IAA与亚种间杂交稻籽粒发育的关系及烯效唑的调节

 以汕优413及其父本品种中413为材料,研究了内外源IAA在籽粒发育过程中的作用及植物生长延缓剂S-07对其强、弱势粒灌浆过程的影响。在灌浆前期,强势粒抑制弱势粒的发育,外源IAA可代替强势粒的这种抑制作用;灌浆过程中强、弱势粒内源IAA的变化动态存在差异,其中强势粒的内源IAA在开花后急剧上升,8 d左右达最高峰;而弱势粒的IAA水平开花后则有一段约12 d的“滞缓期”,在开花后20 d左右才有一高峰出现。强弱势粒对3H-IAA的合成和吸收能力差异可能是导致其内源IAA水平不平衡的原因之一。孕穗末期喷施S-07可部分抑制强势粒的发育而相对促进弱势粒的发育,提高弱势粒千粒重;孕穗末期喷施S-07溶液可降低强势粒但提高弱势粒灌浆前期的内源IAA水平。     

内源IAA对杂交稻强、弱势粒灌浆增重的影响

以超级杂交稻协优9308和杂交稻协优9312、Ⅱ优162及其相应恢复系为材料,对灌浆初期籽粒中内源IAA、糖分的变化,以及IAA抑制剂对IAA以及3H 标记葡萄糖吸收分配和籽粒灌浆的影响进行了研究。结果表明在籽粒灌浆初期强势粒的IAA含量以及增重的速度始终高于弱势粒。在开花受精7 d以前,强势粒中果糖、葡萄糖及蔗糖的含量高于弱势粒,之后相反。强、弱势粒间存在的这种灌浆势差异,杂交组合大于其相应的恢复系。IAA合成及运输抑制剂明显降低3H 葡萄糖在籽粒中的分配。外源IAA对幼穗的处理,缩小了强、弱势粒间结实率的差异,使整穗的结实率也有所提高。     

亚种间杂交水稻协优413开花灌浆特性的比较研究

 以盆栽试验对亚种间杂交水稻协优413、其父本中413和籼型杂交水稻汕优10号的开花灌浆特性进行了比较研究。结果表明中413单穗籽粒总干物重最高，协优413次之，汕优10号最低，分别为4652.5、4173.9和3194.4 mg，结实率中413和协优413相近，分别为80.8%和83.9%，显著高于汕优10号的70.5%。单穗产量的差异与组合(恢复系)的开花灌浆特性有关，即与单穗颖花开花集中程度和强弱势粒灌浆结实的差异程度有关。对于供试的3个品种(或组合)而言，颖花开花越集中，强弱势粒灌浆结实差异越小，产量越高。还对单穗颖花开花历时作为今后亚种间杂交水稻的育种目标进行了讨论。     

超级稻花后强、弱势粒淀粉合成相关酶活性和激素含量变化及其与籽粒灌浆的关系

 种植4个超级稻品种\[两优培九和Ⅱ优084（杂交籼稻）、淮稻9号和武粳15（粳稻）\]和2个高产对照品种\[汕优63（杂交籼稻）和扬辐粳8号（粳稻）\],观察其结实期强、弱势粒中蔗糖合酶（SuSase）、腺苷二磷酸葡萄糖焦磷酸化酶（AGPase）、淀粉合酶（StSase）和淀粉分支酶（SBE）活性及玉米素+玉米素核苷（Z+ZR）、3 吲哚乙酸（IAA）和脱落酸（ABA）含量的变化,并测定了强、弱势粒灌浆速率。结果表明,超级稻品种强势粒的最大灌浆速率、到达最大灌浆速率的时间、平均灌浆速率和糙米重与对照品种差异较小,超级稻品种弱势粒的灌浆速率和糙米重显著低于对照。灌浆期强、弱势粒的SuSase、AGPase 、StSase 和SBE活性变化及Z+ZR、IAA 和ABA 含量变化均呈单峰曲线。弱势粒的SuSase、AGPase、StSase 和SBE的峰值活性和平均活性及其Z+ZR 和IAA的峰值含量和平均含量均低于强势粒。弱势粒的ABA 峰值含量和平均含量显著高于强势粒,超级稻品种高于对照品种。籽粒灌浆速率与SuSase、AGPase和StSase 活性及Z+ZR 和IAA含量均呈显著或极显著正相关,与SBE活性及ABA含量的相关不显著。说明超级稻品种弱势粒中较低的SuSase、AGPase和StSase活性及较低的Z+ZR和IAA含量是其灌浆速率小、粒重轻的一个重要原因。     

