我国不同年代玉米自交系茎秆性状演替规律

茎秆是玉米植株重要的组成部分,与植株倒伏、籽粒产量密切相关。研究我国玉米茎秆性状变化趋势,探讨不同年代茎秆性状演变规律,为我国玉米抗倒伏及高产品种选育提供参考。本研究以20世纪60-90年代65个代表性玉米自交系为材料,调查植株茎高、穗位高、茎节数、穗位节、茎粗、茎秆含水量、茎秆含糖量7个茎秆性状,及其衍生的穗位系数(穗位高/茎高)和穗节系数(穗位节/茎节数),基于最佳线性无偏估计值,开展性状相关性分析及不同年代自交系茎秆性状演变规律研究。结果显示,玉米自交系间茎秆性状差异显著;不同年代的茎秆性状时代特征不明显;随着年代的更替,玉米茎高、穗位高、茎节数、穗位节呈下降趋势;20世纪60-90年代穗位高改良效果显著;80年代左右玉米茎秆粗细育种目标由粗壮型调整为纤细型,可能与合理密植、提高单产的育种目标有关;90年代,玉米茎秆含水量降低3个百分点,下降显著。总之,抗倒伏研究一直是我国玉米育种的重要研究方向,且穗位高改良效果显著,玉米茎节数、穗位节将成为玉米抗倒伏及高产研究中新的重要关注点,研究结果对玉米抗倒伏及高产育种具有重要的指导意义。     

不同小麦品种茎秆特性及其与抗倒性的关系

以黄淮麦区优良品种矮抗58、周麦18、豫麦49、百农418为研究对象,采用田间试验与实验室分析相结合的方法,对不同小麦品种在不同生育时期的抗倒伏性状进行研究.结果表明: 茎秆机械强度在开花期至花后20 d处于较高水平,在花后30 d明显下降;倒伏指数在开花期最小,花后30 d最大,其余两个时期处于中间水平.相关分析表明,开花期机械强度与重心高度呈显著负相关,与纤维素、木质素含量呈显著正相关,倒伏指数与节长、株高、重心高度呈显著正相关,与纤维素、木质素含量呈显著负相关;花后10 d和花后20 d机械强度与节长、株高、重心高度呈显著负相关,与茎粗、纤维素、半纤维素、木质素含量呈显著正相关,倒伏指数这段时期正好与之相反;花后30 d机械强度与株高、重心高度呈显著负相关,倒伏指数与株高、重心高度呈显著正相关,与木质素含量呈显著负相关.因此,明确各个生育时期与抗倒性相关的茎秆特性,可为黄淮麦区高产抗倒性品种的选育提供依据.     

谷子抗倒伏性和株高、穗部性状的相关性研究

倒伏是限制作物产量提高的重要因素,而株高、穗长、穗粗、穗粒重等性状与产量密切相关,因此弄清抗倒伏性与这些性状的关系,对开展抗倒伏高产育种具有重要意义。本研究系统调查了41份谷子材料倒伏指数、株高、穗长、穗粗、穗码数、码粒数、穗粒重7个性状,结果表明：所有调查的7个性状指标在41份谷子材料中存在显著差异,除穗粗变异幅度较小,其余6个性状指标均存在丰富的遗传变异。相关性分析表明谷子基部第一、第二、第三节倒伏指数均与株高呈一定负相关,但未达到显著水平,与穗长、穗码数、码粒数、穗粒重均呈一定正相关,但只有第二节倒伏指数与穗长间的相关达到了显著水平（P<0.05）。倒伏指数与穗粗的相关性较复杂,第一、第三节倒伏指数与穗粗呈负相关,而第二节倒伏指数与穗粗呈正相关,但都未达到显著水平。株高与穗长、穗粗、穗码数、穗粒重4个产量关键性状间呈显著（P<0.05）或极显著（P<0.01）正相关;穗长、穗粗、穗码数、码粒数、穗粒重5个性状间呈极显著正相关（P<0.01）。研究结果认为在80 cm范围内,增加株高不会减弱谷子的抗倒伏性,谷子倒第二节抗倒伏性对整株植株抗倒伏性起到关键作用,应在抗倒伏高产育种中加以重视。     

