A field experiment on stabilization of Cd in contaminated soils by surface-modified nano-silica (SMNS) and its phyto-availability to corn and wheat

Journal of Soils and Sediments - Cd-contaminated soil is a common environmental problem. Stabilization is an effective way of in situ remediation for Cd contamination in soils, but there is a lack...     

1966-2017年贵州省降雨侵蚀力的时空分布特征

[目的] 分析贵州省1966—2017年降雨侵蚀力R值的时空演变规律,为评估该地区降雨对土壤侵蚀的防治、制定水土保持措施及农业生产规划提供参考。[方法] 基于贵州省33个气象站点1966—2017年的日降雨资料,利用克里金插值法、经验正交函数（EOF）方法、Mann-Kendall检验、Morlet小波分析法等,对贵州省52 a的降雨侵蚀力R值的时空特征进行了分析。[结果] ①EOF分析方法可以较好地解释降水侵蚀力的时空分布特征,其前两个特征向量累计贡献率达52%,揭示了贵州省降雨侵蚀力全局型和东西反向型两种典型的分布模态。分析特征向量所对应的时间系数可得,贵州省的降水侵蚀力主要表现为全省全年偏大、全省全年偏小、东大西小、东小西大4种类型;②贵州省降雨侵蚀力R值年内主要受汛期降雨影响,全省各县市汛期降雨侵蚀力R值均占全年总量的60%以上;③在年际变化上,降雨侵蚀力R值存在多突变的现象,1971—1981年突变频率最为频繁。通过周期检验发现其变化主周期为28 a,次周期分别为12 a和6 a。[结论] 贵州省降雨侵蚀力的时空分布与降雨量的时空分布趋势近似,整体呈现南部大北部小,夏季大冬季小的趋势,在未来几年内降雨侵蚀力R值有上升的趋势。     

滩地造林抑螺作用机理研究进展

长江流域滩地是我国钉螺分布的主要区域,也是血吸虫病的主要流行区。近些年我国大力实施的林业血防工程通过滩地营造人工杨树林,使得钉螺原有孳生地的多种生物要素和非生物要素发生了明显变化,显著减少了钉螺种群的分布空间,从而有效控制了血吸虫病的传播。目前,国内外在滩地造林后单一要素改变对钉螺的影响方面已有较多研究,但有关生物要素与非生物要素对钉螺分布的交互作用还未有深入探索,对钉螺孳生产生抑制作用的关键要素尚不明确。文中综述了滩地造林后林下的草本植物群落、土壤理化性质、光照、地温等诸多要素发生变化对钉螺生存的不利影响,总结了滩地造林抑螺作用机理的研究进展,提出该领域今后的重点研究方向,以期为滩地造林抑螺作用机理的深入研究提供参考和借鉴。     

Performance of four Chinese Trichogramma species as biocontrol agents of the rice striped stem borer, Chilo suppressalis, under various temperature and humidity regimes

The striped stem borer, Chilo suppressalis (Walker), is one of the most economically important rice pests worldwide. However, biological control of this pest using natural enemies has rarely been documented. Indigenous natural populations of four Trichogramma species (i.e., T. japonicum, T. chilonis, T. dendrolimi, and T. ostriniae) were collected from the eggs of C. suppressalis in paddy fields. With the objective of screening suitable candidate species for controlling the striped stem borer, parasitism by these four Trichogramma species of the eggs of their native host, C. suppressalis, was evaluated at five temperatures (18, 22, 26, 30, and 34?°C) and four relative humidity (RH) regimes (30, 50, 70, and 90?%). The temperature and the humidity significantly affected the ability of all of the Trichogramma species to parasitize the eggs of their host. T. chilonis parasitized more eggs at 26?°C than at the other temperatures. By contrast, T. dendrolimi, T. ostriniae, and T. japonicum performed best within a wider temperature range. The host number parasitized was highest at 70?% RH and differed significantly among the Trichogramma species at all of the temperatures and humidities tested, except at 30?°C and 50?% RH. Generally, T. dendrolimi and T. japonicum performed better than the other species at 18–26 and 30–34?°C, respectively, whereas T. ostriniae parasitized the fewest host eggs at 30–70?% RH. Both T. dendrolimi and T. japonicum appear to be promising candidates for augmentative release against C. suppressalis in northeastern China.     

