覆膜对冬小麦穗分化进程的影响

通过对6个品种穗分化进程连续2a的研究表明，覆膜能显著加快冬小麦穗分化发育进程，其主茎伸长期和单棱期穗分化开始日期比露地小麦平均提前6．5d和9．5d，持续天数则相应缩短2．0d和6．1d，二棱期分化开始日期比露地小麦提前12．0d，持续天数延长9．5d。二棱期分化天数增加是地膜小麦形成大穗的主要原因，覆膜能缩短分薛穗与主茎穗之间（开始）穗分化的差异天数，地膜小麦分薛穗单棱期分化开始日期与主茎开始日期差异天数比露地小麦缩短，I薛平均缩短2．3d,Ⅱ薛平均缩短4．7d，Ⅲ薛平均缩短16．2d；地膜小麦分薛穗的二棱期与露地小麦分薛穗的二棱期相比，I薛比露地小麦缩短2．9d，Ⅱ薛缩短4．5d，Ⅲ薛缩短10．0d，覆膜缩小了分薛穗与主茎穗之间的差异，有利于成穗率的提高和形成穗匀的发育态势。     

普甜玉米的穗分化

普甜玉米为雌雄同株异花作物，雄穗（圆锥花序）和雌穗（肉穗花序）的穗分化各自进行。经立体解剖镜和扫描电镜观察，雌、雄穗的分化由下而上向顶式分化。雄穗分为四期１１个阶段；雌穗分为四期１０个阶段。雄穗穗分化开始时的叶龄指数为２７．４；雌穗为４１．１。单株各叶腋的穗分化阶段由上至下阶梯形下降，前期各叶位的穗分化阶段较 接近，以后差距逐渐拉大。掸株芽的分化数随肥水水平的提高而增加，但高肥水对穗分化进程的影响     

玉米雄穗分枝性状的数量遗传分析

以2个株型不同的玉米自交系自330和PH4CV构成的6世代群体为材料,目测计数玉米不同群体雄穗分枝数量。通过P1、P2、F1、F2、B1和B2共6个世代联合分析法,以玉米雄穗分枝数为性状,研究控制玉米雄穗分枝性状的基因遗传分离规律。结果表明:该性状在F2分离世代群体呈双峰分布,B1和B2群体分离世代呈多峰分布,说明玉米雄穗分枝性状遗传为多基因数量性状控制,且符合加性-显性-上位性多基因遗传模型(即C模型)。显性效应起主要作用,多基因遗传力较高,在74.83%～80.42%之间,若选择雄穗分枝较少的自交系必须从基础材料入手。这一研究结果为玉米雄穗分枝选择提供方法和理论依据。     

浇水与深耘断根对冬小麦穗分化进程的影响

于二棱期对主茎优势不同的 2个冬小麦品种 (系 )进行浇水或深耘断根后浇水 ,与对照相比 ,分蘖穗的穗分化速度相对加快 ,主茎穗与分蘖穗之间的穗分化差异减小 ,从而使小麦群体穗分化进程达到整齐一致 ,特别是提高了施用化学杀雄剂的适宜时期 (雌雄蕊原基分化～药隔形成期 )的主茎穗与分蘖穗穗分化的一致性 ,可提高化学杀雄效果 ,从而提高杂交种纯度     

地膜玉米穗分化进程的研究

研究表明,(1)地膜玉米中单2号雄穗和雌穗分化历时分别为 34,26 d时,分化始期的可见叶和叶龄分别为 8.8,6.5和 11.0,7.7。与露地玉米相比,雄穗分化期缩短 16 d,雌穗分化期缩短12人在穗分化的前期和中期,地膜玉米的叶数均显著多于露地玉米。(2)地膜玉米雌雄穗分化期的对应关系与露地玉米基本一致。(3)地膜玉米要求栽培措施比露地玉米早而及时。前期和中期管理的叶龄值比露地王米多1,后期与露地玉米基本一致。(4)地膜玉米各分化期的叶面系数均显著大于露地玉米是其增产的主要原因之一。     

玉米穗分化与品种及外界条件的关系

作者于1981～1983年,对玉米早、中、晚熟5个单交种进行了穗分化观察与产量测定。表明,雄穗分化始期品种间差异较小,晚熟单交种在高温干旱或低温多雨年份对雌雄穗分化变化小。玉米穗分化的进程可利用出苗后天数推算穗分化阶段,雌穗小花形成后根多叶茂的品种和采取延长雌穗分化Ⅰ～Ⅲ阶段的措施可获得增产。     

