黄瓜嫩果皮颜色的遗传研究

 以2 个嫩果皮颜色不同的黄瓜自交系为试验材料,通过目测分类、色彩色差仪测定果皮色L 值和C 值,并利用P₁、P₂、F₁、B₁、B₂ 和F₂ 等6 个世代联合分析方法,研究了黄瓜嫩果皮颜色的遗传规 律。结果表明：黄瓜嫩果皮颜色性状符合两对加性-显性-上位性主基因 + 加性-显性-上位性多基 因模型（E-0 模型）;L 值和C 值F2 代主基因遗传力分别为93.61%和80.86%,遗传力较高;多基因遗传 力和环境效应都较低,在育种时对黄瓜嫩果皮颜色的选择应在早期分离世代进行。     

A portable device to measure soil erosion/deposition in quarter‐drains

Assessment of soil loss/deposition from quarter‐drains (drainage ditches perpendicular to furrows) at specific locations or determining sediment transport within ditch systems following a rainfall event is difficult and time consuming. Automatic samplers are stationary and usually located at the end of plots to assess total sediment loss from a whole area. However, to quantify changes to cross‐sectional areas at specific points within a ditch system, a portable measuring tool is required. To precisely assess soil erosion along the length of a quarter‐drain, a portable device was designed and tested under typical field conditions. One person can effectively operate the device and because of its low cost, it is ideal for cases where budget constraints exist. The tool can measure depths up to 500 mm and easily be modified for usage with large ditches. The device was successfully employed in the spring and summer of 2003 and 2004 where it was utilized after rainfall events to assess soil erosion/deposition from quarter‐drains on sugarcane fields in southern Louisiana.     

自动电位滴定仪测定饲料及饲料添加剂中氟化物的探讨

本文比较了自动电位滴定仪与pH计测定饲料及饲料添加剂中氟化物,自动电位滴定仪用于测定饲料及饲料添加剂中的氟化物具有较高的精密度和较高的准确性。     

A Comparison of Methods Used to Determine Biomass on Naturalized Swards

An experiment was conducted in 2000 to compare simple visual estimate, sward height and rising plate meter (RPM) methods for determining forage biomass in mixed-species, naturalized, rotationally grazed dairy and beef pastures. Measurements were taken pre- and post-grazing on 10 sampling dates at the dairy pasture, and post-grazing at 13 sampling dates at the beef pasture. For each sampling date, the effectiveness of each method for estimating the actual biomass from a quadrat was evaluated using regression analysis. The results for the visual estimate method were not consistent, with non-linear relationships occurring early and late in the season. While the meter stick was most effective in the dairy pasture, the RPM was most effective in the beef pasture. Species composition and structural characteristics of the stand were important factors affecting accuracy of biomass estimation. Equations developed for each method and site using data from all dates had low R²-adjusted values, and were unreliable predictors of biomass. The results from individual sites and dates were extremely variable, with no single method effective in all circumstances. To estimate forage biomass in mixed-species, naturalized pastures, standard quadrat harvesting remains the most reliable method, provided that enough quadrats are clipped to adequately represent a given area.     

欧盟法和国标法对食品中苏丹红检测的比较

采用欧盟法和国标法对食品中苏丹红的含量进行了检测,并比较了两种方法的差异。结果表明,欧盟法灵敏度高,粉状样品回收率高,但成本较高;国标法油状样品回收率高,成本低,大部分机构可用此法,但氧化铝活性需要控制适当才不会影响检测结果。     

常用流量计及其使用选择

流量计量是专门研究物质质量变化的一门科学,在各行各业中应用非常广泛,对其进行深入了解和科学使用具有非常重要的现实意义。为此,介绍了工农业生产和科研中常用的各种流量计及其工作原理;分析了各种流量计的特点及其使用场合;并以中小流量计为例,分析了流量计的选择方法。     

在线含水监测系统在原油交接过程中的应用

介绍了在线含水监测系统的工作原理,在原油交接过程中,该系统可有效地控制和捕捉瞬间含水率的变化,解决了原油含水频繁变化带来的计量误差,减少了输差损失,确保了原油交接计量的准确性。     

浅析自动抄水表系统

自动抄水表系统是利用当代微机技术,数字通讯技术与水表计量技术完满结合,集计量、数据采集、处理于一体,将城市居民用水信息加以综合处理的系统.     

玉米水平圆盘精密排种器排种性能试验研究

为了改善玉米水平圆盘精密排种器的排种性能，找出影响其排种性能的关键因素，按照GB6973-86《单粒(精密)播种机试验方法》中排种性能指标的计算方法，应用Lab Windows CVI软件编制的排种性能指标统计计算程序，计算各性能指标值；在自制的排种器试验台和多功能性能检测装置上，通过改变排种动盘不同的结构参数、转速、推刮种器型式和品种等因素，对其排种性能进行了对比试验。试验得出选择型孔数量为28、型孔型式为开槽小倒角和推刮种器选择滚珠式、转速取17 r/min，农大108选取动盘厚度为6 mm时，对应的合格指数A、重播指数D和漏播指数M分别为90.71、8.58和0.71，而唐玉十号选取动盘厚度为5 mm时，对应的合格指数A、重播指数D和漏播指数M分别为91.52、6.56和1.92，各性能指标均达到国标精密播种的要求。排种性能试验结果表明，提高水平圆盘精密排种器性能的途径和措施是保证动盘厚度、型孔型式、型孔数量和种子几何尺寸的合理匹配，且选择滚珠式推刮种器，能够达到高的性能指标。     

The influence of clipping frequency on reserve carbohydrates and regrowth of Eragrostis curvula

Increasing the frequency of clipping over a 12 week period resulted in decreasing root and stubble weight at the end of the 12 week period. During the regrowth period, following the clipping treatment, the aerial dry matter production was found to increase with the more lenient treatments.

The pattern of depletion and restoration of Total Available Carbohydrates (TAC) following clipping was found to conform to a U‐shaped curve, except where the initial TAC values were low. This pattern was found for the roots and stubble, whether expressed on an intensity of deposition or quantity of TAC basis. The degree of reduction in TAC during the first week of regrowth was found to be dependent on the level of TAC at the time of cutting, the higher the initial value the greater the reduction.

The results indicate that reserve carbohydrates play an important role in regrowth, although the relationship is of relatively short duration.