不同世代水稻与稗草竞争对开放式空气CO_2浓度升高(FACE)的适应

通过田间试验,研究了开放式空气CO2浓度升高(FACE,Free-air CO2 enrichment)条件下不同生育期子代与0代水稻(Oryzasativa)和稗草(Echinochloacrus-galli)的生长和竞争关系。结果表明,FACE条件下水稻/稗草比例为12∶1时,在分蘖期和抽穗期,子代水稻和稗草的生长和光合能力比0代都有所降低,其中水稻的子代干物质量与0代相比分别降低了18.8%和61.9%,子代净光合速率则分别降低了22.4%和27.8%;而稗草子代干物质量与为0代相比在分蘖期和抽穗期则分别下降了34.5%和31.0%,子代净光合速率也分别下降了28.4%和16.3%。FACE条件下,两代水稻与稗草的竞争能力(子代的稻稗比)都随着生长期的不同而发生了变化:稻稗干物质量比在分蘖期子代比0代增加了26.6%,而抽穗期则减少了44.1%;净光合速率稻稗比在分蘖期子代比0代增加了8.3%,抽穗期减少了13.8%,即FACE条件下子代水稻的竞争能力相比0代水稻在分蘖期有一定程度的增强,而在抽穗期却减弱。说明生长后期子代水稻/稗草的竞争已对FACE表现出一定的适应性。     

Effect of elevated CO2 on vegetative and reproductive growth characteristics of the CAM plants Hylocereus undatus and Selenicereus megalanthus

This study examined the vegetative and reproductive growth responses of the crassulacean acid metabolism (CAM) vine-cactus fruit crop species Hylocereus undatus and Selenicereus megalanthus to CO₂ enrichment (1000 μmol mol⁻¹ vs. control of 380 μmol mol⁻¹). H. undatus plants enriched with CO₂ demonstrated 52%, 22%, 18%, and 175% increases, relative to plants measured in ambient CO₂, in total daily net CO₂ uptake, shoot elongation, shoot dry mass, and number of reproductive buds, respectively. The responses of S. megalanthus plants exposed to elevated CO₂ were greater than those of H. undatus under the same conditions. Compared to plant responses in ambient CO₂, under conditions of CO₂ enrichment, S. megalanthus showed 129%, 73%, 68%, and 233% increases in total daily net CO₂ uptake, shoot elongation, shoot dry mass, and number of reproductive buds, respectively. Moreover, for H. undatus, there was no significant change in fruit fresh mass although it showed a slight (7%) upward trend. On the other hand, fruit fresh mass of S. megalanthus significantly increased by 63% in response to elevated CO₂. These results indicate the high potential of CAM plants to respond to CO₂ enrichment. It is thus apparent that S. megalanthus grown under CO₂ enrichment may benefit from elevated CO₂ to a greater extent than H. undatus grown under sub-optimal growth conditions.     

宁夏枸杞富硒条件及富硒效应的研究

为了系统地研究宁夏枸杞硒的吸收富集规律,促进富硒枸杞安全生产,通过采用宁夏枸杞的主栽品种‘宁杞1号’为材料,在枸杞叶面施用亚硒酸钠,经枸杞树的吸收转化而形成富硒枸杞,利用原子荧光检测器进行定量分析。结果表明：设定的7个施硒浓度,在0.1~200.0 mg/kg之间,枸杞含硒量均有显著提高,取枸杞果实进行富硒效果分析,含硒量在0.17~3.34 mg/kg之间,线性关系良好（r=0.9992）。喷施浓度、次数是通过叶面喷施亚硒酸钠,生产富硒枸杞的关键因素,制干工艺对枸杞含硒量无显著影响。     