16个玉米新品种叶龄指数与穗分化关系的试验初报

以16个玉米新品种为材料,连续2a进行春夏播玉米的叶龄指数与穗分化回归关系的试验研究,结果表明：各品种的叶龄指数与雄穗分化期之间均呈极显著的正相关关系;回归方程的方差分析均达极显著水准。依据叶龄指数的观测值来预测雄穗分化期,可为玉米指标化高产栽培管理提供必要的理论指导根据。     

12个玉米新品种叶龄指数与穗分化关系的试验初报

以12个玉米新品种为材料,连续2 a进行夏播玉米的叶龄指数与穗分化回归关系的试验研究,结果表明：各品种的叶龄指数与雄穗分化期之间均呈极显著的正相关关系;回归方程的方差分析均达极显著水平。     

不同播期对洛旱7号小麦幼穗分化及产量的影响

采用4个不同的播期,对洛旱7号小麦幼穗分化进程进行研究,旨在探讨不同播期下小麦幼穗分化特点和最佳播期.结果表明:4个播期下洛旱7号小麦幼稳分化进程表现明显不同,并且4个不同播期对其产量要素的影响也较为明显,在C播期(10月15日)下,小麦幼穗分化进程所用时间为155d,12月23日进入二棱期、4月8日进入四分体时期较为...     

早熟玉米穗分化的研究

对早熟品种鲁原单4号玉米雌雄穗分化过程进行观察,并研究其不同穗分化时期追肥浇水对产量的影响。结果表明:雌穗与雄穗分化时期有相关性,雌、雄穗分化时期和展开叶、可见叶等外部形态有对应性;夏直播玉米,以雄穗分节期追肥浇水产量最高,其叶龄指数为35。该研究结果可为黄淮海地区夏直播玉米肥水运筹提供参考。     

8984×GY220F2∶3家系植株性状的分离特征及相关分析

[目的]研究由优良普通玉米自交系8984与高油玉米自交系GY220杂交构建的F2∶3家系的分离特征及其相关性。[方法]在夏播环境条件下对8个植株性状进行分析。[结果]F2∶3家系间各性状均存在极显著的差异,并呈连续性正态分布,存在明显的双向超亲分离;株高与穗位高、顶高、穗上叶片数、叶面积、雄穗长和雄穗分枝数,穗位高与顶高、穗上叶片数、叶面积、雄穗长和雄穗分枝数,顶高与顶高/株高、穗上叶片数、叶面积、雄穗长和雄穗分枝数,顶高/株高与穗上叶片数,穗上叶片数与叶面积、雄穗分枝数,叶面积与雄穗长间均呈显著或极显著的表型和遗传正相关;顶高/株高与株高、穗位高、叶面积和雄穗分枝数间均呈显著或极显著的表型和遗传负相关。[结论]该研究可以为高油玉米育种及其相关性状的分子遗传研究提供一定的科学依据。     

光周期对冬小麦穗分化的影响(Ⅱ)

[目的]进一步了解光周期对小麦穗分化的影响。[方法]以泰山9818、J30等冬小麦品种为材料,采用盆栽方式,于小麦返青后不同时期进行长日照转短日照、短日照转长日照的光周期处理,解剖镜观察小麦分化期的不同。[结果]随着短日照处理后延,短日延迟作用减弱。在前期长日照的基础上,小麦雌雄蕊后短日照延迟作用最小或无。二棱期转短日照后,光周期敏感型品种J30未能抽穗。短日延迟作用有一定的"滞后期"。二棱期短日照转长日照后,各品种的穗分化进程明显加快,J30也能抽穗,再次表现出光周期反应的滞后。光周期不敏感型品种的反应较小。[结论]光周期不敏感型品种受光周期的影响小于光周期敏感型品种。     

