冷冻方法和冷冻保护液对山羊卵母细胞发育的影响

比较了不同冷冻方法和冷冻保护液对山羊卵母细胞冷冻-解冻后体外受精和激活后的发育效果.结果表明,开放式拉长塑料细管(OPS)法的效果好于玻璃化细管法和常规冷冻法;在OPS法中,20%EG 20%DMSO对卵母细胞的冷冻保护效果好于EDFS40,而在玻璃化细管法冷冻中,则是EDFS40好于20%EG 20%DMSO.对于常规冷冻法而言,则是1.5mol/L EG的冷冻效果好于1.5mol/L PROH.     

Effects of deficit irrigation strategies on cluster microclimate for improving fruit composition of Moscatel field-grown grapevines

The grapevine plays a very important role in the economic, social and cultural sectors of many regions; however vineyards are often grown in regions under stressful conditions and thus they are vulnerable to climate change. The objective of this research was to investigate the effect of partial root-zone drying (PRD) irrigation on vine water relations, vegetative growth, plant microclimate, berry composition and yield components, compared to conventional deficit irrigation (DI, 50% ETc), full irrigation (FI, 100% of ETc) and non-irrigated vines (NI). The study was undertaken in mature ‘Moscatel’ grapevines (Vitis vinifera L.) grown in Pegões, South of Portugal. Compared to the other irrigated treatments, PRD vines showed a better microclimate at the cluster zone with higher incident photosynthetic photon flux density (PPFD). Within the more open canopies of NI and PRD treatments, berry temperatures were higher than those of denser ones (DI and FI). Compared to the conventional irrigation technique the better microclimate observed in PRD vines was a consequence of a reduction in vine growth, where lower values of leaf layer number, leaf area, canopy wideness, water shoots and shoot weight were observed. In PRD vines we observed a tendency to a development of a deeper root system, while DI and FI showed a more homogeneous root distribution throughout the different soil layers. PRD showed an improvement in berry quality with higher values of flavour precursors, and total phenols concentration without any significant yield reduction compared to DI and FI.     

河龙水库溢洪道闸门冬季防冰冻措施的实施

阐述水库溢洪道闸门防冰冻的设备结构、安装和运行维护防法。延边河龙水库地处吉林省东部严寒地区,水库溢流坝闸门的冬季防冰冻措施尤为重要,该水库采用潜水泵直接射流方式,防止闸前冰冻,取得很好的效果。     

变量筛选方法对郁闭度遥感估测模型的影响比较

比较基于偏最小二乘回归的Bootstrap方法与传统的平均残差平方和(RMSq)准则所选变量建立模型的精度差别.结果表明:Bootstrap方法是一种更优秀的变量筛选方法,比RMSq方法精度提高约5%;而且它不受变量多带来的运算困难的限制,更便于实际应用.     

Effect of Freezing Snow Disaster on Forest Fuel and Fire Behavior in Southern China

After freezing snow disaster,stands of Pinus massoniana,Cunninghamia lanceolata. Liquidambar formosana,Cinnamomum camphora and Phyllostachys pubescens and new burned areas in Hunan Province were surveyed by setting field plots.Moisture content and fuel load were measured by sampling and fire behavior(such as rate of fire spread) was calculated.The results showed that fuel load got doubled instantly,fuel thickness enhanced,fuel continuity swelled and water content of fuel decreased as shrubs and herbs die...     

Photosynthetic Apparatus Responses to Short‐term low‐temperature Flooding May Contribute to Freezing Tolerance Changes in Forage Grasses

Winter conditions are subjected to rapid climate changes. Increased precipitation and snow melting during warmer winters may result in low‐temperature flooding. These factors probably affect plant overwintering strategies. This study investigated the relationships between the photosynthetic adjustment and freezing tolerance following a short‐term low‐temperature flooding in two forage grasses (Lolium perenne and Festuca pratensis). The effect of flooding on the photosynthetic apparatus acclimation to cold was determined using chlorophyll a fluorescence measurements. Freezing tolerance was estimated using an electrolyte leakage test. It has been shown that genotypes activating non‐photochemical mechanisms of photosynthetic acclimation to cold during low‐temperature flooding may show increased freezing tolerance. Freezing tolerance reduction observed in Festuca pratensis was probably connected with decreased photochemical activity and photoinhibition of photosynthesis. It can be concluded that photosynthetic apparatus response to low‐temperature flooding may contribute to changes in the freezing tolerance. The direction of the changes is associated with different photosynthetic apparatus performance.     

