植酸形成与水稻籽粒充实的关系

研究了6个水稻品种（组合）的籽粒灌浆特征及植酸合成过程中相关生化成分变化与籽粒充实的关系。籽粒充实度好的亚杂1号(ISHR1)、亚杂2号（ISHR2）、R198和JW21,强、弱势粒灌浆不表现两段灌浆现象,而籽粒充实度差的亚杂3号（ISHR3）和559两段灌浆现象则十分明显。孕穗期至开花期,籽粒充实度好的品种其植酸、肌醇含量显著高于籽粒充实度差的品种;灌浆期,籽粒充实度差的品种无机磷含量明显高于籽粒充实度好的品种。相关分析表明,在孕穗期至开花期籽粒中植酸、肌醇含量与起始灌浆势（P0）、平均灌浆速率（RA）和籽粒充实率（GFP）均呈极显著正相关;灌浆期,无机磷含量与P0、RA和GFP呈极显著负相关,肌醇含量与P0、RA和GFP无明显相关性。提出了提高水稻籽粒充实度的有效途径。     

水稻和陆稻籽粒灌浆特性的比较

应用Richards方程对水作和旱作水稻与陆稻的籽粒灌浆过程进行拟合,研究两种稻灌浆特性在不同水分管理条件下的差异。结果表明,与水作相比,水稻旱作穗数和粒重明显降低,产量下降;强势粒和弱势粒的灌浆速率降低,活跃灌浆期缩短,强势粒和中势粒的起始生长势减弱,到达最大灌浆速率的时间延迟,强、弱势粒进入灌浆盛期的间距缩短,从而影响弱势粒的灌浆,强、弱势粒灌浆速率的差异增大,最终导致粒重和结实率降低。陆稻旱作与水作相比,除活跃灌浆期略有缩短以及强、弱势粒进入灌浆盛期的间隔略有延长外,整体上灌浆过程变化不大。与水稻相比,陆稻在两种水分条件下灌浆过程和产量及其构成因子的差异较小,表现为籽粒灌浆的起始生长势特别是强、中粒位势的起始生长势低,灌浆前、中期灌浆较强,强、中势籽粒对同化物的激烈竞争使弱势粒灌浆变差,籽粒灌浆期短,特别是灌浆后期持续时间短,导致结实率和粒重低,最终影响产量。旱作条件下,水稻与陆稻相比,籽粒灌浆速率较小,活跃灌浆期较长,强、弱势粒灌浆呈现明显的异步性。     

超级稻的产量构成特点和籽粒灌浆特性分析

在大田条件下．以汕优63为对照,分析了超级稻玉香油占、胜泰1号和准两优527的产量构成持点。结果表明：玉香油占和胜泰1号的高产主要是因为颖花数和结实率的优势,而准两优527高产的获得主要是由于结实率和千粒重的优势。在此基础上．进一步采用Logistic方程拟合了上述4个品种的籽粒灌浆进程,分析相关参数后得知：各供试超级稻品种的粒重潜力存在差异,且弱势粒的充实均不如对照品种汕优63。此外。各供试超级稻品种的灌浆均表现出了异步性,但异步的程度并不一致。因此,在生产上应当根据各超级稻品种本身的特性来制定配套的栽培方法,进而使其产量潜力得以更加充分的发挥。     

两种穗型水稻源库关系及籽粒灌浆特性的研究

应用Richards方程对弯穗型和半直立穗型水稻品种的籽粒灌浆过程进行了拟合,研究两种穗型水稻品种的灌浆特性。结果表明:弯穗型品种和半直立穗型品种强、弱势粒在籽粒充实程度上有较大差异。半直立穗型品种整体灌浆速率、弱势粒灌浆效率均明显高于弯穗型品种。对两种穗型品种抽穗后籽粒、地上部单茎干重和源库增量比等生理指标的测定表明,半直立穗型水稻品种有很好的光合能力,生长期长、不早衰,其光合作用更加切合籽粒灌浆的需求。     

水稻籽粒灌浆期间茎鞘贮存物质含量变化及其影响因素研究

 以库限制型水稻品种盐粳235和源限制型水稻品种汕优63和亚优2号进行研究，水稻籽粒的灌浆因品种源库关系而有很大差异，剪叶或疏花对强势粒的灌浆影响不大，但显著地延缓或加速弱势粒的灌浆进程，库限制型品种盐粳235抽穗前叶鞘和茎秆中临时性贮存物质积累高峰出现迟，单位库容占有贮存性物质比例低，两类型品种茎鞘中贮存物质均在籽粒发育早期输出，但盐粳135的输出持续时间长于汕优63和亚优2号的。疏花、剪叶和激素处理主要通过改变库源大小，增加或减少单位库容占有光合同化物比例及改变茎鞘贮存物质在整个籽粒灌浆物质中的比例来影响籽粒生长和发育。还就茎鞘贮存物质在籽粒早期发育中的作用进行了讨论。     

