水稻品种茎集散度分析及评价记载标准探讨

对578份广东省育成品种(系)和470份台湾品种(系)的茎集散度进行了分析,广东育成品种的茎集散度分布为3°～23°,96.37%集中分布在5°～17°;台湾品种茎集散度分布为3°～17°,97.02%集中分布在4°～12°.广东育成的代表性品种茎集散度为7°～16°.提出水稻理想株型最适茎集散度的计算公式:α=arcsin D/2H.建议籼稻栽培稻茎集散度的评价记载标准分为集、中、散3个等级:茎集散度≤5°为集;茎集散度6°～15°为中;茎集散度＞15°为散.     

小麦目标产量设计及适宜品种选择的动态知识模型

运用知识工程和系统建模方法,在综合考虑决策点光温生产潜力、历史平均产量水平、土壤肥力、肥水管理水平和生产技术水平等诸多因子对增产系数影响的基础上,通过定量计算动态增产系数,建立了具有时空适应性的小麦目标产量设计知识模型;通过定量计算小麦品种特征值与环境因子和生产需求之间的符合度,建立了适宜品种选择的量化知识模型．利用南京、郑州、泰安、保定和太原5个不同生态点的不同年型每日气象资料以及不同历史平均产量水平、土壤肥力和肥水管理水平,对目标产量设计模型进行了实例分析;利用广州、南京、泰安、北京、哈尔滨5个不同生态点常年气象资料以及15个不同品种资料,对品种选择知识模型进行了实例分析．结果表明,所建知识模型具有较好的决策性和广泛适应性．     

我国1950s～1990s推广的玉米品种叶片光合特性演进规律研究

自1950s以来,我国玉米（Zea mays L.）产量以年递增幅度为126kg     

红鲫近交系的建立

目的应用人工雌核发育繁殖技术建立红鲫近交系.方法红鲫卵子被经紫外线照射的鲤鱼精子激活后,在0～4℃的温度下进行冷休克处理30min,再在常温下静水孵化;以红体色为遗传标记,在连续2代雌核发育子代中选择二倍体红鲫,放置水泥池中常规饲养;用同样的人工雌核发育繁殖技术进行保种,随机交配繁殖1～2代供应实验;用常规方法测量形态学指标.结果红鲫卵子激活率在91%以上;实验组2中摄食期仔鱼成活率为15.20%,80%的成鱼为二倍体红鲫,其中有较高比例的遗传上真实的雄性个体.鳞式主要为27(5)/(6)28;鳍式主要为D.i,17～18;A.i,6;V.i,7～8;P.i,15～16;C.24～25;其他外部形态指标与封闭群红鲫近似.结论本实验建立的人工雌核发育繁殖技术,设备要求简单,操作安全可靠,并且省时节资,完全能够用于培育鱼类近交系,本实验结果完全可以满足育种繁殖的要求;所获得的二倍体红鲫,经同工酶电泳等检测,被证实是纯合的,具备鱼类近交系品系特征;出现遗传上真实的雄性个体是正常的.     

Distribution and accumulation of PVM and PVY,PVX in infected potato plants

The ability of PVM, PVY and PVX viruses and their progeny to distribute themselves and accumulate in primary infected potato plants by mono‐ and mixed infections is analysed. It is shown, that the transport and accumulation of virus in inoculated potato plants depends on variety resistance, combination of viruses and sequence of their application.     

High levels of arbuscular mycorrhizal fungus colonization on Medicago truncatula reduces plant suitability as a host for pea aphids (Acyrthosiphon pisum)

This study sheds light on a poorly understood area in insect-plant-microbe interactions,focusing on aphid probing and feeding behavior on plants with varying levels of arbuscular mycorrhizal(AM)fungus root colonization.It investigates a commonly occurring interaction of three species:pea aphid Acyrthosiphon pisum,barrel medic Medicago truncatula,and the AM fungus Rhizophagus irregularis,examining whether aphid-feeding behavior changes when insects feed on plants at different levels of AM fungus colonization(42% and 84% root length colonized).Aphid probing and feeding behavior was monitored throughout 8 h of recording using the electrical penetration graph(EPG)technique,also,foliar nutrient content and plant growth were measured.Summarizing,aphids took longer to reach their 1st sustained phloem ingestion on the 84% AM plants than on the 42% AM plants or on controls.Less aphids showed phloem ingestion on the 84% AM plants relative to the 42% AM plants.Shoots of the 84% AM plants had higher percent carbon(43.7%)relative to controls(40.5%),and the 84% AM plants had reduced percent nitrogen(5.3%)relative to the 42% AM plants(6%).In conclusion,EPG and foliar nutrient data support the hypothesis that modifications in plant anatomy(e.g.,thicker leaves),and poor food quality(reduced nitrogen)in the 84% AM plants contribute to reduced aphid success in locating phloem and ultimately to differences in phloem sap ingestion.This work suggests that M.truncatula plants benefit from AM symbiosis not only because of increased nutrient uptake but also because of reduced susceptibility to aphids.     

A nexus of intrinsic dynamics underlies translocase priming

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Subset Selection Procedures for Randomized Designs

Starting from the principle that there exists a randomization procedure that assigns treatments to experimental units, four subset selection rules for the problem of selecting the best treatment from a set of different treatments are proposed. Two of these are extensions of already existing subset selection procedures, which were defined for unbalanced designs, and need a separate selection constant for each individual treatment. The other two rules proposed are new and need only one selection constant for all treatments. The various procedures are compared, and illustrated by application to a plant breeding variety trial.     

Searching for pharmacophoric patterns in databases of three-dimensional chemical structures

This paper provides an overview of the research that has been carried out in Sheffield over the last decade into searching techniques for databases of three-dimensional (3D) chemical structures. A 3D structure or query pattern is represented by a labelled graph, in which the nodes and the edges of the graph are used to represent atoms and the associated inter-atomic distances, respectively. The presence of a pharmacophore in each of the structures in a database can then be tested by means of a subgraph isomorphism algorithm, the computational requirements of which are minimized by the use of an initial screening procedure that eliminates the majority of the structures from the subgraph-isomorphism search. Analogous graph-based representation and searching methods can also be used with flexible 3D structures: in this case, the edges of the graphs represent inter-atomic distance ranges and a final conformational search needs to be carried out for those molecules that match the query pharmacophore in the subgraph-isomorphism search. The paper also reviews related work on the automatic identification of pharmacophoric patterns and on 3D similarity searching.