倒伏是玉米生产中常见的现象。玉米倒伏可分为茎折和根倒,其中,茎秆在穗位节或穗位节以下的折断称为茎折,茎秆与垂直线大于一定角度（30°或45°）而茎秆不发生折断称为根倒[1,2]。玉米根倒多发生在吐丝期之前的暴雨加大风天气,吐丝期之后玉米以茎折为主,且多发生在穗下基部节间[3]。生理成熟前玉米发生倒伏后影响了籽粒灌浆速率,对产量影响较大[4];生理成熟后倒伏对玉米产量形成影响较小,但是增加了机械粒收过程中的落穗量,降低了籽粒品质,收获难度加大,收获效率以及玉米种植效益明显降低[5,6,7]。玉米大面积倒伏后,农户人工捡拾果穗的成本往往高于果穗自身的价值[8,9]。国家标准“玉米收获机械技术条件”（GB/T-21962-2008）中规定机械粒收的条件为田间植株倒伏率应低于5%[10]。在我国玉米全程机械化发展的重要时期,分析玉米倒伏研究现状及其对机械粒收的影响,探讨影响玉米生育后期倒伏发生的关键因素及提高玉米抗倒能力的途径与方法,对实施玉米密植高产机械化生产过程中抗倒品种的选育和栽培具有重要意义 。
1 玉米倒伏研究现状
前人从植株形态学、茎秆力学特性、茎秆解剖结构与物质积累分配、根系生长特性、病虫害发生与危害、区域气候生态特点、品种遗传特性、种植密度、水肥管理及化学调控等方面对玉米倒伏问题进行了较为全面的研究。植株形态学的研究认为,玉米基部节间较长的植株具有较高的穗位和重心高度,倒伏风险大;相反,基部节间较短且粗壮的植株具有较强的抗倒伏能力[2, 5]。玉米茎秆力学特性、解剖结构及物质积累与分配的研究表明,茎秆力学强度,如茎秆外皮穿刺强度、压碎强度和弯曲强度均与田间倒伏率呈显著负相关[11,12];而茎秆外皮机械细胞、机械组织和维管束是提供力学强度的结构基础[13];茎秆中纤维素、木质素和半纤维素等结构性碳水化合物是形成机械细胞和机械组织的物质基础,其含量多少决定了玉米茎秆强度的高低[13,14,15]。根系研究表明,根系数量、总根体积、根与竖直方向夹角、根系直径及根系垂直拉力（vertical root pulling resistance,VRPR）与倒伏密切相关[16,17,18]。在病虫危害方面,玉米螟和茎腐病是造成玉米倒伏的主要病虫害,其中,玉米螟通过钻到茎秆内部,蛀空茎秆,使玉米茎折率大幅增加[19,20];玉米茎腐病病原菌产生细胞壁降解酶,分解细胞壁中的纤维素,降解寄主细胞（图1）[21];同时孢子迅速萌发成菌丝并从茎秆表面进入表皮细胞、皮层和维管束组织,使茎秆组织失水干缩,空心变软甚至腐烂,造成茎折[22,23,24]。玉米种植区生态环境条件对倒伏发生具有重要影响[25]。前人研究表明,降雨是我国黄淮海地区倒伏发生的主要胁迫因子[26],抽雄前后的降雨加大风可造成86%—99%的植株倒伏[27]。遗传因素作为控制玉米倒伏的核心因素,也已表明,控制玉米倒伏性状是由多个基因位点共同作用的结果;利用数量性状位点（QTL）分析方法发现一些与节间伸长、株高及茎秆穿刺强度相关的基因位于玉米的第3号染色体[28,29,30]。在栽培管理方面,增加种植密度后玉米茎秆会变的纤细,茎秆中纤维素、木质素和半纤维素含量下降,穿刺强度降低,根系较小,倒伏风险增大[3, 15, 31];合理的水肥及化学调控可以降低玉米茎秆基部节间伸长速率,降低节间长粗比、穗位高及株高,促进节间干物质积累及结构形成,增强茎秆机械强度及抗倒伏能力[32,33,34,35,36]。
显示原图|下载原图ZIP|生成PPT图1玉米茎秆茎腐病对细胞壁降解的影响[
-->Fig. 1The structural changes of cell wall by maize stalk rot [
-->
2 玉米生育后期植株衰老对茎秆质量及倒伏的影响
关于倒伏问题的研究以往多集中在玉米茎秆前期发育过程或生理成熟之前的某一个阶段[2, 5, 11-36],对生育后期和生理成熟后茎秆衰老及倒伏研究较少。而玉米生育后期植株衰老过程中茎秆会发生一系列变化,如茎秆失水、活性下降、碳水化合物分解、细胞壁降解、病虫害发生加重等,这些变化会影响玉米后期茎秆质量,从而导致倒伏发生。2.1 玉米生育后期植株衰老对茎秆质量的影响
可溶性碳水化合物是茎秆结构性碳水化合物合成的物质基础。玉米生育后期植株自然衰老,根系活性迅速下降,对水分和营养物质吸收能力降低;叶片衰老,光合能力显著下降,产生的碳水化合物总量减少,分配到茎秆中的碳水化合物量下降[37]。同时,籽粒库对茎秆中可溶性碳水化合物的拉力和茎秆自身的呼吸消耗,使生育后期茎秆可溶性碳水化合物含量逐渐下降。此外,与纤维素和木质素相比,半纤维素稳定性较差,生育后期半纤维素含量的下降也会导致茎秆中总结构性碳水化合物含量降低[13]。在生育后期,茎秆中水分含量也是影响其机械强度的重要因素[15, 38],ANDERSON等[23]认为,玉米抽雄后茎秆含水量逐渐降低,并且茎秆髓部含水量与茎秆强度呈显著正相关。DJORJEVIC等[39]认为成熟期玉米茎秆含水量与倒伏率呈显著负相关。因此,生育后期玉米茎秆衰老过程中的碳水化合物和水分含量降低使茎秆质量下降。玉米生理成熟期至收获阶段,由于叶片蒸腾作用降低,加之根系迅速衰老,水分吸收能力会显著降低,使茎秆含水量逐渐下降。CHEN等[15]研究表明,在我国吉林地区,从8月30日至9月30日,玉米茎秆总碳水化合物降低31%—42%,含水率由77%—79%降低至52%—56%。2.2 玉米生育后期衰老对茎秆抗病能力的影响
玉米生育后期茎秆衰老使植株抗病能力下降,病虫害易于发生。生育后期茎腐病是导致玉米倒伏发生的重要因素,植株抗茎腐病能力与茎秆含水率、生理活性及可溶性糖含量有关。ANDERSON等[23]认为玉米生育后期茎秆髓部含水量高的植株茎腐病发生率较低;苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）、多酚氧化酶（PPO）等抵抗病原微生物侵染的关键酶活性高的植株抗茎腐病能力强[40,41,42];另外,茎腐病属于低糖害病,茎秆总糖含量降低可引起茎秆髓组织衰退,增加玉米对茎腐病的敏感性[42,43],而糖含量越高,对茎腐病的抗性越强[44]。玉米生育后期,自然衰老过程中茎秆和根系PAL、POD、PPO酶活性下降,同时茎秆水分散失和可溶性糖分解,均会导致植株抗茎腐病能力下降,茎腐病发生程度加重。此外,茎腐病病原菌产生的孢子又会堵塞维管束等疏导组织[21],使植株的运输系统遭到破坏,进一步加速植株衰老,在玉米茎秆衰老和茎腐病发生之间形成恶性循环。2.3 玉米生育后期衰老对倒伏的影响
生育后期,玉米茎秆质量和抗病能力的变化影响倒伏发生。玉米生育后期茎秆碳水化合物分解和水分含量下降导致细胞萎缩,细胞壁降解变薄,细胞之间缝隙加大,韧性降低,脆性增加,机械强度降低,倒伏风险加大[23, 39, 45]。NOLTE[46]等研究表明,在美国俄亥俄州10月15日之后,每推迟一周,玉米倒伏率增加5%。同时,玉米生理成熟后,由于茎腐病引发的倒伏会逐渐上升,且上升幅度远高于生理成熟前。THOMISON[47]等研究认为在59 000株/hm2条件下,收获期由10月中上旬推迟至11月中上旬时,田间茎腐病发生率由33%提高至85%,倒伏率由4%提高至23%;收获期推迟至12月中上旬时,茎腐病高达100%,倒伏率达51%。综上,在玉米生育后期自然衰老过程中,茎秆碳水化合物含量和水分丧失使茎秆强度下降,田间倒伏风险上升;同时,生育后期根系和茎秆活性降低,茎秆中可溶性糖含量下降,导致茎秆抗病能力下降,茎腐病发生严重,而茎腐病发生又进一步加快植株衰老。玉米茎秆衰老和茎腐病发生形成恶性循环,衰老加速,茎腐病发生率和发病程度加重,植株抗倒能力迅速下降,倒伏率显著上升（图2）。
显示原图|下载原图ZIP|生成PPT图2生育后期玉米衰老和茎腐病对茎秆机械强度及倒伏的影响
-->Fig. 2Effects of maize senescence and stalk rot on stalk strength and lodging
-->
3 玉米生育后期倒伏对机械粒收的影响
全程机械化是现代玉米生产的发展方向,当前,机械粒收是我国玉米全程机械化生产中急需解决的关键环节[48]。增密种植与田间站秆籽粒脱水是机械粒收技术发展和推广的重要措施[49]。以往我国玉米收获以人工收获和机械穗收为主,对倒伏问题的研究多集中在生理成熟之前,生理成熟后田间站秆脱水至收获阶段的研究较少,而此阶段发生的倒伏与增密种植和田间站秆时间密切相关,需要引起高度关注。3.1 玉米倒伏对增密种植的影响
过去几十年,世界范围内玉米单产水平的提高与种植密度的增加关系密切。与美国玉米种植密度及产量相比,我国玉米种植密度仍有很大的提升空间,增密种植仍将是未来玉米单产水平提升的重要途径[49]。同时,机械粒收玉米品种要求成熟期略提早,而早熟品种生物量通常较小,通过增密种植,可以弥补单株产量较低带来的产量损失[50]。但是增密种植在不同程度上增加了玉米植株间的竞争压力,造成冠层内部光照不良,改变了个体和群体的结构与功能,影响了玉米茎秆形态建成、碳水化合物积累与分配、茎秆解剖结构、力学强度、根系形态与结构等,增大倒伏风险[2-3, 16, 51]。增密种植也会影响玉米植株衰老进程,使生育后期玉米茎秆质量发生改变。卢霖等[52]研究表明,提高种植密度,植株叶片、根系和茎秆的活性降低,根系对水分和养分的竞争加大,并且冠层内部光照减弱,这些变化促使叶片和根系功能期缩短,衰老进程加快。因此,高密度种植的玉米收获期茎秆质量变差和更容易发生倒伏。THOMISON等[47]认为,生理成熟后一定时间段内,种植密度越高,茎秆质量下降幅度越大,群体倒伏率增加趋势也越明显。此外,与低密度种植相比,密植条件下玉米植株个体之间距离变近,冠层内部通风透光条件变差,也有利于茎腐病病原菌和孢子传播;加之玉米根系和茎秆中可溶性糖含量、生理活性均下降,抗茎腐病能力下降,不论是抗病品种还是易感病品种,茎腐病发病率均随植株密度的增加而提高[53,54]。种植密度越高,推迟收获后的茎腐病发病率和倒伏率也越高[47]。因此,玉米生育后期倒伏是限制种植密度进一步提升的重要因素。3.2 玉米倒伏对生理成熟后田间站秆脱水的影响
机械粒收要求玉米籽粒含水量控制在27%以下[55,56],一般生理成熟后田间站秆自然脱水2—4周才能达到机械粒收的要求,推迟收获后提高了茎秆倒伏风险。在田间站秆脱水阶段,玉米雌穗重达到最大,茎秆受种植区大风、降雨、茎秆碳水化合物变化等影响,茎秆衰老进程加快,茎腐病发生率和发生程度显著提高,导致茎秆强度降低,田间倒伏加重[47, 57]。ALLEN[58]等观测到,在田间站秆脱水过程中,当玉米籽粒含水量从25%降至15%时,倒伏率增加了42%。因此,玉米生理成熟至收获期的倒伏问题将会影响田间站秆籽粒脱水的时间,从而降低机械粒收玉米的籽粒品质,增大高水分收获籽粒的烘干成本。总之,基于玉米密植高产机械化生产技术需求的增密种植和田间站秆籽粒脱水均会加速玉米生育后期茎秆衰老进程,降低茎秆抗病能力,使茎秆质量下降,倒伏风险加大。因此,玉米密植高产机械粒收生产技术的推广和应用对生育后期茎秆的抗倒伏能力提出了更高的要求。
4 提高玉米生育后期抗倒伏能力的措施与建议
与发达国家相比,我国玉米机械粒收起步晚,对生育后期和生理成熟后倒伏问题关注不够,制约了玉米密植高产机械粒收技术的推广和发展。今后,需要加强倒伏问题相关理论基础研究,通过品种创制、栽培调控及因地种植改善生育后期玉米的抗倒伏能力,适期收获,推进玉米机械粒收和增密种植技术的发展。4.1 加强倒伏问题相关理论基础研究,为抗倒伏技术创新提供依据
玉米生育后期和生理成熟后的倒伏问题受基因型、环境和措施的共同作用,是一个复杂的过程,以往相关研究较为薄弱,今后需要组织开展系统攻关,为品种创制、栽培调控提供依据。玉米茎秆后期活性是影响倒伏的重要因素,前人研究认为保持玉米生育后期的持绿性有助于将茎秆活性和质量维持在较高水平、降低倒伏风险[59,60],然而后期持绿性高的植株往往不利于籽粒脱水,因此,需要进一步研究玉米植株持绿性和籽粒脱水速率之间的关系,解决籽粒脱水和茎秆持绿抗倒之间的矛盾,为玉米站秆脱水过程保持高抗倒能力提供物质基础。4.2 加强玉米抗倒种质创制,选育适宜机械粒收品种
国内外经验证明,选育耐密植、适宜机械粒收品种是推广机械籽粒收获技术的关键。不同玉米品种籽粒脱水速率不同,生理成熟后茎秆水分下降和干物质分解速率不同,抗茎腐病能力不同[47, 57]。因此,田间站秆持续时间和抗倒伏能力有明显的差异。20世纪60—90年代,美国开始大面积推广机械粒收技术,同期开展了大量玉米抗茎腐病、抗倒伏和适合机械粒收关键技术方面的研究。通过田间观察、化学分析、解剖观测、物理机械、病虫害诱导、高密度育种等手段选育出了一系列适合机械粒收的耐密、抗病、抗倒品种[61]。60多年来,我国玉米品种演替过程中抗倒伏能力逐渐提高,自20世纪80年代起重视紧凑型耐密品种的选育[62]。同时,我国也引进了国外BSSS群体,选育出一些配合力高、抗倒性好的优良自交系[63]。但是在玉米品种选育过程中,并没有特意关注玉米生育后期,尤其是生理成熟后的倒伏问题,品种抗倒伏能力的提高是单纯追求产量目标的附带结果。今后应以籽粒生产效益为导向,通过高密度育种、田间站秆观察、分子设计等手段选择后期青秆成熟、生理成熟期籽粒含水率低且耐密植的玉米品种,降低潜在倒伏风险。4.3 构建高质量健康群体,减缓生育后期茎秆衰老进程,提高植株抗倒伏能力
玉米生育前期高质量茎秆是生育后期维持高抗倒伏能力的基础。在选用适合机械粒收抗倒品种的基础上,应用构建优质土壤耕层,头水适当晚浇与蹲苗、喷洒生长调节剂、科学施肥和防治病虫害为核心技术的综合调控栽培措施;构建高质量健康群体,延缓玉米后期茎秆衰老速率,防止后期茎秆干物质分解及水分下降过快;提高茎秆抗茎腐病能力,改善生育后期茎秆抗倒伏能力。4.3.1 构建优质土壤耕层 深厚的耕层有利于玉米根系下扎,提高根系生物量和固着力;还可以提高根系活力,有利于水分养分吸收,促进地上部茎秆干物质积累和机械强度形成,能够有效地容纳更大的群体[64]。我国玉米田耕层普遍较浅,全国平均仅为18.5 cm,远低于美国35 cm左右的耕层,植株易发生根倒[65]。高密度条件下采用深耕和耕层构建技术,可促进玉米根系纵向生长,提高植株根系生物量和根系活力,增强根系固着能力和养分吸收,防止后期茎秆衰老过快以及抗病、抗倒能力的过快下降。
4.3.2 精准水肥调控 有灌溉条件的地区,头水适当晚浇,通过蹲苗,可以促进根系下扎、缩短基部茎节,增强玉米抗倒性能。生育前期氮肥施用过多会促进玉米基部节间快速生长,导致基部节间长度增加[33, 66];同时不利于玉米茎秆中纤维素的合成和积累[67]。钾肥可以促进茎秆中结构性碳水化合物积累,单位面积维管束增加,提高茎秆穿刺强度[32, 68-69];另外,追施钾肥可以稳定细胞结构,防止细胞间隙的扩大,加固细胞壁,降低病原菌侵入的机率[70]。水钾互作的抗倒伏效果更好[71],尤其是在滴灌条件下更为明显[72]。因此,在拔节期追施钾肥,大喇叭口期追施氮肥,可以通过精准施肥来控制穗下节间伸长,提高茎秆中结构性化学组分合成和外皮组织形成。
4.3.3 适时化学调控 植物生长调节剂可以缓解由于施用氮肥而引起的茎秆快速生长现象, 6—8展叶时喷施乙烯利可以显著降低株高,提高玉米抗倒伏能力和产量[34,35]。XU等[36]认为在夏玉米7展叶时喷施EDAH可以提高茎秆的维管束数目,增强茎秆机械强度。近年来,我国农资市场上涌现出“吨田宝”、“羟基乙烯利”、“玉黄金”等一批玉米化控制剂,在密植栽培条件下能有效控制下部节间伸长,降低穗位高和重心高度,促进节间干物质积累和力学强度形成,具有较好的抗倒效果。
4.4 因地制宜制定综合应对措施
玉米种植区生态环境会影响茎秆发育阶段的质量形成[6, 25],对生育后期茎秆活性变化、物质分解和病虫害发生也会造成一定影响[73],是影响后期倒伏发生的重要因素之一。基于近年气候特点,可以分析我国不同区域玉米倒伏发生的时期、程度和频率,制作倒伏风险分布图,为适合粒收抗倒品种的鉴选确定联合测试网点。在不同玉米产区,以生态区气候条件为基础,建立环境条件（风、雨、光照等）、玉米种植密度和抗倒伏指标（形态和生理指标）之间的定量化关系,筛选推荐适合机械粒收的品种,确立合理的种植密度及适宜的收获时期,以降低生育后期倒伏风险。综上,玉米生育后期植株衰老使茎秆质量下降和茎腐病发生,提高了倒伏风险。基于机械粒收技术需求的增密种植和田间站秆籽粒脱水加剧和延长了茎秆衰老进程,使茎秆质量大幅下降,倒伏问题更为突出。今后,应从理论基础、品种选育和栽培措施的应用方面研究玉米生育后期的倒伏问题,推进玉米密植高产和机械粒收技术的健康发展。
The authors have declared that no competing interests exist.
参考文献 原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子
| [1] | . Grain yield and resistance to root and stalk lodging currently require major emphasis in maize (Zea mays L.) breeding programs. Selection for high expression for one of these characters is often at the expense of the others. Oar objective was to evaluate the effect of grain sink level on root and stalk strength. Fourteen entries were grown including the CO, C4, C8, and Cll of MoSQA, a white endosperm synthetic population selected for high stalk crushing strength; the CO, C4, C8, and Cll of MoSQB, a yellow endosperm synthetic population selected for high stalk crushing strength; two single crosses with high root strength; two single crosses with low root strength; B73 x Mo17, a high-yielding, widely grown single cross; and ‘US13’ a lower yielding double-cross hybrid with poor root and stalk strength. Grain sink levels were established by allowing open pollination (100% sink level), preventing pollination (0% sink level), and by physically removing the top half of the ear 10 after pollination (50% sink level). Root strength was measured vertical root pulling resistance and stalk strength was determined by crushing a 2.5-cm stalk section. Results from four environments indicated that vertical root pulling resistance declined linearly as sink level increased for all entries. Stalk crushing strength declined with increased sink level for all hybrids and for most of the cycles of MoSQA and MoSQB. Exceptions were Cycle 11 of both MoSQA and MoSQB for which stalk crushing strength was similar at all sink levels. |
| [2] | . Twin rows are being promoted as a means to increase maize yield through increased interception of photosynthetically active radiation (PAR) and plant morphology modification. The objective of this research was to explore the interactive effects of maize hybrid, plant population, and row configuration on grain yield and grain yield components, interception of PAR during vegetative growth, plant morphology, and percent lodging. Twin-row irrigated maize produced the same grain yield as single-row production. Small changes in plant morphology and grain yield components and 2.3 to 4.2% increased interception of PAR at the V9 (nine leaves with visible collars) stage were documented for twin rows, but the sum of these did not result in changes in grain yield. Twin-row production increased lodging by 3.5%. Few interactions between row configuration and hybrid and target population were found, leading to the conclusion that twin-row production of maize affords little opportunity to increase maize grain yields. Hybrid and plant population had a much larger effect on grain yield and lodging. Increasing the maize target population to 93,000 plants ha(-1) maximized grain yield at 14.3 Mg ha(-1), and led to small changes in plant morphology that increased lodging from 6.8 to 14.9%. Ear height had the highest direct effect on lodging in both the low (2009) and high (2010) percent lodging years. Based on these results, current promotion of twin rows is not justified for irrigated maize production in the western Maize Belt. |
