抽样方式对评价小麦种质资源遗传多样性统计数的影响

摘要：以中国、澳大利亚、墨西哥、俄罗斯、荷兰和智利6个国家的733份小麦种质资源为总体,以每个国家为一个亚区,设置19种抽样方式,研究了不同抽样方式对性状平均值、变异系数和多样性指数的影响。结果表明,在均衡抽样条件下,当样本容量小于60时,样本容量大小对性状的平均值和变异系数无显著影响,但对多样性指数值具有显著影响;当样本容量大于120时,样本容量大小对性状的平均值、变异系数和多样性指数均无显著影响。在非均衡抽样条件下,当样本容量大于150时,增加样本容量可有效减少非均衡抽样对变异系数和多样性指数的影响;当样本容量在90-150之间时,缩小各亚区材料数量差异比例可有效减少非均衡抽样对变异系数和多样性指数的影响;当各亚区所取材料最小数量多于20时,可有效降低非均衡抽样对平均值、变异系数和多样性指数的影响。增加性状变异较大亚区内的资源取样数量可提高统计数的准确度。     

RAPD多态位点数变化对小豆遗传变异信息估计的影响

以163份来自于中国、日本、韩国、不丹、尼泊尔和越南6国的各种类型小豆种质资源的大样本群体为材料,利用27条RAPD引物检测该群体得到的261个等位基因数据构建成"总群体",采用完全随机抽样方法,研究不同样本容量(样本位点数)与系统遗传相似系数(Jaccard系数)变化的关系,并进一步配置出不同引物数量、多态位点与Jaccard系数的变异系数曲线方程,通过分析回归曲线的相应切点,确定在一定精度下适合的引物数量及多态位点数。研究结果表明:不同引物数量之间的Jaccard系数的标准差、平均数、变异系数差异极显著。不同引物数量、不同多态位点与Jaccard系数的变异系数、标准差回归方程为Y=a+b/X形式,决定系数均在0.95以上。RAPD遗传信息分析精度控制在5%~10%时的最适样本容量为15~32条随机引物或120~230个多态性位点。     

样本正态分布对降低空间抽样数量的重要性

【研究目的】样本总体的分布特征是影响抽样样本数量的主要因素，对于样本总体为非正态分布的情况，正态转换是降低抽样样本数量、提高抽样调查效率的有效手段。【方法】该文采用中国大陆区域2005年耕地空间分布数据，以1:10万地形图图幅框作为抽样单元，统计每个图幅框内耕地面积占比。分别采样1.5次开方、2次开方、2.5次开方、3次开方和4次开方运算的方式对原始数据进行正态转换。在此基础上对比分析了转换前后数据的峰度及偏度、抽样个数及抽样结果误差等。【结果】结果表明，基于2.5次开方运算后的分层抽样可以大大降低抽样率，由92.26%降低为22.55%，耕地面积指数平均值相对误差由7.06%降低为5.66%。利用2015年耕地面积指数进行抽样方法的精度检验，抽样平均值相对误差仅为3.27%。【结论】研究提出的抽样方法具有较高的适用性，同时也表明空间抽样中数据分布正态转换是非常必要的。本研究成果为广大学者在空间抽样调查方面的研究提供了有益的借鉴。     

农作物三种基本抽样调查方法的比较

采用随机抽样法、顺序抽样法、典型抽样法时芝麻试验地出苗率进行调查，各用工时20h、6h、4h，其出苗率分别为53．8％、53．8％、71．3％。结果表明。典型抽样调查比随机抽样调查、顺序抽样调查出苗率高17．5个百分点，差异这极显著水平，工时分别为随机抽样调查、顺序抽样调查的20．0％．66．7％。其精度典型抽样法最高为81．0％。随机抽样法次之为67．5％，顺序抽样法最低为49．1％。对农作物抽样调查，当总体为正态分布时，适宜采用随机抽样；当总体中群体内差异明显、样拳容量较小时，可选用典型抽样；抽样单位在总体内较均匀分布时，则采用顺序抽样较为合适。     

基于玉米BC2F2群体的穗部性状QTL分析

以农系110为受体、农系531为供体材料,采用回交法构建了样本容量为95株的BC2F2回交群体,选取126个均匀分布在10条染色体上的多态性SSR标记进行6个穗部性状QTL分析.结果表明,受体农系110的穗长、穗粗、穗行数、行粒数、百粒重和穗粒重6个穗部性状表型值分别增加了9.4%,9.6%,4.1%,2.7%,0.35%和4.4%;构建一张含126个SSR标记的玉米分子标记连锁遗传图谱,总长度为2 317.4 cM,平均区间长18.4 cM;采用复合区间作图法,定位了19个与玉米穗部性状有关的QTL,其中穗长QTL 4个,穗粗QTL 2个,行粒数QTL 1个,穗行数QTL 3个,百粒重QTL 4个,穗粒重QTL 5个.     

