夏玉米花丝与穗轴伸长动态特征研究

利用中单909(ZD909)与安农591(AN591)两个夏玉米主栽品种,调查雌穗基、中、顶部花丝伸长动态与叶片和穗轴关系特征.结果 表明,雌穗基、中部花丝比顶部花丝先发育、先吐丝、先脱落.当有效积温达到900℃·d时,基、中部花丝开始发育,穗轴发育到最终长度的10％;当有效积温达到1000℃·d时,基、中部花丝发育到...     

玉米花丝和穗轴中可溶性糖、淀粉变化规律的研究

在一般大田环境中,控制玉米果穗的授粉情况,研究果穗在套袋和自然授粉时可溶性糖和淀粉在花丝和穗轴中的变化情况。结果表明:花丝和穗轴中的可溶性糖、淀粉浓度均呈单峰变化,可溶性糖以及花丝中淀粉浓度峰值出现在吐丝后第5天,而穗轴中的淀粉浓度峰值出现时间提前2天。花丝不同部位间可溶性糖浓度由基部向顶部依次下降。而积累量随着生育进程的推进而上升,但后期花丝中的物质含量相对稳定。从总体来说,无论套袋还是自然授粉的果穗,各物质变化趋势一致,但后期授粉果穗的可溶性糖和淀粉积累量高于套袋果穗。     

玉米自交系的繁育难点及质量控制

通过玉米抽雄期隔行去雄，吐丝期剪短苞叶，使果穗不离茎拜进行晾晒等技术措施，克服了某些自交系花丝不易吐出，果稳脱水漫、易烂尖、易受冻等缺点，减轻了自交系多年大面积繁殖造成的混杂退化，使种子产量和质量都得到相应提高。     

玉米自交系花丝生理活力研究

以不同类型的 6个玉米自交系昌 7-2、 S122、 PH4CV、 M54、 12H21、 CL85为材料,测定其花丝伸长速率、花丝逐日吐出数目、不同日龄花丝授粉后的结实率及穗粒数和百粒重、完全吐丝授粉后花粉管通道的形成时间。结果表明,昌 7-2、 S122、 PH4CV、 M54、 CL85花丝伸长速率峰值出现在吐丝后第 2天, 12H21出现在第 3天,昌 7-2、 M54花丝伸长速率较快,S122花丝持续伸长过程最短。不同自交系吐丝数量呈先升高后降低趋势,日吐丝数量最大值出现在吐丝后第 2～3天。昌 7-2、 PH4CV、 M54、 12H21、 CL85花丝授粉结实持续日数最长, S122结实持续日数最短,PH4CV第 2天结实率达到峰值。吐丝后第 1～2天授粉百粒重较高但差异不明显。昌 7-2、 S122、 PH4CV、 M54、12H21、 CL85花丝授粉后 2 h剪去其花粉管通道均未打通,结实子粒数均为 0,花丝授粉后从 4 h剪去开始结实,直至8 h剪去花丝其结实子粒数处于升高阶段, 10 h之后结实子粒数趋于平缓。     

多胺、乙烯对玉米子粒发育早期的影响

本文对子粒败育与乙烯、多胺的关系进行了探讨.采用两类不同基因型(典型的顶端败育类型和正常类型)玉米杂交种为材料,对子粒发育前期乙烯的代谢变化,以及果穗中下部正常子粒上部败育子粒内原精胺(Spm)、亚精胺(SPd)和腐胺(Put)的含量进行了研究,结果表明:败育子粒在受粉后8～12天阶段中多胺含量明显低于正常子粒,子粒的乙烯释放量在授粉后的0～8天也出现.研究认为,乙烯的释放量,及果穗顶部子粒较低的多胺含量都与子粒败育密切相关,同期败育类型玉米子粒的乙烯释放量显著高于正常类型,同一类型中又表现为顶部高于中部。     

甜玉米果穗不同计产方法对产量评价的影响

以30个鲜食甜玉米品种为试材,研究果穗不同计产方法(第1果穗计产、所有果穗计产和商品果穗计产)对产量评价的影响。结果表明,3种计产结果在甜玉米不同品种间存在极显著差异,第1穗净果穗计产结果比商品穗产量高0～35.78%(除个别品种外);所有净穗计入产量结果比商品穗产量高0.08%～35.78%,且各百分率在不同品种间存在差异,以商品果穗计产比较科学。商品果穗标准为非霉变果穗,除去苞叶、花丝、穗柄、虫咬、损伤、秃尖及秃基部分的完好净穗有效长度至少不短于10cm的果穗。     

玉米空秆秃顶和缺粒产生的原因及防止措施

空秆是指玉米植株不结果穗或有果穗不能结实长大的现象。秃顶是指果穗顶部不结实,当雌穗顶部花丝抽出时,雄穗已散粉完毕,或者是不良气候影响,导致花粉败育,因而得不到花粉授粉受精。缺粒有两种,一是果穗的一面有若干行由基部到顶部都不结实,即缺行；一种是满天星缺粒，即果穗上只结少数子粒。     