不同熟期夏玉米品种生长发育特性与产量形成的关系

【目的】研究不同熟期夏玉米品种生长发育特性与产量形成的关系,以期为早熟、高产、适应机械粒收的玉米新品种的筛选提供理论依据。【方法】2017年以早熟玉米品种登海518（DH518）、衡早8号（HZ8）和中晚熟玉米品种登海605（DH605）、郑单958（ZD958）为试验材料,2018年以早熟玉米品种登海518（DH518）、京农科728（JNK728）和中晚熟玉米品种登海605（DH605）、郑单958（ZD958）为试验材料,种植密度为75 000株/hm²,研究玉米生长发育过程中的叶片建成规律、穗部发育特性以及各生育阶段对光温需求的差异。【结果】不同熟期夏玉米品种各生育阶段的光温需求大小表现为吐丝期（R1）—生理成熟期（R6）>出苗期（VE）—吐丝期（R1）>播种期（sowing）—出苗期（VE）。不同品种花后对积温的需求高于花前,中晚熟和早熟夏玉米品种对积温需求的差异主要在拔节期—吐丝期,具体表现为第9—16片叶建成期;花后对积温的需求品种间差异不显著。相关性分析表明,不同熟期夏玉米品种的产量与穗位高、穗高系数呈极显著正相关关系。不同熟期夏玉米品种的雄穗发育特性不同,晚熟品种的雄穗长度显著低于早熟品种,但晚熟品种的雄穗分枝数、雄穗总小花数、小花败育率、有效小花数显著高于早熟品种;而雌穗分化到籽粒形成受品种基因型影响较大。【结论】不同熟期夏玉米品种生长发育特性具有较大差异,在75 000株/hm²条件下,中晚熟品种的产量显著高于早熟品种;植株总叶片数较少,拔节期—吐丝期所需时间短,后期脱水速率快是早熟宜机收玉米品种的典型特征。     

杏树花芽分化期叶片矿质元素含量动态变化的研究

为了揭示杏树雌蕊发育不良的机理,通过测定杏树6个品种在花芽分化期叶片的Fe、Mn、Zn、Mg、N、K元素含量的动态变化,研究了杏树花芽分化期的一些生理生化变化。杏树花芽分化期叶片中Fe、Mn、Mg、K元素含量品种间差异显著,Zn元素含量在不同日期间差异显著,N元素含量在品种间和日期间差异均不显著。杏树花芽分化的各个时期间以Zn元素含量差异极显著,不同败育率的各品种间以Fe、Mg、Mn、K元素含量差异显著,这几种矿质元素是影响杏树花芽发育质量的因素之一,为揭示杏树雌蕊败育机理提供了理论基础。     

How plant density affects maize spike differentiation,kernel set,and grain yield formation in Northeast China?

A two-year field experiment was conducted to evaluate the effects of plant density on tassel and ear differentiation, anthesissilking interval(ASI), and grain yield formation of two types of modern maize hybrids(Zhongdan 909(ZD909) as tolerant hybrid to crowding stress, Jidan 209(JD209) and Neidan 4(ND4) as intolerant hybrids to crowding stress) in Northeast China. Plant densities of 4.50×104(D1), 6.75×104(D2), 9.00×104(D3), 11.25×104(D4), and 13.50×104(D5) plants ha~(-1) had no significant effects on initial time of tassel and ear differentiation of maize. Instead, higher plant density delayed the tassel and ear development during floret differentiation and sexual organ formation stage, subsequently resulting in ASI increments at the rate of 1.2–2.9 days on average for ZD909 in 2013–2014, 0.7–4.2 days for JD209 in 2013, and 0.5–3.7 days for ND4 in 2014, respectively, under the treatments of D2, D3, D4, and D5 compared to that under the D1 treatment. Total florets, silking florets, and silking rates of ear showed slightly decrease trends with the plant density increasing, whereas the normal kernels seriously decreased at the rate of 11.0–44.9% on average for ZD909 in 2013–2014, 2.0–32.6% for JD209 in 2013, and 9.7–28.3% for ND4 in 2014 with the plant density increased compared to that under the D1 treatment due to increased florets abortive rates. It was also observed that 100-kernel weight of ZD909 showed less decrease trend compared that of JD209 and ND4 along with the plant densities increase. As a consequence, ZD909 gained its highest grain yield by 13.7 t ha~(-1) on average at the plant density of 9.00×104 plants ha~(-1), whereas JD209 and ND4 reached their highest grain yields by 11.7 and 10.2 t ha~(-1) at the plant density of 6.75×104 plants ha~(-1), respectively. Our experiment demonstrated that hybrids with lower ASI, higher kernel number potential per ear, and relative constant 100-kernel weight(e.g., ZD909) could achieve higher yield under dense planting in high latitude area(e.g., Northeast China).     

玉米品种多个数量性状的典型相关研究

对２０１份玉米品种四组栽培性状的典型相关分析表明,各组性状间存在着不同显著程度的典型相关,其中的生育期性状与植株性状组间极显著相关（００１水平）,是相关程度最高的两组性状。在００５显著水平下,生育期性状与果穗性状是相关程度最高的一组性状。２０１份玉米品种在生育期、植株、雄穗和果穗性状上,其典型遗传力存在不同程度的差异。     