| [3] | . |
| [4] | . . |
| [5] | In field experiments in 1988 the relationship between morphological characteristics and susceptibility to root lodging was studied in 12 maize cultivars grown on a loam soil (pH 8.1). Natural lodging occurred when plants had 13-15 visible leaves and cultivars were placed in 6 lodging angle classes: 0-6, 6-12, 12-24, 24-48 and 48-90掳 from vertical. Seven of the 12 cultivars were lodged; the mean... |
| [6] | . Mid-season corn (Zea mays L.) stalk breakage in south central Nebraska resulted from 100 mph winds on 8 July 1993 and 80 mph winds on 1 July 1994. Corn growth stages at the time of damage ranged from V10 to V14. Observations of field studies were taken to determine: (i) the impact of stalk breakage on grain yields of different hybrids; (ii) yield compensation by remaining plants; and (iii) the influence of soil and cultural factors on susceptibility to wind damage. We recorded stalk breakage on over 100 corn hybrids in evaluation trials at one site in 1993 and at two sites in 1994 to address objective i. Twelve hybrids were chosen at each site and yield components from broken and standing plants were recorded separately to determine whether remaining standing plants compensated for broken plants (objective ii). We also evaluated stalk breakage on a N management study and a site-specific management/ variable rate study to address objective iii. In 1993 stalk breakage ranged from 7 to 88%, and grain yield was reduced 1.5 bu/acre for every 1% increase in stalk breakage. Breakage in 1994 ranged from 1 to 37% at one site and from 5 to 51% at the other site. Grain yield was reduced by 1.5 and 1.8 bu/acre for every 1% increase in stalk breakage, respectively. Remaining plants did not compensate for grain loss from broken plants at any site. Percentage yield loss is directly related to percentage stalk breakage. Stalk breakage increased with increasing N rate but was reduced with sidedress relative to preplant N application and no-till relative to conventional tillage. Stalk breakage in the site-specific management study correlated (positively) with soil organic matter content. Factors that accelerated plant growth early in the growing season increased susceptibility to stalk breakage. Unfortunately, management practices that result in slow early plant growth also limit yield potential. Planting tolerant hybrids is the best way to avoid losses. More information is needed on why individual plants break and why specific hybrids are more prone than others to mid-season stalk breakage. |
| [7] | . To clear the lodging resistance and mechanized harvesting index of summer maize with different dense population, the density treatments were designed to study the yield, agronomic characters, lodging resistance and mechanized harvesting index of maize.The results showed that the highest yield came from the treatment of 90 000 strains/ha, which reached to 10 124.7 kg/ha.The anti-fracture, crushing strength and puncture strength showed a downward trend with the increase of density, and the lodging capacity increased.Compared with the 75 000 strains /ha treatment, the flexural strength of the third section from base and the first section below ear in 105 000 strains/ha treatment decreased by 22.6% and 17.0%.The lodging resistance decreased.As the planting density goes up, the mechanical harvesting indexes raise too.The grain losing rate under 105 000 strains/ha grows from 3.29% to 9.79%, 66.4% higher than the grain losing rate under 75 000 strains/ha.Indexes of mechanized harvesting showed downward trend with the density increase.There was a significant negative correlation between puncture strength and grain loss rate or ear loss rate, which can use as the decision index of mechanized harvesting.The best planting density of Demeiya 1 in Huang-Huai-Hai plain is 90 000 strains/ha, because the yield is highest, the lodging resistance is lowest and the mechanical harvesting indexes are lowest too. . To clear the lodging resistance and mechanized harvesting index of summer maize with different dense population, the density treatments were designed to study the yield, agronomic characters, lodging resistance and mechanized harvesting index of maize.The results showed that the highest yield came from the treatment of 90 000 strains/ha, which reached to 10 124.7 kg/ha.The anti-fracture, crushing strength and puncture strength showed a downward trend with the increase of density, and the lodging capacity increased.Compared with the 75 000 strains /ha treatment, the flexural strength of the third section from base and the first section below ear in 105 000 strains/ha treatment decreased by 22.6% and 17.0%.The lodging resistance decreased.As the planting density goes up, the mechanical harvesting indexes raise too.The grain losing rate under 105 000 strains/ha grows from 3.29% to 9.79%, 66.4% higher than the grain losing rate under 75 000 strains/ha.Indexes of mechanized harvesting showed downward trend with the density increase.There was a significant negative correlation between puncture strength and grain loss rate or ear loss rate, which can use as the decision index of mechanized harvesting.The best planting density of Demeiya 1 in Huang-Huai-Hai plain is 90 000 strains/ha, because the yield is highest, the lodging resistance is lowest and the mechanical harvesting indexes are lowest too. |
| [8] | . . |
| [9] | . Based on sample data of maize producers in Shandong Province, the author focused on the determinants of farmers鈥 adoption of mechanized maize harvesting with binary Logistic modeling, an Ordered Probit model was further applied to analyze factors affecting the degree what farmers applied machines to harvest maize. The results showed that: education level, information acquiring ability, proportion of non-agricultural income, planting scale, perceived effectiveness and the subsidy of government were significantly positive with the adoption of maize mechanized harvesting, whereas land fragmentation and serious natural disasters had significant negative effect on it. Among all the farmers who had adopted mechanized harvesting, factors like the frequency of information acquiring, proportion of non-agricultural income, planting scale and perceived effectiveness were significantly positive with the extent of farmers鈥 using of machines while harvesting. The author suggested that accelerate the promotion of reasonable land transfer, expand the publication of mechanization, effectively use the subsidy policy tools and actively carry out agricultural mechanization innovation can improve the adoption of mechanized maize harvesting among farmers. . Based on sample data of maize producers in Shandong Province, the author focused on the determinants of farmers鈥 adoption of mechanized maize harvesting with binary Logistic modeling, an Ordered Probit model was further applied to analyze factors affecting the degree what farmers applied machines to harvest maize. The results showed that: education level, information acquiring ability, proportion of non-agricultural income, planting scale, perceived effectiveness and the subsidy of government were significantly positive with the adoption of maize mechanized harvesting, whereas land fragmentation and serious natural disasters had significant negative effect on it. Among all the farmers who had adopted mechanized harvesting, factors like the frequency of information acquiring, proportion of non-agricultural income, planting scale and perceived effectiveness were significantly positive with the extent of farmers鈥 using of machines while harvesting. The author suggested that accelerate the promotion of reasonable land transfer, expand the publication of mechanization, effectively use the subsidy policy tools and actively carry out agricultural mechanization innovation can improve the adoption of mechanized maize harvesting among farmers. |
| [10] | |
| [11] | . Prolificacy associated with higher grain yield in maize (Zea mays L.) has been widely documented. However, one serious concern is that prolificacy appears associated with poor stalk strength and plant standability. The objective of this research was to compare stalk strength and other agronomic characters of one- and two-eared sub-populations derived from three maize populations (MoSQA(S7-H)C8 x Georgia Cow Corn [ACC]; MoSQB(S8-H)C8 x Georgia Cow Corn [BCC]; SI171). Entries were evaluated by using nine combinations of three levels of nitrogen (N) application (90, 180, and 270 kg [ha.sup.-1] N) and three levels of plant density (35 800, 47 800, and 59 800 plants [ha.sup.-1]). Stalk crushing strength showed significant differences between one- and two-eared subpopulations for ACC and BCC, but it was not significant for SI171. One-eared subpopulations had higher rind penetrometer resistance than two-eared subpopulations for all populations. Two-eared selections generally resulted in poorer root and stalk strength. However, total grain yield of the two-eared subpopulations was significantly higher than that of the one-eared subpopulations for BCC and SI171, but not for ACC. Prolificacy has significant potential as a novel character for grain yield improvement in the future. Selection for prolificacy alone, representing indirect selection for grain yield, would produce undesirable effects on other agronomic characters, especially root and stalk strength. Concurrent improvement for total grain yield, prolificacy, and root and stalk strength by using a standardized, weighted selection index should be used to extract the real benefit of the prolific character. |
