Accumulation of High Molecular Weight Glutenin Subunits in Superior and Inferior Grains of Winter Wheat

The difference in accumulation of high molecular weight glutenin subunits （HMW-GS） in superior and inferior grains results in the non-uniformity of grain quality in winter wheat （Triticum aestivum L.）. The HMW-GS accumulation and glutenin macropolymer （GMP） content were studied in superior and inferior grains during the grain filling period, using the sodium dodecyl sulfate polyacrylamide gel electrophoresis （SDS-PAGE）. Compared to inferior grains, HMW-GS was formed earlier and total accumulation amount was higher in superior grains. The total HMW-GS content was higher in superior grain than that in inferior grain except at maturity. For individual HMW-GS types, the accumulation and content of subunit 7 were the highest, followed by subunit 12, while that of subunit 8 were the lowest, followed by subunit 2 in superior grain. In contrary, the accumulation and content of subunit 7 at maturity were significantly higher than subunit 8, but they were similar between subunit 2 and subunit 12 in inferior grain. Moreover, the accumulation of subunit 7 and 12 in superior grain were significantly higher than that in inferior grain. However, compared to the inferior grain, the GMP accumulation was higher, while content was lower in superior grain at maturity.

Higher Grain-Filling Rate in Inferior Spikelets of Tolerant Rice Genotype Offset Grain Yield Loss under Post-Anthesis High Night Temperatures

Increased nighttime respiratory losses decrease the amount of photoassimilates available for plant growth and yield. We hypothesized that the increased respiratory carbon loss under high night temperatures(HNT) could be compensated for by increased photosynthesis during the day following HNT exposure. Two rice genotypes, Vandana(HNT-sensitive) and Nagina 22(HNT-tolerant), were exposed to HNT(4 ℃ above the control) from flowering to physiological maturity. They were assessed for alterations in the carbon balance of the source(flag leaf) and its subsequent impact on grain filling dynamics and the quality of spatially differentiated sinks(superior and inferior spikelets). Both genotypes exhibited significantly higher night respiration rates. However, only Nagina 22 compensated for the high respiration rates with an increased photosynthetic rate, resulting in a steady production of total dry matter under HNT. Nagina 22 also recorded a higher grain-filling rate, particularly at 5 and 10 d after flowering, with 1.5- and 4.0-fold increases in the translocation of ^(14)C sugars to the superior and inferior spikelets, respectively. The ratio of photosynthetic rate to respiratory rate on a leaf area basis was negatively correlated with spikelet sterility, resulting in a higher filled spikelet number and grain weight per plant, particularly for inferior grains in Nagina 22. Grain quality parameters such as head rice recovery, high-density grains, and gelatinization temperature were maintained in Nagina 22. An increase in the rheological properties of rice flour starch in Nagina 22 under HNT indicated the stability of starch and its ability to reorganize during the cooling process of product formation. Thus, our study showed that sink adjustments between superior and inferior spikelets favored the growth of inferior spikelets, which helped to offset the reduction in grain weight under HNT in the tolerant genotype Nagina 22.

Wetting alternating with partial drying during grain filling increases lysine biosynthesis in inferior rice grain

Lysine content is a criterion of the nutritional quality of rice.Understanding the process of lysine biosynthesis in early-flowering superior grain(SG)and late-flowering inferior grain(IG)of rice would advance breeding and cultivation to improve nutritional quality.However,little information is available on differences in lysine anabolism between SG and IG and the underlying mechanism,and whether and how irrigation regimes affect lysine anabolism in these grains.A japonica rice cultivar was grown in the field and two irrigation regimes,continuous flooding(CF)and wetting alternating with partial drying(WAPD),were imposed from heading to the mature stage.Lysine content and activities of key enzymes of lysine biosynthesis,and levels of brassinosteroids(BRs)were lower in the IG than in the SG at the early grainfilling stage but higher at middle and late grain-filling stages.WAPD increased activities of these key enzymes,BR levels,and contents of lysine and total amino acids in IG,but not SG relative to CF.Application of 2,4-epibrassinolide to rice panicles in CF during early grain filling reproduced the effects of WAPD,but neither treatment altered the activities of enzymes responsible for lysine catabolism in either SG or IG.WAPD and elevated BR levels during grain filling increased lysine biosynthesis in IG.Improvement in lysine biosynthesis in rice should focus on IG.

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.

