Genetic interpretations of the effects of bulk breeding on four populations of beans (Phaseolus vulgaris L.)

Summary The effects of bulk breeding on yield and its components in two high-yeilding and two low-yielding bean populations when grown at crop densities are interpreted in terms of gene action and selection. There was considerable additive variation in the crosses, dominance effects were variable but tended to be negative. The results were compared with results obtained at low density by another worker with the same populations, and this showed that interpretations of gene action in hybrid vigour depend on the test environment used. The interpretations were also compared with plant breeding interpretations made on the same material (Hamblin, 1977), and it was found that a single pattern of response to natural selection, in plant breeding terms, may be explained by more than one genetic interpretation and, conversely, a single genetic interpretation may result in different patterns of response in plant breeding terms. The value of composite crosses in plant breeding are discussed and it is concluded that there is a greater chance of producing improved lines from a large number of simple crosses than from a smaller number of composite crosses.     

籼稻巨胚不育系龙特浦geA的选育

通过辐射诱变获得籼稻保持系龙特浦B巨胚隐性单基因突变体 (龙特浦geB) ,为龙特浦B的巨胚同型系 ,主要农艺性状无明显差异 ,但绝对胚重和相对胚重分别由原龙特浦B的 0 63mg和 2 78%提高到 1 1 5mg和 6 0 7% ,从而糙米粗脂肪含量由 2 50 %提高到 5 0 6% ,蛋白质由 9 0 0 %提高到 9 60 % ,各种氨基酸含量的相对值也相应提高 5 45%～ 3 0 3 6% ;用龙特浦geB回交龙特浦A育成巨胚不育系龙特浦geA ,其与龙特浦A的主要农艺性状、雄性育性特征及构成产量配合力无明显差异。     

矾根主要品种的叶色表型性状分析

通过目测进行分类的方式很难准确界定矾根品种叶色。为建立一套更为科学的基于叶色表型的矾根品种分类体系,笔者利用色差仪对72个矾根品种共计432个样品的叶色进行测定,对获得的L、a、b 3个色度值进行聚类分析,将72个矾根品种分为褐色系、深绿色系、黄色系、灰绿色系、浅绿色系5类色系。对矾根品种各色系的L、a、b值进行相关性分析,发现叶片正面的L值与a值、a值与b值呈负相关,L值与b值呈正相关,但相关性不明显;叶片背面的L值与a值、a值与b值呈负相关,L值与b值呈显著正相关。从多重比较的结果中可以看出,矾根品种各色系之间的L、a、b色度值差异显著,尤其是各色系间叶正面的颜色差异较大,在矾根品种选育工作中,叶片正面的颜色将作为主要参考。     

优质早熟超级稻品种龙粳18的选育

优异种质的收集、鉴定、利用是选育多优集成新品种的关键.采用有性杂交和系统育种技术路线培育的优质、抗病、耐冷超级稻新品种龙粳18,其主要品质指标达到国家一级优质粳米标准;两年区试平均产量8 168.8 kg·bm-2,比对照增产9.1%,其中最高点达到9 119.0 kg·hm-2,生试平均产量7 995.1 kg·hm-2,比对照增产10.7%;经省种子管理局指定单位鉴定,中抗稻瘟病;耐寒性较强.     

水稻籽粒镉积累KASP分子标记LCd-38的开发与利用

水稻(Oryza sativaL.)是我国主粮作物之一,稻米镉污染对我国粮食安全造成一定威胁.镉低积累水稻品种的选育可有效降低水稻籽粒镉污染风险,高效准确的镉积累相关分子标记在镉低积累水稻品种选育中具有至关重要的作用.以水稻微核心种质为材料,基于籽粒镉积累关联基因的功能性SNP位点开发了KASP分子标记LCd-38.选...     

Expression profiling of transgenes (Cry1Ac and Cry2A) in cotton genotypes under different genetic backgrounds

Transgenic cotton carrying the CrylAc gene has revolutionized insect pest control since its adoption,although the development of resistance in insect pests has reduced its efficacy.After 10 years of cultivating Bacillus thuringiensis(Bt) cotton with a single Cry1 Ac gene,growers are on the verge of adopting Bt cotton that carries the double gene(Cry1 Ac+Cry2 A) due to its better effectiveness against insect pests.Thus,the current study was designed to evaluate the role of each gene in the effect...     

航天紫花苜蓿中黄酮的提取及抑菌活性

用索氏回流法正交提取航天紫花苜蓿(Medicago sativa)中的黄酮(芦丁),以510 nm最大吸光度进行可见光谱检测,测定芦丁含量,并对两种供试菌进行体外抑菌活性测定。结果表明,通过单因素试验确定的各因素影响能力大小为超声提取时间料液比乙醇浓度,芦丁含量最高为10.04 mg·g-1;大肠埃希氏杆菌的最小抗菌浓度为0.40 mg·g-1,金黄色葡萄球菌的最小抗菌浓度为0.70 mg·g-1。     

Observations on calf scours in New Zealand

Extract

Scouring syndromes constitute a major disease group in dairy calves in New Zealand.     

Establishment of an in vitro method for evaluating whitefly resistance in tomato

An accurate and simple evaluation method is crucial for identifying whitefly resistance in tomato breeding. We developed an in vitro method for evaluating resistance of tomato leaves and tested this on wild and cultivated tomato varieties. We found that young leaves observed for whitefly oviposition after 8 hours provided appropriate comparative conditions. This method effectively distinguished resistance among tomato cultivars and wild species and also demonstrated significant difference in oviposition rates among leaf positions on susceptible cultivars. The in vitro test was as precise as in vivo test using intact plants and had advantages over in vivo test, and can be used for evaluating resistance in large populations.     

中蜂越夏及秋季繁殖试验

在贵州锦屏进行的中蜂越夏及秋繁试验表明，４框以上的群势越夏较为安全。越夏期间每框足蜂约需补喂白糖１．５公斤。越夏后，蜂群群势约下降１／３左右。蜂群在越夏期间飞逃的主要原因是缺蜜及巢虫危害。当地中蜂在秋季大流蜜初期发生分蜂，分蜂群势均为８框足蜂以上，７框左右不分群。为控制不同起繁群势的蜂群在秋季大流蜜初期正好繁殖到７框左右，不致因分蜂影响秋冬蜜的采集，应分期起步秋繁。根据本试验所建秋季起繁群势（ｘ）与达７框群势所需繁殖天数（ｙ）之间的回归直线方程推算，在起繁群势为１～５框蜂量时，最适的秋繁开始期，１框群为７月３１日，２框群８月１０日……蜂群的基础群势每增加一框，则秋繁开始期应相应推迟１０～１１天。