Pollination of chasmogamous flowers and the effects of light and emergence time on chasmogamy and cleistogamy in Monochoria vaginalis

Monochoria vaginalis is one of the most serious weeds of rice fields in Asia. The species has both chasmogamous (CH) and cleistogamous (CL) flowers on individual plants. The objective of this study is to clarify the reproductive characteristics that affect the selfing rate of M. vaginalis. An emasculation experiment revealed that the CH flowers emasculated just after flower opening produced seeds. The seed production in the flowers emasculated just after flower opening was less than that of the flowers emasculated and hand‐pollinated with pollen from another plant. These results indicate that, although self‐pollination before anthesis occurs, cross‐pollination also can produce seeds. An experimental manipulation of light and the emergence time of the plants revealed that more than half of the flowers produced were CL flowers and the CH/CL ratio decreased with reduced light availability. The plants that emerged later produced as many CH flowers as those that emerged earlier. There was no significant difference between the CH and CL flowers in the seed number per fruit and the seed mass. These results suggest that M. vaginalis has reproductive characteristics that make the selfing rate high; however, outcrossing also can occur. Under favorable light intensity conditions, such as on the edges of paddy fields or in fallow fields, M. vaginalis will produce more CH flowers and will have a higher outcrossing rate than in shaded conditions.     

Persistence of naturally occurring and genetically modified Choristoneura fumiferana nucleopolyhedroviruses in outdoor aquatic microcosms

BACKGROUND: To assess the persistence of genetically modified and naturally occurring baculoviruses in an aquatic environment, replicate (three) outdoor, aquatic microcosms were spiked with spruce budworm viruses [Ireland strain of Choristoneura fumiferana multiple nucleopolyhedrovirus (CfMNPV) and the recombinant CfMNPVegt(-)/lacZ(+)] at a rate of 1.86 x 10(10) occlusion bodies (OBs) m(-2) of surface area. The presence of virus in water samples collected at various times after inoculation was determined by PCR amplification of baculoviral DNA extracted from OBs.RESULTS: Although UV radiation rapidly degrades baculoviruses under natural conditions, both viruses persisted above the level of detection (>100 OBs 450 microL(-1) of natural pond water) for at least 1 year post-inoculation, with little difference between the viruses in their patterns of persistence.CONCLUSION: The present microcosm study suggests that occlusion bodies of baculoviruses can persist in the flocculent layer of natural ponds. On disturbance, OBs could re-enter the main water column and thus be available for transport to new locations. Implications for environmental risk assessment are discussed. (c) 2008 Her Majesty the Queen in Right of Canada. Canadian Forestry Service. Published by John Wiley & Ltd.     

基于DEA模型的中国水产上市公司经营绩效评价研究

为了提高水产上市公司经营绩效和盈利状况。本研究运用数据包络分析(DEA)中的CCR模型和BCC模型对水产行业15家上市公司的技术、纯技术、规模效率进行了分析。结果表明：水产行业15家上市公司的综合效率值偏低,纯技术效率值较高,规模效率值偏低。并根据以上评价结果,结合水产行业现状,提出了培养龙头企业、使渔业增长方式由粗放式向集约式转变和优化产品结构等政策建议。     

世界主要渔业国家水产品生产与贸易特征分析

渔业不仅为人类提供大量优质动物蛋白,同时还关乎世界数亿人口的收入和生计问题。借助FAO统计数据,对2000～2009年世界主要渔业国家水产品生产发展趋势进行了分析,得出以下结论:(1)总体而言,全球水产品产量呈现增长率下降、年均增长量上升、产量与贸易结构稳定的态势;(2)在水产品产量位居前15位的国家中,一半以上国家的产量仍呈现增长趋势,其中产量居前六位的国家约占世界水产品总量的比重超过50%;(3)从不同结构来看,海洋捕捞水生动物产量呈现下降趋势,而养殖产量则呈现上升趋势,按照水产品进出口数量与价值的对应关系,认为日本和德国属于进口均衡型国家,而中国、挪威和西班牙属于水产品出口均衡型国家。     

电站开发对哈巴河水生高等植物生物多样性的影响

2009年至2011年连续3年的7～8月累计调查数据分析表明,电站开发使得额尔齐斯河的一级支流———哈巴河部分河段由原来的天然河流型生态群落逐步演变为水库型生态群落,水生高等植物多样性和种类组成也随之发生改变：由河流型的挺水、湿生草本植物逐渐演替为水库型的沉水、沼生植物;植物最远分布区域Lmax也从33 m减少到了12 m。正在新建的电站A库区无水生高等植物,电站A坝下河段物种丰富度指数为0.57,已建成多年的电站C库区为0.42,电站C坝下河段为0.57,表明电站开发对物种丰富度指数的影响只是暂时的,其水生植物种类数量变动不明显。从β多样性指数来看,电站开发修建过程中多样性变化为100%,电站运行前后多样性变化高达87%,表明电站开发对水生高等植物β多样性指数的影响较为明显。     

舟山市初级水产品质量监测与评价

利用2010-2011年舟山市初级水产品质量监测结果,分析并评价了舟山市初级水产品质量安全状况。结果表明:舟山市初级水产品质量基本符合相关标准,食用安全。但仍存在海捕鱼中含有微量甲醛,焦亚硫酸钠在渔船上普遍使用,养殖贝类中铅、镉少量超标等问题。     

Aquatic macroinvertebrate biodiversity: patterns and surrogates in mountainous Spanish national parks

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