化肥优化减施对麦茬旱直播稻强、弱势粒食味与营养品质的影响

以常规施肥处理(F0,施N 350 kg/hm^(2)、P_(2)O_(5)135 kg/hm^(2)、K_(2)O 135 kg/hm^(2))为对照,研究不同化肥优化减施处理(F1:施N 280 kg/hm^(2)、P_(2)O_(5)108 kg/hm^(2)、K_(2)O 135 kg/hm^(2);F2:施N 210 kg/hm^(2)、P_(2)O_(5)81 kg/hm^(2)、K_(2)O 135 kg/hm^(2);F3:施N 140 kg/hm^(2)、P_(2)O_(5)54 kg/hm^(2)、K_(2)O 135 kg/hm^(2))对麦茬旱直播稻强、弱势粒食味与营养品质的影响,以期为直播稻优质高产施肥管理提供参考。结果表明,各化肥优化减施处理总体上均显著提高了直播稻强、弱势粒崩解值和峰值黏度,改善了食味品质,F1、F2、F3处理强势粒的崩解值分别比F0处理显著提高8.35%、7.65%、9.78%,F1、F3处理弱势粒的崩解值分别比F0处理显著提高13.25%、11.13%。各化肥优化减施处理总体上均显著降低了强、弱势粒中组氨酸、脯氨酸及锰含量,总体上均显著提高了强、弱势粒中酪氨酸、精氨酸、赖氨酸含量和弱势粒中铜、锌含量,另外,F1处理还显著提高弱势粒中铁含量,F2处理显著提高强势粒中铁、铜含量及强、弱势粒中钙含量。与F0处理相比,F1、F2、F3处理强势粒的酪氨酸含量分别显著提高100.28%、44.76%、41.08%,弱势粒的酪氨酸含量分别显著提高85.21%、61.64%、22.47%;F1、F2、F3处理强势粒的赖氨酸含量分别显著提高28.87%、27.32%、70.62%,F1和F3处理弱势粒的赖氨酸含量分别显著提高27.23%、39.44%;F1、F2、F3处理强势粒的精氨酸含量分别显著提高6.54%、11.84%、2.18%,弱势粒的精氨酸含量分别显著提高32.83%、33.59%、23.02%。与F0处理相比,F1处理弱势粒铁含量显著提高27.16%,F1、F2、F3处理弱势粒锌含量分别显著提高18.86%、6.56%、3.39%,F1、F2、F3处理弱势粒铜含量分别显著提高2.49%、2.95%、3.11%。综上,化肥优化减施在提高强、弱势粒食味品质的同时,可以改善营养品质,总体上以F1处理最优。

不同秸秆还田技术模式对冬小麦强弱势粒灌浆特性的影响

为揭示砂姜黑土区不同秸秆还田技术模式对冬小麦籽粒灌浆进程的影响,该研究基于农业农村部华东地区作物栽培科学观测站15a的长期定位试验,设置单季小麦秸秆全量粉碎覆盖还田(T1)、小麦秸秆全量粉碎覆盖还田+玉米秸秆全量粉碎翻埋还田(T2)、单季玉米秸秆全量粉碎翻埋还田(T3)和小麦玉米秸秆全年不还田(CK)4种不同秸秆还田技术模式,采用Richards方程模拟冬小麦籽粒灌浆过程,研究不同秸秆还田技术模式对冬小麦强弱势粒灌浆特征参数的调控效应。结果表明:1)相较于秸秆不还田,秸秆还田处理能提升冬小麦强、弱势粒的籽粒体积、千粒质量和产量,T1、T2、T3处理下强势粒千粒质量和籽粒产量较CK分别显著提升11.02%、10.63%、13.75%和16.28%、14.29%、13.94%,弱势粒千粒质量和籽粒产量较CK分别显著提升9.73%、6.64%、7.57%和19.24%、23.25%、11.50%。Richards方程能极显著模拟不同秸秆还田技术模式下冬小麦籽粒灌浆过程,拟合方程决定系数(R^(2))均在0.997以上。2)对冬小麦强势粒,秸秆还田可延长小麦强势粒灌浆时间,主要通过缩短灌浆渐增期持续时间和提高其灌浆速率,延长灌浆缓增期的持续时间来提升强势粒千粒质量。其中T1、T3处理下冬小麦强势粒灌浆持续时间较CK分别延长2.137 d和4.443 d,T1、T2处理下强势粒单粒最大灌浆速率较CK分别显著提高了7.81%和12.26%。3)对冬小麦弱势粒,T1处理下弱势粒灌浆持续时间较CK延长1.477 d,T1、T2、T3弱势粒单粒最大灌浆速率较CK分别显著提升16.46%、22.69%和17.13%。该研究表明秸秆全量还田可提升砂姜黑土区冬小麦籽粒库容和籽粒灌浆速率,最终增加粒质量。研究可为砂姜黑土区秸秆资源的高效利用提供理论指导和技术支撑。

