不同地区黄瓜霜霉病菌毒力的差异

为选择黄瓜抗性品种,对来自全国8个省市18个黄瓜霜霉病菌株的孢子囊长度和宽度进行研究,以期明确定黄瓜霜霉病在各地区间的差异。结果表明:18个黄瓜霜霉病菌株的孢子囊存在差异,来自同一城市的菌株间差异不显著,并从供试的10个黄瓜品种中筛选出7个对不同致病菌株反应型各异,抗病感病界限明显的品种,可初步作为黄瓜霜霉病菌生理小种分化的鉴别寄主,利用所筛选出的鉴别寄主将18个菌株分为12个致病性类型。     

Ozone sensitivity of Phaseolus vulgaris in relation to cultivar differences,growth stage and growing conditions

Exposure of Phaseolus vulgaris cv. Lit to ambient ozone caused a 14% pod yield reduction in 1994. This yield loss was assessed by comparing plants that were protected against ozone by treatment with EDU (ethylenediurea) with unprotected plants, both cultivated in pots with a continuous water supply. The plants had experienced an AOT40 of 8135 ppb.h during their growth. However, plant response to ozone depends on a large number of environmental and plant-specific conditions. Visible injury increased mainly after flowering and was much less severe on soil-grown bean cultivars (Lit, Stella and Groffy) not receiving additional water. Ozone fumigations in closed chambers before or after flowering proved that the growth stage during which the plants are exposed also plays a very important role with regard to injury development. Plants seem to be more susceptible during the generative growth stage and the relative cultivar sensitivity was related to the developmental stage during fumigation. However with regard to yield effects the timing of the ozone exposure seems to be less important.     

不同基因型糯玉米氮素吸收利用效率的研究Ⅰ.氮素吸收利用的基因型差异

为明确糯玉米的氮素吸收利用特性及为因种施肥和氮素高效利用提供依据,开展了同一氮素供应水平下31个糯玉米品种氮素吸收利用的基因型差异研究。结果表明,生产鲜穗、鲜子粒和成熟子粒糯玉米的氮素利用效率品种间变异范围分别为57.829~8.65、39.436~1.31和31.705~3.70 kg/kg。聚类分析指出,无论其收获产品是鲜穗、鲜子粒还是成熟子粒,均属于高产、氮素高效吸收利用的品种有6个,其百公斤鲜穗、鲜子粒及成熟子粒需氮量平均值分别为1.244、1.884和2.091 kg。通径分析表明,提高品种鲜穗和鲜子粒产量,改良吸氮总量起主导作用;提高成熟期子粒产量,改良吸氮总量和氮素利用效率并重。     

Genetic variation in desiccation tolerance of Dendrobaena octaedra cocoons originating from different climatic regions

The aim of this study was to examine genetic variation in desiccation tolerance in cocoons of the parthenogenetically reproducing earthworm Dendrobaena octaedra by comparing populations originating from different geographic regions (Denmark, Norway and Finland), representing large differences in precipitation and temperature. In one experiment, the tolerance of the three populations to increasing desiccation stress in the range from 100 to 91.6% relative humidity (RH) was examined, aiming to represent ecologically relevant RH values. In a second experiment, the effect of cocoon size on desiccation tolerance was investigated at 92.3% RH in the same three populations. There were highly significant differences in desiccation tolerance between populations, indicating a high genetic differentiation of this trait in D. octaedra. Cocoons from Denmark were much more sensitive (71±14% mortality at 91.6% RH) than cocoons from Norway (21±4% mortality) and Finland (4±5% mortality). Cocoons of worms from Finland and Norway were significantly larger than cocoons produced by worms from Denmark suggesting that cocoons from Denmark lost water at a higher rate when subjected to low humidity. Assuming that slow dehydration is necessary for physiologically based protection mechanisms it may be expected that desiccation tolerance is positively correlated with cocoon size. However, within each of the populations cocoon fresh weight did not have any significant impact on desiccation tolerance. When all populations were pooled there was a significant positive effect of cocoon fresh weight on desiccation tolerance, explaining about 20% of the total variation (linear regression). It seems therefore that genetic variation of desiccation tolerance in D. octaedra cocoons is related to variation in both cocoon size and other, physiologically based tolerance mechanisms.     

Improving minimum detectable differences in the assessment of soil organic matter change in short‐term field experiments