| [12] | . ABSTRACT Weak stems or stalks in grass crop species increase the likelihood of stalk failure, thereby reducing yield. Three-point bending tests are often employed in selective breeding studies to characterize stalk strength. However, it is hypothesized that the loading setup used during three-point bending experiments may significantly alter test results. To investigate this hypothesis, two different loading configurations were employed in conducting three-point bending experiments of corn (Zea mays L.) stalks. In the first configuration, stalks were loaded and supported at nodes. In the second configuration, stalks were loaded and supported at internodal segments. Significantly higher bending moments were experienced at internodal segments during the node-loaded configuration than was required to fail the same segment during internode-loaded tests. This is because the loading anvil significantly deforms the stalk鈥檚 cross section when it is placed on an internodal segment, thereby inducing premature failure. In addition, internode-loaded tests were observed to produce unnatural failure patterns, while node-loaded tests demonstrated natural variability in failure location. While transverse deformation of the stalk cross section cannot be eliminated in three-point bending tests, its effects can be mitigated by placing the loading anvil at nodal locations, which are much stiffer than internode regions. Maximizing the span length of bending tests likewise reduces transverse deformation of stalk cross sections. These results are relevant to selective breeding studies designed to produce lodging resistant crop hybrids. |
| [13] | . Abstract High plant density of maize (Zea mays L.) reduces the stalk quality of the basal internodes and increases stalk lodging. The objective of this experiment was to explore the mechanism by which plant density influences basal internodes. The morphological, mechanical, anatomical, and biochemical characteristics of the third basal internode were compared at three plant densities. High plant density increased internode length due to an increase in the rate of rapid elongation. High plant density decreased the duration of internode thickening and dry matter accumulation, causing the diameter and dry weight per unit length to decline. However, rind penetration strength (RPS) did not increase rapidly until after the termination of rapid morphological growth. The mid-to-late stage of dry matter accumulation was critical for RPS formation. The rapid increase in RPS was closely related to cellulose and lignin accumulation. High plant density reduced the rates of cellulose and lignin accumulation, which was adverse to the formation of cortex tissue and RPS. High plant density caused rapid elongation, thickening, and structural carbohydrate accumulation to begin and end earlier. These results indicate that measures should be implemented as early as possible in the growing season to increase lodging resistance at high plant density of maize. These measures need to reduce the rate of rapid internode elongation and increase the rate of rapid cellulose and lignin accumulation. 漏 Crop Science Society of America | 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved. |
| [14] | |
| [15] | . Shearing force, one of physical characteristics, is an important indictor of forage value. Maize stem abounds in agro-pastoral ecotone in north-east China and can be utilized as ruminant forage in cold season. The objective of this study is to investigate temporal dynamics and vertical change of shearing force of maize stem because stem is the dominant morphological component contributing to stover nutritive value. Three maize varieties were selected in the study. The stem was cut into 4 segments, and every segment was measured at the approximate midpoint. The results show that shearing force increases with advancing maturity of maize. On same sampling date, shearing force of bottom part of stem is higher than that of upper part. Maize should be harvested as early as possible to avoid the decrease of forage value of stover. Of course, grain yield cannot be sacrificed greatly because maize is grown for its grain in this area. The upper part of stover should be selected as ruminant forage in order to improve the forage digestibility. If maize stover is utilized efficiently, it can play an important role for filling forage shortage gap in agro-pastoral ecotone in north-east China. There is positive relationship between shearing force and cellulose content, and between shearing force and lignin content. Measuring shearing force is very simple, so it can be used to predict forage value of maize stover. |
| [16] | |
| [17] | . |
| [18] | . Root lodging and poor soil fertility are major constraints to production in the Guinea savannah of West Africa. Vertical root-pulling resistance is an indicator of the rooting characteristics of cultivars and could be used to select cultivars which have higher resistance to root lodging, take up efficiently and have high yield. Twenty breeding lines were evaluated in the southern Guinea savannah of Nigeria for vertical root-pulling resistance, yield and root lodging in the 2000 and 2001 cropping seasons. There were significant differences amongst the breeding lines for all the characteristics measured. Vertical root-pulling resistance correlated positively with grain yield (r = 0.71, P < 0.01). There was a moderate negative correlation between vertical root-pulling resistance and root lodging (r =66610.46, P < 0.05). This suggested that selecting for high root-pulling resistance will improve grain yield and reduce root lodging. There was no significant association between root lodging and grain yield (r =66610.14, P < 0.22). This was attributed to two factors; weak root systems and high weight, both of which caused significant lodging. |
| [19] | . ABSTRACT Corn (Zea mays L.) grain yield is affected by a number of factors, including stalk lodging and pests such as the European corn borer (Ostrinia nubilalis Hubner; ECB). European corn borers contribute to stalk lodging and also cause a direct grain yield reduction through physiological effects that decrease the plant's ability to produce and translocate photosynthates. Although much progress has been made in improving standability, stalk lodging remains a major problem, and breeding for stalk lodging resistance continues to be important, especially if it also plays a role in ECB resistance. Missouri Second Cycle Stiff Stalk Synthetic (MoSCSSS) was selected for stalk strength by using a rind penetrometer. Twelve cycles of bidirectional selection have been completed, which has resulted in increased and decreased stalk strength in the high and low directions of selection, respectively. Selected cycles were evaluated for grain yield, stalk lodging, rind penetrometer resistance, first- and second-generation ECB damage, leaf penetrometer resistance at the whorl stage and anthesis, and stalk traits including crude fiber, cellulose, lignin, and silica. Evaluation showed a decrease in grain yield in both directions of selection. Selection for high rind penetrometer resistance was effective at providing resistance to second-generation ECB damage as well as resistance to stalk lodging. Leaf penetrometer resistance was higher in the high direction of selection at whorl stage, but reversed by anthesis where the low direction of selection had higher leaf penetrometer resistance. Crude fiber, cellulose, and lignin increased in the high direction of selection, but silica decreased in the high direction of selection. Significant correlations between the stalk traits analyzed demonstrated that stalk composition was important in providing rind penetrometer resistance, stalk lodging resistance, and second-generation ECB resistance. |
| [20] | pAbstract/p pBackground/p pTo elucidate the role of the length of the internode basal ring (LIBR) in resistance to the Mediterranean corn borer (MCB), we carried out a divergent selection program to modify the LIBR using two maize synthetic varieties (EPS20 and EPS21), each with a different genetic background. We investigated the biochemical mechanisms underlying the relationship between the LIBR and borer resistance. Selection to lengthen or shorten the LIBR was achieved for each synthetic variety. The resulting plants were analyzed to determine their LIBR response, growth, yield, and borer resistance./p pResults/p pIn the synthetic variety EPS20 (Reid germplasm), reduction of the LIBR improved resistance against the MCB. The LIBR selection was also effective in the synthetic variety EPS21 (non-Reid germplasm), although there was no relationship detected between the LIBR and MCB resistance. The LIBR did not show correlations with agronomic traits such as plant height and yield. Compared with upper sections, the internode basal ring area contained lower concentrations of cell wall components such as acid detergent fiber (ADF), acid detergent lignin (ADL), and diferulates. In addition, some residual 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3-(4H)-one (DIMBOA), a natural antibiotic compound, was detected in the basal area at 30 days after silking./p pConclusion/p pWe analyzed maize selections to determine whether the basal area of maize internodes is involved in borer resistance. The structural reinforcement of the cell walls was the most significant trait in the relationship between the LIBR and borer resistance. Lower contents of ADF and ADL in the rind of the basal section facilitated the entry of larvae in this area in both synthetic varieties, while lower concentrations of diferulates in the pith basal section of EPS20 facilitated larval feeding inside the stem. The higher concentrations of DIMBOA may have contributed to the lack of correlation between the LIBR and borer resistance in EPS21. This novel trait could be useful in maize breeding programs to improve borer resistance./p |