小麦抗倒性研究进展

倒伏是严重影响小麦子粒产量和品质的一个重要因素。本文系统阐述了小麦茎秆形态和结构特性、茎秆化学成分与抗倒伏关系以及抗倒性的遗传和分子标记等方面的最新研究进展。株高、基部节间长度与抗倒性呈负相关;而基部节间粗度、秆壁厚、单位长度干重与抗倒性呈正相关。茎秆机械组织细胞层数、厚度,维管束数目、面积以及髓腔大小与抗倒性密切相关。茎秆化学成分中纤维素、木质素以及碳水化合物含量和硅、钾元素含量与抗倒性呈正相关。小麦抗倒性呈数量性状遗传特征,除受多对主基因控制外,可能还受微效修饰基因作用。采用分子标记技术已将抗倒性以及与抗倒性相关的茎秆形态性状进行了QTL定位。     

施钙对超级杂交稻抗倒性的影响

在3种不同施钙水平下,研究了超级杂交稻品种“准两优527”、“两优293”生育后期的抗倒伏能力、抗倒形态及生理性状指标变化情况。结果表明：施钙（特别是中、高量）对提高“准两优527”生育后期的抗倒伏能力作用明显,但不利于降低“两优293”成熟期的倒伏指数;超级杂交稻的抗倒伏能力品种间差异明显;“准两优527”、“两优293”生育后期的倒伏指数明显上升,但倒伏敏感期不同;单株抗折力、表观倒伏率、株高、单株生物量、茎鞘干质量、茎鞘物质输出率与倒伏指数呈显著或极显著的相关关系。     

甜高粱品系的抗倒伏性评价及相关分析

倒伏一直是影响我国甜高粱高产稳产的主要因素。调查了58份甜高粱品系与抗倒伏性相关的农艺性状,依据倒伏系数,制定分级标准,对抗倒伏性进行了鉴定、分级和评价,并对相关农艺性状进行了遗传多样性、相关性、因子和聚类分析,以期为甜高粱抗倒伏品系的选择和组配抗倒伏杂交种提供理论依据。研究表明,抗倒伏性相关的农艺性状多样性指数均较大,遗传变异丰富。在遗传距离2.57处,58份甜高粱品系可聚类分为8个类群。甜高粱倒伏系数的3个主因子代表90%以上信息,第1主因子包括株高、重心高度和主茎秆鲜重,第2主因子为茎秆抗折力,第3主因子为茎粗,育种中应加强选择。保持系品系Tx3047B、Tx3048B、墨彩B、张02427B、抗蚜60B、MAMAMAMA、R111B/Sug中杆、P236/R111-1、E35/糖/9047B的倒伏系数小,抗倒伏性好。恢复系品系甜C-1-1杂-1、HAT-1、15069、帚黄矮/品02283的抗倒伏性好。     

水稻茎秆抗倒伏的综合评价

利用力学理论和方法,综合分析了水稻茎秆各性状对抗倒伏的影响．突破以往的单性状分析方法,得到水稻茎秆抗倒伏的综合评价指标λ(茎秆柔度),它综合反映了秆长、截面尺寸和形状等茎秆性状．λ是一个无量纲的量,λ值越小,抗倒伏能力越强．     

