小麦茎顶端原基分化的动态模式与特征研究

小麦各类茎顶端原基分化与播种后累积生长度日(GDD)之间均呈S曲线关系, 符合Logistic数学模型, 表明小麦茎顶端各类原基的分化一旦启动, 其分化速率均随着GDD的增加呈现“慢-快-慢”的动态变化规律。 虽然不同播期对苞叶原基和小穗原基的分化模式具有调节作用, 但冬性与春性品种以及主茎与分蘖顶端原基分化的模式基本一致     

小麦小花发育与退化的研究

从研究和应用的角度出发将小麦小花发育过程分为八个阶段，即：小花原基形成期、雌雄药原基形成期、药隔形成期、花药四分期、花药伸长期、冠毛形成期、羽状柱头形成期、花药黄化期（开花期）。可以利用活动积温预测小花发育阶段。小花退化集中在冠毛形成期—羽状柱头形成期，但是当小花发育到花药伸长期时还处于花药四分期以前的小花都将退化。退化小花多分布于基部小穗各小花和中上部小穗的上位小花。     

乙烯利与1-甲基环丙烯调控小麦穗部籽粒形成的研究

为探明植物激素乙烯对小麦穗发育和籽粒形成的影响，以春小麦扬麦15为材料，在药隔期使用乙烯利与乙烯受体抑制剂1-甲基环丙烯（1-MCP）处理植株，分析籽粒形态并观察穗部性状，探究乙烯利和1-MCP处理前后穗发育进程和穗部不同部位籽粒形成过程。结果表明，乙烯利对小麦小花退化过程无显著影响，而1-MCP能显著降低小花退化率；乙烯利能够促进籽粒成熟，加速籽粒发育，减小籽粒体积；1-MCP会延缓小麦的生长发育，促进颖果生长，增加籽粒体积；乙烯利显著降低了小麦株高、顶部穗粒数、顶部穗粒重以及千粒重；高浓度乙烯利还能显著降低小穗数、顶部和中部穗粒数、每穗粒数等。1-MCP能够显著提高小麦颖果干重、颖果鲜重、小穗数、中部穗粒数、基部穗粒数、每穗粒数以及穗粒重，最终增加千粒重。     

基于顶端发育的小麦产量结构形成模型

小麦产量由单位面积穗数、每穗粒数与粒重构成。本研究以试验资料为基础,通过定量分析小麦茎顶端发育过程及其与环境因子和品种特性的动态关系,构建了小麦穗粒发育与结实的模拟模型,包括对叶原基数、叶片数、小穗原基数、小穗数、籽粒数及籽粒重的预测;进一步结合茎蘖发生与穗数决定模型,最终建立了小麦产量结构形成的模     

小麦穗粒数形成的基因型差异及增粒途径分析

以27个穗粒性状不同的小麦品种为材料,对小麦穗粒数形成过程中的各构成因素进行了相关、通径和聚类分析。结果表明：不同穗粒性状基因型在分化小穗数、结实小穗数、分化小花数和可孕小花数上均有明显差异。特大穗型小麦的小花分化速率最快,分化持续时间最短。穗粒数对小麦产量提高的贡献最大,穗粒数与千粒重之间不存在负相     

温光互作对春性小麦小穗建成的效应

利用6个来自不同生态区的春性小麦品种,在温室和生长箱温光控制条件下,研究了温度和光周期对小穗数调节作用的形态学基础。结果表明,温度和光周期从叶原基的分化转化及穗分化持续期两方面调节了小穗数,具体表现为:(1)从温度的影响出发,在长日条件下,低温主要通过延迟二棱以后小穗原基的分化过程而增加小穗数的多少,而     

冬小麦籽粒生长特性及其遗传研究

研究了小麦籽粒生长特性及其遗传交异和性状相关。结果表明，不同材料间籽粒生长特性在显著差异。籽粒生长特性与穗下节长，小穗密度以及开花期显著相关，根据籽粒生长特性互补原则评选出佳杂交组合。     

水稻颖花分化与退化的动态特征

研究了田间条件下水稻颖花分化与退化的动态模式及品种、播期和施氮水平的影响。结果表明,按幼穗各类原基数的增长动态,幼穗发育可分为一次枝梗分化期、二次枝梗与颖花同步分化期、颖花退化期3个阶段,可用Logistic方程和线性方程分别描述原基分化和退化随生长度日的变化动态。早播增加了分化颖花数,以大穗型品种尤为显著     