烯效唑对杂交水稻籽粒灌浆及产量的影响研究

以杂交稻组合汕优63为材料,探讨了不同施药时期(浸种、孕穗期喷施)和不同质量浓度(0,10,20,40,80 mg/L)烯效唑处理对籽粒生长过程及产量的影响.结果表明,烯效唑对强势粒生长有一定抑制作用,但同时却促进了弱势粒的生长,在一定程度上具有协调强、弱势粒灌浆的作用,降低成熟期强势粒单粒重而提高弱势粒单粒重;使强势粒的终极生长量降低,达最大生长速率的时间延后,从而延长弱势粒的灌浆时间,提高弱势粒的灌浆速率及最大干重;由于烯效唑对弱势粒生长的促进作用,显著提高了其穗实粒数,进而提高了单穗籽粒干重及水稻产量.处理时期不同,其最佳浓度不同;浸种处理以质量浓度为40mg/L时产量最高,喷施处理以20mg/L时的产量最高.     

施氮量对旱地小麦强势粒和弱势粒灌浆及产量的影响

为给旱地小麦高产栽培中合理施氮提供依据,在盆栽条件下,以两个旱地小麦品种长武134和长旱58为材料,研究了施氮量对旱地小麦强势粒和弱势粒灌浆特性和产量的影响。结果表明,两个品种的产量、穗粒数和穗粒重均随施氮量的提高呈增加趋势,但千粒重受施氮量影响较小。强势粒的灌浆速率在整个灌浆过程中均明显高于弱势粒。随施氮量的增加,强、弱势粒的灌浆速率都呈现先升后降的趋势。强势粒粒重与平均灌浆速率和总灌浆时间呈正相关,而弱势粒粒重与最大灌浆速率持续时间和各阶段灌浆持续时间呈正相关。     

水稻强弱势籽粒核酸和蛋白质代谢差异

以两系杂交稻两优培九和培两优500为试验材料,对强弱势粒核酸和蛋白质含量进行了测定。水稻抽穗当天,强势粒单位质量子房中总RNA、mRNA含量都高于弱势粒,蛋白质含量却低于弱势粒。抽穗后第5天,强势粒单位质量子房中总RNA含量仍然高于弱势粒,mRNA含量两者差异不大,蛋白质含量依然低于弱势粒。不论是强势粒还是弱势粒,从抽穗到开花后第5天,其总RNA、mRNA和蛋白质单粒含量都有显著的增加,且各时期强势粒都高于弱势粒。抽穗当天强势粒有两条特异蛋白质带出现,而弱势粒没有,抽穗后第5天弱势粒才出现其中的一条。这说明强势粒与籽粒灌浆有关的基因表达比弱势粒早,强度高。     

亚种间杂交水稻低结实率的生理原因分析

比较了亚种间杂交稻"W6154S×培C3111"、品种间杂交稻"W6154S×特青"和常规稻"特青"的籽粒灌浆过程中生理活性变化和结实率情况.结果表明所有供试组合(品种)的强势粒对弱势粒都具有较强的抑制作用,表现在灌浆初期弱势粒的细胞色素氧化酶活性低丽IAA氧化酶活性高,直至强势粒灌浆接近完成时,弱势粒的细胞色素氧化酶活性升高、IAA氧化酶活性降低.尤其是亚种间杂交水稻的强势粒对弱势粒的抑制作用最强,导致弱势粒灌浆不充实成为秕粒,甚至发育停止成为受精空粒.亚种间杂交稻的秕粒率、受精空粒率和未受精率分别为16.86%,15.55%和6.55%,而品种间杂交稻和常规稻上述三种比率分别为12.29%,3.03%,4.70%和6.75%,2.88%,5.09%.     