干旱胁迫对冬小麦物质转运和不同小穗位籽粒产量的影响

【目的】探究不同冬小麦品种物质转运和不同小穗位产量对拔节至成熟期干旱胁迫的响应。【方法】试验以常规品种济麦22和抗旱品种中麦36为材料,在自动防雨水肥控制池内进行,采用测墒补灌技术实现水分条件的控制。设置顶端小穗形成期到成熟期持续干旱(WS:40%~45%FC,FC为田间持水量)和对照处理(CK:80%~85%FC)。调查拔节后不同小穗位小花发育动态,强、弱势粒灌浆速率和产量等指标,以及各器官花前、花后干物质积累运转量。【结果】1)干旱胁迫促进济麦22穗中部和上部的小花原基发育进程,显著减少了小花原基数量,导致穗部发育不平衡,而对中麦36各部位小花原基发育进程和数量无显著影响。2)干旱胁迫下,抗旱品种中麦36的开花前营养器官贮藏干物质转运量(Pre-DT)和转运率(Pre-DTE)较对照条件下分别显著降低34.8%和33.2%,降低了花前贮藏干物质运转对籽粒的贡献率(Pre-DCR),但开花后干物质积累量(Post�DA)及其对籽粒的贡献率(Post-DCR)分别提高5.1%和25.7%;常规品种济麦22的花前营养器官贮藏干物质转运量对籽粒的贡献率比对照提高了32.1%,Post-DA和Post-DCR分别降低了40.4%和21.3%。干旱胁迫下,中麦36 Pre-DCR的下降主要因为茎秆Pre-DCR的降低,而济麦22的Pre-DCR比对照提高了1.4倍,主要是由穗轴和颖壳Pre-DCR的增加所致。3)济麦22叶鞘、茎秆及穗轴+颖壳中的干物质向籽粒转运受到干旱的抑制,而中麦36仅茎秆和穗轴+颖壳受到干旱的抑制。与正常条件相比,干旱致使济麦22的籽粒灌浆速率下降42%,对中麦36无显著影响。济麦22上部和中部小穗位强势粒受干旱影响较大,而中麦36上部小穗位弱势粒受干旱影响较大,表现为济麦22的穗粒数、单粒重和单穗产量降幅(7.6%、15.9%和24.3%)均高于中麦36(3.3%、9.5%和16.3%)。【结论】抗旱品种主要靠开花后干物质积累来增加籽粒产量,而常规品种主要靠转运开花前营养器官贮藏干物质来增加籽粒产量。干旱胁迫条件下,常规品种济麦22的籽粒产量降幅显著高于抗旱品种中麦36,主要原因是干旱导致济麦22不同小穗位小花原基的发育不平衡,叶鞘、茎秆及穗轴+颖壳的干物质转移到籽粒的过程均受抑制,且中部和上部小穗位强势粒受到影响,导致灌浆速率显著降低。抗旱品种中麦36在干旱胁迫下通过降低茎秆开花前营养器官贮藏干物质转运量,提高开花后营养器官干物质积累量对籽粒贡献率应对干旱胁迫,且干旱胁迫主要影响弱势粒。

