Determination of visual detection thresholds of selected iron fortificants and formulation of iron-fortified pocket-type flat bread

Wheaten pocket-type flat breads were baked from refined flours fortified to contain iron from ferrous sulphate (FeSO₄), hydrogen-reduced elemental iron (Fe) or sodium iron ethylenediaminetetraacetic acid (NaFeEDTA). Individual and group visual detection thresholds were determined by the 3-alternative forced choice (3-AFC) test according to the American Society of Testing and Materials (ASTM) method E-1432. The group visual detection thresholds of FeSO₄, NaFeEDTA and Fe in bread were established in samples baked from the corresponding wheat flours fortified with 69.46, 236.82 and 304.97 mg iron/kg flour, respectively. Sensory testing showed that iron-fortified pocket-type flat breads were similar (P < 0.01) to regular bread when baked from flours formulated to contain iron at levels lower by 25% than the group visual detection thresholds of Fe and FeSO₄ and two 25% increments lower than the threshold of NaFeEDTA. These findings indicate that iron-fortified pocket-type flat breads, which are sensorially similar to regular bread, baked from flours that contained 52.1, 133.22 and 228.73 mg iron/kg flour as FeSO₄, NaFeEDTA and Fe, would provide the segment of the population at the highest risk of iron-deficiency anaemia, specifically women of childbearing age, with 91%, 207% and 346% of their recommended daily intakes for iron, respectively.     

水分胁迫下3个旱地小麦品种幼苗光合作用的比较研究

 水分胁迫下,抗旱品种云麦29、祥云爬地麦净光合速率高于干旱敏感品种科拜,其净光合速率差异达极显著水平(F测验P=0.01),云麦29、祥云爬地麦、科拜的临界水势值分别为-14.3,-13.3,-12.6(bar),随着水分胁迫加剧,各品种幼苗叶片明显地积累蔗糖,积累量的顺序是科拜>祥云爬地麦>云麦29。科拜与云麦29、祥云爬地麦蔗糖积累之差异达极显著水平,而云麦29、祥云爬地麦之间差异不显著,蔗糖积累与各品种抗旱性呈相反趋势,水分胁迫下,果糖、葡萄糖变化大致与各品种净光合速率相一致。     

小麦纹枯病(Phizoctonia cerealis)产量损失和防治指标的研究

田间试验结果指出,在山东文登市,种植感病品种济南13,肥力和密度水平越高,小麦纹枯病发病越重,所致产量损失越大。根据试验数据,导出了产量损失率与小麦纹枯病扬花期,灌浆期,乳熟期病指的多元回归方程,回归均达极显著水平(α=0.01)。根据纹枯病病指增长曲线和起身期与扬花期病指的相互关系,初步推算出,在一般气侯条件下,纹枯病防治指标为拨节期病指是2%,如预报4、5月份雨量大幅度多于常年,则防治指标还要降低。     