灌浆期低温对离体玉米子粒灌浆过程及内源激素的影响

以郑单958为材料,采用子粒离体培养方法,研究灌浆期低温对玉米强、弱势粒灌浆特性及内源激素的影响。研究表明,灌浆期低温分别减缓强、弱势粒平均灌浆速率15%、23%,延长灌浆时间约8 d,最终粒重分别降低3%、9%。低温处理下,GA_3、IAA、ZR含量与灌浆速率显著相关;受低温影响,强、弱势粒的激素含量变化趋势相近,与常温相比,子粒GA_3含量先增加后减少,IAA、ZR含量低于对照,且对弱势粒的影响大于强势粒。低温对内源激素含量的影响是导致灌浆速率降低的主要原因之一。     

梯度减除颖花对水稻弱势粒稻米品质的影响

通过梯度减除上部颖花(减库)处理,研究稻穗下部二次枝梗(弱势粒)籽粒外观和碾磨品质的变化,并分析了logistics方程模拟籽粒灌浆过程的有关参数与稻米品质的相关性,以明确籽粒自身活性对品质的影响。结果表明:自然状态下,稻穗下部弱势粒较各部位强势粒在粒长、粒宽、粒厚、糙米率、精米率及整精米率等性状存在显著差异;仅保留稻穗下部枝梗能使弱势粒的粒长、粒宽、糙米率、精米率、整精米率得到显著改良,但弱势粒的有关性状基本没有达到强势粒水平;简单相关分析表明,粒形与灌浆时间极显著负相关,与灌浆速率极显著正相关,碾磨品质与灌浆中、后期持续期及整个灌浆持续期显著负相关,与灌浆速率相关不显著。可见,稻穗下部弱势粒稻米品质较差与营养物质供应无必然联系,籽粒内部固有的生理活性可能是导致粒间品质差异的主要原因。     

Changes in Enzyme Activities Involved in Starch Synthesis and Hormone Concentrations in Superior and Inferior Spikelets and Their Association with Grain Filling of Super Rice

The changes in activities of key enzymes involved in sucrose-to-starch conversion and concentrations of hormones in superior and inferior spikelets of super rice were investigated and their association with grain filling was analyzed.Four super rice cultivars,Liangyoupeijiu,IIyou 084,Huaidao 9 and Wujing 15,and two high-yielding and elite check cultivars,Shanyou 63 and Yangfujing 8,were used.The activities of sucrose synthase (SuSase),adenosine diphosphoglucose pyrophosphorylase (AGPase),starch synthase (StSase) and starch branching enzyme (SBE),and the concentrations of zeatin + zeatin riboside (Z + ZR),indole-3-acetic acid (IAA) and abscisic acid (ABA) in superior and inferior spikelets were determined during the grain filling period and their relationships with grain filling rate were analyzed.Maximum grain filling rate,the time reaching the maximum grain-filling rate,mean grain filling rate and brown rice weight for superior spikelets showed a slight difference between the super and check rice cultivars,but were significantly lower in the super rice than in the check rice for inferior spikelets.Changes of enzyme activities and hormone concentrations in grains exhibited single peak curves during the grain filling period.The peak values and the mean activities of SuSase,AGPase,StSase and SBE were lower in inferior spikelets than in superior ones,as well as the peak values and the mean concentrations of Z + ZR and IAA.However,the peak value and the mean concentration of ABA were significantly higher in inferior spikelets than in superior ones and greater in the super rice than in the check rice.The grain filling rate was positively and significantly correlated with the activities of SuSase,AGPase and StSase and the concentrations of Z + ZR and IAA.The results suggested that the low activities of SuSase,AGPase and StSase and the low concentrations of Z + ZR and IAA might be important physiological reasons for the slow grain filling rate and light grain weight of inferior spikelets in super rice.     

Hormonal changes are related to the poor grain filling in the inferior spikelets of rice cultivated under non-flooded and mulched condition