密度对不同品种水稻生育及产量构成因素的影响

水稻不同品种之间生长量差异较大，但不同密度间差异小．不同品种在稀植（３０×２６ｃｍ）处理下有效分蘖终止期同密植（３０×１３ｃｍ）相比，普遍向后延迟，且其叶龄指数分别为２０和６４，但最高分蘖期无明显差异，其叶龄指数分别为８０和７９；二次分蘖穗明显增多，提高了有效分蘖率；茎基部伸长节间短而粗，上部节间拉长，折损重大，抗倒能力增强，不同品种间都有同样的趋势．产量与结实率（ｘ１）、千粒重（ｘ２）、ｍ２穗数（ｘ３）、穗粒数（ｘ４）间回归方程为经产量方差分析结果表明不同品种、不同密度间和互作差异不显著．据各种农艺性状的终合分析，秋田３２是较适合烯植栽培的优良品种．     

玉米自交系选育方法初探

以6个基础材料为选育对象,在自交2代之后,分别采用混粉法、自交法、姊妹交法选系.对各所得系进行生活力测定并用测验种测配,结果表明,混粉法和姊妹交法生活力显着高于自交法的选系,配合力无显着差异.在自交选系基础上,以S₂或S₃进行系内姊妹交法和混粉法,可增加一定程度的遗传差异,能大幅度提高自交系产量,降低单交种生产成本.     

The Inflorescences of Maize

1) The development of the maize plant, from germination to the maturation of the seed, is divided into the vegetative, transitional, reproductive, and seed stages. The ear and tassel differentiate and develop in the reproductive stage. 2) The mature tassel is a terminal, staminate inflorescence consisting of a symmetrical, many-rowed central axis and asymmetrical, two-ranked lateral branches. Paired spikelets, one terminal (pedicellate) and the other lateral (sessile), each containing two functional staminate flowers, are borne on the central axis and the lateral branches. 3) In contrast with the tassel, the ear is a pistillate inflorescence produced on a lateral branch. The ear consists of a symmetrical, many-rowed axis on which are paired spikelets, each containing two flowers. In the mature ear, it is difficult to distinguish the pedicellate from the sessile spikelet. There are two pistillate flowers in each spikelet of the ear, but only the terminal flower is functional, while the lateral flower aborts. 4) The mature ear and tassel appear to be different kinds of inflorescences, but if they are examined at the earliest stages in their development they will be found to be basically alike. The differences in the appearance of the two inflorescences at maturity are the result of differences in the differentiating and development of their parts. 5) Each of the morphological characteristics found in the maize inflorescences, except one, is present in other grasses, but the collection of morphological characteristics found in the ear and tassel is unique. One morphological characteristic not found in other grasses but found in the maize ear is the presence of a terminal, fertile, and aborted, lateral flower in each of the paired spikelets. 6) Axillary shoots are produced in acropetal succession in the axil of each leaf. Some of the axillary shoots that are produced at the beginning of the development of the plant may develop as tillers (suckers). The last-produced axillary shoot (or shoots) that is far enough advanced in its development at the initiation of the tassel develops into the ear (or ears). 7) The amount of seed produced per ear is determined by the number of rows of kernels and the number of kernels per row. The number of rows of kernels is determined at the beginning of the initiation of the ear, but the number of kernels per row may vary with the strain and with changes in the environment. Under comparable condition, seed produced per ear is less in plants without tillers than in plants with tillers. The average seed yield per ear is less in multiple-eared types than single-eared types growing under similar conditions. 8) The three major parts of the maize kernel are endosperm, 82 percent; germ, 11 percent; pericarp, seed coats, and tip cap, 7 percent. The composition of the maize kernel is 83 percent carbohydrate, 10 to 11 precent protein, and 4.3 percent oil. Fifty generations of selection for high- and low-protein strains and high- and low-oil strains produced marked changes in the chemical composition of the maize kernel. Beginning with 4.7 percent oil, after 50 generations of selection, the high-oil strain has 15.36 percent and the low-oil strain has 1.01 percent of oil. The protein content was 10.92 percent at the beginning of the selection and reached 19.45 percent in the high-protein strain and 4.91 percent in the low-protein strain after 50 generations of selection. Recovered inbred lines from backcrosses to the high strains have resulted in good-yielding hybrids that produce more protein or oil per acre than standard hybrids. 9) Several factors contribute to the superiority of maize over other cereals as a seed producer. The maize plant is large and, concomitant with its size, it has a large leaf surface, large stem, large root system, and an extensive vascular system. Branching is restricted to a few lateral, pistillate branches in which vegetative development is suppressed. The lateral ear-producing branch (or branches) is so placed on the plant that there are many leaves above and below it. The ear is large in diameter and has seeds that are many times larger than those of other cereals. All the afore-mentioned characteristics, many of which are not present in other grasses, contribute to making the maize plant a superior seed producer.