玉米品种筛选试验

<正>1材料和方法1.1供试品种龙作1号、辽禾6号、东方红1号、九单100、大民3307、费玉3号、先玉335(对照)。1.2试验设计试验采用大区对比设计,不设重复。每个品种为6行区,行长为100m,每个处理面积为420m2。收获时每个处理区取3点,每点取5m2测产考种。1.3试验概况试验地设在沈家街道吉堡村。试验地地势平坦,肥力中等,土质为黑土,前茬为玉米,春旋整地。试验于4月     

珍稀植物细枝岩黄耆自适应群团抽样的比较研究

对于稀少、群团状总体的调查,自适应群团抽样（adaptive cluster sampling,简称ACS）被认为是一种有效的抽样方法。针对中国西部森林植被的集聚、稀少的分布特征,以乌兰布和沙漠边缘地区细枝岩黄耆株数密度为研究对象,进行6种抽样方法（简单放回随机抽样、简单不放回随机抽样、最初样本放回基于修正Hansen-Hurwitz估计量的ACS、最初样本不放回基于修正Hansen-Hurwitz估计量的ACS、最初样本放回基于修正Horvitz-Thompson估计量的ACS和最初样本不放回基于修正Horvitz-Thompson估计量的ACS）的重复抽样模拟试验,并对模拟试验的结果进行了比较和分析,指出最初样本不放回基于Horvitz-Thompson估计量的自适应群团抽样的效果最佳,其均值估计相对误差为0.037%,均值方差估计为0.03571。研究结果有助于提高稀少、群团状森林资源的清查的精度和效率。     

玉米籽粒蛋白质双向电泳技术体系的优化

为了获得玉米籽粒双向电泳中蛋白质提取的最佳方法,建立最佳的玉米籽粒蛋白双向电泳技术体系,对酚抽提法、三氯乙酸/丙酮沉淀法(TCA/丙酮沉淀法)和可溶性蛋白提取法3种不同提取方法得到的蛋白质进行了分析,并在相同条件下进行双向电泳比对分析,结果表明:可溶性蛋白提取法获得的蛋白纯度高、浓度适中、双向电泳蛋白质点最丰富,最适合双向电泳研究;利用可溶性蛋白提取法获得的蛋白,对第一向等电聚焦参数等条件,以及不同p H值范围的IPG预制凝胶条进行了比较分析,结果表明:采用p H值3~10的IPG预制凝胶条时,采取电压梯度上升的方式,总聚焦70 000 Vhs、上样量800μg效果最佳,采用p H值4~7的IPG预制凝胶条时,总聚焦80 000 Vhs、上样量900μg效果最佳,并且采用p H值4~7的IPG预制凝胶条相比p H值3~10的凝胶条能分离到更多的点,最后结合蛋白质点MALDI-TOF-TOF质谱鉴定分析,建立了一套适用于玉米籽粒的蛋白质双向电泳技术方法,即采用可溶性蛋白提取法提取蛋白,采用24 cm、p H值4~7的IPG干胶条,上样900μg电泳效果最佳,等点聚焦程序:500 V、1 h,1 000V、1 h,2 000 V、1 h,4 000 V、2 h,8000 V、4 h,8 000 V、80 000 Vhs,500 V保持。试验研究为后续玉米籽粒发育差异蛋白研究奠定了技术基础。     

对微贮秸杆在瘤胃中降解率的测定

试验采用了3个重复对比设计，将玉米、小麦和稻草秸杆用微贮样与原样放置在永久兼管牛体内，分别在6、12、24、36、48和72小时时间点取出样本进行降解率试验测定分析，结果表明：秸杆处理样在各个时间点的瞬间降解率和有效降解率均极显著优于原样，而玉米秸杆处理样极显著优于小麦和稻草处理样。     

极大似然法探测主基因的效能

采用Monte Carlo模拟数据和极大似然法探测F2群体主基因(MG). 研究了遗传力、显性比和样本容量三因素对探测F2群体MG的影响. 结果表明: 1) 在主基因的被发现率上, 三因素的影响力为: 遗传力>样本容量>显性比. 当遗传力较小时, 如0.3, 即使样本容量高达1000, 其发现能力也仅有51.63%; 当遗传力大于0.5时, 样本容量大于300, MG     