The demand for information on cropping system impact on soil organic matter (SOM) calls for efforts to improve the utilization of short‐term field experiments (e.g., to evaluate the parameterization of cropping systems in models). Those approaches have coped with the problem of determining small SOM changes within a large background mass. Thus, objectives of this survey are (1) the improvement of the minimum detectable difference (MDD) in SOM in the hudycrop short‐term field experiment by methods of sampling design and data treatment, (2) the verification to what extend the hudycrop short‐term field experiment allows for the determination of management induced effects on SOM, and (3) the investigation to what extent the obtained results may be suitable to evaluate the parameterization of a SOM balance model. The design of the hudycrop is suitable for excluding outliers plotwise. The estimation of plot means can be improved by the sampling design. Instead of determining a single plot mean in a mixed sampling procedure, the design provides multiple values for each plot, allowing for the identification of extreme values before calculating plot means. In consequence, minimum detectable differences decrease by a factor of 0.53 for soil organic C (SOC) and 0.63 for soil total N (STN) masses, allowing for detection of changes in the magnitude of 3.7 and 2.6% of background SOC and STN levels, respectively. Differences between treatments, however, are significant with corrected values (after outlier exclusion) for the crop production systems with the highest impact (potatoes and mulched red clover). Determining outliers based on Student's t‐test gives the lowest MDD and is therefore considered to be the most suitable method in this case. Correlations between apparent changes and SOM balances according to the HU‐MOD–2 model, used in this survey, indicate that the experimental design, in principal, is suitable for the evaluation of the parameterization of crop production systems in models. Still, an improved precision in SOM change detection is necessary. Reasonable options for that purpose are discussed in the paper.     

河北省征地补偿标准的时空差异及其相关影响因素

为河北省征地补偿标准的修订提供借鉴依据,利用 ArcGIS 对河北省2008年和2011年各县（市）平均征地补偿标准空间分布及时间变化进行研究,并通过 SPSS 进行相关分析找出影响征地补偿标准时空变化的主要影响因子。结果表明：河北省2008年全省平均征地补偿标准为3．59万元／667m2,各县（市）平均征地补偿标准为2～4万元／667m2;2011年全省平均征地补偿标准为4．40万元／667m2,比2008年提高23％,各县（市）平均征地补偿标准为3～5万元／667m2,各县（市）平均补偿标准增长幅度集中在15．00％～30．00％。农村居民人均纯收入、地区生产总值和人口密度是征地补偿标准最重要的影响因素,总人口、常用耕地面积和参加农村医疗保险人数也对征地补偿标准具有重要影响。     

我国粮食劳动生产率地区差异及分解研究——基于回归分解方法的实证

针对我国各粮食主产区间劳动生产率发展不均衡,阻碍粮食产业可持续发展,不利于保持粮食产量稳定增长的问题,利用13个粮食主产区省级面板数据,采用随机前沿生产函数模型测算粮食全要素生产率以及技术效率;在此基础上基于回归的分解方法对我国粮食劳动生产率地区差异进行分解,进一步对影响地区差异的各个因素及作用机制进行分析研究。实证分析结果表明:1)劳动力规模、劳均资本投入以及前沿技术水平对粮食劳动生产率地区差异呈正向影响,即这3种因素加剧了地区间劳动生产率的不平衡;2)技术效率水平、劳均土地、劳均用工以及粮食生产劳动力结构等因素则对地区间的劳动生产率差异有抑制作用,通过提高这些因素的投入水平能有效促进粮食产业的地区间均衡发展。     

居民收入水平影响因素及其城乡和区域差异

针对城乡间、区域间居民收入水平存在差异的问题,采用动态面板数据实证研究方法,对居民收入水平的影响因素及城乡和区域差异进行研究,结果表明:1)居民消费能有效促进城乡居民收入水平提高,居民消费性支出每提高1个百分点城市居民收入提高0.2个百分点,农村居民提高约0.1个百分点。2)总人口抚养比具有显著抑制作用,其每提高1个百分点东中部农村居民收入水平下降0.25个百分点,西部城市居民收入水平下降0.21个百分点。3)城乡收入差距对东中部地区农村居民收入水平的影响更为显著,每提高1个百分点,东中部地区农村居民收入水平下降0.5个百分点。城市化水平、经济增长、财政支出、居民消费、产业占比以及人口抚养比等因素显著影响居民收入水平,且影响存在明显的城乡和区域差异。     

我国沿海渔业碳生产率的区域差异及影响因素

针对提高渔业碳生产率的问题,测算1978—2011年我国沿海11个省市的渔业碳生产率,利用省际面板数据对其影响因素进行实证分析。结果表明:我国渔业碳生产率整体在逐年提高,但各省市间的渔业碳生产率水平差异较大。天津、江苏和山东的渔业碳生产率排名前3位,广西、海南和浙江排在最后;从海域视角看,呈现出由渤海、黄海和东海到南海渔业碳生产率逐渐降低的趋势。对我国沿海渔业碳生产率水平有显著正向影响效应的因素主要有渔业发展水平(0.023)、产业结构(0.438)、对外开放度(0.044)和技术进步(0.760)。从低碳渔业经济模范市、渔业科技进步和渔业外贸3个方面提出了提高我国沿海渔业碳生产率的政策建议。     

灯塔站迁站气象要素差异对比及影响因素分析

为了分析灯塔迁站对气象要素的影响,通过差值统计方法,选取新站与旧站2014年1月、4月、7月、10月4个月的观测资料,对灯塔国家一般站(54348站)的气温、相对湿度、气压、风速4个气象要素的观测资料进行差值对比分析。结果表明:新站月平均气温偏低0.6~0.9℃,气压偏低0.9~1.0 h Pa,相对湿度偏高3~6个百分点,风速偏大0.7~1.4 m/s;造成气象要素差异的主要原因为城市热岛效应。