enhancing formation of complete canopy and improving competitiveness of plantsagainst weeds during vegetative growth.On the other hand,erect tillers at reproductive stagecould improve aeration and light penetration within a canopy,thus enhancing anti-biotic stressability and lodge resistance of rice plants.In the previous research,we obtained a rice genotypeDI508,which is characterized by semi-scattered tillers at vegetative stage and erect tillers afterbooting,i.e.showing dynamic change of tiller angle with the growth.It was also found that thetrait of dynamic tiller angle was related to their responses to photoperiod.In this paper,wecompared DI508 with erect genotype（Xieyou 9308 or 9308） and semi-scattered genotype（M09 or DI444） in morphological and growth characters,light and nutrient utilization.Thephysiological and genetic mechanisms for the tiller angle change was also were studied usingthe experiments involving sowing date and controlled temperature and photoperiod.Moreover,the QTL analysis of tiller angle change was conducted using a RIL population developed froma cross of Zhenshan97B and Miyang46 and RIL population developed from a cross ofXieqingzaoB and Miyang46.The main results are as follows:1.DI508 is typically characterized by fast growth at tillering stage,and erect shoots andvigor leaves in terms of photosynthesis after booting.At initial tillering stage,the angles of thefirst,second and third on the main shoots of DI508 were 59.74°,62.94°and 68.54°respectively,very similar to those of M09.After booting the angle was close to 90°,very similar to those oferect type rice 9308.The percentage of effective tillers developing into panicles in DI508 was68.35%,being 3.09% higher than that in M09.Dry biomass per plant of DI508 was 155.54 g atmaturity stage,being 15.84% and 64.09% higher than that of M09 and 9308,respectively,anddry biomass per tiller of DI508 was 9.15g,being 63.69% and 44.78% higher than that of M09and 9308 respectively.After booting until maturity,photosynthetic capacity of the most top 3leaves in DI508 kept stable and higher,being 26.89,25.69 and 24.83μmol.m^-2.s^-1 for 1th,2nd and 3rd leaves,respectively.In comparison,other two rice genotypes had lower photosyntheticrates.2.DI508 showed a better adaptability to light intensity in comparison with that of theother two rice genotypes.During tillering and milking stages,the maximum net photosyntheticrate and light saturation point of DI508 were the medium of Xieyou9308（erect tiller angle） andDI444（semi-scattered tiller angle）.DI508 had obviously higher photosynthetic rate andapparent quantum yield,and lower light compensation point under weak light conditionrelative to those of the other two rice genotypes,Under all light intensities,carboxylationefficiency in DI508 were similar to that of the other two genotypes.However,at milking stage,DI508 had a higher value in carboxylation efficiency than DI444.In addition,DI508 hadhigher water use efficiency than the other two rice genotypes.3.The tiller angle of DI508 showed the dynamic change during its growth under all Nlevels,and its convergent index increased gradually after maximum tillering.However,thetiller angle and convergent index of DI508 was significantly affected by N level.Thus,tillerangle and convergent index were obviously greater in the treatment of 200 kg/ha or 400 kg/hathan that in the treatment 0 or 100 kg/ha.Similarly,tiller angle of DI508 showed the dynamicchange during the growth under different ratios of N,P and K application rates.Tiller angleand convergent index of DI508 were significantly affected by ratios of the three fertilizers,decreasing with increased ratios of P and K application.DI508 had higher N utilizationefficiency in terms of morphological traits and grain yield,as reflected by improved plant andcanopy height,tillers per plant,effective tiller percentage,net photosynthetic rate,specific leafweight,leaf area per plant,leaf area index,dry matter and yield with increased N fertilizer andratios of P and K fertilizer.4.DI508 plants gradually changed into erect when photoperiod became shorter(10-15 dafter 21^st June,the Summer Solstice),irrespective of seeding dates(4^th April,5^th May and 4^thJune) in a natural field.Under the controlled photoperiod,the tiller angle of DI508 plantschanged in the same way as happened in the field.Shorter lighting treatment（10 hours）advanced the angle changing while longer lighting treatment（14 hours） delayed the changing.The results showed that the critical photoperiod for tiller angle changing of DI508 is about 10hour.On the other hand,the tiller angle changing of DI508 was not affected by accumulated temperature or growing degree day（GDD）.5.QTL analysis was conducted using a RIL population developed from a cross ofZhenshan97B and Miyang46 and RIL population developed from a cross of XieqingzaoB andMiyang46.At initial tillering,the QTLs for tiller angle of main shoots were detected inchromosomes 1 and 9 in both RIL and RIL populations.While at full-heading,the detectedQTLs for tiller angle were located on more chromosomes.The conditional QTLs for tillerangle from initial tillering to full-heading were detected in the both genetic populations usingconditional variable analysis and composite interval mapping.The conditional QTLs detectedin the genetic population of Zhenshan97B/Miyang46 were mainly located in chromosome 5and 9,and the conditional QTLs detected in the genetic population of XieqingzaoB/Miyang46were located in chromosome 6,8,9 and 11.更多还原