Non-flooded plastic mulching cultivation (PM) of rice can save much irrigation but usually exhibits a poor grain filling and low grain weight when compared to traditional flooding cultivation (TF). This study measured the variations of plant hormones during grain filling and investigated whether they were related to the grain-filling problem under mulching in a field experiment. Hormonal levels in the grains and the grain development of both superior (early flowered) and inferior spikelets (later flowered) were monitored continuously during the grain filling period. The contents of indole-3-acetic acid (IAA), zeatin riboside (ZR) and abscisic acid (ABA) were higher in superior grains than in inferior ones at early grain-filling stage. For individual spikelets, the peaks of IAA and ZR contents appeared just before the peak grain-filling rate but the peak ABA content matched it. The earlier flowered superior spikelets did not show much difference in grain filling characteristics and hormonal changes under the two cultivation treatments. Distinctively with the inferior spikelets in a panicle, PM led to lower grain weight, higher grain-filling rate at early stage and shorter active grain-filling period than the TF. PM also resulted in less IAA and ZR but more ABA contents in the grains than TF at early and middle grain filling stages in these inferior spikelets. Peaks of these hormone contents in the PM inferior grains usually appeared earlier and also disappeared more quickly than those in TF inferior grains. When exogenous IAA was applied to plants at the initial grain-filling stage, IAA and ZR were increased and ABA was reduced in the inferior grains. The treatment prolonged the active grain-filing period and reduced the peak grain-filling rate of inferior grains, similarly as the case with TF. As a result, IAA spraying enhanced the weight of PM inferior grains but reduced that of TF ones. Exogenous ABA spraying led to the opposite effects to those of IAA. The results suggest that the shortened grain-filling period in the inferior grains under PM is related to the increased ABA and reduced IAA and ZR in the grains. Regulation of the ratio of ABA to IAA in grains could potentially increase the weight of inferior grains under the water-saving cultivation with film mulching.     

亚种间杂交稻大穗形成机理研究I．颖花的形成特点

比较了亚种间杂交稻赣化７号与品种间杂交稻汕优６３的枝梗和颖花的分化及发育特性，分析了颖花的分化、发育及一、二次枝梗对大穗形成的作用，提出了增加颖花数的主攻方向。     

两系杂交稻扬两优6号源库特征与结实特性的分析

以两系杂交稻扬两优6号和两优培九及三系杂交稻汕优63为材料,研究了源、库、流特征及其与籽粒充实的关系。 扬两优6号和汕优63的结实率、籽粒充实度和产量明显高于两优培九;扬两优6号和汕优63茎鞘物质输出率和转换率显著高于两优培九;扬两优6号和汕优63籽粒中蔗糖合成酶、腺苷二磷酸葡萄糖焦磷酸化酶、淀粉合成酶和淀粉分支酶的活性显著高于两优培九,且上述各酶的活性与籽粒最大灌浆速率、平均灌浆速率、谷粒充实度和粒重呈极显著的正相关;扬两优6号和汕优63的单位维管束和韧皮部的颖花负荷、现实产量负荷、总库容负荷显著小于两优培九,且负荷越大的组合结实率就越低,充实度也就越差。扬两优6号单位面积韧皮部的物质转运速率显著高于两优培九和汕优63。表明扬两优6号具有源足、库强、流畅的特点,这是它结实率高和籽粒充实度好的生理基础。     

小麦秸秆还田条件下轻简栽培水稻的生长特性

 以粳稻品种扬辐粳8号作试验材料,设小麦秸秆还田处理,以秸秆不还田作对照,进行直播、机械插秧、抛秧,并对水稻物质生产、产量形成及有关生理指标进行了分析。与秸秆不还田相比,秸秆还田处理穗数均有所下降,每穗粒数、结实率和千粒重均有所增加,产量均显著提高;各生育期的茎蘖数均明显降低。光合势、叶面积指数和干物质积累抽穗前低于秸秆不还田,抽穗后则相反;各生育期的根冠比均较高。抽穗期高效叶面积、高效叶比例以及粒叶比均较大,结实期茎鞘中贮存的碳水化合物的输出率及转换率以及收获指数明显大于秸秆不还田。结实期根系活力、伤流液、光合速率和ATP酶活性均高于秸秆不还田。阐明了秸秆还田轻简栽培水稻的生育特性和增产效应。同时,对秸秆还田水稻高产的生理原因进行了讨论,并提出秸秆还田水稻的关键调控技术。     

三角形强化栽培技术对水稻光合生理特性及产量形成的影响

以杂交水稻冈优527为材料,研究了水稻在三角形强化栽培、正方形强化栽培、抛秧栽培和常规高产栽培等不同栽培方式下的生理指标、灌浆特性及产量。结果表明,在三角形强化栽培技术体系下适宜密度的水稻群体具有独特的优势:在关键生育时期叶面积指数(LAI)较大,齐穗后剑叶衰老减缓,光合速率较高,能够充分发挥个体生长优势,贮存积累并向穗部转运较多的光合同化产物,不仅保证了强势粒的灌浆,而且弱势粒灌浆也较为顺畅,产量构成因素得到优化配置,从而获得高产。