| [21] | |
| [22] | Abstract Fusarium graminearum is a destructive pathogen of cereals that can cause stalk rot in maize. Stalk rot results in yield losses due to impaired grain filling, premature senescence, and lodging, which limits production and harvesting of ears. In addition, mycotoxins can make infected tissues unfit for silage. Our objectives were to evaluate the natural variation in stalk rot resistance among maize inbreds, to establish whether deoxynivalenol (DON)- and zearalenone (ZEA)-deficient strains are pathogenic on a panel of diverse inbreds, and to quantify the accumulation of DON in infected stalk tissue. Wild-type F. graminearum and mycotoxin mutants (DON and ZEA) were used to separately inoculate stalks of 9-week-old plants of 20 inbreds in the greenhouse. Plants were evaluated for lesion area at the inoculation point at 0, 2, 14, and 28 days postinoculation and tissues around lesions were sampled to determine the DON content. Regardless of their ability to produce DON or ZEA, all tested F. graminearum strains caused stalk rot; however, significant differences in disease levels were detected. Among the tested inbreds, Mp717 was resistant to all three F. graminearum strains while Mp317 and HP301 were only partially resistant. Accumulation of DON was significantly lower in infected stalks of the resistant and partially resistant inbreds than the susceptible inbreds. Analysis of the 20 inbreds using data from 17 simple-sequence repeats revealed population structure among the individuals; however, there was no association between genetic clustering and stalk rot resistance. These findings are an additional step toward breeding maize inbreds suitable for planting in fields infested with F. graminearum. |
| [23] | . Methods of evaluating maize stalk quality at or near anthesis and stalk rot susceptibility following inoculation were examined for 3 years to identify those most effective in predicting premature death of plants and stalk lodging in multiple environments. Stalk quality measurements, including rind puncture, rind thickness, stalk push test, pith density or pith moisture, and susceptibility to th... |
| [24] | . . |
| [25] | Negative correlations between crushing strength of mature corn stalks and field stalk lodging have been shown by several workers. The objective of the study reported here was to determine the relative effects of years and locations on stalk-crushing strength, rind thickness, and weight of 2-inch stalk sections. Twelve inbred lines representing a wide range in inherent stalk lodging performance were grown at two locations for a 3-year period. Data for the three stalk traits indicated a good agreement between locations within years while crushing strength and rind thickness varied more between years. Variation in crushing strength was attributed in part to pith destruction by stalk rots which are more prevalent in some seasons than in others. It was concluded that stalk quality data obtained in a single year at a single location would usually be adequate to screen a group of strains for inherent stalk lodging resistance. For greater precision data for more than one year and one location would be necessary. Crushing strength was affected more by different environments than the other two traits. The coefficients of variation for crushing strength ranged from 11.7 to 18.8%; rind thickness from 5.2 to 8.5%; and weight of 2-inch section from 8.7 to 13.0%. |
| [26] | . 为指导玉米新品种的推广,采用回归模型分析玉米主产区倒伏胁迫空间分布成因。该文用多元逐步线性回归法筛选黄淮海夏播玉米区的倒伏胁迫的决定因素,比较普通最小二乘法线性回归模型和地理加权回归模型的结果,以确定倒伏胁迫及其决定因素是否存在空间非平稳性和空间依赖性。结果表明:在探索倒伏的空间异质性时,地理加权回归模型显著优于普通最小二乘法线性回归模型;日降水量是玉米倒伏胁迫的主要环境成因,且倒伏程度随日降水量增加而加重;土壤含氮量、留苗密度和日平均风速与倒伏的关系随空间位置而发生正负向变化,因地制宜的分析倒伏成因才能客观有效的指导农民种植生产。 . 为指导玉米新品种的推广,采用回归模型分析玉米主产区倒伏胁迫空间分布成因。该文用多元逐步线性回归法筛选黄淮海夏播玉米区的倒伏胁迫的决定因素,比较普通最小二乘法线性回归模型和地理加权回归模型的结果,以确定倒伏胁迫及其决定因素是否存在空间非平稳性和空间依赖性。结果表明:在探索倒伏的空间异质性时,地理加权回归模型显著优于普通最小二乘法线性回归模型;日降水量是玉米倒伏胁迫的主要环境成因,且倒伏程度随日降水量增加而加重;土壤含氮量、留苗密度和日平均风速与倒伏的关系随空间位置而发生正负向变化,因地制宜的分析倒伏成因才能客观有效的指导农民种植生产。 |
| [27] | . <p>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<sup>-2</sup>，产量随播期的推迟而减少；郑单958平均为6026.1 kg·hm<sup>-2</sup>，随播期变化不明显.总体上，郑单958品种抗倒性好于浚单20.</p> . <p>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<sup>-2</sup>，产量随播期的推迟而减少；郑单958平均为6026.1 kg·hm<sup>-2</sup>，随播期变化不明显.总体上，郑单958品种抗倒性好于浚单20.</p> |
| [28] | . With 2 figures and 5 tablesAbstractTwo populations, one comprising 98 near-isogenic introgression lines (Z3HBILs) with a Zong3 genetic background, and the other comprising a backcross population developed by crossing introgression lines per se with Zong3, were employed to identify quantitative trait loci (QTL) for plant height and ear height (EH) in maize grown at 2 years representing different environments. Nine QTL for plant height (PH) were detected, on chromosomes 1, 2, 3, 5 and 6, using inclusive composite interval (ICI) mapping. The extent of their contribution to phenotypic variation ranged from 3.1% to 22.6%. Fifteen QTL for EH were detected, on chromosomes 1, 2, 3, 4, 5, 6 and 8, and their contribution to phenotypic variation ranged from 5.6% to 31.2%. These QTL mainly showed non-additive effects. In addition, 158 interacting pairs were detected among the QTL for the two traits. Interactions among the identified QTL accounted for only a small proportion of QTL pairs (19.6%), the percentage of phenotypic variation explained by an individual QTL pair ranged from 4.2% to 32.0% for PH and from 3.6% to 31.0% for EH respectively. Contrarily, non-additive pairs accounted for a higher proportion. In addition, 30 additive 脳 additive pairs accounted for only 19.0% of the interaction pairs. Overall, the non-additive effect was the predominant genetic component of PH and EH in maize. |
| [29] | . Maize plant height is closely associated with biomass, lodging resistance and grain yield. Determining the genetic basis of plant height by characterizing and cloning plant height genes will guide the genetic improvement of crops. In this study, a quantitative trait locus (QTL) for plant height, qPH3.1, was identified on chromosome 3 using populations derived from a cross between Zong3 and its chromosome segment substitution line, SL15. The plant height of the two lines was obviously different, and application of exogenous gibberellin A3 removed this difference. QTL mapping placed qPH3.1 within a 4.0 cM interval, explaining 32.3% of the phenotypic variance. Furthermore, eight homozygous segmental isolines (SILs) developed from two larger F2 populations further narrowed down qPH3.1 to within a 12.6 kb interval. ZmGA3ox2, an ortholog of OsGA3ox2, which encodes a GA3 尾-hydroxylase, was positionally cloned. Association mapping identified two polymorphisms in ZmGA3ox2 that were significantly associated with plant height across two experiments. Quantitative RT-PCR showed that SL15 had higher ZmGA3ox2 expression relative to Zong3. The resultant higher GA1 accumulation led to longer internodes in SL15 because of increased cell lengths. Moreover, a large deletion in the coding region of ZmGA3ox2 is responsible for the dwarf mutant d1-6016. The successfully isolated qPH3.1 enriches our knowledge on the genetic basis of plant height in maize, and provides an opportunity for improvement of plant architecture in maize breeding. |
| [30] | . Background Maize (Zea Mays L.) is one of the most important cereal crops worldwide and provides food for billions of people. Stalk lodging can greatly undermine the standability of maize plants and therefore decrease crop yields. Rind penetrometer resistance is an effective and reliable method for evaluating maize stalk strength, which is highly correlated with stalk lodging resistance. In this study, two recombinant inbred line populations were constructed from crosses between the H127R and Chang7-2 lines, and between the B73 and By804 lines. We genotyped these two populations and their parents using 3,072 single nucleotide polymorphism markers and performed phenotypic assessment of rind penetrometer resistance in multiple environments to dissect the genetic architecture of rind penetrometer resistance in maize. Results Based on two linkage maps of 1,397.1 and 1,600.4聽cM with average interval of 1.7 and 2.1聽cM between adjacent makers, respectively, seven quantitative trait loci (QTL) for rind penetrometer resistance were detected in the two recombinant inbred line populations. These QTL were distributed in seven genomic regions, and each accounted for 4.4???18.9% of the rind penetrometer resistance variation. The QTL with the largest effect on rind penetrometer resistance, qRPR3-1, was located on chromosome 3 with the flanking markers PZE-103123325 and SYN23245. This locus was further narrowed down to a 3.1-Mb interval by haplotype analysis using high-density markers in the target region. Within this interval, four genes associated with the biosynthesis of cell wall components were considered as potential candidate genes for the rind penetrometer resistance effect. Conclusions The inheritance of rind penetrometer resistance is rather complex. A few large-effect quantitative trait loci, together with a several minor-effect QTL, contributed to the phenotypic variation in rind penetrometer resistance in the two recombinant inbred line populations that were examined. A potential approach for improving stalk strength and crop yields in commercial maize lines may be to introgress favorable alleles of the locus that was found to have the largest effect on rind penetrometer resistance (qRPR3-1). |
| [31] | . |