套作大豆苗期茎秆纤维素合成代谢与抗倒性的关系

为从茎秆强度的角度研究套作大豆苗期对荫蔽胁迫的响应及耐荫抗倒机制,采用耐荫性不同的3个大豆材料,在玉米大豆套作和单作两种种植模式下,对茎秆的纤维素、可溶性糖、蔗糖、淀粉含量及蔗糖代谢中关键酶活性以及茎秆抗折力、抗倒伏指数等进行测定,研究它们与套作大豆苗期倒伏的关系.套作大豆苗期倒伏严重,茎秆抗折力、抗倒伏指数、纤维素、可溶性糖、蔗糖、淀粉含量和相关酶活性均显著低于单作.不同大豆材料受套作荫蔽影响程度不同,强耐荫性大豆南豆12茎秆抗折力降低幅度最小,在套作环境下其茎秆抗折力、抗倒伏指数大,纤维素、可溶性糖、蔗糖、淀粉含量高,酶活性强.相关分析表明： 套作大豆苗期茎秆糖含量均与抗折力呈极显著正相关,与倒伏率呈极显著负相关;蔗糖含量与蔗糖磷酸合酶(SPS)、蔗糖合酶(SS)、中性转化酶(NI)活性呈极显著正相关,与酸性转化酶(AI)活性相关性不显著;纤维素含量与SPS、SS呈极显著正相关,与NI呈显著正相关,与AI相关性不显著.套作环境下,强耐荫性大豆苗期茎秆中较高的SPS、SS活性是其维持高蔗糖和纤维素含量的酶学基础,而高纤维素含量有利于提高茎秆强度,进而增强其抗倒伏能力.本研究应用玉米大豆套作种植系统,从苗期抗倒角度,探明了光环境对不同基因型大豆茎秆纤维素代谢的影响机制,为下一步筛选耐荫抗倒大豆品种提供了理论依据.     

不同养分和水分管理模式对水稻抗倒伏能力的影响

大田试验下,通过对水稻茎秆基部物理性状、形态特征和硅、钾含量的测定和比较,系统研究了不同养分和水分管理模式对水稻茎秆抗倒伏能力的影响．结果表明,有机无机肥配施,特别是秸秆与化肥配施(CS)养分模式可明显提高水稻植侏茎秆粗度、茎壁厚度和茎重,从而有效提高了基部茎秆的抗折力(RS)和明显降低了水稻的倒伏指数(LI),秸秆与化肥配施(CS)养分模式对水稻抗倒伏能力的效果在干湿交替(AWD)和控水模式(DRA)下表现更为明显。有机无机肥配施,特别是秸秆与化肥配施(CS)的养分模式在干湿交替(AWD)和控水模式(DRA)下更有助于提高水稻茎秆的硅、钾含量、相关分析表明,水稻基部茎秆茎壁厚度、茎重和抗折力与茎秆硅、钾含量存在显著(P<0．05)或极显著正相关(P<0．01)。     

甘蓝型油菜抗茎倒材料的筛选与候选基因挖掘

该研究采用茎秆抗折力指标评价了200份甘蓝型油菜种质资源抗茎倒伏能力,据此筛选出极端抗茎倒材料和不抗茎倒材料各1份,随后测定了2份材料成熟期茎秆的理化组分含量,并对2份极端抗茎倒差异材料蕾苔期、盛花期茎秆进行转录组测序分析,为甘蓝型油菜抗茎倒伏的遗传改良奠定基础。结果表明:(1)200份甘蓝型油菜种质资源的茎秆抗折力和茎粗均为正态分布,均属于数量遗传性状,并依据茎秆抗折力和农艺性状筛选出生育期相近,株型相似,茎秆粗度差异不显著,但茎秆抗折力差异显著的极端不抗茎倒材料GY172和抗茎倒材料GY199。(2)GY199的韧皮部比GY172更加致密,而GY172成熟期茎秆中的半纤维素、木质素、中性洗涤纤维及总可溶性糖含量均显著高于GY199,而其纤维素含量极显著低于GY199,即成熟期茎秆纤维素含量与这2个材料的茎秆抗折力呈正相关。(3)蕾苔期、盛花期茎秆转录组测序发现,碳代谢、碳固定、磷酸戊糖途径、氨基酸的生物合成、糖酵解/糖异生等途径的14个基因(BnaA10G0056100ZS、BnaC08G0455100ZS、BnaA08G0262400ZS、BnaC08G0239700ZS、BnaA07G0362300ZS、BnaC02G0081300ZS、BnaC04G0273000ZS等)以及纤维素合成相关的9个基因(BnaA05G0152200ZS、BnaA01G0411100ZS、BnaA03G0018900ZS、BnaA03G0037800ZS等)在抗茎倒材料GY199中显著上调表达,这些基因可能参与调控了茎秆强度性状,可作为油菜抗茎倒候选基因。     

