RAPD analysis reveals a low rate of outcrossing in burr medic (Medicago polymorpha L.)

Although burr medic (Medicago polymorpha L.) is commonly considered a self-pollinating species, intrapopulational variation for morphological, biochemical and molecular markers is relatively high. To investigate whether part of this variation is the result of outcrossing, we designed RAPD analysis experiments to reveal both inter- and intra-accession crossing. No cases of inter-accession hybrids were documented, but an intra-accessional crossing rate of 0 to 4% was estimated for one of the four accessions studied. Therefore, a rare outcrossing event between local individuals and migrating genotypes may contribute to high genetic variability observed in natural M. polymorpha. A better understanding of the factors which influence outcrossing in M. polymorpha is pertinent both for medic breeding programmes and for assessing risks associated with releasing transgenic herbicide-resistant crops.     

高异交率、抗稻瘟病水稻三系不育系全丰A的选育与利用

全丰A 是福建省农业科学院水稻研究所以福伊B为母本、谷丰A的低世代保持系材料为父本进行杂交配组选育的保持系， 再与福伊A转育而成的野败籼型三系不育系。于2004年通过福建省科技成果鉴定， 2008年获得植物新品种权。多年研究结果表明， 全丰A表现配合力强、 异交率高、 抗稻瘟病、 适应性广等特点。目前已利用全丰A配制出10个杂交水稻组合通过22次新品种审（认）定。笔者概述了全丰A的选育过程、 特征特性及高产繁殖技术。     

高异交率偏粳型广亲和不育系春江19A的选育与利用(英文)

[目的]对高异交率偏粳型广亲和不育系春江19A的选育与利用研究。[方法]以春江16A为母本,用籼粳杂交后代材料B125作父本杂交,经连续多代回交转育,以筛选得到高异交率偏粳型广亲和不育系。[结果]春江19A为迟熟中粳不育系,育性稳定,不育株率和花粉败育率均为100%,程氏指数14,属偏粳型,花时早,部分柱头外露,异交结实率高,广亲和性好,条纹叶枯病抗性好,配合力好。利用春江19A所配制的杂交稻组合具有分蘖力强、杂种优势明显、条纹叶枯病抗性好、产量潜力大、后期转色好等特点。[结论]春江19A的转育成功,为选育制种产量高、杂种优势强的杂交粳稻和籼粳亚种间杂交稻组合奠定了良好的基础,具有良好的应用前景。     

小苍兰开花特性与繁育系统研究

综合运用杂交指数、花粉活力及柱头可授性、花粉/胚珠比、人工控制授粉试验等,对小苍兰的花部结构及繁育系统进行研究。结果表明：小苍兰雄蕊和雌蕊空间分离,花药紧贴花柱外侧,低于柱头约2 mm,在花朵开放的整个过程中雌、雄蕊的相对位置不变。小苍兰雌雄异熟现象明显,花药开裂时间与柱头可授期不同步,当花粉活力达到最高值时,柱头可授性还较低。小苍兰杂交指数（OCI）为 5,花粉/胚珠比（P/O）为1 614,人工授粉的坐果率高于自然传粉,由此判断其交配方式是以异交为主,自交为辅,繁育系统为兼性异交。     

水稻两用核不育系帮191S的特征特性及米质分析

为充分了解水稻两用核不育系帮191S的特征特性,在湖南农业大学对帮191S和对照株1S的部分农艺性状、异交特性、不育起点温度及稻米品质进行了研究。结果表明:帮191S的播始历期为64 d,主茎叶片为11.4叶,分蘖个数为17.4,着粒密度为6.6粒/cm,株高为61.55 cm;育性转换起点温度低于23.0℃,花时高峰时段为10∶00～13∶30,午前花率为59.1%,开颖角度为34.90°,开颖历期为162.40 min,包颈粒率为7.12%,柱头外露率为81.73%,异交结实率44.19%;整精米率为58.36%,长宽比为2.93,米胶长度达到124.50 mm。帮191S在农艺性状、开颖习性、异交结实率等方面较株1S具有一定的优势,对配制广适性的超高产杂交稻新组合和提高制种产量有利。     

水稻红莲型优质米不育系竹籼A的选育

介绍了红莲型优质米不育系竹籼Ａ的选育经过及其主要特征特性，并通过竹优６１等优质、高产、抗病组合的选配成功，讨论了优质杂交稻选育中优质与高产、优质与抗稻瘟病协调统一等问题。     

Variability Resulting from Selfing and Outcrossing in Phytophthora cactorum

Self and hybrid oospore progeny and zoospore progeny of two pairs of Phytophthora cactorum mutants carrying a metalaxyl-resistance (M^r) nuclear gene or a chloroneb resistance (Cn^r) mitochondrial gene were compared for variation in growth rate, production of sporangia and oospores, and pathogenicity. Zoospore progeny were relatively uniform, whereas oospore progeny resulting from both selfing and outcrossing displayed great dissimilarity in all the traits tested. For pathogenicity, both pairs of tested mutants had greater variation in hybrid progeny than self progeny. For growth rate and oospore production, the same is true only for the first pair, but not the second pair. The variation in sporangium production displayed by one parental self progeny was greater than that by hybrid progeny in both pairs tested. These results show that isolates and traits selected for study have considerable effect on the variation in hybrid and self progeny and suggest that different mechanisms may be operating in creating variation in these two types of progeny. Received 23 October 2000/ Accepted in revised form 11 January 2001     

侧金盏花的花部特征与繁育系统观察

侧金盏花(Adonis amurensis)是东北地区常见的一种早春类短命植物,也是一种观赏性状优秀的园林草本种质资源。本研究针对黑龙江省哈尔滨市帽儿山老山人工林试验站的野生侧金盏花,对其花部综合特征、开花动态、授粉特性进行了研究。结果表明,侧金盏花花期为3-4月,花型大,单花花期持续6~10 d,花部具有吸引传粉者的特征。侧金盏花雌蕊先熟,开花过程中花药与柱头无空间间隔,杂交指数结果为3,花粉胚珠比为2 280,结合套袋试验结果,判定侧金盏花繁育系统为兼性异交,自交可孕,需要传粉者进行传粉。     

马尾松无性系种子园结实初期异交水平分析

利用１９９３年和１９９４年测定数据,采用球果饱满种子百分率方法估算马尾松无性系种子园异交率。研究发现８￣９年生马尾松无性系种子园在结实初期自交率较高,异交水平较低。利用不同杂交组合估算的各亲本无性系在自由授粉情况下的异交率差异较大,两年中分别为４４．７％￣９８．１％和３０．８％￣９６．８％,平均为７３．５％（标准误差ＳＥ＝１７．３％）和６９．２％（标准误差ＳＥ＝２１．３％）。异交率在无性系间变异较     

Variation in outcrossing rate and genetic structure on six cultivars of Vicia faba L. as affected by geographic location and year

The present study was conducted to evaluate the importance of two environmental factors, year and geographic location, on the cultivar outcrossing rate and genetic structure of Vicia faba L. Under natural field conditions. Outcrossing rates were estimated for six cultivars using isozyme markers, the mixed mating model and the multilocus method. The genetic structure was described by Wright's fixation index and the inbreeding equilibrium coefficient. Faba bean outcrossing rate, as measured by multilocus estimates was relatively invariable among cultivars within locations. Our results suggest substantial variation in outcrossing rate associated with geographic location (Mediterranean subtropical and temperate climates enhancing the cross-pollination). Year variation was far less important than geographic variation.