小麦品种抗耐黄矮病性鉴定初步研究

1983—1987年田间人工鉴定4211份主要小麦品种资源材料,对黄矮病的反应虽有不同程度差异,但无免疫品种。症状表现最为抗病并且较为稳定的是远缘杂交小麦品种中4、中5、多年生1号及普通小麦品种复壮30号。小麦品种抗耐黄矮病性与其症状表现不一定一致,需结合被害损失综合鉴定。     

小麦梭条斑花叶病毒(WSSMV)提纯、粒子性质和血清学

 采用冰冻患病小麦叶片,经0.5M磷酸钾缓冲液pH7.0抽提,1/4体积四氯化碳澄清,6%聚乙二醇,3% NaCl和1% Triton X-100沉淀,二次差速离心(含20%蔗糖垫,0.3% Triton X-100).一次10-50%蔗糖密度梯度离心,最后经一次超速离心浓缩,成功地获得部分提纯制剂。经电镜观察,可见大量线状病毒粒子,很少有杂质。病毒粒子在中性条件下稳定,在酸性条件下变形。病毒粒子直径13-14nm.长度250-1800nm,其中在300-400nm,550-700nm之间具有二个主要分布峰。经紫外读数,病毒制剂表现为典型的核蛋白吸收特性.其中OD260/OD244为1.19,OD260/OD280为1.29。病毒粒子外壳蛋白有二个组分,分子量分别约为30kd和27kd。
在免疫电镜实验中,小麦梭条斑花叶病毒(WSSMV)和小麦黄花叶病毒(WYMV)抗血清不仅均能显著而有效地捕获汁液中的WSSMV粒子,而且还可在粒子外面包上一层厚厚的抗血清外套。     

超临界流体萃取技术在农药残留分析中的应用进展

从萃取过程控制的角度，综述了近几年来国外超临界流体技术不同形态的基体的农药残留分析中的应用情况、研究现状及前景。     

鸳鸯越冬期日活动行为时间分配的研究

越冬期鸳鸯（Ａｉｘｇａｌｅｒｉｃｕｌａｔａ）日活动行为的时间分配有明显规律性。休息（４０％－８０％）是越冬期鸳鸯的主要行为．早晨和傍晚是鸳鸯的取食高峰时间。在下午的取食强度高于上午的取食强度。越冬中期（１２－１月）鸳鸯的游泳时间相对减少，休息时间相对延长。在雌雄个体日活动行为的差别上，雄性个体理羽行为的时间比雌性个体多；警戒活动大部分是由雄性个体担任；雌性个体的休息时间比雄性个体多。季节变化，气候条件，以及温度、时间对鸳鸯的日活动行为都有一定的影响。     

Nitrogen balance in barrows fed low-protein diets supplemented with essential amino acids

This study was conducted to determine the effect of addition of essential amino acids (EAA) to low-protein diets on N balance in barrows. Thirty barrows (Duroc × Yorkshire) with an initial BW of 36 kg were fed 5 corn- and soybean meal-based diets containing 13.6 to 18.2% crude protein (CP) for 10 d in a randomized complete block design. The 18.2% CP diet was formulated without addition of EAA (Lys, Met or Thr). The other diets contained 13.6 to 16.5% CP and were supplemented with EAA to provide 0.83% true digestible lysine equal to that in the 18.2% CP diet. Fecal, urinary, and total N excretion as well as N retention (g/d) decreased with decreasing dietary CP level (P < 0.01). The apparent digestibility of N was almost the same for the 18.2 and 16.5 CP diets, but the value was 2% higher (P = 0.07) than that for the 13.6% CP diet. These findings indicate that, compared with the 18.2% CP diets, supplementation with three EAA to the lowest-protein diets (13.6 CP) is inadequate for maximum intestinal protein digestion, amino acid absorption, or tissue protein deposition in growing barrows.     

国内外水果农药残留管理概况

总结和分析了我国主要水果贸易国在水果农药残留方面的标准情况概况。相对欧美、日本、加拿大等国家在水果上设立越来越苛刻的农药残留限量,我国的水果农药残留限量标准的制订和研究还比较缺乏,迫切需要根据国际食品法典要求和我国及其主要水果贸易伙伴国的水果生产和农药管理实际,制订或修订我国水果农药残留标准。