施磷量对不同耐低磷型水稻品质及淀粉合成酶活性的影响

适宜磷肥用量对水稻品质具有一定影响。为明确施磷量对不同耐低磷型水稻品质及其强、弱势粒淀粉合成相关酶活性的影响,以‘连粳7号’(弱耐低磷)和‘甬优2640’(强耐低磷)为供试水稻品种进行盆栽试验,设置4个磷肥施用量(按P_(2)O_(5)计):0 kg·hm^(-2)(P0)、60 kg·hm^(-2)(P60)、120 kg·hm^(-2)(P120)、180 kg·hm^(-2)(P180),分析不同施磷量下稻米品质与淀粉合成酶活性之间的关系,为高品质稻米栽培提供参考。结果表明:1)与P0相比,增施磷肥改善了稻米品质。随着施磷量增加,糙米率、精米率、整精米率呈先增加后降低趋势,垩白粒率、垩白面积、垩白度、碱消值、直链淀粉含量先降低后增加。‘连粳7号’与‘甬优2640’分别在P120、P60时稻米品质最优,糙米率、精米率和整精米率分别比P0增加19.6%、25.3%、79.7%(‘连粳7号’)与17.8%、23.5%、38.4%(‘甬优2640’);‘甬优2640’稻米品质优于‘连粳7号’。2)与P0相比,增施磷肥提高了水稻籽粒淀粉合成相关酶活性。腺苷二磷酸葡萄糖焦磷酸化酶(AGPase)、可溶性淀粉合成酶(StSase)、蔗糖合成酶(SuSase)、淀粉分支酶(Q-酶)、三磷酸腺苷酶(ATPase)活性随施磷量增加先增加后降低。总体来看,‘连粳7号’与‘甬优2640’分别在P120、P60时淀粉合成相关酶活性最高,灌浆中期强势粒AGPase、StSase活性分别比P0增加18.4%、51.1%(‘连粳7号’)与20.0%、51.5%(‘甬优2640’);‘甬优2640’籽粒酶活性高于‘连粳7号’。3)不同耐低磷型品种淀粉合成相关酶活性与蛋白质含量、直链淀粉含量相关性不同。淀粉合成相关酶显著或极显著影响‘连粳7号’蛋白质含量,对直链淀粉含量影响较小;淀粉合成相关酶活性显著或极显著影响‘甬优2640’直链淀粉含量,对蛋白质含量影响较小。‘连粳7号’与‘甬优2640’分别在P120、P60处理下能够提高强弱势粒中淀粉合成相关酶活性,促进籽粒中淀粉的合成与积累,有利于水稻品质改善。

Removal of superior wheat kernels promotes filling of inferior kernels by changing carbohydrate metabolism and sink strength

Poor filling and low weight of inferior kernels limit the further improvement of wheat yield. Two cultivars, Shuangda 1 and Xinong 538, with different grain weights, were selected to investigate the physiological changes of inferior kernels by removal of superior kernels(RS) at the flowering stage. i TRAQ combined with physiological indexes was used to identify factors limiting the filling of inferior kernels.Removal of superior kernels significantly increased the mean filling rate of inferior kernels and thus increased their weight. A set of 6012 proteins in inferior wheat kernels were differentially expressed between the RS and control. These differentially expressed proteins were involved mainly in carbon metabolism and energy metabolism. The main reason for the promoting effect of RS on the filling of inferior kernels may be that RS downregulated proteins involved in glycolysis and pyruvate metabolism while upregulating proteins involved in carbon fixation and photosynthesis. Consequently, RS greatly increased the ATP content in inferior kernels, supplying energy for them to absorb photosynthetic assimilates. Removal of superior kernels increased the activities of sucrose synthase, soluble starch synthase,adenosine diphosphate glucose pyrophosphorylase, and starch branching enzyme in inferior kernels and promoted starch accumulation in them. Thus, RS promoted the filling of inferior kernels and increased their weight. The promoting effect of RS on starch synthesis in inferior kernels was associated with their endogenous IAA and ABA levels.

氮素水平对籼粳杂交稻产量和贮藏蛋白的影响

氮素对稻米蛋白质含量的影响研究颇广,但籼粳杂交稻强弱势粒蛋白组分的积累动态、蛋白质分布及其对氮素的响应鲜有报道。以两个籼粳杂交稻(甬优12和甬优17)为材料,设置4个氮肥水平,即N0(不施氮)、低氮(100 kg·hm^(-2))、中氮(200 kg·hm^(-2))和高氮(300 kg·hm^(-2)),比较了产量、粒型、强弱势粒干物质积累与贮藏蛋白的积累特征。结果显示,施氮显著提高两品种的产量以及蛋白质含量,但品种间对氮素响应存在差异。甬优12在低氮下就能获得较高产量,且其蛋白质积累对氮素响应也较稳定,能实现高产优质的平衡。低氮对粒型无显著影响,高氮显著降低长宽比,导致粒重轻微下降。醇溶蛋白和谷蛋白积累过程存在此起彼伏的现象,从而维持总蛋白的相对平衡。弱势粒蛋白质含量高于强势粒,但因其粒重小导致总积累量仍然低于强势粒。贮藏蛋白主要富集在籽粒外层胚乳中,甬优17对氮素响应较甬优12更敏感。研究结果可为籼粳杂交稻的高产优质栽培技术提供理论依据。