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。     

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。     

不同穗型水稻品种籽粒灌浆特性比较及与后期生理特性的关系

应用Richards方程对散穗型和紧穗型水稻品种的籽粒灌浆过程进行了拟合,研究两种穗型水稻品种的灌浆特性。结果表明,散穗型品种和紧穗型品种强、弱势粒在籽粒充实程度上有较大差异。散穗型品种整体灌浆速率、弱势粒灌浆效率均明显高于紧穗型品种。对两种穗型品种叶绿素含量和根系伤流强度两项生理指标的测定表明,散穗型品种虽然低于紧穗型品种,但其下降幅度亦低于紧穗型品种。总之,水稻籽粒灌浆特性与叶绿素含量和根系伤流强度间存在一定的相关性。     

水稻不同遗传分化品系(种)杂种籽粒充实度的比较分析

对5个不同遗传分化程度的水稻品系(种)与釉稻品种杂交所得杂种的籽粒充实度进行了比较分析。结果表明，不同遗传分化程度的品系(种)杂种间的平均籽粒充实度存在极显著的差异，其中以偏粳型品系G3005-4-1的杂种平均籽粒充实度表现最好，达正常水平；两个偏籼型品系G2417-1及G2123的杂种平均籽粒充实度表现次之，低于中亲值及对照的籽粒充实度，但无显著差异；粳型品系G2615及粳型广亲和品种02428的杂种平均籽粒充实度表现较差，但部分组合的籽粒充实度表现正常。杂种籽粒充实度主要与每穗实粒数、结实串、单株粒重和千粒重存在显著的相关关系；提高每穗实粒数和结实率，适当降低千粒重有助于改善杂种的籽粒充实度。     

大麦不同光合器官对籽粒灌浆及产量的影响

大麦的不同光合器官对籽粒的灌浆及产量的影响作了初步探索。在大麦灌浆前期,籽粒物质积累主要来源于茎杆贮藏物质,在中期,倒２叶以上各光合器官对籽粒的物质积累起关键作用,在后期,倒２叶作用消失,而剑叶和芒仍对籽粒的灌浆发挥很大作用;大麦倒２叶以上的光合器官对籽粒产量的贡献卓越,其中剑叶的贡献最大,而芒的作用也很显著;大麦各光合器官在抽穗后对结实率的影响不大。     

Pre-anthesis non-structural carbohydrate reserve in the stem enhances the sink strength of inferior spikelets during grain filling of rice

Sink strength plays an important role in grain filling of cereals but how it is related to the pre-anthesis non-structural carbohydrate (NSC) reserves is not clear. This study investigated if and how an increase in NSC reserves could enhance sink strength, and consequently improve grain filling of later-flowering inferior spikelets (in contrast to the earlier flowering superior spikelets) for rice varieties with large panicles. Two “super” rice varieties (the recently bred high-yielding rice) and two New Plant Type (NPT, named in IRRI for the extra-large panicle) rice lines were compared with two elite inbred varieties under field-grown conditions. Three nitrogen (N) treatments, applied at the stages of panicle initiation, spikelet differentiation or both, were adopted with no N application during the mid-season as control. Both super rice and NPT rice showed a greater yield capacity as a result of a larger panicle than the elite inbred rice. However, a lower percentage of filled grains limited the realization of higher yield potential in super rice and especially in NPT rice, due to their lower grain filling rate and the smaller grain weight of their inferior spikelets. The low grain filling rate and small grain weight of inferior spikelets are mainly attributed to a poor sink strength as a result of small sink size (small number of endosperm cells) and low sink activity, e.g. low activities of sucrose synthase (SuSase) and adenosine diphosphoglucose pyrophosphorylase (AGPase). The amounts of NSC in the stem and NSC per spikelet at the heading time are significantly and positively correlated with sink strength (number of endosperm cells and activities of SuSase and AGPase), grain filling rate, and grain weight of inferior spikelets. Nitrogen application at the spikelet differentiation stage significantly increased, whereas N application at the panicle initiation or at both panicle initiation and spikelet differentiation stages, significantly reduced, NSC per spikelet at the heading time, sink strength, grain filling rate, and grain weight of inferior spikelets in super rice. The results suggest that pre-anthesis NSC reserves in the stem are closely associated with the sink strength during grain filling of rice, and N application at the spikelet differentiation stage would be a good practice to increase pre-anthesis NSC reserves, and consequently to enhance sink strength for rice varieties with large panicles, such as super rice varieties.     

Variations in Carbohydrate and Protein Accumulation among Spikelets at Different Positions Within a Panicle During Rice Grain Filling