玉米禾谷镰孢穗腐病抗性鉴定接种方法比较

通过子粒注射法和花丝通道法,在玉米吐丝初期至乳熟后期间隔 5～127 d接种 3个不同玉米品种,明确东北地区玉米禾谷镰孢穗腐病抗性鉴定的最佳接种方法。结果发现,禾谷镰孢在玉米吐丝期至乳熟期均能侵染玉米子粒和花丝。子粒注射法在玉米吐丝 1～12 d内接种的病情指数显著高于 16 d以后接种的处理;花丝通道法在玉米吐丝 1～5 d内的病情指数显著高于 12 d以后接种的处理。子粒注射法的抗性鉴定结果为吐丝 1 d接种的果穗表现为感病,吐丝 5～12 d为中抗或抗病,吐丝 16 d之后为抗病或高抗;花丝通道法接种的结果为吐丝 1 d为中抗或抗,吐丝 5 d及以后为抗或高抗。结果表明,子粒注射法在玉米吐丝 10～15 d左右接种发病稳定、抗感差异明显、鉴定结果准确。     

夏玉米最佳收获期试验研究

选用掖单4号、掖单12两个品种为试材,通过连续两年进行夏玉米最佳收获期试验和灌浆速度测定。结果表明,在我市自然条件下,以吐丝后52～55天收获产量最高,比传统苞叶发黄时收获晚收6～9天,增产11.1％～20.2％,并建立两品种回归模型,找出最佳收获期及与积温、含水量关系。     

玉米花丝生长发育过程中水势、pH值变化规律的研究

以两个夏玉米品种掖单12和掖单19为材料,通过室内测定的方法,研究了花丝生长发育过程中水势和pH值的动态变化。结果表明,不同品种间变化规律稍有不同,但总趋势一致。吐丝前花丝水势变化平稳,吐丝后花丝水势的变化呈下降趋势;吐丝前花丝pH值变化平稳,吐丝后pH值变化呈上升-下降-上升趋势。较高的花丝水势和pH值有利于维持花丝活力,花丝水势在-0.1～-0.4 MPa之间时,花丝活力较强;花丝pH值在6.8～6.9时,花丝活力较高。     

不同日龄玉米花丝授粉对产量相关性状的影响

以浚单29、浚单3136和浚单509为试材,通过对不同日龄花丝人工授粉,收获后统计3个玉米品种的穗长、穗粗、秃尖长、百粒重、穗粒数和穗粒重。结果表明,随着授粉花丝日龄的增大,穗粗和百粒重呈下降趋势;穗长先增加后水平波动,最后快速下降;秃尖长在第1天授粉处理最长,第4天授粉处理降到低谷;穗粒数和穗粒重变化相似,先上升,第4天授粉处理达到峰值后缓慢下降,第10天以后授粉处理下降较快。对各性状的相关系数分析后发现,穗粒数与穗粒重相关性最大。以自然授粉为参照,3个玉米品种在吐丝后的第4天授粉处理花丝活力最高,吐丝后第6天左右授粉处理花丝活力仍与对照相当。花丝日龄影响穗行数,授粉花丝日龄越小穗行数越多。     

不同株型高产玉米蒸腾作用的研究

在夏玉米亩产吨粮的研究中,测定了平展型玉米各单40和紧凑型玉米掖单6号大喇叭口期和吐丝期不同叶位不同密度的蒸腾速率(Tr)及其日变化.结果看出:鲁单40的Tr高于掖单6号,大喇叭口期Tr高于吐丝期.玉米前期上部展开或即将展开的叶Tr较高,后期中部和上部较高.Tr的日变化为单峰曲线,中午最高.增加种植密度使Tr减少,鲁单40玉米的Tr受密度影响较大.     

玉米DUS测试性状在春播与夏播间的表达差异研究

对24个玉米品种进行春播与夏播两种方式种植,研究春播与夏播两种播种方式对玉米品种特异性、一致性和稳定性(DUS)测试有关性状表达的影响。结果表明,玉米的果穗形状、果穗子粒颜色数量、果穗子粒排列形式和叶鞘花青甙显色强度4个性状表达不受播种方式的影响;抽丝期、散粉期、叶片宽度和果穗长度等4个性状表达受播种方式的影响明显;叶片弯曲程度等8个性状表达受播种方式的一定影响;雄穗花药花青甙显色强度等8个性状表达基本不受播种方式的影响。播种方式对玉米品种DUS测试性状表达有一定的影响。     

Heat stress effects around flowering on kernel set of temperate and tropical maize hybrids