小麦不同粒位、粒重及其种子活力研究

对4个小麦品种各粒位上的粒重及种子活力进行了研究。结果表明：各粒位的粒重差异显著，其大小在麦穗上的分布具有明显的区域性。穗中下部小穗的第1、2花位籽粒最大（43.9mg)，上部小穗及中部高位小花所结籽粒最小（26.2mg），除种子大小影响种子活力外，粒重相同的种子，位于下部小穗上的籽粒具有较高的种子活力。     

小麦小穗不同粒位粒重形成的生理特性差异

为探明小麦小穗上不同粒位籽粒粒重形成的生理机制,明确限制小穗上位弱势粒充实的主要原因,本试验选用大穗型小麦品种泰农18(TN18)和多穗型小麦品种山农20(SN20)为材料,调查检测了灌浆过程中小穗上不同粒位籽粒内源激素、可溶性糖、全氮含量的动态变化以及籽粒与籽粒柄连接处横面的组织结构与不同粒位籽粒粒重的关系。花后籽粒灌浆过程中灌浆速率与籽粒内GA和IAA含量呈极显著或显著相关,小穗基部籽粒中较高的GA和IAA含量可使蔗糖向淀粉转化开始早,籽粒分化快,灌浆速率高,是小穗基部籽粒粒重高的生理机制;扫描电镜图显示小麦籽粒灌浆初期小穗基部籽粒柄维管束横面面积明显大于上位籽粒,微观空隙小且排列较整齐,有利于同化物和生理活性物质的运输,是小穗基部籽粒粒重增长快、灌浆速率高的解剖学基础。     

山西省冬小麦地方品种形态特征和生物学特性的遗传多样性分析

为了有效利用山西省冬小麦地方品种质资源,了解不同生态区的冬小麦地方品种在主要农艺性状上的遗传多样性,对551份山西省冬小麦地方品种的遗传多样性进行聚类与主成分分析。结果表明:16个质量性状和7个数量性状都存在着丰富的遗传多样性。对比2个冬麦区的小麦23个性状发现:芒形、幼苗习性、粒质和穗长4个性状的遗传多样性指数比其他性状高,遗传变异较丰富。其中,南部中熟麦区的芒形、抗倒伏性、穗长和小穗着生密度4个性状多样性指数较高,茎粗和整齐度多样性指数偏低;中部晚熟麦区的芒形、幼苗习性、穗长和千粒重4个性状多样性指数较高,株高、小穗着生密度、整齐度和叶姿多样指数偏低。根据材料间各性状的遗传差异,经聚类分析将材料分为5大类群,其中第Ⅳ类群属于矮杆、穗粒数多和千粒重高的丰产亲本材料。7个数量性状的主成分分析结果表明:前3个主成分累计贡献率达72.78%,第一主成分反映每穗小穗数和每穗粒数,第二主成分反映小穗着生密度,第三主成分反映千粒重。本研究对深入探索山西小麦地方品种的遗传多样性提供理论参考,并为小麦新品种选育提供优异的亲本材料。     

不同播期和品种小麦小花结实的粒位差异

确定小麦不同小穗位和小花位发育与结实特性是实现大穗多粒的重要前提，本文通过对冬，春性小麦品种分期播种试验得出，较高的小穗结实力是增加穗粒数的重要因素，不同播期，品种之间，小穗粒重和粒数呈现相同的变化趋势，中部以及基部小穗粒重与穗粒重之间呈高度正相关，体现环境差异的播期效应以对中部小穗发育的影响为主，而冬，春性品种的基因型差异可反映在各个小穗位上，第2小花粒的子粒发育状况反映整个小穗的生产能力，结果表明，促进中部优势小穗（第5－15小穗）结实和第1－3小花位子粒发育是提高小花结实率和穗粒重的关键。     

玉米雌穗分化与籽粒发育及败育的关系

以郑单958 (ZD958)和登海661 (DH661)为试材,比较研究了4.5、7.5、10.5万株hm^-2三个种植密度下,雌穗分化与籽粒发育及败育的关系。结果表明,密度对玉米雌穗原基开始分化的时间无影响(不同密度下,穗原基均在播后28~29 d左右开始分化),对吐丝期分化的小花总数影响很小。但是高密度推迟了雌穗的分化进程,增加了败育花和未受精花的数目,导致正常成熟小花数目的降低。与低密度相比,高密度下DH661正常小花数减少了100.0个,ZD958减少了76.4个。高密度加大了雌雄穗吐丝开花间隔,降低了吐丝植株的比例(DH661吐丝植株占93.64%;ZD958的占81.80%),推迟了吐丝时间,使单株吐丝量减少,散粉持续时间缩短,导致败育增加。正常受精的小花在灌浆期也会发生籽粒败育,尤其是在花后10 d左右败育严重。相关分析表明,玉米最终的穗粒数与开花期以及花后10 d、20 d的冠层底部透光率相关性显著,花败育率与开花前冠层底部透光率显著负相关。     