3种叶类蔬菜对镉污染的生长发育响应及累积特征

叶类蔬菜易受重金属镉污染,为筛选一种适宜在镉污染潜在区种植的叶类蔬菜,降低生态风险,提高食品安全。[方法]通过盆栽试验,研究了不同镉污染水平对3种蔬菜的生长发育的影响,及其土壤—蔬菜系统中的迁移分配情况,比较不同蔬菜对镉的耐受能力和累积情况。[结果]结果表明,小白菜、生菜在较低的镉浓度下表现为株高、单株质量增加趋势,在较高镉浓度下两种蔬菜的生长量均随着镉浓度升高出现迅速降低趋势。菠菜的耐镉胁迫能力最差,随着镉浓度升高,其生长量降低且在土壤镉污染水平为50 mg/kg 时已全部死亡。镉胁迫刺激了小白菜叶绿素含量的增加,生菜为低浓度镉胁迫促进叶绿素增加,高浓度下无显著差异,菠菜在随镉浓度升高叶绿素含量不断降低。根、茎和叶累积镉能力的顺序为：小白菜＜ 生菜＜ 菠菜;低浓度镉胁迫下生菜、菠菜的镉转移能力无显著差异,但均显著(P﹤0.05)高于小白菜的转移能力;根、茎和叶的富集能力均为小白菜＜ 生菜＜ 菠菜,且茎、叶中差异更显著。[结论]3种蔬菜中小白菜的耐镉能力最高,在镉污染风险区种植叶类蔬菜,小白菜的食品安全性较高。     

毛乌素沙漠萨拉乌苏组地下水特征与植被分布关系

利用钻探和抽水试验资料,结合遥感资料和植被实地样方调查资料,分析了该区地下水富集特征和开发利用对生态环境的影响。结果表明:含水层的厚度是地下水富集的主控因素,二者呈正相关关系;基底古凹陷分布区含水层厚度较大,是地下水的富集区;埋深3m是滩地地下水开采的约束水位,过量的开采可能造成湖盆滩地植被向沙地植被的演替或退化,甚至消亡,加快沙漠化进程;地下水开采对沙地、沙丘生长的耐干旱植被物种的影响较小。研究结果可为该区内水源地选址、地下水合理开发利用、水土保持和生态环境保护提供基础理论和数据。     

外源氮输入对生长季黄河口碱蓬湿地土壤无机硫形态变化特征的影响

选择黄河口北部滨岸高潮滩的碱蓬湿地为研究对象,基于野外原位氮输入模拟试验,探讨了不同氮输入梯度下(对照处理(N0)、低氮处理(N1)、中氮处理(N2)、高氮处理(N3))湿地土壤无机硫赋存形态在生长季的变化差异。结果表明:不同氮处理下各形态无机硫含量均表现为水溶性硫(H2O-S)吸附性硫(Adsorbed-S)盐酸溶解性硫(HCl-Soluble-S)盐酸挥发性硫(HCl-Volatile-S),且总无机硫(TIS)占全硫(TS)的比例介于34.52%~39.58%。外源氮输入不同程度地改变了湿地土壤的H2O-S、Adsorbed-S、HCl-Soluble-S和HCl-Volatile-S含量,且这种影响在生长季的某些时期达到了显著水平(P0.05)。相对于N0,N1和N2处理下H2O-S含量分别增加了6.12%和7.07%,而在N3处理下降低了0.98%;Adsorbed-S含量在N1处理下增加了11.73%,但在N2和N3处理下分别降低了23.53%和13.77%;HCl-Soluble-S和HCl-Volatile-S在N1、N2和N3处理下均呈降低趋势,降幅分别为5.21%,19.63%,59.59%和0.28%,16.10%,6.44%。尽管不同氮输入处理下土壤养分条件、水盐及酸碱状况均是影响无机硫赋存的关键因素,但pH和EC对其动态变化的影响尤为明显。研究发现,外源氮输入可能通过改变植物生长节律和土壤酸碱状况来影响植物对不同形态无机硫的吸收与利用,进而间接改变了土壤中不同形态无机硫含量及TIS赋存量。     

The application of palaeolimnology to evidence‐based lake management and conservation: examples from UK lakes