一个新的抗玉米矮花叶病基因的发现及初步定位

由SCMV引起的矮花叶病是我国的主要玉米病害之一, 鉴定和发掘新的抗病基因对于玉米抗病遗传育种具有重要意义。以抗病自交系海9-21和感病自交系掖478杂交的一个BC₂F₃群体为试验材料, 通过人工接种矮花叶病毒进行抗病性鉴定, 发现该分离群体中抗病植株与感病植株数符合1∶3的分离比例, 推测其抗病基因是由1对隐性基因控制。抗感池和SSR标记连锁分析表明, 存在一个新的玉米矮花叶病隐性抗病基因(或等位基因), 将该基因命名为scm3。scm3基因来源于抗病玉米自交系海9-21, 位于第3染色体短臂3.04~3.05区域, 在SSR标记umc1965和bnlg420之间, 遗传距离分别为45.7 cM和6.5 cM。连锁的标记还有umc1307、umc2265、bnlg2241和umc2166, 它们与scm3之间的遗传距离分别是8.3、13.3、15.5和19.7 cM, 这些SSR标记与scm3基因在染色体上的排列顺序为umc1965—scm3—bnlg420—umc1307—umc2265—bnlg2241—umc2166。     

Influence of sample size on precision of heritability and expected selection response in red clover

Limited attention has been given to the effect of sample size on the precision of heritability estimates and expected selection responses. The objectives of this study were to evaluate the effect of sample size on the point estimate, its sampling error and interval width. Monte Carlo simulation and non-parametric bootstrap were used to estimate parameters in a red clover (Trifolium pratense L.) data set. We conducted separate analyses for two and four replications, and for combinations of six, 12, 24, 42 and 66 families, each having three, six, nine, 12 and 18 plants. Results showed that the effect of increasing number of families and replications on reduction of sampling error and interval width was greater than that of increasing plants per family. The sampling error and interval width of parameters decreased at a decreasing rate as sample size increased. To reduce the chances of having negative estimates of family variance components and to achieve a narrow confidence interval, an experiment of 42 families, each having six seedlings in four replications would be required.     

Yield and yield components of wheat and maize in wheat–maize intercropping in the Netherlands

Intercropping is widely used by smallholder farmers in developing countries, and attracting attention in the context of ecological intensification of agriculture in developed countries. There is little experience with intercropping of food crops in Western Europe. Yields in intercrops depend on planting patterns of the mixed species in interaction with local growing conditions. Here we present data of two years field experimentation on yield and yield components of a wheat–maize intercrop system in different planting configurations in the Netherlands. Treatments included sole crops of wheat (SW) and maize (SM), a replacement intercrop consisting of strips of six wheat rows alternating with two maize rows (6:2WM), as well as subtractive or additive designs, based on skip-row (6:0WM, 0:2WM) and add-row (8:2WM, 6:3WM) configurations. The land equivalent ratio (LER) of intercrops varied from 1.18 to 1.30 in 2013 and from 0.97 to 1.08 in 2014. Wheat grown in the border rows of wheat strips had higher ear number per meter row, greater kernel number per ear, and greater yield per meter row than wheat in inner rows and sole wheat, indicating reduced competition. Wheat in the border rows in the intercrops had, however, reduced thousand kernel weight and harvest index, indicating that competition in border rows intensified over time. Intercropping negatively affected maize biomass and thousand kernel weight, especially in add-row treatments. This study indicates that there is a potential yield benefit for the wheat–maize intercropping system under Western European growing conditions. However, the LER was affected by yearly variation in weather conditions and significantly greater than one in only one of the two years of the study.     

The effect of varying the number of drills per plot and the amount of replication on the efficiency of potato yield trials

Summary The effect on yield trials of altering plot size was examined by investigating plots with varying numbers of drills (each with six tubers) planted. No evidence was found of the ware yield per drill being affected by different plot sizes nor any effect attributable to neighbouring drills, whether these were planted with another clone or left unplanted. Increasing the number of drills per plot did increase the precision of the estimated clone means as did, of course, increasing the number of replicates. It appeared, however, that increasing the number of replicates was a more efficient way to increase precision. Thus it was concluded that the most efficient utilization of limited planting space was to grow single drill plots with maximum replication.     