基于枝条、叶和花的油梨种质表型多样性分析

【目的】明确当前粤西已收集油梨种质资源的表型多样性，加强油梨种质资源的利用。【方法】以保存于国家热带果树种质资源圃的 53 份油梨种质资源为试验材料，采用偏相关分析、主成分分析和聚类分析等方法，对油梨的 7 个质量性状（叶形、叶缘、叶尖形状、叶片颜色、叶面状态、花型、叶柄凹槽）和 12 个数量性状（枝条粗度、节间长度、叶长、叶宽、叶形指数、叶柄长度、花序侧轴长度、花序宽度、花序主轴长度、花梗长度、花瓣长度、萼片长度）进行调查分析。【结果】已收集油梨种质资源表型性状多样性丰富，质量性状与数量性状的多样性指数范围分别在 0.094~1.228 和 1.373~1.921 之间，表明油梨数量性状相对质量性状多样性更丰富。19 个油梨表型性状间呈极显著相关的有 29 对，呈显著相关的 21 对。主成分分析表明，6 个主成分因子的累计贡献率达 72.396%，其中叶柄长度、枝条粗度、花瓣长度、花序侧轴长度、叶缘和叶面状态为主要性状。聚类分析显示，当欧氏距离为 15 时，可将 53 份油梨种质资源分为 4 大组群，组群Ⅰ花序较小，组群Ⅱ枝条粗度最粗，组群Ⅲ叶宽最窄，组群Ⅳ花序侧轴长度最长。【结论】粤西已收集保存的 53 份油梨资源的表型多样性丰富，调查的 19 个表型性状间有一定的相关性，其中叶柄长度、枝条粗度、花瓣长度、花序侧轴长度、叶缘和叶面状态可作为油梨资源评价及育种的主要指标。     

How much variation can be explained by seasonal,spatial and environmental effects in nekton assemblages of the Terminos Lagoon?

• 1. The coastline is very sensitive to both climatic and human influences but also provides essential goods and services upon which human welfare depends. Species inhabiting these coastal areas provide valuable resources and enhance ecosystem functioning: it is therefore essential to understand the main factors influencing species abundance patterns. The aim of this study is to estimate the amount of variation in nekton coastal assemblages explained by spatial, temporal and environmental variables.
• 2. Nekton sampling was carried out over 17 months in the Terminos Lagoon, a reserve area situated in the Gulf of Mexico, using a shrimp trawl. At each station, 11 environmental variables were recorded. The influence of seasonal, spatial and environmental variables on nekton species abundance was analysed using Partial Canonical Correspondence Analysis (PCCA).
• 3. The explanatory variables explained only 19.7% of the total observed variation in the nekton community for the Terminos Lagoon. The major part of the explained variation was due to the spatial effect (9.2%), while environmental variables and seasonality explained only 3.6% and 0.8%, respectively, suggesting the necessity to consider experimental fishing design in such artisanal fisheries.
• 4. Results also suggest focusing on more integrative indicators of community structure such as measures of taxonomic diversity based on presence/absence or on measures related to functional attributes of communities rather than using species abundance patterns to predict changes in coastal ecosystems.

Copyright © 2007 John Wiley & Sons, Ltd.     

湖北省近200年大冻年表的建立及频率特征的初步分析

本文根据历史文献灾情记载以及近代气象资料,按照一定标准,建立了湖北省过去204年(1805～2008年)大冻年表,并依据大冻年表分析了大冻的年代际变化、周期性及其与太阳黑子变化和拉马德雷现象的关系.结果表明:1)过去204年共发生大冻33次,平均每10年发生1.62次(约6.2年一遇);2)在冷期平均每10年出现2次大冻,而在暖期平均每10年出现1次大冻;3)20世纪70年代以前,大冻年存在准80、24、10、4～6年周期震荡,此后24、10年周期快速衰减,4～6年周期依然存在;4)近100年,在拉马德雷冷位相时期,大冻年平均每10年出现2.3次,重现期为4.3年;暖位相时期,大冻年平均每10年出现1.3次左右.重现期为7.5年左右;5)近200年的大冻年并不都出现在太阳黑子的峰值或谷值年,不过最近100年太阳黑子谷值年大冻出现频率增加.     

不同成熟度沾化冬枣冰点测定及适宜贮藏温度的研究

贮藏温度是影响沾化冬枣贮藏寿命的关键因素,对白熟果、初红果、半红果和全红果4种成熟度冬枣冰点的温度进行了测定,分别为-2．1℃、-3．1℃、-3．9℃和-4．0℃。在此基础上确定了不同成熟度冬枣的适宜贮藏温度,为沾化冬枣贮藏提供了理论和技术依据。