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苎麻种植密度对重金属Pb、As富集能力影响研究

本研究以两个苎麻主栽品种为研究对象,设计了2种种植密度,研究苎麻在Pb、As污染农田中的生长情况及植物体内不同部位的Pb、As含量,期望从中发现不同的种植密度对苎麻产量以及对重金属Pb、As富集能力的影响。试验结果表明:不同的种植密度对苎麻的产量影响较大,“湘3”和“中1”正常密度产量分别为10.49kg/亩和8.80kg/亩,而高密度依次分别达到22.82 kg/亩和20.86 kg/亩;正常密度2个品种苎麻地上部Pb、As含量均高于高密度,Pb、As的小区迁移量都是湘3高密度最高,分别达到4.97mg/m2和0.194mg/m2,高密度会减少苎麻单株地上部重金属的含量,但是总迁移量有所提高。     

利用天然沸石富集酒精糟水中B族维生素、氨基酸和矿物质的基础试验

在静态吸附试验中,用1.8％盐酸和3％醋酸处理的60～80目丝光沸石的核黄素吸附量为294.0和288.6μg/g。用1.8％,3.6％,7.2％和18％盐酸处理的80目以上丝光沸石,其核黄素吸附量分别为298.5,330.8,345.2和298.2μg/g。斜发沸石的核黄素吸附量高于丝光沸石。80目以上丝光沸石对糟水中核黄素、硫胺素、烟酸和赖氨酸吸附量分别为78.6,115.0,31.8μg/100g和10.4mg/100g,80目以上斜发沸石对糟水中核黄素和硫胺素的吸附量为114.3和194.7μg/100g。吸附饱和的丝光佛石中含铁1411.4ppm,铜3.1ppm,锌36.0ppm,而原矿中含铁754.2ppm,铜0.9ppm,锌13.Oppm,锰43.1ppm。饱和丝光沸石和斜发沸石中含铅3.2和4.5ppm。原矿丝光和斜发沸石中含铅5.9和33.9ppm。     

Detection and characterization ofSalmonella typhimurium from a dairy herd in North Dakota

Nasal secretions, faecal samples and buffy coats were obtained from 102 cattle from a North Dakota dairy herd with a history of calf scours. Treated buffy coats, faecal samples and nasal secretions were inoculated into tetrathionate broth (TB), incubated at 37°C overnight, and plated onto brilliant green agar medium with novobiocin (BGAN). The TB was left at room temperature for 5 days and then used to inoculate fresh TB. The fresh TB was incubated at 37°C over night and plated onto BGAN medium. All the plates were incubated at 37°C over night and observed forSalmonella-like growth. Suspect colonies were further tested andSalmonella isolates were serotyped by the National Veterinary Services laboratory. Twenty-two of the 36 calves sampled harbouredS. typhimurium in their faeces, but no samples from cows were positive. NoSalmonella were isolated from the buffy coats, but 4 calves were shown to haveSalmonella in their nasal secretions. Extended enrichment of the faecal cultures in TB resulted in a significant increase inSalmonella isolations, although 2 samples were positive following the initial enrichment period and not after secondary enrichment. The typicalSalmonella isolate detected from this herd contained a transmissible R-plasmid encoding resistance to tetracycline, kanamycin, sulphisoxazole and ampicillin. This study confirmed that delayed secondary enrichment in TB is superior to primary enrichment for detection ofSalmonella from cattle.Abbreviations Ap ampicillin - BGAN brilliant green agar with novobiocin - Cm chloramphenicol - DSE delayed secondary enrichment - Gn gentamicin - Kn kanamycin - NA nalidixic acid - NADC National Animal Disease Center in Ames, Iowa - NVSL National Veterinary Services Laboratory in Ames, Iowa - PB polymyxin B - PE primary enrichment - Sm streptomycin - Su sulphisoxazole - TB tetrathionate broth - Tc tetracycline - TSI triple sugar iron agar