不同性质农田土壤中铜的可提取性与生物有效性及毒性

以重金属总量为基础的土壤环境质量标准已不适用于当前土壤管理的需求，基于重金属生物有效性的生态风险评估和环境阈值研究对土壤重金属环境质量标准的修订具有重要的意义。本研究选取4种化学提取剂（HNO3、EDTA-Na2、NH4OAc和CaCl2）对我国3种不同性质的模拟Cu污染农田土壤（黑土、潮褐土和脱潜水稻土）进行有效态Cu提取，通过敏感性生态物种生菜和赤子爱胜蚓的Cu暴露实验，推导基于化学提取有效态的土壤Cu生态毒性阈值。研究结果表明，HNO3（41.38%）和EDTA-Na2（56.81%）对3种土壤中Cu的平均提取效率显著高于NH4OAc（0.12%）和CaCl2（8.70%）。CaCl2提取态Cu含量与生菜Cu富集量和毒性效应之间存在显著或极显著相关， HNO3提取态Cu含量则能很好地指示蚯蚓Cu富集量和30 d死亡率。不同生态受体毒性终点对土壤可提取态Cu的敏感性存在差异，选用物种最敏感指标推导了3种土壤中Cu的有效态毒性阈值EC 20和EC 50。基于不同化学提取态Cu含量的生菜毒性阈值EC 20范围分别是90.45~170.10 mg/kg（HNO3），102.78~195.31 mg/kg（EDTA-Na2），3.97~20.06 mg/kg（NH4OAc），和0.21~8.68 mg/kg（CaCl2）；EC 50范围分别是110.48~187.60 mg/kg（HNO3），118.63~230.49 mg/kg（EDTA-Na2），5.69~32.23 mg/kg（NH4OAc）和0.26~9.62 mg/kg（CaCl2）。基于不同化学提取态Cu含量的赤子爱胜蚓死亡率毒性阈值EC 20范围分别是138.26~193.16 mg/kg（HNO3）， 107.80~225.88 mg/kg（EDTA-Na2）， 8.92~11.58 mg/kg（NH4OAc），和0.36~10.57 mg/kg（CaCl2）；EC 50范围分别是183.07~221.23 mg/kg（HNO3），180.38~331.09 mg/kg（EDTA-Na2），13.06~18.30 mg/kg（NH4OAc）和0.54~13.21 mg/kg（CaCl2）。研究结果可为我国农田土壤重金属有效态化学提取方法的比选与优化提供科学依据，同时对基于生物有效性的土壤重金属环境质量基准与标准的研究和制定具有重要意义。     

Landscape-level thresholds of habitat cover for woodland-dependent birds

Theory suggests that a disproportionate loss of species occurs when total habitat cover decreases to 10-30% of the landscape. To date, little empirical evidence has been collected to test for such thresholds in habitat cover, especially at the landscape scale. Here, we present empirical data on the species richness of woodland-dependent birds collected systematically from 24 landscapes (each 100 km²) that sample a gradient in habitat cover from <2% to 60%. To compare the relative effects of habitat cover and habitat configuration, landscapes with similar amounts of habitat but contrasting configuration (i.e., aggregated versus dispersed) were surveyed and the richness of woodland-dependent birds collated for each landscape. The relationship between species richness, habitat cover and habitat configuration was examined using analysis of co-variance (ANCOVA), multiple linear regression and univariate non-linear modelling. There was a significant effect of habitat cover (co-variate) in the ANCOVA, but the main treatment effect of configuration was not significant. However, comparison of non-linear models indicated that the shape of the response curve of species loss with decreasing habitat cover differed between aggregated and dispersed landscapes. Species richness was significantly related to habitat cover in all analyses, explaining between 55% and 60% of the variance in regression models. Mean patch shape complexity and the extent of habitat aggregation were also significant explanatory variables, but explained less than 10% of the variance in richness of woodland birds. Biogeographic variables (range in elevation and geographic location) explained up to 14% of the variance in species richness. There was strong evidence for a threshold response in species richness: non-linear models (broken-stick, exponential, inverse) exhibiting a sharp decline in species richness in landscapes with less than 10% habitat cover provided a better fit to the observed data than linear models. To our knowledge, this is the first empirical demonstration of landscape-level thresholds in species richness. We emphasise that thresholds in species richness denote multiple species’ extinction events, the end point of the process of species decline. For viable populations, habitat cover must be maintained well above the threshold level. Finally, thresholds of assemblage measures, such as species richness, potentially mask compositional changes in the avifauna community and may also conceal the loss of species with greater sensitivity to landscape change.     

Modelling start of oak pollen season in different climatic zones in Spain

Quercus pollen and meteorological data for several years from eight sites in Spain have been statistically analysed to select the threshold temperature and calculate the mean heat accumulation for predicting the Quercus pollination start in different climatic areas. The growing degree days method, which assumes the daily temperature varies as a sine wave, was used for heat accumulation calculations. Threshold temperatures between 4 and 12 °C were chosen using linear regression equations forced through the origin and their root mean square error (RMSE) of predicted against the observed dates for each observation site. Above the threshold, the average growing degree days (up to 1999) for the studied years was taken as the predictor value. Results showed a relationship between the selected threshold and elevation and a stronger and statistically significant correlation between threshold and yearly mean temperature, for each site. Regression analysis indicated that the selected threshold and the calculated heat accumulation were optimum for most of the localities. The validity of the results was tested using the meteorological data for the year 2000 as independent variable and this confirmed that there were only a few days difference between the predicted and observed day of the first pollen release for most of the studied localities.     