甜高粱品系的抗倒伏性鉴定及评价

倒伏一直是影响我国甜高粱高产稳产的主要因素。以倒伏系数为分级依据,制定分级标准,对一些主要甜高粱品系（种）抗倒伏性进行了鉴定、分级和评价。研究表明：甜高粱品系间倒伏相关性状差异较大,遗传变异丰富。保持系品系Tx3047B、Tx3048B、墨彩B、张02427B、抗蚜60B、MAMAMAMA、R111B/Sug中杆、P236/R111-1、E35/糖/9047B的倒伏系数小,抗倒伏性好。恢复系品系甜C-1-1杂-1、HAT-1、15069、帚黄矮/品02283的抗倒伏性好。选育出茎秆粗壮、机械强度大、抗倒伏性好的品种是可能的。     

Characterising the morphological characters and carbohydrate metabolism of oat culms and their association with lodging resistance

• Lodging resistance can be improved by enhancing the mechanical strength of culms, and culm carbohydrates could improve this mechanical strength. Culm carbohydrates can regulate development of the culm and affect its toughness.
• The present study determines the relationship between lodging and carbohydrate content in oat culms. Field experiments were conducted in alpine regions in 2017 and 2018 using three oat varieties with different lodging resistance. Lodging‐related morphological characteristics were directly determined and culm carbohydrate content and enzyme activity related to cellulose synthesis and sucrose metabolism were evaluated with ultraviolet spectrophotometry.
• Results showed that the lower the gravity height or the lower ratio of gravity height to plant height, the stronger the lodging resistance of the varieties. Higher culm nonstructural (NSC) and structural (SC) carbohydrate content contributed to the ability of culms to resist lodging, especially the content of cellulose and sucrose. PCA showed that sucrose metabolism and SC content were closely related to lodging resistance. Correlation analysis showed that the lodging index (LI) was significantly negatively correlated with NSC. Sucrose content was highly and significantly positively correlated with NSC. Additionally, the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SS) were highly and significantly positively correlated with sucrose and cellulose content.
• The relationship between field characters and oat lodging, as well as the regulatory mechanism of carbohydrate content on lodging resistance of the culm are discussed.

     

Quantitative trait loci for lodging resistance in a segregating wheat×spelt population

 Lodging can strongly affect both the grain yield and the quality of wheat. Lodging represents a quantitative trait and is difficult to assess on a phenotypic basis. Marker-assisted selection (MAS) could therefore become an important tool in breeding for lodging resistance. In this study, we mapped and characterised quantitative trait loci (QTLs) for lodging resistance, as well as morphological traits correlated with lodging, in a segregating population of 226 recombinant inbred lines derived from the cross of the lodging-resistant wheat variety Forno with the susceptible spelt variety Oberkulmer. Lodging, plant height, leaf width, leaf-growth habit, culm stiffness, culm swinging, culm thickness, days to ear emergence and days to flowering were assessed in field trials at two locations in 1996 and at one location in 1997. Additionally, at one location weight and length parameters were also assessed. Plant height and culm stiffness explained 77% of the phenotypic variance of lodging in a multiple regression model over all three environments. QTL analysis of lodging and morphological parameters was based on a genetic map containing 230 loci with 23 linkage groups (2469 cM). With the method of composite interval mapping nine QTLs for lodging resistance were detected, explaining 63% of the phenotypic variance in a simultaneous fit. Seven of these QTLs coincided with QTLs for morphological traits, reflecting the correlations between these traits and lodging. In our population the most efficient way to improve lodging resistance would be by a combination of indirect selection on plant height and culm stiffness together with MAS on the two QTLs for lodging resistance which did not coincide with QTLs for morphological traits. Received: 3 August 1998 / Accepted: 28 November 1998     