Superior grains determined by grain weight are not fully correlated with the flowering order in rice

Rice panicles are composed of many branches with two types of extreme grains,the superior and the inferior.Traditionally,it has been well accepted that earlier flowers result in superior grains and late flowers generate inferior grains.However,these correlations have never been strictly examined in practice.In order to determine the accurate relationship between superior and inferior grains and the flowering order,we localized all the seeds in a panicle in four distinct rice species and systematically documented the rice flowering order,flower locations and the final grain weight for their relationships.Our results demonstrated that the grain weight is more heavily determined by the position of the seeds than by the flowering order.Despite earlier flowering has a positive correlation with the grain weight in general,grains from flowers blooming on the second day after anthesis generally gained the highest weight.This suggests earlier flowers may not result in superior grains.Therefore,we concluded that superior and inferior grains,commonly determined by grain weight,are not fully correlated with the flowering order in rice.Following the order of the grain weight,the superior grains are generally localized at the middle parts of the primary branches,whereas inferior grains were mainly on the last two secondary branches of the lower half part of the panicle.In addition,the weight of inferior grains were affected by spikelet thinning and spraying with exogenous plant growth regulators,indicating that physiological incompetence might be the major reason for the occurrence of the inferior grains.

施氮量对高粱籽粒灌浆及淀粉累积的影响

本试验于2019-2020年以汾酒粱1号为材料,在0、75、150、225、300和450 kg N hm^(-2)6个施氮水平下,于花后每隔7 d采集不同穗位籽粒分析其灌浆特性及淀粉形成过程,探究不同氮素用量对高粱籽粒灌浆及单粒淀粉累积的影响。结果表明,与不施氮相比施氮75 kg hm^(-2)显著提高了穗粒数和产量,但随施氮量的增加产量没有显著变化;氮素对优势粒(始花日开始2 d内开花的籽粒)和劣势粒(始花日开始5~6 d间开花的籽粒)的单粒重及单粒体积、灌浆特性和单粒淀粉累积的影响趋势基本一致,施氮条件下单粒重、单粒体积和灌浆速率随施氮量增加而增加,但不施氮处理的单粒重和单粒体积仍高于各施氮处理,且缺氮显著延长了灌浆活跃期。籽粒淀粉累积速率与参与籽粒淀粉合成的关键酶ADP-葡萄糖焦磷酸化酶(AGPase)和可溶性淀粉合酶(SSS)活性显著相关;过量施氮(450 kg N hm^(-2))灌浆前期籽粒中AGPase和SSS的活性最高,促进了灌浆前期籽粒淀粉累积;施氮75 kg hm^(-2)灌浆前期籽粒中AGPase和SSS的活性和淀粉累积速率次之;虽然缺氮降低了灌浆前期籽粒中AGPase和SSS的活性,但在灌浆后期维持较高活性而延长了灌浆活跃期,因而后期具有较高的单粒淀粉累积速率,提升了单粒淀粉累积量和单粒重。

稻田土壤铜含量对水稻籽粒灌浆特性与产量的影响

为探究稻田土壤铜含量对水稻产量及籽粒灌浆特性的影响,于2019和2021年通过盆栽试验分析24.32(对照,CK)、100(Cu100)和200 mg·kg^(-1)(Cu200)稻田土壤铜含量下水稻的产量差异,并通过Richards方程对籽粒灌浆过程进行拟合,比较籽粒灌浆参数之间的差异,探讨铜含量对不同粒位籽粒灌浆特性的影响。结果表明,2019和2021年Cu200处理水稻产量较CK分别减少31.18%和39.50%(P<0.05);而Cu100处理水稻产量较CK分别表现为减少12.94%(P<0.05)和增加10.07%(P>0.05)。土壤不同铜含量处理下水稻籽粒灌浆特性表明,与对照相比,Cu100处理强势粒延长了活跃灌浆期(D)和到达最大灌浆速率的时间(Tmax),最终生长量A值提高,而弱势粒D值及Tmax明显缩短,A值明显降低;Cu200处理强、弱势粒D值及Tmax明显减小,A值显著降低。总体而言,各处理对弱势粒灌浆影响大于强势粒。进一步分析不同土壤铜含量下水稻产量变化规律发现,与CK相比,Cu100处理水稻增产是由于强势粒粒重增加的同时有效穗数也有所增加,一定程度上抵消了弱势粒灌浆不充分所带来的负面影响;而Cu200处理产量显著下降是由于强、弱势粒灌浆不充分共同作用,导致有效穗数及千粒重显著降低。本研究结果可为进一步合理利用铜污染土壤提供理论依据。