改良S1选择法对12个玉米群体改良效果的比较分析

为了对玉米群体进行合理有效的改良利用,通过改良S1选择法对12个玉米群体改良一轮后进行效果比较分析。结果表明,穗行数、行粒数和百粒重是构成产量的三因素,遗传增益最大的群体为蒙群2,其他依次为蒙群4、蒙群1等7个群体,蒙群3及3个国外引进群体遗传增益为负值;玉米群体在穗部、植株性状以及遗传变异中均存在一定的变化。试验研究得出,蒙群2、蒙群4、中综7号、蒙C群、蒙A群产量遗传增益均较大,并在其他农艺性状中改良效果显著,可直接选择优株自交进行选系,而其余7个群体遗传增益小,改良利用潜力不大。     

Soyabean-seed Yield Response in Row- and Hill-plots under a Recurrent Selection Programme

Several studies have indicated a possible link between genome size and earliness in maize. In this study, an original maize population, South African photo-period insensitive maize composite II (C₀) and several selected generations were analyzed for days to flowering, plant height, ear height, and yield. The selection criterion was earliness. Over six cycles of selection a 14-day decrease in days to flowering was obtained with no significant reduction in grain yield. In the initial population (C₀) and the most advanced selection (C₆) 101 plants were analyzed for nuclear DNA content. A significant decrease in the mean nuclear DNA content of the C₀ population (102 AU) was observed with respect to the C₀ population (105 AU). This reduction was the result of a decrease in frequency of plants in the C₆ population with large genome sizes. Therefore it was concluded that selection for earliness resulted in selection against plants with large genome sizes. Hence, the nucleotype of a maize plant can be modified by selection such as early flowering time.     

陕西省不同年代玉米品种产量和氮效率性状的变化

明确陕西省不同年代玉米产量和氮效率性状响应氮肥的变化趋势,对西北旱区玉米高产氮高效品种选育具有重要的实践意义。本文以1981—2010年间陕西省12个玉米主栽品种为材料,于2011年和2012年在典型旱区陕西长武进行3个氮水平(0、120和240 kg hm–2)的田间试验,分析了不同年代玉米品种农艺和氮效率性状变化趋势。结果显示,不同年代玉米品种籽粒产量随氮水平增加而提高,在施氮0、120和240 kg hm–2处理下籽粒产量增益分别为每年46、65和83 kg hm–2。所有氮水平下2000—2010年间品种产量和生物量显著高于1980—1989年间品种,而秸秆产量变化不明显;现代玉米品种(2000—2010年)产量的增加归因于穗粒数、千粒重和生物量的提高。不同年代玉米品种消光系数随氮水平增加而降低,说明现代玉米品种(2000—2010年)较老品种(1980—1989年)叶片直立,截获更多的光能,致使产量和生物量高。随着年代的递进,玉米品种氮肥农学利用率呈递增趋势,在低氮水平下现代品种氮肥利用效率最高,且显著高于老品种。氮肥农学利用率与氮吸收效率(NUpE)和花后氮素积累量呈显著相关(r=0.75;r=0.72),而与氮生理效率(NUtE)和花前氮素积累量相关性不显著(r=0.42;r=0.39)。说明现代玉米品种氮肥农学利用率提高主要来自氮肥吸收效率和花后氮素积累量的增加。上述结果表明,陕西玉米育种应注重穗粒数、千粒重、氮吸收效率性状和株型结构改良,低氮环境压力选择将有助于旱区玉米高产氮高效新品种培育。     

Effect of Okra Planting Density and Spatial Arrangement in Intercrop with Maize on the Growth and Yield of the Component Species

The effects of three okra planting densities (28 000; 56 000 and 111 000 plants ha¹) intercropped within or between maize rows were investigated in two field trials during the 1990 and 1991 wet seasons at Nsukka. The plant height and the leaf area index (LAI) increased as the planting density increased in sole or intercropped okra while the number of branches per plant decreased with increasing okra planting density. The height of maize plants also increased as okra planting density increased but the LAI decreased. Intercropping reduced the yield and yield components (number and weight of pods per plant) of okra and maize (number of cobs, cob length and 100-grain weight). Increasing okra planting density reduced the sole and the intercropped okra and also the maize intercrop yield by reducing the number of pods and grains as well as the pod and grain size, respectively. Assessment of the productivity ofthe mixtures showed that the highest yield advantage (35%) of growing okra and maize together was obtained at 28000 okra plants ha¹ while the highest monetary return was realized at the highest okra planting density of 111000 plants ha¹ intercropped between maize rows. The patterns of row arrangement did not have effect on the growth, yield and yield components of the mixtures.