| [32] | . 倒伏是玉米高产的重要限制因素之一。本研究旨在探讨施钾量对高产夏玉米抗倒伏能力的影响,为钾肥科学施用提供科学依据。选用登海661(DH661)和郑单958(ZD958),设置6个施钾水平,研究高产条件下施钾量对夏玉米基部茎节穿刺强度、伤流量和产量的影响,并观察基部第3茎节显微结构。结果表明,施钾肥能显著提高茎秆的穿刺强度,DH661和ZD958最大提高幅度分别为17.90%和25.57%,但不同茎节提高幅度不同。伤流液的强度随着施钾量的增大先增加后减小,开花前促进作用大,吐丝期DH661和ZD958施钾180kghm2时最高,分别比对照提高24.30%和29.68%。单位面积内维管束增加,特别是小维管束增多是提高茎秆穿刺强度的关键。施钾肥可以显著提高玉米产量,随施钾量的增加,籽粒产量呈先增高后降低的趋势,DH661和ZD958分别在施钾180kghm2和240kghm2时达到最高产量。 . 倒伏是玉米高产的重要限制因素之一。本研究旨在探讨施钾量对高产夏玉米抗倒伏能力的影响,为钾肥科学施用提供科学依据。选用登海661(DH661)和郑单958(ZD958),设置6个施钾水平,研究高产条件下施钾量对夏玉米基部茎节穿刺强度、伤流量和产量的影响,并观察基部第3茎节显微结构。结果表明,施钾肥能显著提高茎秆的穿刺强度,DH661和ZD958最大提高幅度分别为17.90%和25.57%,但不同茎节提高幅度不同。伤流液的强度随着施钾量的增大先增加后减小,开花前促进作用大,吐丝期DH661和ZD958施钾180kghm2时最高,分别比对照提高24.30%和29.68%。单位面积内维管束增加,特别是小维管束增多是提高茎秆穿刺强度的关键。施钾肥可以显著提高玉米产量,随施钾量的增加,籽粒产量呈先增高后降低的趋势,DH661和ZD958分别在施钾180kghm2和240kghm2时达到最高产量。 |
| [33] | . 【目的】针对黄淮海平原区夏玉米倒伏严重的问题,探讨不同施氮时期对夏玉米茎秆发育及倒伏情况的影响,以期为黄淮海平原区高产夏玉米氮素管理、提高夏玉米植株抗茎倒伏能力提供理论依据。【方法】以不同植株形态的玉米品种先玉335(XY,高秆低穗位型)、浚单20(XD,中秆高穗位型)和京单28(JD,中秆低穗位型)为试验材料,每个品种设种肥(N1)、苗肥(N2)、拔节肥(N3)、大喇叭口肥(N4)和抽雄肥(N5)5个施氮时期处理,以不施氮肥(N0)为对照,研究施氮时期对夏玉米茎秆形态学、解剖学和机械力学特征以及田间倒伏率的影响。【结果】施氮时期对夏玉米茎秆形态学、解剖学及机械力学特征均有显著影响(P0.05)。N1、N2、N3处理能明显促进夏玉米茎秆发育,植株重心、穗高系数、基部第3节间长与粗、硬皮组织厚度、表皮层厚度及大小维管束数目、节间抗折力、硬皮穿刺强度和植株抗拉力均显著大于N0处理;其中,N1、N2处理夏玉米基部第3节间长粗比值显著小于N0处理,N3处理则表现出略大于N0趋势;田间倒伏率表现为N1、N2显著低于N0和其他施氮处理,N3略大于N0处理;N4处理下,夏玉米植株穗高系数、基部第3节间长与N0无明显差异,节间粗、各项解剖学及力学指标显著高于N0,节间长粗比值表现为略低于N0处理,田间倒伏率较N0显著降低;N5处理对夏玉米茎秆发育无明显影响,节间各项形态学、解剖学和力学特征与N0差异不显著,田间倒伏率随着夏玉米植株重心和穗高系数的显著降低而明显低于N0处理。从产量及产量构成因素来看,各施氮处理夏玉米穗粒数、粒重及产量均显著大于N0处理(P0.05),其中,N3、N4处理穗粒数和粒重均处于较高水平,增产幅度最大;N1、N2处理穗粒数最多,但粒重较低,增产幅度低于N3、N4处理;N5处理虽然粒重最高,但穗粒数较其他施氮处理显著降低,最终增产幅度不大。【结论】合理的施氮时期可显著促进夏玉米茎秆基部节间发育,显著降低节间长粗比值,增强植株抗茎倒伏能力;种肥、苗肥作用最显著,但因粒重较低进而降低了增产幅度;拔节期施氮节间长增长迅速进而导致了节间长粗比值增加,植株抗茎倒伏能力降低,玉米栽培管理中应尽量避免;大喇叭口期施氮可明显促进茎粗增加,进而降低节间长粗比和田间倒伏率,同时穗粒数和粒重较高,增产幅度最大。因此,结合前人研究结果表明,采用播种或苗期少量施氮,大喇叭口期重施氮肥的分次施氮措施有利于促进夏玉米茎秆和雌穗发育,提高夏玉米产量及植株抗茎倒伏能力。关于最佳氮肥配比有待进一步系统研究。 【目的】针对黄淮海平原区夏玉米倒伏严重的问题,探讨不同施氮时期对夏玉米茎秆发育及倒伏情况的影响,以期为黄淮海平原区高产夏玉米氮素管理、提高夏玉米植株抗茎倒伏能力提供理论依据。【方法】以不同植株形态的玉米品种先玉335(XY,高秆低穗位型)、浚单20(XD,中秆高穗位型)和京单28(JD,中秆低穗位型)为试验材料,每个品种设种肥(N1)、苗肥(N2)、拔节肥(N3)、大喇叭口肥(N4)和抽雄肥(N5)5个施氮时期处理,以不施氮肥(N0)为对照,研究施氮时期对夏玉米茎秆形态学、解剖学和机械力学特征以及田间倒伏率的影响。【结果】施氮时期对夏玉米茎秆形态学、解剖学及机械力学特征均有显著影响(P0.05)。N1、N2、N3处理能明显促进夏玉米茎秆发育,植株重心、穗高系数、基部第3节间长与粗、硬皮组织厚度、表皮层厚度及大小维管束数目、节间抗折力、硬皮穿刺强度和植株抗拉力均显著大于N0处理;其中,N1、N2处理夏玉米基部第3节间长粗比值显著小于N0处理,N3处理则表现出略大于N0趋势;田间倒伏率表现为N1、N2显著低于N0和其他施氮处理,N3略大于N0处理;N4处理下,夏玉米植株穗高系数、基部第3节间长与N0无明显差异,节间粗、各项解剖学及力学指标显著高于N0,节间长粗比值表现为略低于N0处理,田间倒伏率较N0显著降低;N5处理对夏玉米茎秆发育无明显影响,节间各项形态学、解剖学和力学特征与N0差异不显著,田间倒伏率随着夏玉米植株重心和穗高系数的显著降低而明显低于N0处理。从产量及产量构成因素来看,各施氮处理夏玉米穗粒数、粒重及产量均显著大于N0处理(P0.05),其中,N3、N4处理穗粒数和粒重均处于较高水平,增产幅度最大;N1、N2处理穗粒数最多,但粒重较低,增产幅度低于N3、N4处理;N5处理虽然粒重最高,但穗粒数较其他施氮处理显著降低,最终增产幅度不大。【结论】合理的施氮时期可显著促进夏玉米茎秆基部节间发育,显著降低节间长粗比值,增强植株抗茎倒伏能力;种肥、苗肥作用最显著,但因粒重较低进而降低了增产幅度;拔节期施氮节间长增长迅速进而导致了节间长粗比值增加,植株抗茎倒伏能力降低,玉米栽培管理中应尽量避免;大喇叭口期施氮可明显促进茎粗增加,进而降低节间长粗比和田间倒伏率,同时穗粒数和粒重较高,增产幅度最大。因此,结合前人研究结果表明,采用播种或苗期少量施氮,大喇叭口期重施氮肥的分次施氮措施有利于促进夏玉米茎秆和雌穗发育,提高夏玉米产量及植株抗茎倒伏能力。关于最佳氮肥配比有待进一步系统研究。 |
| [34] | . Nitrogen (N) supply is essential for achieving high grain yield in maize production, but excessive N application can lead to lodging risks and potential yield loss. The main objective of the present study was to investigate the effect of ethephon application under different N fertilizer rates in reducing maize lodging. Field experiments were conducted to determine the interactive effects of ethephon (0 and 180 g/ha) and N rate (0, 75, 150 and 225 kg N/ha) on the morphological and chemical characteristics of basal internode and yield across two summer maize-growing seasons (2011/12) in Wuqiao of the North China Plain. Findings showed that ethephon significantly increased the maximum diameter of the 7th to 14th internodes, and decreased the internode lengths, which led to a decrease in plant and ear heights under different N rates. Significant ethephon 脳 N interaction effects were observed on the diameter and length of internode, dry weight per unit internode length and breaking resistance. Ethephon significantly increased N, cellulose and hemicellulose contents of the basal internode, but cellulose and hemicellulose contents decreased as the rate of N application increased. Internode diameter, dry weight per unit internode length, and N content of the basal internode were significantly positively correlated with breaking resistance. Ethephon significantly increased grain yield and harvest index in 2011, but not in 2012. Grain yield and above-ground biomass were increased with increasing N application in both growing seasons, showing linear and quadratic responses. These results suggested that ethephon could increase stalk strength by improving the morphological and chemical characteristics of the basal internode, and maintain high yield and biomass under high N rates. |
| [35] | . To determine if ethephon ((2-chloroethylphosphonic acid) would reduce lodging while maintaining or increasing harvestable yield, the influence of timing and rate of ethephon application on harvestable yield, yield components, lodging, and grain quality of corn (Zea mays L.) was studied in 1985 and 1986. Ethephon was applied at rates of 0, 0.14, 0.28, and 0.56 kg ha–1 at tassel elongation (TE), 6 d after tassel elongation (TE+6), and at ear elongation (EE), to Pioneer hybrids P3475, P3377, and P3183 grown in the field near Mead, NE. Application of ethephon reduced lodging of corn plants. Ethephon application of 0.56 kg ha–1 at the EE stage reduced lodging of P3377 and P3183 from 30 to 9%. This rate resulted in production of 52 fewer kernels per ear, and 7 to 17 mg lighter kernel weight, while increasing the number of harvestable ears by 0.2 to 0.6 ears m–2. Increasing the rate of ethephon resulted in a linear decrease in harvestable grain yield, except when applied at the EE stage in 1986, when ethephon application had no influence. In this case, increasing the rate of ethephon resulted in an increased number of harvestable ears per square meter, which compensated for reductions in the number of kernels per ear and kernel weight. Application of 0.56 kg ha–1 ethephon at TE in 1986, TE+6 in both years, and EE in 1985 resulted in approximately 1 Mg ha–1 reduction in harvestable grain yield. Ethephon application had small but significant influence on the protein content, kernel density, and kernel breakage susceptibility of grain produced. Application of ethephon is effective in reducing lodging of corn plants. However, ethephon never increased and usually reduced harvestable grain yields. Based on these results, there is little incentive for producers to consider application of ethephon to corn grown under conditions similar to those in this study. |
| [36] | . High yields of modern maize are typically obtained at high plant densities. However, maize lodging rates also increase at high densities. In China, EDAH (a plant growth regulator containing 27% ethephon and 3% DA-6) has been widely used by farmers to increase yield in maize at high densities, but the underlying mechanism is unclear. In this study, we conducted experiments during the 2014 and 2015 growing seasons. Hybrid maize cultivars ‘Xundan20’ (lodging-susceptible) and ‘Zhengdan958’ (lodging-resistant), which are widely planted in China, were grown at a density of 90,000 plants ha611. EDAH solution at a concentration of 2mLL611was sprayed onto summer maize foliar surfaces at the seven-expanded-leaves stage. Grain yield, stalk quality (rind penetration strength, dry weight per cm, amount and area of vascular bundles, and bleeding sap) and leaf area were determined. EDAH significantly decreased lodging rate (by 60.1% on average), plant height, ear height and the location of the center of gravity in both varieties over two years, and increased rind penetration strength, dry weight per cm, cross section area, cortex thickness, and number and area of stalk vascular bundles. EDAH also significantly decreased leaf area by 26.8% among upper leaves and by 13.3% among ear leaves. Additionally, EDAH significantly increased grain yield by 14.3% by increasing kernel number and thousand-kernel weight resulting from optimization of the leaf layer structure and higher bleeding sap levels. Lodging-resistance indicators and yields of ‘Xundan20’ increased more greatly than those of ‘Zhengdan958’ under the EDAH treatment. In conclusion, the risk of lodging at high plant densities can be avoided by spraying EDAH at a proper growth stage due to the improved stalk quality, and an optimized canopy structure can be achieved, proving a stable method to increasing grain yield of maize. |
| [37] | . Twenty maize plants each of the varieties Boss and Bezemara were harvested on four (4 September, 16 September, 30 September and 14 October) and three (16 September, 30 September and 14 October) dates, respectively. The plant stem below the ear was divided into 5-cm height portions, and the stalk over the ear and the ear formed two further fractions. Neutral detergent fibre (NDF), acid detergent fibre (ADF), hemicellulose, cellulose and lignin were determined for selected fractions (height 0–5 cm, 5–10 cm, 20–25 cm, 40–45 cm, over ear and ear). Rumen dry matter degradability (DMD) of all fractions was evaluated in situ using three rumen fistulated male sheep. The rumen incubation time for all samples was 48 h. Later harvest dates increased the cell wall content of all stalk fractions of the variety Boss (NDF: 55.2%, 64.9%, 75.4% and 85.7%; ADF: 35.3%, 41.5%, 48.8% and 58.6%; lignin: 6.6%, 7.7%, 8.7% and 11.6% of DM for harvest dates 4 September, 16 September, 30 September and 14 October, respectively). The latest harvest date did not enhance the fibre content of Bezemara (NDF: 60.8%, 76.6% and 76.1%; ADF: 38.8%, 49.6% and 49.1%; lignin: 7.5%, 9.9% and 8.5% of DM for 16 September, 30 September and 14 October, respectively). The lignin content decreased with height of stem (0–5 cm: 11.0%; 20–25 cm: 9.3%; 40–45 cm: 8.5%; over ear: 5.0% of DM). The cell wall content of ears was reduced with later harvest date. The in sacco DMD of residual plants of both varieties decreased with later growing stages. The higher fractions of residual plants showed a higher DMD than the lower ones (0–5 cm: 59.3%; 20–25 cm: 65.3%; 40–45 cm: 67.3%; over ear: 72.2%). The DMD of ears was less influenced by harvest date (88.5–93.8%), and was closely correlated with lignin content of fractions (= 610.93). A higher cut of corn plant may increase the digestibility of corn silage and probably also the performance of ruminants. |