不同降雨年型施氮量对延迟收获夏玉米产量、强弱势粒形态与粒重的影响

【目的】华北平原热量资源有限,夏播玉米收获期籽粒含水率高,影响机械粒收质量,限制了该项技术在该区域的应用。延迟收获条件下,施氮量差异对夏玉米籽粒产量、强弱势粒形态、粒重等关键产量性状的影响尚不明确。通过对不同施氮水平强弱势粒形态、灌浆及脱水过程的系统观测,明确氮肥调控效应,为区域机械粒收夏玉米稳产减氮增效栽培提供支持。【方法】2020—2021年选用粒收夏玉米品种京农科728为材料,采用收获时期和施氮量二因素区组试验设计,收获时期设正常果穗收获(NH)和延迟籽粒收获(DH),6个纯氮施用水平分别为0(N0)、120(N120,2021)、180(N180)、240(N240)、300(N300)、360(N360)和450 kg hm^(-2)(N450,2020),测定产量(GY)、籽粒鲜体积(GFV)、鲜重(GFW)、干重(GDW)、含水率(GMC)及其变化速率。【结果】与干旱年型(2020年)相比,多雨年型(2021年)弱势粒的GFV、GFW和GDW的最大变化速率(Gmax)、生长量(Wmax)和起始势(R0)显著降低,到达最大变化速率时间(Tmax)推迟,活跃期(P)延长,导致弱势粒的GFV、GFW和GDW显著降低15.4%—50.6%、25.4%—62.0%和31.2%—57.3%,而强势粒不显著,GY显著降低3.03×10^(3)—5.44×10^(3)kg·hm^(-2)。多雨年型条件下,弱势粒的GDWGmax、GDWWmax和GDWR0比强势粒显著降低55.1%—258.1%、13.4%—143.0%和12.0%—126.6%,GDWTmax推迟4.2—20.7 d,强势粒的GFV、GFW和GDW比弱势粒显著提高56.8%—69.6%、67.0%—80.4%和54.1%—92.1%。与NH相比,延迟收获籽粒的Gmax和R0提高,强、弱势粒的P显著延长;在干旱年型和多雨年型下,GFV、GFW显著降低2.1%—8.1%和12.2%—17.1%、4.0%—5.2%和15.7%—19.5%,GDW自25.1—28.2 g/100 grains提高到28.0—34.4 g/100 grains,GMC降至22.6%—26.0%,降幅达31.3%—40.4%,产量提高0.02×10^(3)—1.67×10^(3)kg·hm^(-2)。干旱年型施氮水平间的GFV、GFW、GDW无显著差异;多雨年型N240-N360处理的GDWGmax、GDWWmax比N180提高,GDWTmax推迟,GDWP延长,差异均达显著水平,且对弱势粒影响强于强势粒。DH处理下,N240-N360弱势粒的GFV、GFW和GDW比N180显著提高25.7%—85.3%、59.4%—83.6%和17.9%—43.9%。多雨年型下氮肥的增产效应(74.4%—169.5%)显著高于干旱年型(51.5%—99.1%),N240 GY比N120-N180显著提高12.6%—54.5%。【结论】华北平原热量资源限制区小麦-玉米种植制度,将冬小麦变为春小麦,夏玉米延迟收获23—33 d,显著提高弱势粒库容与粒重,籽粒含水率降低至籽粒机收含水率标准,实现周年机械化粒收。优化施氮247.2—248.6 kg·hm^(-2),实现不同降雨年型下产量稳定在7.0×10^(3)—12.0×10^(3)kg·hm^(-2)的稳产减氮增效的生产目标。