Final kernel number in the uppermost ear of temperate maize (Zea mays L.) hybrids is smaller than the potential represented by the number of florets differentiated in this ear, and than the number of silks exposed from it (i.e., kernel set <1). This trend increases when stressful conditions affect plant growth immediately before (GS₁) or during (GS₂) silking, but the magnitude of change has not been documented for heat stress effects and hybrids of tropical background. In this work we evaluated mentioned traits in field experiments (Exp₁ and Exp₂), including (i) two temperature regimes, control and heated during daytime hours (ca. 33-40 °C at ear level), (ii) two 15-d periods during GS₁ and GS₂, and (iii) three hybrids (Te: temperate; Tr: tropical; TeTr: Te × Tr). We also measured crop anthesis and silking dynamics, silk exposure of individual plants, and the anthesis-silking interval (ASI). Three sources of kernel loss were identified: decreased floret differentiation, pollination failure, and kernel abortion. Heating affected all surveyed traits, but negative effects on flowering dynamics were larger (i) for anthesis than for silking with the concomitant decrease in ASI, and (ii) for GS₁ than for GS₂. Heat also caused a decrease in the number of (i) florets only when performed during GS₁ (−15.5% in Exp₁ and −9.1% in Exp₂), and only among Te and TeTr hybrids, (ii) exposed silks of all GS × Hybrid combinations, and (iii) harvestable kernels (mean of −51.8% in GS₁ and −74.5% in GS₂). Kernel abortion explained 95% of the variation in final kernel numbers (P < 0.001), and negative heat effects were larger on this loss (38.6%) than on other losses (≤11.3%). The tropical genetic background conferred an enhanced capacity for enduring most negative effects of heating.     

Fusarium proliferatum侵染玉米花丝的解剖学研究

层出镰刀菌(Fusarium proliferatum)分生孢子喷洒在玉米花丝上,可侵入玉米柱头的茸毛细胞、表皮细胞以及花丝的表皮细胞,菌丝沿花丝的薄壁组织细胞、维管束细胞向子房方向生长。F.proliferatum侵染花丝后,导致花丝薄壁细胞、表皮细胞皱缩,花丝萎缩变形。结果显示,F.proliferatum可直接侵染玉米花丝,借助花丝通道侵入玉米雌穗,花丝通道是F.proliferatum侵染玉米雌穗的途径之一。     

Intra-specific competition in maize: Ear development,flowering dynamics and kernel set of early-established plant hierarchies

Maize canopies with a synchronous seedling emergence and a uniform plant spatial distribution exhibit early-established plant hierarchies (at the 4-leaf stage; V₄). The dominant and dominated individuals of the stand differ in plant growth rate during both the pre-silking period (i.e. from V₇ to V₁₃; PGR_PS) and the period around silking (i.e. a 30 d period centered in silking; PGR_S), and in the ear growth rate around silking (EGR_S). Based on the depleted availability of assimilates of the dominated plants, we tested the hypotheses that (i) the low PGR_PS of dominated individuals affects the morphogenesis of the apical ear leading to a low number of completely developed flowers per ear, and (ii) the low EGR_S of dominated individuals results in a pronounced asynchrony of flowering dynamics and uneven silk exsertion from the husks. Two hybrids with contrasting tolerance to crowding stress (DK752 and DK765 as the tolerant and the intolerant hybrid, respectively) were cropped under different intensities of interplant competition (6, 12, 12 plants m⁻² thinned to 6 plants m⁻² at V₉ and 6 plants m⁻² shaded from V₉ onwards) during 2004/2005 and at 12 plants m⁻² during 2005/2006 at Pergamino (34°56′S 60°34′W), Argentina. Dominant plants were the individuals of the stands with the highest PGR_PS (ca. 1.72 and 2.56 g d⁻¹ for dominated and dominant plants, respectively), PGR_S (ca. 3.05 and 3.94 g d⁻¹ for dominated and dominant plants, respectively) and EGR_S (ca. 1.06 and 1.55 g d⁻¹ for dominated and dominant plants, respectively). This plant type also exhibited the most synchronous flowering dynamics (anthesis–silking interval ca. 1.49 and 1.15 days for dominated and dominant plants, respectively) and the highest kernel set (ca. 401 and 572 kernels plant⁻¹ for dominated and dominant plants, respectively). Apical ears of dominated plants exhibited a delayed in the rate of progress to successive floral stages, but the final number of completely developed flowers per ear did not differ between extreme plant types (ca. 967 and 803 completely developed flowers per ear for DK752 and DK765, respectively). Hence, kernel number per plant was not limited by the number of completely developed flowers per ear, but flowering dynamics were a decisive factor in kernel set of both plant types. Asynchronous silking within the ear of dominated plants determined a greater proportion of flowers per ear with non-exposed silks on silking + 5 d and a larger asynchrony in silk extrusion within the ear. These responses increased kernel abortion rate respect to figures obtained for dominant individuals.