The accumulation dynamics of kernel components for spikelets at different positions within a rice panicle were investigated during grain filling to understand the physiological reasons for the variation of grain quality.Two rice cultivars,Yangdao 6 (indica) and Yangjing 9538 (japonica),were field-grown,and the grain filling characters and contents of starch,soluble sugar,and protein of the spikelets at different positions were studied.There were significant differences in matter accumulation among spikelets at different positions during grain filling.The early-flowering spikelets presented dominance over the late-flowering spikelets in initial time and initial rate of accumulation.At the initial and mid filling stages,the contents and the rates of starch and amylose accumulation in spikelets decreased with the flowering sequence,but soluble sugar content (SSC) exhibited the opposite trend.The difference in SSC among the spikelets of Yangjing 9538 was greater than that of Yangdao 6,but amylose content in mature spikelets showed no obvious relationship to their flowering sequence.The crude protein content (CPC) of early-flowering spikelets decreased more rapidly than that of late-flowering ones at the initial filling stage,and CPC in the spikelets on the secondary branch was higher than that on the primary branch,but CPC in early-flowering ones was lower than that in late-flowering across the whole grain filling period.Grain water content (GWC) of early-flowering spikelets decreased more rapidly than that of late-flowering spikelets on the same branch at the initial and mid filling stages,especially for the top grain on each primary branch.The results suggested that poor grain filling of late-flowering spikelets may be attributed to their low biological activity rather than carbohydrate supply limitation.     

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.     

水稻强、弱势粒灌浆差异的激素调控机理研究进展

水稻弱势粒充实差不仅影响产量和品质,而且还限制了对水分和养分的高效利用。本文概述了脱落酸、乙烯、细胞分裂素、吲哚乙酸、赤霉素、多胺和油菜素类固醇等植物激素对籽粒灌浆的调控作用,比较分析了强、弱势粒内源激素的差异;从激素时空分布对籽粒灌浆的调控作用、激素对蔗糖-淀粉代谢途径关键酶活性的调控、激素对环境的响应及其栽培调控途径等方面提出了水稻籽粒灌浆激素调控机理的研究展望。     

Association of Phytate Formation with Grain Filling in Rice

The grain-filling characteristics of six rice varieties (combinations) and the relationships between their relative biochemistry composition during phytate synthesizing and grain plumpness were studied. Regarding results for ISHR1,ISHR2, R198 and JW21, with good grain plumpness, the two-step-filling in superior spikelets and inferior spikelets was not clear, while for ISHR3 and 559, with poor grain plumpness, it was very clear. From booting stage to flowering stage, the contents of phytate and inositol in varieties with good grain plumpness was obviously higher than those in varieties with poor grain plumpness. While at grain filling stage, the content of inorganic phosphorus in varieties with poor grain plumpness was obviously higher than that in varieties with good grain plumpness. The contents of phytate and inositol from booting stage to flowering stage was highly significantly correlated with the initial filling power (RO), the mean filling rate (RM) and grain filling percentage (PGF), and the content of inorganic phosphorus at grain filling stage was negatively significantly correlated with R0, FM and PGF. Furthermore, effective approach to improving grain filling was put forward.     

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。     

Activities of Enzymes for Sucrose-Starch Conversion in Developing Endosperm of Rice and Their Association with Grain Filling in Extra-Heavy Panicle Types

Abstract

Rice cultivars with numerous spikelets per panicle (extra-heavy panicle types) frequently fail to exhibit their high yield potential due to low grain filling. Existing genetic variation in grain filling, however, opens possibilities for genetic improvement for this trait. We studied the correlation between grain filling and the activities of enzymes for sucrose-starch conversion in developing endosperm. The activity of sucrose synthase (EC 2.4.1.13, SuSy) and ADPglucose pyrophosphorylase (EC 2.7.7.27, AGPase), were measured in three extra-heavy panicle types and a standard cultivar grown at two locations under different environmental conditions. The proportions of grains with definite specific gravities and the rate of grain filling were adopted as the parameters related to grain filling. AGPase activity, but not that of SuSy, was consistently correlated to high proportions of high-density grains (specific gravity > 1.20) and high rates of grain growth in spikelets, particularly in those on secondary branches in which low grain filling is the rule. Such correlation was also detected in spikelets on primary branches which generally show better grain filling, but only early stages. Therefore, a high activity of AGPase might contribute to the reduction of the sucrose concentration by accelerating sucrose metabolism at the developing seed, a sink terminus of the phloem. Thus the sink-directed phloem transport of sucrose would be promoted, resulting in improved grain filling of extra-heavy panicle types. SuSy would play some roles in such a cultivar difference in grain filling, but depending on environments.     

Association of Phytate Formation with Grain Filling in Rice

The grain-filling characteristics of six rice varieties (combinations) and the relationships between their relative biochemistry composition during phytate synthesizing and grain plumpness were studied. Regarding results for ISHR1,ISHR2, R198 and JW21, with good grain plumpness, the two-step-filling in superior spikelets and inferior spikelets was not clear, while for ISHR3 and 559, with poor grain plumpness, it was very clear. From booting stage to flowering stage, the contents of phytate and inositol in varieties with good grain plumpness was obviously higher than those in varieties with poor grain plumpness. While at grain filling stage, the content of inorganic phosphorus in varieties with poor grain plumpness was obviously higher than that in varieties with good grain plumpness. The contents of phytate and inositol from booting stage to flowering stage was highly significantly correlated with the initial filling power (R0), the mean filling rate (RM) and grainfilling percentage (PGF), and the content of inorganic phosphorus at grain filling stage was negatively significantly correlated with R0, FM and PGF. Furthermore, effective approach to improving grain filling was put forward.     

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.