低芥酸油菜（Brassica napus L.）每角果粒数的基因效应研究

采用改良的 Hayman-Jinks 双列杂交方法,研究了5个低芥酸甘蓝型油菜品种每角果粒数的遗传。结果表明,参试的亲本品种中,81007控制每角果粒数的显性基因最多,其它依次为81018、81004、81006和81033。其中除了亲本81033隐性基因多于显性基因外,其余亲本都以显性基因占优势。按增效基因的多少排序,依次为81004>81007>81006>81018>81033。试验揭示了显性减效基因的存在,但显性基因主要为增效基因。供试的油菜群体中,每角果粒数的增效基因频率为0.7940,显性基因与隐性基因之比为2.0930.广义遗传力 h_B~2=47.81%,狭义遗传力 h_B~2=27.54%,符合加性显性模型,属于超显性遗传.根据研究结果,作者认为,低芥酸油菜每角果粒数的改良应重视在进一步积累增效基因的基础上培育优良自交系,进行杂种优势的利用。杂交后代的选择宜在较晚世代进行。本性状的改良可考虑采用相互轮回选择和单倍体育种等途径。     

Opaque-2玉米遗传表达特点的研究

选北京农业大学有代表性的O_2玉米自交系15个,作半完全双列杂交,考察包括农艺学及籽粒品质等性状共16个,用Griffing及Hayman模型分析,结果表明,15个基因型间差异达显著的性状,以显性效应为主的有10个,其中以穗重的产量σ_h/σ_G为最高;赖氨酸、籽粒硬度以加性效应为主,蛋白质含量二者均占重要地位。考虑到玉米籽粒2N+3N的遗传构成,蛋白质含量和好粒硬度的显性效应必须予以重视,对国内O_2玉米群体一般配合力选择较之特殊配合力选择在育种及亲本选配中占有更为重要的也应,对几个主要品质性状尤为如此,这是我国O_2玉米现状所决定的。文中同时给出了O_2玉米育种中亲本选配的若干原则。     

Screening for Fusarium resistance in seedling populations of Asiatic hybrid lily

A test to select Fusarium resistant seedlings of the Asiatic hybrid lily is described. Young seedlings of 28 populations, obtained from an incomplete diallel between eight parents with different levels of Fusarium resistance, were tested for resistance. Significant differences in Fusarium resistance between and within populations were detected. The average percentage of selected seedlings ranged from 34% in resistant × resistant crosses to 2% in susceptible × susceptible crosses. Although resistant descendants were obtained in susceptible × susceptible crosses, using at least one resistant parent produced higher percentages of resistant seedlings. The resistance level of the parents correlated highly with the general combining ability for Fusarium resistance based on the seedling test. For eight populations, seedlings selected for Fusarium resistance and non-tested (control) seedlings of the same cross were compared, after propagation, in a clonal test. Variation between and within populations, found at seedling level, was confirmed at clonal level. A positive selection response was found for all eight populations. In the seedling test, approximately 18% of the seedlings were selected as resistant of which 15% (2.7% of seedlings tested) appeared to be susceptible escapes. Comparison between selection at seedling level and at clonal level indicated that approximately 25% of the seedlings tested were missed (rejected resistant plants) in the seedling test. The practical use of a seedling test for Fusarium resistance in lily breeding programs is discussed.     

普通小麦八个品种对赤霉病抗扩展性的双列杂交分析

本文用8个对赤霉病不同抗性的普通小麦双列杂交的试验结果,分析了病小穗数的配合力、遗传力、性状相关及扩展速度等。小麦对赤霉病的抗性主要是由基因加性效应所决定的,非加性效应虽有一定的影响,但不显著。抗赤霉病性的遗传力较低,受环境的影响较大。病小穗数与有效小穗数和小穗密度的表现型和基因型呈正相关,与株高、穗长、无效小穗数和穗粒数呈微弱负相关,对赤霉病抗性与上述性状在遗传上似无明显的关系。高感品种福龙选的潜育期最长(9.2天),高抗品种望水白的最短(5.3天),其余的差异不大(6.2～6.9天)。高抗品种的赤霉病扩展速度较慢,高感品种的较快。     

江淮下游大豆亲本品种（系）双列杂交衍生世代农艺性状的遗传分析

本文研究江淮下游8个大豆品种(系)双列杂交F_2至F_4表现的亲本配合力;证实F_2与F_3间有产量配合力与世代互作;评选出7206—934、诱变30、493—1、1138—2等具优良一般或特殊配合力的亲本与组合。按Hayman方法推演了综合F_2至F_4三世代信息的多基因体系遗传分析;除每株粒数外,产量、百粒重、生育前期、株高等均有上位性作用;从加性、显性效应估计值及上位性度量的组成对优良亲本与组合作分析和解释;进而对亲本性状基因显性方向及分布作出估计。     

珍珠豆型花生产量和含油率遗传特性的双列分析

本文采用完全双列杂交对4×4杂种一代产量和含油率遗传特性进行研究,结果表明:单株果重和含油率两性状均受加性和显性遗传效应的控制,加性遗传效应较显性重要,此外,含油率可能还受上位性遗传效应的控制。单株果重和含油率的平均显性变为部分显性,亲本中控制两性状的隐性等位基因较显性基因多。高产呈显性,高油为隐性。控制果重和含油率的显性基因组数分别为3组和1组。含油率与产量和产量构成性状呈显著负相关,而与株高,侧枝长,总分枝数,有效分校数和主茎青叶数等农艺性状无关,表明试图通过容易辨认的农艺性状的间接选择来提高含油率是较困难的。     

弱光下黄瓜苗期几个生理指标的遗传分析

以6份黄瓜自交系为试材,采用完全双列杂交设计GriffingⅡ配制了21个组合。对正常温度(25℃/15℃)弱光条件下黄瓜苗期几个生理指标作了配合力、遗传力和遗传分析的研究,其中包括过氧化物酶(POD)、多酚氧化酶(PPO)两种酶的活性,丙二醛(MDA)含量,叶绿素a与b的比值(Chl a/Chl b)4个指标,得到表现较好的3个亲本和5个组合。结果表明,在正常温度弱光条件下这4个指标的狭义遗传力均很低。PPO活性、MDA含量和Chl a/Chl b值的遗传均不符合加性-显性模型。