中国小麦主推品种和育成品系的抗倒伏性评价

倒伏是影响小麦产量的主要因素之一,选育抗倒伏性强的品种是育种研究的重点目标。本研究以528份我国主推的小麦品种和育成品系为材料,对影响小麦倒伏的主要性状进行测定,利用无偏线性估计值进行遗传变异分析、相关分析、主成分分析、线性回归分析和聚类分析,综合评价不同小麦品种的抗倒伏性。研究表明,6个抗倒伏性状在品种间都存在着广泛的遗传变异。基部节间长度、株高与抗推力呈极显著负相关,基部节间直径与抗推力呈极显著正相关,节间长度与节间直径相关性不显著。主成分分析表明,所有性状的信息可以用3个主成分代表,其累计贡献率达83.837%。回归分析结果表明,第1节间直径、第1节间长度、第2节间直径、第2节间长度和株高等5个性状均对抗推力有显著影响。依据抗推力将528份材料聚类为4类,其中第Ⅰ类群有66份小麦品种(系),其抗倒伏能力最强。研究结果为小麦抗倒伏品种利用、抗倒伏育种亲本的筛选以及育种后代品系的选育评价提供理论依据和技术支撑。     

Loss of the beta-catenin homologue aardvark causes ectopic stalk formation in Dictyostelium

Aardvark (Aar) is a Dictyostelium beta-catenin homologue with both cytoskeletal and signal transduction roles during development. Here, we show that loss of aar causes a novel phenotype where multiple stalks appear during late development. Ectopic stalks are preceded by misexpression of the stalk marker ST-lacZ in the surrounding tissue. This process does not involve the kinase GSK-3. Mixing experiments show that ectopic ST-lacZ expression and stalk formation are cell non-autonomous. The protein-cellulose matrix surrounding the stalk of aar mutant fruiting bodies is defective, and damage to the stalk of wild-type fruiting bodies leads to ectopic ST-lacZ expression. We postulate that poor synthesis of the stalk tube matrix allows diffusion of a stalk cell-inducing factor into the surrounding tissue.     

Combining QTL and candidate gene analysis with phenotypic model to unravel the relationship between lodging and related traits in soybean

Lodging is one of the major influencing factors of yield and quality in soybean [Glycine max (L.) Merr.] and other crops. To dissect the genetic basis of lodging in soybean, a recombinant inbred line population consisting of 165 lines was used to evaluate lodging percentage and eight related traits (branch number, internode length, number of nodes, plant height, stem diameter, stem strength, root length, and root weight) in three environments. Regression analysis indicated that plant height and root weight, which explain more than 55% of the variation in lodging percentage, might be the key factors influencing lodging in soybean. Nine consensus quantitative trait locus (QTLs) of lodging percentage were detected in one to three environments. Of which, eight consensus QTLs were colocated with 16 consensus QTLs of lodging-related traits by meta-analysis. In addition, seven candidate genes with the biological functions of shoot branching, root development, internode elongation, and lignin biosynthesis were identified on four pleiotropic QTL regions (oq.13-1, oq.13-2, oq.19-2, and oq.19-3) for lodging percentage and related traits. These findings showed that the consensus QTLs of lodging percentage might result from the pleiotropic QTLs affecting the lodging-related traits. Soybean lodging is determined by the cumulative effect of many traits/processes of growth and development. The combination of MAS, statistical model, and phenotypic selection will provide a powerful breeding strategy for lodging resistance in soybean.     

The effect of nitrogen and growth regulators on stem and root characteristics associated with lodging in two cultivars of winter wheat

The effects of nitrogen and plant growth regulators (stem shorteners)on root and shoot characteristics associated with lodging resistancewere investigated in two winter wheat (Triticum aestivum L.)cultivars of contrasting lodging resistance: the susceptibleGalahad and the resistant Hereward. The morphology and mechanicalstrength of the stems and anchorage systems grown at two levelsof nitrogen and with or without growth regulators were measuredand related to the incidence of lodging recorded in a fieldtrial. In both cultivars high levels of nitrogen increased theheight of the stem, thereby increasing the ‘self-weight’moment transmitted into the ground and weakened both the stemsand the anchorage coronal roots. As a result, the anchoragestrength was also reduced, plants failing in the root systemin simulated lodging tests. Growth regulators, in contrast,had little effect on the bending strength of the shoots androot systems, but reduced plant height so that the over turningmoments generated by the weight of the shoot were less. Therewere also differences between cultivars: Galahad plants hadweaker anchorage due to the smaller number and lower strengthof the coronal roots. The morphological and mechanical measureswere used to calculate a safety factor against both stem androot lodging. Five factors were found to influence the safetyfactors, these were: cultivar type, the type of lodging, therate of nitrogen and growth regulator application, and time,being lowest in Galahad plants at high levels of nitrogen andwithout growth regulators and at grain filling when the earswere heaviest. This was consistent with the observed patternof lodging: root lodging occurred at grain filling and onlyin Galahad which had been treated with high nitrogen rates,most strongly in plants without growth regulators. Key words: Lodging, safety factors, anchorage, ‘self-weight’ moment     