| [38] | |
| [39] | . |
| [40] | . 为了明确苯丙氨酸解氨酶活和过氧化物酶活与玉米对镰刀菌茎腐病的 抗性关系,探讨玉米对镰刀菌茎腐病的抗病机制及其在玉米抗病性鉴定中的利用,用禾谷镰刀菌孢子悬浮液对抗病品种陕单931和感病品种西农11号在抽雄初期 进行接种,并于接种后测定茎秆髓部组织内的PAL、POD活性变化以及POD同工酶谱的变化.结果表明,玉米植株受镰刀菌侵染后,抗病品种的PAL酶活上 升快,活性强,且形成两个活性高峰,高活性时间持续长;感病品种PAL酶活上升慢,活性相对较弱,且只形成一个峰,高活性持续时间短.抗病品种POD酶活 峰值高,感病品种峰值低;抗病品种高酶活持续的时间长,感病品种高酶活持续的短.POD同工酶谱研究表明,抗、感品种POD同工酶带都有增多.抗病品种增 5条,感病品种新增2条.PAL活性变化、POD活性变化及同工酶谱酶活变化与其对茎腐病的抗性有密切的关系,可作为抗病育种的生理生化指标. 为了明确苯丙氨酸解氨酶活和过氧化物酶活与玉米对镰刀菌茎腐病的 抗性关系,探讨玉米对镰刀菌茎腐病的抗病机制及其在玉米抗病性鉴定中的利用,用禾谷镰刀菌孢子悬浮液对抗病品种陕单931和感病品种西农11号在抽雄初期 进行接种,并于接种后测定茎秆髓部组织内的PAL、POD活性变化以及POD同工酶谱的变化.结果表明,玉米植株受镰刀菌侵染后,抗病品种的PAL酶活上 升快,活性强,且形成两个活性高峰,高活性时间持续长;感病品种PAL酶活上升慢,活性相对较弱,且只形成一个峰,高活性持续时间短.抗病品种POD酶活 峰值高,感病品种峰值低;抗病品种高酶活持续的时间长,感病品种高酶活持续的短.POD同工酶谱研究表明,抗、感品种POD同工酶带都有增多.抗病品种增 5条,感病品种新增2条.PAL活性变化、POD活性变化及同工酶谱酶活变化与其对茎腐病的抗性有密切的关系,可作为抗病育种的生理生化指标. |
| [41] | Guaiacol-peroxidase (POX) and polyphenol oxidase (PPO) activities were measured spectrophotometrically in resistant (cvs. Sumai#3 and Wang shui-bai) and susceptible (cvs. Falat and Golestan) wheat heads at flowering, milk, dough and ripening stages following the inoculation with Fusarium graminearum at anthesis. POX specific activity in resistant and susceptible wheat cultivars showed a significant increase during the milk stage as compared with the non-inoculated control plants. POX activity reached the highest level in heads of Wang shui-bai followed by those of Falat, Sumai#3 and Golestan cultivars at milk stage. The optimal pH for POX activity was 5.4. POX was inhibited by KCN. Native polyacrylamide gel revealed the presence of upto three basic (cationic) and six acidic (anionic) isozymes in wheat heads after a specific activity stain. PPO specific activity in wheat heads reached a maximum level during the milk stage and subsequently declined. This activity was three times higher in the resistant cultivars than the non-inoculated control plants. In Falat and Golestan cultivars, PPO activity level was half of those in resistant cultivars. The optimal pH for PPO was 6.4. PPO-catalyzed reaction was inhibited by ascorbic acid. Activity stain in non-denaturing polyacrylamide gel revealed the presence of one basic and six acidic isozymes in wheat heads. The susceptible Falat heads pre-treated with an autoclaved mycelial wall preparation showed induced resistance against FHB and increased activities of POX and PPO. |
| [42] | . At Univ. Ill., Urbana, inoculations of 12 inbred lines and analyses of samples from corresponding uninoculated plants indicated an association of increased sucrose, reducing sugar, and total sugar, and high pith density with resistance to [: cf. 37, 407, 717]. It is suggested that senescence of pith tissue, indicated by reduced density, is caused by a decrease in the sugar level of the stem, and that such senescent plants are susceptible. The reasons for differential sugar trends in maize vars. need further investigation, but a possible incompatibility between max. stalk rot resistance and max. yield is indicated. |
| [43] | Maize plants with rotted stalks had more kernels than genetically identical neighbouring plants with healthy stalks. This was observed in comparisons of adjacent rotted and healthy plants of 30 hybrids at many USA locations and in another study of 7 hybrids in 2 plant populations in 1 location. Relationship of data to effects of rate of carbohydrate translocation to grain and roots, including t... |
| [44] | . Although maize (Zea mays L.) is a major forage crop, little attention has been given to possible alteration of forage quality associated with breeding for increased resistance to stalk lodging. This study was designed to evaluate changes in stalk composition and digestibility resulting from three cycles of recurrent selection each for improved stalk strength (BSlMS) and stalk-rot [Diplodia maydis (Berk.) Sacc.] resistance (BSlSR). The second elongated internmode plus half of each adjacent internode from plants of the original population (BSlCO) and from C1 to C3 for the BSlMS and BSlSR populations were sampled approximately 35 days after midsilking for chemical and in vitro digestible dry matter (IVDDM) evaluation. Major composition changes from the BSlCO to BSlMSC3 and BSlSRC3 populations, respectively, were: concentration of cell wall constituents, 616 to 520 and 542 g kg–1; concentration of acid detergent fiber, 422 to 353 and 373 g kg–1; concentration of lignin, 57 to 42 and 47 g kg–1; concentration of total nonstructural carbohydrates (TNC), 184 to 258 and 244 g kg–1; and concentration of IVDDM, 514 to 621 and 594 g kg–1. Both selection regimes increased TNC concentration, which diluted stalk fiber concentration and resulted in a net increase in IVDDM. Recurrent selection for traits associated with improved stalk lodging resistance did not have negative effects on the forage quality of maize stalks in late reproductive stages. |
| [45] | . 【目的】研究玉米秸、小麦秸和稻草剪切力与其形态学指标、营养成分和瘤胃降解率之间的关系。【方法】选用成熟期收获的玉米秸、小麦秸和稻草，分别测定其秸秆的剪切力，同时测定秸秆的直径、茎厚与线性密度（单位长度重量）及其营养成分含量，采用尼龙袋法测定秸秆干物质（dry matter，DM）、中性洗涤纤维素（neutral detergent fiber，NDF）和酸性洗涤纤维素（acid detergent fiber，ADF）的瘤胃降解率。【结果】试验中3种秸秆收获时的剪切力、形态学指标（线性密度、直径和茎厚）及剪切力/线性密度均差异显著（P＜0.05）。玉米秸、小麦秸和稻草的剪切力与其线性密度、直径和茎厚均呈高度正相关（P＜0.001）。3种秸秆的线性密度与剪切力的相关性最高（P＜0.05），且以剪切力反映玉米秸线性密度的灵敏程度最高。3种秸秆中的营养成分含量及其营养成分（DM和 NDF）瘤胃降解率与剪切力均有不同程度的相关性，且剪切力预测秸秆型粗饲料NDF瘤胃降解率最精准。剪切力较适于预测玉米秸和稻草的营养成分含量及其瘤胃降解率。【结论】作物秸秆剪切力与其饲料营养特性存在相关性。剪切力可不同程度地预测玉米秸、小麦秸和稻草的营养物质含量、物理性状及养分（DM、NDF和ADF）瘤胃降解率的大小，且3种秸秆中剪切力较适于预测玉米秸和稻草的营养价值评定。选用剪切力评定作物秸秆的营养价值，其灵敏程度不同，需根据秸秆种类确定预测模型。 . 【目的】研究玉米秸、小麦秸和稻草剪切力与其形态学指标、营养成分和瘤胃降解率之间的关系。【方法】选用成熟期收获的玉米秸、小麦秸和稻草，分别测定其秸秆的剪切力，同时测定秸秆的直径、茎厚与线性密度（单位长度重量）及其营养成分含量，采用尼龙袋法测定秸秆干物质（dry matter，DM）、中性洗涤纤维素（neutral detergent fiber，NDF）和酸性洗涤纤维素（acid detergent fiber，ADF）的瘤胃降解率。【结果】试验中3种秸秆收获时的剪切力、形态学指标（线性密度、直径和茎厚）及剪切力/线性密度均差异显著（P＜0.05）。玉米秸、小麦秸和稻草的剪切力与其线性密度、直径和茎厚均呈高度正相关（P＜0.001）。3种秸秆的线性密度与剪切力的相关性最高（P＜0.05），且以剪切力反映玉米秸线性密度的灵敏程度最高。3种秸秆中的营养成分含量及其营养成分（DM和 NDF）瘤胃降解率与剪切力均有不同程度的相关性，且剪切力预测秸秆型粗饲料NDF瘤胃降解率最精准。剪切力较适于预测玉米秸和稻草的营养成分含量及其瘤胃降解率。【结论】作物秸秆剪切力与其饲料营养特性存在相关性。剪切力可不同程度地预测玉米秸、小麦秸和稻草的营养物质含量、物理性状及养分（DM、NDF和ADF）瘤胃降解率的大小，且3种秸秆中剪切力较适于预测玉米秸和稻草的营养价值评定。选用剪切力评定作物秸秆的营养价值，其灵敏程度不同，需根据秸秆种类确定预测模型。 |
| [46] | |
| [47] | . Many corn (Zea mays L.) growers in Ohio delay harvest as a management strategy for reducing grain drying costs. However, this practice increases the risk of yield loss due to extended crop weathering. Field studies were conducted at three Ohio locations in 2002 to 2004 to determine effects of three harvest date periods, early to mid-October (HD1), early to mid-November (HD2), and early to mid-December (HD3), and four plant densities (59,000; 74,000; 89,000; and 104,000 plants ha611) on the agronomic performance of four corn hybrids differing in maturity and stalk strength. Interactions between harvest date, plant population, and hybrid indicated that decreases in grain yield and increases in stalk rot and lodging associated with harvest delays were influenced by plant population and hybrid characteristics. Significant yield losses due to delayed harvest were evident only after HD2. When harvest was delayed until HD3, yields decreased at the higher plant populations, especially at 104,000 plants ha611. Stalk rot and lodging increased at the higher plant populations, and this effect was magnified by late harvesting. Hybrids with lower stalk strength scores exhibited greater stalk lodging and yield loss when harvest was delayed beyond HD2. Stalk rot showed a greater increase between HD1 and HD2, whereas stalk lodging generally showed a greater increase after HD2. Harvest delays after HD2 achieved little or no additional grain drying. Results of this study indicate that harvest delays should be avoided when using plant populations above 74,000 plants ha611, especially if planting hybrids that are not highly rated for stalk strength. |
| [48] | . 玉米是全球也是中国第一大作物,在保障国家粮食安全中占有重要地位。当前,面对经济社会的快速发展和人增地减、资源紧缺、生态环境恶化等一系列突出问题,玉米栽培学科正面临着严峻挑战和新的历史发展机遇,在此重要历史关头,回顾中国玉米栽培研究历程和科技进展,探索未来发展方向具有重要的意义。分析表明,经过60年不懈努力,玉米栽培研究的目标已由产量为主向高产、优质、高效、生态、安全等多目标协同发展,研究内容不断拓宽与深入,形成了具有显著中国特色的玉米栽培科学与技术体系。进入21世纪以来,玉米栽培研究进入黄金发展期,在栽培理论、关键技术创新与应用方面取得一系列重要突破,在保障国家粮食安全中发挥了重要的作用。围绕未来玉米生产对科技的需求,依据现代科技的发展趋势,笔者认为高产、优质、高效、生态、安全仍将是未来玉米栽培研究的主要目标,并提出今后20年重点研究的方向与任务：一是继续探索不同生态区玉米产量潜力及突破技术途径,努力提高单产水平;二是转变生产方式,围绕籽粒生产效率,以提高资源利用效率和劳动生产效率为目标,降低生产成本,提高商品质量,增强玉米市场竞争力;适度发展青贮玉米和鲜食玉米等,促进玉米生产向多元化方向发展;三是应对全球气候变化,开展抗逆、减灾、稳产理论和技术研究,实施保护性耕作,实现玉米可持续生产;四是依托现代信息技术,开展智能化栽培技术研究,实现玉米精准生产与管理;五是强化栽培学科基础研究,玉米设计栽培,夯实玉米科技研究和生产发展基础。 . 玉米是全球也是中国第一大作物,在保障国家粮食安全中占有重要地位。当前,面对经济社会的快速发展和人增地减、资源紧缺、生态环境恶化等一系列突出问题,玉米栽培学科正面临着严峻挑战和新的历史发展机遇,在此重要历史关头,回顾中国玉米栽培研究历程和科技进展,探索未来发展方向具有重要的意义。分析表明,经过60年不懈努力,玉米栽培研究的目标已由产量为主向高产、优质、高效、生态、安全等多目标协同发展,研究内容不断拓宽与深入,形成了具有显著中国特色的玉米栽培科学与技术体系。进入21世纪以来,玉米栽培研究进入黄金发展期,在栽培理论、关键技术创新与应用方面取得一系列重要突破,在保障国家粮食安全中发挥了重要的作用。围绕未来玉米生产对科技的需求,依据现代科技的发展趋势,笔者认为高产、优质、高效、生态、安全仍将是未来玉米栽培研究的主要目标,并提出今后20年重点研究的方向与任务：一是继续探索不同生态区玉米产量潜力及突破技术途径,努力提高单产水平;二是转变生产方式,围绕籽粒生产效率,以提高资源利用效率和劳动生产效率为目标,降低生产成本,提高商品质量,增强玉米市场竞争力;适度发展青贮玉米和鲜食玉米等,促进玉米生产向多元化方向发展;三是应对全球气候变化,开展抗逆、减灾、稳产理论和技术研究,实施保护性耕作,实现玉米可持续生产;四是依托现代信息技术,开展智能化栽培技术研究,实现玉米精准生产与管理;五是强化栽培学科基础研究,玉米设计栽培,夯实玉米科技研究和生产发展基础。 |
| [49] | . 为探索生产方式转变,实现玉米产量与效益协同提高,分析了玉米种植密度提高与单产增加的关系、不同产区玉米种植密度现状、增密种植的增产效果以及子粒机械直收技术的优势,构建了以筛选耐密抗倒适合机械化生产品种、密植增穗增产、提高群体整齐度、构建高质量群体、全程机械化作业、强化规模种植与统一管理、实施全成本核算为核心的玉米密植高产全程机械化生产技术模式。该模式2013年起被农业部遴选为全国玉米主推技术,在全国玉米主产区推广,创建了一批高产高效典型。其中,经农业部组织专家验收,2014年在新疆兵团71团创造了18 414kg/hm~2的全国玉米大面积高产纪录,净利润达到24 118.2元/hm~2,实现了玉米高产与高效协同,为玉米生产方式转变和发展现代玉米生产提供了典型案例。 . 为探索生产方式转变,实现玉米产量与效益协同提高,分析了玉米种植密度提高与单产增加的关系、不同产区玉米种植密度现状、增密种植的增产效果以及子粒机械直收技术的优势,构建了以筛选耐密抗倒适合机械化生产品种、密植增穗增产、提高群体整齐度、构建高质量群体、全程机械化作业、强化规模种植与统一管理、实施全成本核算为核心的玉米密植高产全程机械化生产技术模式。该模式2013年起被农业部遴选为全国玉米主推技术,在全国玉米主产区推广,创建了一批高产高效典型。其中,经农业部组织专家验收,2014年在新疆兵团71团创造了18 414kg/hm~2的全国玉米大面积高产纪录,净利润达到24 118.2元/hm~2,实现了玉米高产与高效协同,为玉米生产方式转变和发展现代玉米生产提供了典型案例。 |