温麦6号和鲁麦22小麦小花发育与籽粒灌浆特性的研究

在超高产栽培条件下,温麦６号小麦小花分化起始日与结束日均早于鲁麦２２,小花分化总数鲁麦２２多于温麦６号,小药分化强度主茎穗为温度６号高于鲁麦２２,一级分蘖穗为鲁麦２２高于温麦６号,小花退化强度主茎穗和一级分蘖穗一致,均为温度６号高于鲁麦２２;提高小花结实率是增加每穗粒数的主要途径。鲁麦２２的籽粒灌浆速率和千粒重均高于温麦６号,在豫西成熟较温麦６号晚４天。文中还讨论了提高小花结实率,增加穗粒数的栽培     

Wheat Development as Affected by Radiation at Two Temperatures

A wheat cultivar (Condor) was grown in two experiments (thermal regimes 18/13 and 21/16°C) under low (298 μE m^-2: s^-1) radiation regimes during either an early phase from seedling emergence to terminal spikelet initiation (S₂), a late phase from terminal spikelet initiation to anthesis (S₂), or for the full period from seedling emergence to anthesis (S₁₂), or high (560 μE m^-2s^-1) radiation throughout the growing period (S₁₂) to determine whether developmental events are affected by radiation. The main developmental events considered in this study were the timing of terminal spikelet initiation and anthesis, the final number of leaf and spikelet primordia initiated in the apex and the rate of leaf appearance. Number of grains per spike and culm height were also measured. The duration of each phenophase was not affected by radiation intensity. Temperature affected the rate of wheat development, but the acceleration of development due to temperature during the seedling emergence - terminal spikelet initiation phase only slightly reduced (from 24.8 to 23.2 days). Differences in time from terminal spikelet initiation to anthesis were greater than in the earlier phases, having been the duration reduced from 24.6 to 20.0 days due to high temperature. Associated with the lack of effect of radiation on phasic development and the negligible effect of temperature on the duration of the early phases of development, final Leaf number was practically unchanged in this study by either the radiation level or the growing temperature. Thus, radiation did not affect the rate of leaf initiation. The number of spikelets was affected by neither the treatments nor the thermal environment. The rates of leaf appearance were accelerated by temperature. Radiation, on the other hand, did not significantly alter the rates of leaf appearance in any of the treatments. As expected from many sources in the literature, the number of grains per spike was significantly affected by radiation during the phase from terminal spikelet initiation to anthesis. Due to the lack of significant effects of radiation on the developmental patterns of wheat, the changes in number of grains per spike were due to changes in the number of grains born in each spikelet. The results of the present study were compared with others available in the literature on the effects (or lack of them) of radiation and CO₂ concentration on phasic development, plastochron and phyllochron in wheat to reach the general conclusion that the rate of developmental events in wheat, in contrast to other plants, is almost completely independent of the availability of assimilates, with a possible exception for the Equatorial latitudes.     

Use of AFRCWHEAT2 to predict the development of main stem and tillers in winter triticale and winter wheat in North East Germany

Winter triticale (cv. Grado) and winter wheat (cv. Taras) were grown in Rostock, Germany (54.2°N) for 5 years (1985–91) each with up to four sowing dates. Shoot apex development of the main stem and the two most developed tillers was observed by sampling eight plants every 3–10 days. The developmental submodel of the AFRCWHEAT2 simulation model was tested to predict the developmental events: emergence, start of floral initiation, double ridge, start of floret initiation, end of spikelet initiation and anthesis.Anthesis of main shoots was observed 8 days earlier for triticale than for wheat which was explained by an earlier start of reproductive development in triticale than in wheat. Variation in the dates of phenological events was greater for floral initiation and double ridges than for floret initiation and anthesis in both cereals. Dates of the early stages of development varied more in triticale than in wheat and more for main shoots than for tillers. For both species, standard deviations of the differences between observed and model predicted dates of phenological events were larger among developmental stages than between cultivars. Prediction of the early stages of development (floral initiation and double ridge) was poor for both species. The beginning of floret initiation and anthesis were simulated more accurately. We suggest that progress in simulating the development of cereals is more limited by lack of knowledge about plant physiology, rather than by the process of modelling. Better quantification of the vernalization requirements of different species is identified as an important topic for future work. Developmental parameters calculated for main shoots could also be used to closely predict the development rates of tillers. Differences between the development rates of main shoots and tillers were explained by the weather conditions each tiller group experienced and not by differences in their physiological responses to climatic factors. More research is needed to describe differences in development and vernalization requirements of a tiller when compared with that of a main shoot.