大麦强、弱势粒胚乳淀粉体发育及淀粉理化性质的比较研究

以大麦品种白青稞C2-2为材料,通过树脂切片观察大麦胚乳淀粉体发育的结构特征,同时提取成熟大麦籽粒的淀粉,测定其形态、结构、功能等理化性质,研究大麦强、弱势粒胚乳淀粉体发育及理化性质的差异。结果表明:大麦强势粒胚乳中淀粉体的发育较弱势粒好,胚乳淀粉的充实度更高;强、弱势粒淀粉的形态和晶体类型基本相似,但淀粉结构存在一定差异;强势粒淀粉的相对结晶度显著高于弱势粒,但1022/995 cm^(-1)吸收峰强度的比值却显著低于弱势粒;大麦强势粒淀粉的峰值黏度、低谷黏度和最终黏度均显著高于弱势粒,表现出较好的糊化特性。

不同叶位功能叶片对不同穗型水稻籽粒灌浆特性及稻米品质的影响

为明确不同穗型水稻不同叶位功能叶片与灌浆特性、产量和稻米品质的关系,以半直立大穗型水稻辽粳401和弯穗型优质稻辽粳371为试验材料,研究不同叶位功能叶片[剪剑叶(T1)、剪倒2叶(T2)、剪倒3叶(T3)和不剪叶(对照,CK)]对不同穗型水稻强、弱势粒灌浆特性和产量、品质的影响,并对籽粒灌浆参数与稻米品质指标进行相关性分析。结果表明,剑叶和倒2叶缺失均显著降低辽粳401强、弱势粒和辽粳371弱势粒的最大灌浆速率和平均灌浆速率;不同叶位功能叶片缺失均显著延长了辽粳401的活跃灌浆期,缩短了辽粳371的活跃灌浆期;不同叶位功能叶片缺失均提前了辽粳401的最大灌浆时间,推迟了辽粳371的最大灌浆时间;剑叶和倒2叶缺失均显著降低结实率、籽粒充实度和千粒质量,进而显著降低产量。对上述指标的影响均表现为剑叶>倒2叶>倒3叶。与CK相比,剪剑叶处理中辽粳401和辽粳371的千粒质量分别降低18.32%和6.44%,产量分别降低16.52%和8.05%。随着缺失叶位升高,稻米的加工品质、外观品质、崩解值和最终黏度逐渐下降,其中对垩白度和垩白粒率的影响较大。不同叶位功能叶片对水稻产量和品质的影响均表现为弯穗型小于半直立大穗型。综上,不同叶位功能叶片对水稻灌浆特性、产量和品质的影响表现为剑叶>倒2叶>倒3叶,且对半直立大穗型水稻的影响大于弯穗型。

外源ABA和GA对小麦籽粒内源激素含量及其灌浆进程的影响

【目的】探讨喷施外源脱落酸(ABA)或赤霉素(GA)对小麦籽粒内源激素含量及其灌浆进程的影响,为激素调控提高籽粒的粒重提供理论依据。【方法】试验选用山农1391和藁城8901两个品种,籽粒灌浆初期喷施ABA或GA两种外源激素于穗部,定期取籽粒样品,用高效液相色谱法测定籽粒内源激素含量,用三次多项方程式对籽粒灌浆进程进行模拟并分析相关参数。【结果】喷施外源ABA或GA均能显著增加两个品种的粒重。外源ABA或GA对粒重的调控存在粒位效应。喷施ABA显著增加强势粒粒重,喷施GA使强势粒和弱势粒粒重均显著增加。喷施外源ABA显著提高籽粒ABA含量,喷施外源GA显著提高籽粒GA含量,喷施外源ABA或外源GA均显著提高灌浆中后期籽粒IAA和CTK的含量,尤其是喷施外源GA效果更为明显。喷施外源ABA或外源GA均能延长籽粒的灌浆持续期,喷施ABA显著提高灌浆初期强势粒的灌浆速率,而喷施GA显著提高灌浆中后期强势粒和弱势粒的灌浆速率。【结论】喷施外源ABA或外源GA通过改变籽粒内源激素水平,调节灌浆起始时间和籽粒灌浆持续期,进而调控籽粒粒重的形成。喷施ABA是通过提高强势粒粒重来增加粒重的,喷施GA是通过提高强势粒和弱势粒的粒重来增加粒重的。