| [50] | . 籽粒田间机械直接收获是我国玉米机械收获和实现全程机械化的关键环节,是今后我国玉米生产转变方式的方向。本文对国内外玉米机械粒收技术相关研究进行总结和分析认为：（1）破碎率偏高是当前我国玉米机械粒收存在的主要质量问题;（2）收获时籽粒水分含量是影响玉米机械粒收质量、安全贮藏和经济效益的关键因素,已经成为一个重要的经济性状;（3）玉米机械粒收技术的推广受品种遗传因素、生态气象因素与栽培措施、收获机械及其作业质量、收获时期、烘干收储等多因素影响,不同产区各种因素影响的程度不同;（4）筛选早熟、适合机械粒收品种,研发推广破碎率和损失率低的收获机械,选择最佳收获期收获,建立烘干存贮设施,构建配套收储模式,是未来我国玉米机械粒收技术发展的重点。由此本文构建了玉米机械粒收栽培新理念：通过选用早熟、脱水快的品种,以生育期换水分,实现籽粒田间直接收获、降低烘干成本,提高效益;通过增密种植,以密度换产量,降低熟期缩短对产量的影响;将增密种植、高质量群体调控为核心的高产栽培与以机械粒收技术为核心的全程机械化生产技术相融合,实现玉米高产高效协同发展,提高玉米生产竞争力。 . 籽粒田间机械直接收获是我国玉米机械收获和实现全程机械化的关键环节,是今后我国玉米生产转变方式的方向。本文对国内外玉米机械粒收技术相关研究进行总结和分析认为：（1）破碎率偏高是当前我国玉米机械粒收存在的主要质量问题;（2）收获时籽粒水分含量是影响玉米机械粒收质量、安全贮藏和经济效益的关键因素,已经成为一个重要的经济性状;（3）玉米机械粒收技术的推广受品种遗传因素、生态气象因素与栽培措施、收获机械及其作业质量、收获时期、烘干收储等多因素影响,不同产区各种因素影响的程度不同;（4）筛选早熟、适合机械粒收品种,研发推广破碎率和损失率低的收获机械,选择最佳收获期收获,建立烘干存贮设施,构建配套收储模式,是未来我国玉米机械粒收技术发展的重点。由此本文构建了玉米机械粒收栽培新理念：通过选用早熟、脱水快的品种,以生育期换水分,实现籽粒田间直接收获、降低烘干成本,提高效益;通过增密种植,以密度换产量,降低熟期缩短对产量的影响;将增密种植、高质量群体调控为核心的高产栽培与以机械粒收技术为核心的全程机械化生产技术相融合,实现玉米高产高效协同发展,提高玉米生产竞争力。 |
| [51] | . . Experiments were arranged in a split plot design with four replicates. The irrigation and fertilizer management in the experiment plot was consistent with typical agronomic practices in the local high-yield field. The results indicated that the increase of planting density would cause significant decreases in stalk crushing strength (SCS), rind penetration strength (RPS), internode diameter and dry weight (DW), percentage of dry matter and ratio of dry matter weight to length of internode (RDWL), and dramatic increase in internode length. The relationship between stalk mechanical characteristics and planting density fitted a exponential curve (y = ae) significantly. The stalk mechanical characteristics were highly correlated with the agronomic characteristics. These characteristics of Jingke 519 were susceptive of the increasing planting density above 75 000 plant ha, especially for these above the 4th internode was. The whole plant would have high lodging resistant ability if the dry matter accumulation was high in the 4th and above 4th internods. That the internod length enlarged slowly and diameter of internode decreased significantly with increasing plant density was an adaptability to high planting density for the resistant cultivar. When the percentage of DW of the 4th and above 4th internods was more than 7.5%, and its RDWL was more than 0.2 g cm at a week prior to anthesis, the plants would be resistant to lodging .The stepwise regression analysis revealed that the RDWL contributed positively the most to SCS and RPS. RDWL was definite as an agronomic indicator of maize stalk lodging resistant ability. . . Experiments were arranged in a split plot design with four replicates. The irrigation and fertilizer management in the experiment plot was consistent with typical agronomic practices in the local high-yield field. The results indicated that the increase of planting density would cause significant decreases in stalk crushing strength (SCS), rind penetration strength (RPS), internode diameter and dry weight (DW), percentage of dry matter and ratio of dry matter weight to length of internode (RDWL), and dramatic increase in internode length. The relationship between stalk mechanical characteristics and planting density fitted a exponential curve (y = ae) significantly. The stalk mechanical characteristics were highly correlated with the agronomic characteristics. These characteristics of Jingke 519 were susceptive of the increasing planting density above 75 000 plant ha, especially for these above the 4th internode was. The whole plant would have high lodging resistant ability if the dry matter accumulation was high in the 4th and above 4th internods. That the internod length enlarged slowly and diameter of internode decreased significantly with increasing plant density was an adaptability to high planting density for the resistant cultivar. When the percentage of DW of the 4th and above 4th internods was more than 7.5%, and its RDWL was more than 0.2 g cm at a week prior to anthesis, the plants would be resistant to lodging .The stepwise regression analysis revealed that the RDWL contributed positively the most to SCS and RPS. RDWL was definite as an agronomic indicator of maize stalk lodging resistant ability. |
| [52] | . 为探讨乙矮合剂对密植夏玉米叶片衰老及后期早衰的调控机制，建立华北夏玉米区密植高产稳产化学调控技术，以中单909和浚单20为材料，设置乙矮合剂(ECK)和密度梯度处理，研究密度梯度对夏玉米花粒期不同部位叶片衰老特性的影响与 ECK 的调控效应。结果表明，随密度增加，两品种花粒期单株叶面积减小且降幅增大；各叶位叶片的叶绿素相对含量和可溶性蛋白含量呈下降趋势；超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性呈降低趋势；丙二醛(MDA)含量则呈增高趋势；上述指标在叶位和品种间存在差异。ECK 处理显著提高各密度不同部位叶片 SOD、CAT、POD 活性和叶绿素相对含量及可溶性蛋白含量，显著降低 MDA 含量；单株绿叶面积降幅减小，叶片衰老进程延缓，衰老程度减轻。ECK处理后，较高密度群体下(7.5~10.5万株 hm–2)，中单909和浚单20较各自对照分别增产5.59%~6.63%和6.73%~8.10%。因此，采用合理的种植密度结合喷施乙矮合剂可作为华北夏玉米区高产栽培的重要技术措施。 . 为探讨乙矮合剂对密植夏玉米叶片衰老及后期早衰的调控机制，建立华北夏玉米区密植高产稳产化学调控技术，以中单909和浚单20为材料，设置乙矮合剂(ECK)和密度梯度处理，研究密度梯度对夏玉米花粒期不同部位叶片衰老特性的影响与 ECK 的调控效应。结果表明，随密度增加，两品种花粒期单株叶面积减小且降幅增大；各叶位叶片的叶绿素相对含量和可溶性蛋白含量呈下降趋势；超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性呈降低趋势；丙二醛(MDA)含量则呈增高趋势；上述指标在叶位和品种间存在差异。ECK 处理显著提高各密度不同部位叶片 SOD、CAT、POD 活性和叶绿素相对含量及可溶性蛋白含量，显著降低 MDA 含量；单株绿叶面积降幅减小，叶片衰老进程延缓，衰老程度减轻。ECK处理后，较高密度群体下(7.5~10.5万株 hm–2)，中单909和浚单20较各自对照分别增产5.59%~6.63%和6.73%~8.10%。因此，采用合理的种植密度结合喷施乙矮合剂可作为华北夏玉米区高产栽培的重要技术措施。 |
| [53] | . The predominant pathogens of maize ear rot and maize stalk rot, Fusarium graminearum and Fmoniliforme, could cause the two diseases by reciprocal infection, and could reach ear from the basal part of stem through stem pith and external dissemination separ . The predominant pathogens of maize ear rot and maize stalk rot, Fusarium graminearum and Fmoniliforme, could cause the two diseases by reciprocal infection, and could reach ear from the basal part of stem through stem pith and external dissemination separ |
| [54] | . . |
| [55] | . 设置不同玉米品种和收获时期试验,研究黄淮海地区夏玉米子粒机械收获的可能性及影响收获质量的因素。结果表明,选择适宜品种和收获时期,在黄淮海小麦/玉米一年两作区实施夏玉米机械直接收获子粒是可行的。影响收粒质量的主要因素是子粒水分含量,随含水量增加,机收时子粒损失率、破碎率和杂质率明显上升,适宜子粒收获的含水量建议控制在27%以内。 . 设置不同玉米品种和收获时期试验,研究黄淮海地区夏玉米子粒机械收获的可能性及影响收获质量的因素。结果表明,选择适宜品种和收获时期,在黄淮海小麦/玉米一年两作区实施夏玉米机械直接收获子粒是可行的。影响收粒质量的主要因素是子粒水分含量,随含水量增加,机收时子粒损失率、破碎率和杂质率明显上升,适宜子粒收获的含水量建议控制在27%以内。 |
| [56] | . 为明确夏玉米生理成熟期子粒含水率及其影响因素,2014-2016年,以郑单958、先玉335等玉米品种为研究对象,分别在北京和河南新乡开展品种比较和播期研究.结果表明:生理成熟期玉米子粒含水率平均27.8％,在品种间存在极显著差异,变幅为21.5％～33.1％,按80％置信区间为24.2％～31.4％;环境条件对子粒达到生理成熟的时间和含水率有极显著影响,且环境和品种之间具有明显的交互作用;生理成熟期子粒含水率高低与授粉到生理成熟经历的天数之间相关度较低.夏玉米区主栽品种郑单958、先玉335、农华101、中单909、京农科728、华美1号和农华816生理成熟期子粒含水率平均值分别为28.4％、24.9％、27.9％、29.1％、28.7％、29.2％和29.9％. . 为明确夏玉米生理成熟期子粒含水率及其影响因素,2014-2016年,以郑单958、先玉335等玉米品种为研究对象,分别在北京和河南新乡开展品种比较和播期研究.结果表明:生理成熟期玉米子粒含水率平均27.8％,在品种间存在极显著差异,变幅为21.5％～33.1％,按80％置信区间为24.2％～31.4％;环境条件对子粒达到生理成熟的时间和含水率有极显著影响,且环境和品种之间具有明显的交互作用;生理成熟期子粒含水率高低与授粉到生理成熟经历的天数之间相关度较低.夏玉米区主栽品种郑单958、先玉335、农华101、中单909、京农科728、华美1号和农华816生理成熟期子粒含水率平均值分别为28.4％、24.9％、27.9％、29.1％、28.7％、29.2％和29.9％. |
| [57] | . Abstract Limited capacity for artificially drying maize (Zea mays L.) grain exists in the mid-south USA. Most of the area's production is field-dried and thus subjected to risks inherent to leaving mature crops in the field. A two-year experiment to assess some of the effects of delayed harvest on maize grain yield and other characteristics was conducted at Stoneville, MS. Six maize hybrids (three Bt and three non-Bt) were field grown in 2000 and 2001. Grain was hand harvested and shelled at 14, 28, 42, 56, and 70 d post-physiological maturity (P-PM). Grain moisture levels declined with increased delays in harvest both years. Levels safe for handling and storage (150 mg g -1) were acquired at 28 d P-PM in 2000 and 42 d P-PM in 2001. Grain moisture fell below 120 mg g -1, 28 d P-PM in 2000 making it subject to mechanical damage. Declines in grain bulk density at 70 d P-PM may be explained by such damage. Bt hybrids had less stalk lodging than non-Bt hybrids, and lodging tended to increase as harvests were delayed. Aflatoxin contamination was minimal in 2000 and non-existent in 2001. Fumonisin levels were higher in 2001 than 2000. Adverse effects on yield and grain quality with delayed harvest appear minimal, inherent risks of crop losses due to weather exist though, and monitoring grain moisture and the weather are recommended. |
| [58] | . |
| [59] | . Maize (Zea mays L.) stalk lodging remains a major production-limiting problem despite progress in improving standability. Efforts to improve stalk quality may result in the production of maize with undesirable agronomic features. Two Missouri maize stalk-quality synthetics (MoSQA and MoSQB), were grown at Newark and Georgetown, DE, to determine if any changes in agronomic characteristics were associated with selection for high and low stalkcrushing strength in an environment other than Missouri. Plants from three levels of selection (C6 low = 6th cycle of selection for low crushing strength, C6 high = 6th cycle of selection for high crushing strength, and CIO high = 10th cycle of selection for high crushing strength) and the original population (C0) were evaluated for each synthetic. Plants were grown at 37 064 and 74 129 plants ha–1 at both locations. Both synthetics responded significantly to selection for high crushing strength. Rind puncture pressure values (kg) of MoSQA taken 3 weeks after midsilking were 12.4 (C6 low), 17.0 (C0), 19.1 (C6 high), and 22.2 (C10 high). The corresponding values for MoSQB were 10.5, 15.0, 17.1, and 18.1. A significantly higher percentage of soft and lodged stalks was associated with low crushing strength selections compared with high crushing strength selections. The percentage of soft stalks decreased by 2.8% per cycle for MoSQA and 3.5% per cycle for MoSQB from C0 to C10 high. Stalk lodging was not increased at the high plant density for either synthetic due to the improved stalk quality following selection for high crushing strength. A significant increase in kernel yield for MoSQA with selection for high stalk-crushing strength was associated with increased plant height. An undesired significant increase in ear height, plant height, and a delay in maturity occurred for MoSQB. The MoSQA kernel yield increased 8.6% from C0 to C10 high with no consistent changes in ear height or maturity. However, a nonsignificant 3.1% kernel yield increase for MoSQB from C0, to C10, high was accompanied by a kernel moisture increase of 44.9%. Plant height, ear height, plant maturity, and yield should be carefully monitored when selecting for improved stalk quality in maize. |