抽雄期前后大风倒伏对夏玉米生长及产量的影响

利用2013年8月1日河南省南阳地区夏玉米大风倒伏灾害的调查数据,分析抽雄期前后不同类型倒伏对夏玉米生长及产量形成的影响,研究不同品种的抗倒性差异和适播期.调查对象为5个播期的浚单20和3个播期的郑单958,倒伏类型划分为根斜、根倒、茎折和折断4种.研究表明： 各品种及播期均于抽雄前～抽雄后15 d倒伏率较高.浚单20各播期的总倒伏率为86.0%～98.5%,郑单958各播期的总倒伏率为60.0%～76.4%,且播种越早的播期总倒伏率越低.浚单20倒伏发生时,播期Ⅱ～Ⅴ的夏玉米生育时期接近抽雄,以根倒类型为主,倒伏率为53.0%～84.3%,已过抽雄期的播期Ⅰ夏玉米以茎折倒伏为主,倒伏率为37.5%.倒伏发生后干物质积累显著降低,各倒伏类型对干物质积累的影响总体表现为茎折>根倒>根斜,播种越晚的总干物质积累越少.倒伏对干物质分配比例影响表现为叶片和茎杆干物质比例增大,果穗干物质比例减少.根倒和茎折两种倒伏类型使穗长显著变短,穗粗显著变细,穗粒数显著减少,抽雄后发生倒伏也会使百粒重显著降低;而根斜倒伏类型对各性状的影响均不显著.倒伏后产量损失严重,不同倒伏类型中茎折类型减产最多,浚单20和郑单958平均减产率分别为74.2%和68.7%,尤其是茎折发生在抽雄之前难以形成产量;其次是根倒,平均减产率分别为46.3%和46.5%;根斜产量损失最小,平均分别为8.4%和13.2%.大风倒伏灾害后,浚单20产量平均为4959.9 kg·hm^-2,产量随播期的推迟而减少;郑单958平均为6026.1 kg·hm^-2,随播期变化不明显.总体上,郑单958品种抗倒性好于浚单20.     

Effect of Mowing Cotton Stalks and Preventing Plant Re-Growth on Post-Harvest Reproduction of Meloidogyne incognita

The southern root-knot nematode (Meloidogyne incognita) is a major parasite of cotton in the U.S., and management tactics for this nematode attempt to minimize population levels. We compared three post-harvest practices for their ability to reduce nematode population levels in the field, thereby reducing initial nematode population for the next year's crop. The three practices tested were: 1) chemical defoliation before harvest plus cutting cotton stalks after harvest, 2) chemical defoliation plus applying a herbicide to kill plants prior to cutting the stalks, and 3) chemical defoliation without cutting stalks. Experiments were conducted in both the greenhouse and in the field. The greenhouse experiments demonstrated that M. incognita reproduction (measured as egg counts and root gall rating indices) was significantly greater when stalks were not cut. Cutting stalks plus applying herbicide to kill cotton roots did not significantly reduce nematode reproduction compared to cutting stalks alone. In field experiments, cutting stalks reduced egg populations and root galling compared to defoliation without stalk cutting. In a greenhouse bioassay which used soil from the field plots, plants grown in soil from the defoliation only treatment had greater root gall ratings and egg counts than in the stalk cutting plus herbicide treatment. Therefore, we conclude that cutting cotton stalks immediately after harvest effectively reduces M. incognita reproduction, and may lead to a lower initial population density of this nematode in the following year.