麦秸还田与氮肥运筹对超级稻强弱势粒粒重与品质的影响

以两个超级稻品种(籼稻扬两优6号和粳稻南粳45)为材料,设置麦秸还田和氮肥运筹两种处理方式,研究其对籽粒粒重与主要米质的影响。结果表明,两处理的影响程度在品种类型与不同粒位间(强、弱势粒)存在差异。与麦秸不还田相比,麦秸还田提高籽粒千粒重、粗蛋白含量和崩解值,降低了整精米率、垩白度、直链淀粉含量和消减值;与m基蘖肥∶m穗粒肥=5∶5处理相比,m基蘖肥∶m穗粒肥=7∶3处理增加了千粒重、垩白度、直链淀粉含量、崩解值,降低了整精米率、粗蛋白含量和消减值。两处理对弱势籽粒千粒重、整精米率、垩白度等的调控作用显著大于强势粒;对千粒重、整精米率、粗蛋白含量等的影响,麦秸还田与氮肥运筹之间存在互作效应;麦秸还田方式下,氮肥比例控制在5.5∶4.5或6∶4左右,可以较好地协调粒重与米质。

不同种植方式对超级稻籽粒灌浆特性的影响

为探明不同种植方式下高产水稻的籽粒灌浆特性,以超级稻品种淮稻9号和III优98为材料,应用Richards方程W=A/(1+Be-Kt)1/N对旱育中苗壮秧精量手栽、小苗机插、直播3种种植方式水稻强、弱势粒的灌浆过程进行了比较研究。结果表明:(1)不同种植方式下,超级稻产量差异极显著,手栽最高,机插次之,直播最低。与手栽和机插相比,直播的千粒重和结实率显著降低,而手栽和机插之间千粒重和结实率的变化因品种类型而异。(2)不同种植方式下超级稻强、弱势粒灌浆特征为明显的异步灌浆型。强势粒达到最大灌浆速率的时间(Tmax)早,最大灌浆速率(GRmax)、平均灌浆速率(GRmean)以及终极生长量(A)和起始生长势(R0)均明显大于弱势粒,而活跃灌浆期(D)和有效灌浆时间(T99)明显小于弱势粒。(3)与手栽和机插相比,直播强势粒的GRmax和GRmean显著降低,Tmax明显延迟,D、T99显著增加。弱势粒的GRmax和GRmean机插最大,手栽略小于直播,Tmax直播最早,机插次之,手栽最迟,D、T99手栽、机插、直播依次减少。(4)籽粒灌浆阶段特征方面,平均灌浆速率和贡献率均以中期最大,中期的贡献率强势粒和弱势粒分别达到60.53%和50.78%,不同种植方式间前、中、后各期在灌浆持续天数、平均灌浆速率和贡献率上的差异因粒位不同而异。(5)千粒重与强、弱势粒的GRmax、GRmean和D呈正相关,且与弱势粒的灌浆速率(GRmax和GRmean)显著相关,结实率与强、弱势粒的灌浆参数除强势粒的D外,均不显著相关。说明不同种植方式对超级稻的籽粒灌浆特性有明显影响,虽均为异步灌浆型,但其强、弱势粒的最大灌浆速率及到达最大灌浆速率的时间等灌浆特征参数均差异较大,在保持籽粒最终生长量和结实率稳定的条件下,提高籽粒的灌浆速率,特别是弱势粒的灌浆速率,对提高千粒重有重要的作用。

结实期水分胁迫对水稻强、弱势粒主要米质性状及淀粉粘滞谱特征的影响

以汕优 6 3和武香粳 9号为供试品种 ,研究了结实期土壤水分胁迫对水稻强、弱势粒稻米主要米质性状和淀粉粘滞谱特征的影响。结果表明 :(1)两品种强势粒和弱势粒达到最大粒重和最小垩白时的结实期处理土水势是相同的 ,均为 - 2 0kPa,在此土水势下 ,强势粒和弱势粒加工品质和蒸煮品质无显著变化 ,改善了营养品质 ,米质相对较优 ;(2 )当土水势降到 - 6 0kPa时 ,强势粒和弱势粒粒重、整精米率及弱势粒的直链淀粉含量显著降低 ,胶稠度变硬 ,食味变差 ,米质变劣 ;(3)土壤水分对同一穗上不同粒位籽粒米粉的RVA谱特性的影响因粒位的不同而不同 ,强势粒米粉RVA谱间差异较小 ,弱势粒米粉RVA谱水分处理间存在明显差异 ,RVA谱特征值变化因品种而异 ,当土水势降到 - 6 0kPa时 ,武香粳 9号弱势粒淀粉粘滞谱特征值发生明显变化 ;(4 )同一品种强势粒和弱势粒米质以及RVA谱特性存在明显差异 ,在土水势为 - 2 0kPa时 ,这种差异相对较小。