| [60] | |
| [61] | . |
| [62] | . AbstractRetrospective analyses may provide an understanding of unexploited genetic potential and indicate possible pathways for future yield improvement. The objectives of this study were to present maize(Zea mays L.)yield trends and plant traits changes for maize cultivars from the 1950s to the 2000s in China. Trials were conducted at three locations in 2007 and 2008, and at four locations in 2009. Twenty-seven single hybrids, four double-cross hybrids, and four open-pollinated varieties, were grown at three densities at each location each year. 56% of total yield gain was contributed to breeding from 1950 to 2000. New hybrids had more resistance to compound stress. Levels of response of all hybrids to higher-yielding environments were similar, and greater than that of OPVs. All maize cultivars showed morphological changes for all characteristics tested in a volatile manner from 1950 to 2000, except for relatively stable leaf number. ASI decreased and tolerance to root lodging improved, which were enhanced at higher plant densities. There were no trends for other characteristics at higher densities. Shorter maturity, smaller plant size and more tolerance to root and stalk lodging will be required for further yield improvement. Chinese maize yield improvement can benefit from agronomic strategies at higher plant densities. |
| [63] | . 倒伏严重影响玉米产量而且还影响玉米的机械化收获，是当前玉米生产和育种中一个主要问题。玉米的抗倒性受到植株受力因素与植株支持系统两方面的影响。讨论提高玉米抗倒性的遗传因素以及综述与其相关的遗传机制研究进展。 . 倒伏严重影响玉米产量而且还影响玉米的机械化收获，是当前玉米生产和育种中一个主要问题。玉米的抗倒性受到植株受力因素与植株支持系统两方面的影响。讨论提高玉米抗倒性的遗传因素以及综述与其相关的遗传机制研究进展。 |
| [64] | . . |
| [65] | |
| [66] | . The permanent displacement of plants from their vertical stance is called lodging. It is more common in cereals like wheat, oat and barley. Stalk breakage is also observed in sorghum and maize. Lodging usually occurs near the harvesting period, and cereals are prone to lodging at this period. There are two types of lodging - stem lodging and root lodging. It is a complicated phenomenon influenc... |
| [67] | . The identification of maize nitrogen (N) response for stalk quality is valuable in stalk breeding improvement, stalk lodging resistance and for use in bioenergy. This study analyzed the effect of two N levels and estimated quantitative genetic parameters for stalk quality in summer maize in the north China plain (NCP). Thirty hybrids were sampled and tested from three to four geographic locations under high nitrogen (HN) (225 kg N ha 611) and low nitrogen (LN) (0 kg N ha 611) during 2006–2008. Compared to HN level, stalk crude protein (CP) was significantly reduced (22.06%) under LN level. Ether extract (EE), ash content (AC), in vitro dry matter digestion (IVDMD) and lignin content (LC) were lower under LN level. Cellulose content (CC), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were increased with a reduction in N, however N did not significantly affect EE, ADF and LC. An increase in NDF and ADF content under low vs. high N level was mainly attributed to a reduction in CC. ADF and NDF exhibited positive correlation and both showed a positive correlation with CC but a negative correlation with LC, IVDMD and CP. Negative correlations between IVDMD and CC, IVDMD and LC, and CP and CC were also detected. The interaction variance of genotype × year × location ( σ 2 GYL) for each N level, with the exception of σ 2 GYL for CC under HN, was significant and most stalk quality traits were evaluated in different locations and years. The estimates of genetic variance ( σ 2 G) and heritability ( h 2) were greater under HN, with the exception of LC and EE. The interaction of genotype × nitrogen ( σ 2 GN) for CP was more important than σ 2 G. The genotypic correlation coefficients ( r G) for performance in different stalk quality traits between HN and LN were significant. However, it was necessary to evaluate both HN and LN for IVDMD. For other stalk quality traits, breeding maize under HN levels may serve to develop hybrids well adapted to high and/or low N level. The response to N trend was similar between high oil and normal maize hybrids. |
| [68] | . Two types of lodging, root lodging and stalk breakage, were observed in K-deficient maize. Root lodging was due to smallness of the brace root system and subsequent breakdown of parenchyma cells in the brace root. Stalk breakage resulted from disintegration of parenchyma in the lower part of the stalk. This breakdown is illustrated by micro-photographs. |
| [69] | . 本文从高产水平下的氮、磷、钾肥用量着手,研究了玉米茎秆的化学成分和解剖结构与倒伏之间的相互关系。结果表明,倒伏率与茎秆含钾量、粗纤维含量、硬皮组织厚度、维管束面积的大小有密切关系,增施钾肥可以增加茎秆的含钾量,有利于提高粗纤维含量,促进了硬皮组织和维管束鞘的发育,从而提高了茎秆强度,减轻了玉米倒伏及其对产量的影响。 . 本文从高产水平下的氮、磷、钾肥用量着手,研究了玉米茎秆的化学成分和解剖结构与倒伏之间的相互关系。结果表明,倒伏率与茎秆含钾量、粗纤维含量、硬皮组织厚度、维管束面积的大小有密切关系,增施钾肥可以增加茎秆的含钾量,有利于提高粗纤维含量,促进了硬皮组织和维管束鞘的发育,从而提高了茎秆强度,减轻了玉米倒伏及其对产量的影响。 |
| [70] | . <P><FONT face=Verdana>【目的】从细胞水平探讨钾素营养提高玉米茎腐病抗性的机制。【方法】采用扫描电镜和透射电镜分别观察施钾后玉米茎髓组织和接菌后施钾与不施钾幼根根尖细胞超微结构的变化。【结果】缺钾处理的玉米茎髓薄壁细胞,结构不规则,长边较长。而不缺钾处理茎髓细胞结构规则,呈长方形,整齐排列。缺钾导致维管束间的薄壁细胞破裂,致使茎髓中维管束间失去连接细胞,支撑能力变差。另外,施钾有利于寄主幼根表皮细胞排列紧密而整齐,细胞壁增厚,有效阻碍病原菌的入侵。而且施钾处理细胞中拥有丰富的高尔基体,可以产生大量分泌物将菌丝降解。钾素还有利于菌丝入侵部位乳突的形成及高电子致密物的积累,以阻止菌丝的扩展。【结论】钾素能通过稳定细胞结构,防止细胞间隙的扩大,加固细胞壁,来降低病原菌侵入的机率;通过形成位于胞间及胞内的闭塞物来限制病原物在寄主细胞的进一步发展。<BR></FONT></P> . <P><FONT face=Verdana>【目的】从细胞水平探讨钾素营养提高玉米茎腐病抗性的机制。【方法】采用扫描电镜和透射电镜分别观察施钾后玉米茎髓组织和接菌后施钾与不施钾幼根根尖细胞超微结构的变化。【结果】缺钾处理的玉米茎髓薄壁细胞,结构不规则,长边较长。而不缺钾处理茎髓细胞结构规则,呈长方形,整齐排列。缺钾导致维管束间的薄壁细胞破裂,致使茎髓中维管束间失去连接细胞,支撑能力变差。另外,施钾有利于寄主幼根表皮细胞排列紧密而整齐,细胞壁增厚,有效阻碍病原菌的入侵。而且施钾处理细胞中拥有丰富的高尔基体,可以产生大量分泌物将菌丝降解。钾素还有利于菌丝入侵部位乳突的形成及高电子致密物的积累,以阻止菌丝的扩展。【结论】钾素能通过稳定细胞结构,防止细胞间隙的扩大,加固细胞壁,来降低病原菌侵入的机率;通过形成位于胞间及胞内的闭塞物来限制病原物在寄主细胞的进一步发展。<BR></FONT></P> <P><FONT face=Verdana>【目的】从细胞水平探讨钾素营养提高玉米茎腐病抗性的机制。【方法】采用扫描电镜和透射电镜分别观察施钾后玉米茎髓组织和接菌后施钾与不施钾幼根根尖细胞超微结构的变化。【结果】缺钾处理的玉米茎髓薄壁细胞,结构不规则,长边较长。而不缺钾处理茎髓细胞结构规则,呈长方形,整齐排列。缺钾导致维管束间的薄壁细胞破裂,致使茎髓中维管束间失去连接细胞,支撑能力变差。另外,施钾有利于寄主幼根表皮细胞排列紧密而整齐,细胞壁增厚,有效阻碍病原菌的入侵。而且施钾处理细胞中拥有丰富的高尔基体,可以产生大量分泌物将菌丝降解。钾素还有利于菌丝入侵部位乳突的形成及高电子致密物的积累,以阻止菌丝的扩展。【结论】钾素能通过稳定细胞结构,防止细胞间隙的扩大,加固细胞壁,来降低病原菌侵入的机率;通过形成位于胞间及胞内的闭塞物来限制病原物在寄主细胞的进一步发展。<BR></FONT></P> |
| [71] | . 以郑单958(ZD958)为 试验材料,采用干旱棚池栽试验,研究了水钾互作对夏玉米茎秆结构和功能的影响.结果表明:灌水可显著提高茎秆的伤流量,施钾在一定程度上可以缓解水分缺乏 对茎秆伤流量的影响,在灌水2250 m~3·hm~(-2)时施钾可显著提高各生育时期茎秆的伤流量.水钾互作可显著提高茎秆穿刺强度和茎粗,在灌水2250 m~3·hm~(-2)时施钾处理的穿刺强度和茎粗较不施钾处理分别高46.0%和36.4%,施钾条件下灌水2250 m~3·hm~(-2)较灌水450m~3·hm~(-2)处理的穿刺强度和茎粗分别高30.7%和8.6%.灌水2250 m~3·hm~(-2)时施钾显著提高了茎秆维管束数目、面积及维管束内厚壁细胞、皮层和硬皮组织厚度.即水钾互作能够显著提高夏玉米植株的抗倒伏能力, 本试验条件下,施180kg K_2O·hm~(-2)、适当增加灌水量可显著提高夏玉米抗倒伏能力和产量. . 以郑单958(ZD958)为 试验材料,采用干旱棚池栽试验,研究了水钾互作对夏玉米茎秆结构和功能的影响.结果表明:灌水可显著提高茎秆的伤流量,施钾在一定程度上可以缓解水分缺乏 对茎秆伤流量的影响,在灌水2250 m~3·hm~(-2)时施钾可显著提高各生育时期茎秆的伤流量.水钾互作可显著提高茎秆穿刺强度和茎粗,在灌水2250 m~3·hm~(-2)时施钾处理的穿刺强度和茎粗较不施钾处理分别高46.0%和36.4%,施钾条件下灌水2250 m~3·hm~(-2)较灌水450m~3·hm~(-2)处理的穿刺强度和茎粗分别高30.7%和8.6%.灌水2250 m~3·hm~(-2)时施钾显著提高了茎秆维管束数目、面积及维管束内厚壁细胞、皮层和硬皮组织厚度.即水钾互作能够显著提高夏玉米植株的抗倒伏能力, 本试验条件下,施180kg K_2O·hm~(-2)、适当增加灌水量可显著提高夏玉米抗倒伏能力和产量. 以郑单958(ZD958)为 试验材料,采用干旱棚池栽试验,研究了水钾互作对夏玉米茎秆结构和功能的影响.结果表明:灌水可显著提高茎秆的伤流量,施钾在一定程度上可以缓解水分缺乏 对茎秆伤流量的影响,在灌水2250 m~3·hm~(-2)时施钾可显著提高各生育时期茎秆的伤流量.水钾互作可显著提高茎秆穿刺强度和茎粗,在灌水2250 m~3·hm~(-2)时施钾处理的穿刺强度和茎粗较不施钾处理分别高46.0%和36.4%,施钾条件下灌水2250 m~3·hm~(-2)较灌水450m~3·hm~(-2)处理的穿刺强度和茎粗分别高30.7%和8.6%.灌水2250 m~3·hm~(-2)时施钾显著提高了茎秆维管束数目、面积及维管束内厚壁细胞、皮层和硬皮组织厚度.即水钾互作能够显著提高夏玉米植株的抗倒伏能力, 本试验条件下,施180kg K_2O·hm~(-2)、适当增加灌水量可显著提高夏玉米抗倒伏能力和产量. |
| [72] | . 为探索密植玉米群体茎秆质量改善,抗倒伏能力提高的技术途径和措施,大田滴灌条件下研究了不同肥料配施对夏玉米生长发育及与茎秆质量、抗倒伏相关的农学性状和力学性状的影响.试验设置5个肥料配施处理:仅施氮肥(N)、氮配施磷肥(N+P)、氮配施钾肥(N+K)、氮配施4种微肥(N+4M)、氮配施磷钾和4种微肥(N+P+K+4M),并以传统施肥方式(全部肥料一次性底施)为对照(CK).结果表明,与传统施肥相比,滴灌配施钾肥显著增加了玉米干物质积累量和籽粒产量,各器官干物质积累分配模式也得以优化,同时控制株高和重心高度、缩短基部节间、增加基部节间的直径、干质量从而使单位长度干质量显著增加.玉米茎秆的抗弯曲力、穿刺强度、机械强度以及抗倒伏指数与株高、重心高度和基部节间长呈负相关或(极)显著负相关,而与植株干鲜质量以及基部节间直径、干质量和单位长度干质量呈正相关或(极)显著正相关.滴灌条件下不同肥料配施玉米茎秆的抗弯曲力、穿刺强度、机械强度显著以及抗倒伏指数都高于或者显著高于传统施肥方式,尤其是配施钾肥处理效果最为明显,这可为该地区玉米密植抗倒高产提供理论依据. . 为探索密植玉米群体茎秆质量改善,抗倒伏能力提高的技术途径和措施,大田滴灌条件下研究了不同肥料配施对夏玉米生长发育及与茎秆质量、抗倒伏相关的农学性状和力学性状的影响.试验设置5个肥料配施处理:仅施氮肥(N)、氮配施磷肥(N+P)、氮配施钾肥(N+K)、氮配施4种微肥(N+4M)、氮配施磷钾和4种微肥(N+P+K+4M),并以传统施肥方式(全部肥料一次性底施)为对照(CK).结果表明,与传统施肥相比,滴灌配施钾肥显著增加了玉米干物质积累量和籽粒产量,各器官干物质积累分配模式也得以优化,同时控制株高和重心高度、缩短基部节间、增加基部节间的直径、干质量从而使单位长度干质量显著增加.玉米茎秆的抗弯曲力、穿刺强度、机械强度以及抗倒伏指数与株高、重心高度和基部节间长呈负相关或(极)显著负相关,而与植株干鲜质量以及基部节间直径、干质量和单位长度干质量呈正相关或(极)显著正相关.滴灌条件下不同肥料配施玉米茎秆的抗弯曲力、穿刺强度、机械强度显著以及抗倒伏指数都高于或者显著高于传统施肥方式,尤其是配施钾肥处理效果最为明显,这可为该地区玉米密植抗倒高产提供理论依据. 为探索密植玉米群体茎秆质量改善,抗倒伏能力提高的技术途径和措施,大田滴灌条件下研究了不同肥料配施对夏玉米生长发育及与茎秆质量、抗倒伏相关的农学性状和力学性状的影响.试验设置5个肥料配施处理:仅施氮肥(N)、氮配施磷肥(N+P)、氮配施钾肥(N+K)、氮配施4种微肥(N+4M)、氮配施磷钾和4种微肥(N+P+K+4M),并以传统施肥方式(全部肥料一次性底施)为对照(CK).结果表明,与传统施肥相比,滴灌配施钾肥显著增加了玉米干物质积累量和籽粒产量,各器官干物质积累分配模式也得以优化,同时控制株高和重心高度、缩短基部节间、增加基部节间的直径、干质量从而使单位长度干质量显著增加.玉米茎秆的抗弯曲力、穿刺强度、机械强度以及抗倒伏指数与株高、重心高度和基部节间长呈负相关或(极)显著负相关,而与植株干鲜质量以及基部节间直径、干质量和单位长度干质量呈正相关或(极)显著正相关.滴灌条件下不同肥料配施玉米茎秆的抗弯曲力、穿刺强度、机械强度显著以及抗倒伏指数都高于或者显著高于传统施肥方式,尤其是配施钾肥处理效果最为明显,这可为该地区玉米密植抗倒高产提供理论依据. |
| [73] | . 本研究系统地玉米茎腐病菌置于土壤条件下，研究土壤温度、湿度、酸碱度、土质等因子对病菌在土壤中生长和对寄主侵染的影响。结果表明，禾谷镰刀菌（Ｆｕｓａｒｕｍ ｇｒｍｉｎｅａｒｕｎ）喜欢中性土壤和低湿的环境，不耐高温，在壤土中生长较好；瓜果腐霉菌（Ｐｙｔｈｉｕｍ ａｐｈａｎｉｄｅｒｍａｔｕｍ）喜欢中性土壤和高湿环境，能耐土壤高温，在砂土或粘土中生长较好。病菌对玉米幼苗的侵染受土壤温、湿度、特别是湿度条件 . 本研究系统地玉米茎腐病菌置于土壤条件下，研究土壤温度、湿度、酸碱度、土质等因子对病菌在土壤中生长和对寄主侵染的影响。结果表明，禾谷镰刀菌（Ｆｕｓａｒｕｍ ｇｒｍｉｎｅａｒｕｎ）喜欢中性土壤和低湿的环境，不耐高温，在壤土中生长较好；瓜果腐霉菌（Ｐｙｔｈｉｕｍ ａｐｈａｎｉｄｅｒｍａｔｕｍ）喜欢中性土壤和高湿环境，能耐土壤高温，在砂土或粘土中生长较好。病菌对玉米幼苗的侵染受土壤温、湿度、特别是湿度条件 |