基于图像阈值的年轮识别方法

本文主要讲述了年轮识别在林业信息化中的作用和阈值法的依据与阈值法的原理，以及用阈值法处理年轮图像和采用其他方法处理的结果的不同，从而得出用阈值法进行处理的优点。     

基于图像阈值的年轮识别方法

本文主要讲述了年轮识别在林业信息化中的作用和阈值法的依据与闻值法的原理,以及用阈值法处理年轮图像和采用其他方法处理的结果的不同,从而得出用阈值法进行处理的优点.     

Genetic selection for increased mean and reduced variance of twinning rate in Belclare ewes

It is sometimes possible to breed for more uniform individuals by selecting animals with a greater tendency to be less variable, that is, those with a smaller environmental variance. This approach has been applied to reproduction traits in various animal species. We have evaluated fecundity in the Irish Belclare sheep breed by analyses of flocks with differing average litter size (number of lambs per ewe per year, NLB) and have estimated the genetic variance in environmental variance of lambing traits using double hierarchical generalized linear models (DHGLM). The data set comprised of 9470 litter size records from 4407 ewes collected in 56 flocks. The percentage of pedigreed lambing ewes with singles, twins and triplets was 30, 54 and 14%, respectively, in 2013 and has been relatively constant for the last 15 years. The variance of NLB increases with the mean in this data; the correlation of mean and standard deviation across sires is 0.50. The breeding goal is to increase the mean NLB without unduly increasing the incidence of triplets and higher litter sizes. The heritability estimates for lambing traits were NLB, 0.09; triplet occurrence (TRI) 0.07; and twin occurrence (TWN), 0.02. The highest and lowest twinning flocks differed by 23% (75% versus 52%) in the proportion of ewes lambing twins. Fitting bivariate sire models to NLB and the residual from the NLB model using a double hierarchical generalized linear model (DHGLM) model found a strong genetic correlation (0.88 ± 0.07) between the sire effect for the magnitude of the residual (V_E) and sire effects for NLB, confirming the general observation that increased average litter size is associated with increased variability in litter size. We propose a threshold model that may help breeders with low litter size increase the percentage of twin bearers without unduly increasing the percentage of ewes bearing triplets in Belclare sheep.     

温度及低温贮存天数对丽蚜小蜂成虫羽化率的影响

[目的]探究温度及低温贮存天数对丽蚜小蜂(Encarsia formosa Gahan)成虫羽化率的影响,为贮存和指导田间适期释放丽蚜小蜂提供理论依据。[方法]研究不同温度[(10.0±0.5)、(15.0±0.5)、(25.0±0.5)、(30.0±0.5)℃]对被丽蚜小蜂寄生的烟粉虱(Bemisiatabaci Gennadius)褐蛹成虫羽化率的影响;测定丽蚜小蜂褐蛹在(10.0±0.5)℃下低温贮存10、15、20、25、30 d后分别放入(25.0±0.5)、(30.0±0.5)℃恒温培养箱后的成虫羽化率。[结果]在设定的温度范围内,随着温度的升高,羽化率和羽化速率相应提高,在(10.0±0.5)℃下10 d羽化率仅为15.3%,而在(30.0±0.5)℃下7 d羽化率即达92.5%;低温贮存20 d后,在(25.0±0.5)℃和(30.0±0.5)℃下羽化率可分别达92.9%(11 d)和90.9%(7 d),而贮存25 d后羽化率只有31.2%和41.8%(11 d)。[结论]温室温度应在20℃以上时放蜂,且放蜂时应增加10%放蜂量;丽蚜小蜂褐蛹低温贮存时间最长为20 d。