山西省重要农产品汞、砷、铬和镉含量背景值的研究与应用     

武丕武  董琳  王国桢  韩跃萍 《山西农业科学》2008,36(8)

通过有代表性的采样、检验和数学统计取得了11种农产品汞、砷、镉和铬含量的背景值,为山西省农产品质量安全评价、制定农产品质量地方标准和城乡人民调整食物结构提供了科学依据。  相似文献   

绵羊宿营法防除天然草地灌木杂草研究Ⅲ新鲜羊粪尿对土壤和植物细胞形态结构及生理的影响     

张英俊  蒋文兰  符义坤  于应文 《草业学报》1999,(Z1)

采用盆栽试验研究了绵羊新鲜粪尿对植物组织水势、细胞膜透性和细胞形态结构的影响。结果表明 ,在土壤含水量 30 %左右 ,植物无水分胁迫的可能时 ,各处理植物组织水势呈先上升后下降的趋势 ,而对照则呈持续上升趋势。说明绵羊新鲜粪尿加入土壤后 ,土壤溶液浓度升高 ,影响了植物水势。绵羊新鲜粪尿对植物生理影响表明 ,叶片细胞膜透性在 UD处理与对照差异显著 (P<0 .0 5) ,U和 D单处理与对照间差异不显著 (P>0 .0 5)。根细胞膜透性 UD和 U处理与对照差异显著 (P<0 .0 5)。D处理与对照无显著差异 (P>0 .0 5)。植物细胞形态结构显示 ,各处理均无质壁分离现象 ,但 U和 UD处理的皮层细胞出现叶绿体 ,这可能是尿中尿素水解释放的游离氨被植物吸收所致  相似文献   

不同坡向杉木3代种子园土壤有效养分差异比较分析     

胡永颜 《江西林业科技》2012,(5):4-6,16

以杉木3代种子园为研究对象,分析不同坡向杉木3代种子园土壤有效养分含量差异,从而为实现杉木种子园的合理施肥奠定理论基础。研究结果表明,同一坡向随着坡位上升以及同一坡位随着土层深度的增加,杉木3代种子园土壤有效养分含量呈逐渐下降趋势;同一坡位同一土层深度不同坡向对土壤有效养分含量的影响体现出较为复杂的规律。  相似文献   

Nodule phosphorus requirement and O2 uptake in common bean genotypes under phosphorus deficiency     

Adnane Bargaz  Jean-Jacques Drevon  Khalid Oufdou  Btissam Mandri  Mustapha Faghire 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(7):602-611

Abstract

The effect of P deficiency on nodulation, nodule P content, nodule O₂ permeability and N fixation rates in Phaseolus vulgaris–rhizobia symbiosis was studied under glasshouse conditions. Four recombinant inbred lines (L34, L83, L115 and L147) and one variety cultivated in Morocco (Concesa) were inoculated with Rhizobium tropici CIAT 899 in hydroaeroponic culture. Two P levels i.e. 75 (deficient level) and 250 µmol plant^?1 week^?1 P (sufficient level) were applied and the trial was assessed 42 days after transplanting that coincide with plant flowering stage. Under P-deficiency, decrease of plant growth (18%) and nodule biomass (19%) was detected and significantly pronounced in the sensitive line L147 compared with the remaining genotypes. Additionally, under P-deficiency, the efficiency in use of rhizobial symbiosis, estimated by the slope of the regression model of shoot biomass as a function of nodule biomass, was significantly increased in the four lines. This constraint did not significantly influence nodule P content in Concesa, but it was 24 and 41% lower in the tolerant and in the sensitive lines, respectively. Nodule P content was positively correlated to nodule biomass, r=0.75, and shoot N, r=0.92. These genotypic variations were associated with variability in nodule O₂ permeability that was significantly affected by the P level-bean genotype interaction. Under P-deficiency, nodule O₂ permeability was significantly reduced in the tested genotypes and accompanied with a decrease in shoot N content, especially in the sensitive lines (35%). Moreover, the ratios plant N fixed: nodule P content and plant N fixed:nodule dry weight were affected under P-deficiency in four lines with an exception observed in Concesa. Depending on the observed data we concluded that N₂ fixation efficiency could be influenced by nodulation and level of nodule P requirement which depend on both bean genotypes and P level.  相似文献   

优化高职《汽车保险与理赔》课程教学内容探讨与实践     

方春影  戴庆敏  宣玲娣  吴燕云  唐慧华 《湖南农机》2013,40(3):226-227

优化教学内容是高职《汽车保险与理赔》汽车保险课程教学改革的最为重要的内容之一。要想较好地优化教学内容,必须遵循一定的原则,从实际的工作岗位能力要求出发,整合为典型工作任务,最后转化为课程教学内容。  相似文献   

不同栽培措施对温室油桃含糖量的影响试验研究     

李万年  牟德生  曹虎  张兆铭 《甘肃林业科技》2008,33(4):34-36

通过增施钾肥、铺反光膜、限制产量的栽培措施试验，结果表明：不同K肥水平对油桃含糖量影响有显著差异，株施60g钾肥油桃含糖量最高为13．6％；行间铺设反光膜与未铺反光膜对油桃含糖量影响有显著差异，行间铺设反光膜比未铺反光膜油桃含糖量高1．8％；不同产量水平对油桃含糖量影响有显著差异，产量控制在12000kg／hm2时油桃含糖量最高。  相似文献   

Interaction Between Plant Roots and Soil Water Flow in Response to Preferential Flow Paths in Northern China     

《Land Degradation \u0026amp; Development》2017,28(2):648-663

Preferential flow is expected to provide preferential channels for plant root growth and variations in soil water flow, but few studies were conducted to imply the impacts of these changes, particularly for preferential flow in stony soils. This study aimed to characterize soil water flow and plant root distribution in response to preferential flow paths and quantitatively describe the relation between plant root distribution and soil water flow. Field dye‐tracing experiments centered on experimental plants were conducted to determine the root length density and soil water flow process. Laboratory analyses were performed to characterize changes in the relative concentration of the accumulated effluent and the degree of interaction between plant roots and soil water flow. The amount of fine plant roots with preferential flow paths decreased with increasing soil depth for all experimental plots. The largest plant roots were recorded in the upper soil layers to a depth of 20 cm. The relative concentration of the accumulated effluent increased with time and decreased with soil depth under saturated soil conditions, whereas a distinct early turning point for the relative concentration of the accumulated effluent was observed in the 0–20‐cm soil columns, and the relative concentration of the accumulated effluent initially decreased and then increased with time under unsaturated soil conditions. This study provides quantitative information with which to characterize the interaction between plant roots and soil water flow in response to preferential flow paths in soil–plant–water systems. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

长期接触有机磷农药的农民体内自由基含量的调查报告     

李鹏  尹雅玲  李嘉  李尚志  梁金英  赵繁荣  王倩倩  卢光洲  张玉林 《安徽农业科学》2010,38(4):2020-2021

[目的]调查长期接触有机磷农药的农民体内自由基的含量。[方法]随机抽取豫北农村地区长期接触有机磷农药的农民790人,分别检测其体内MDA、SOD、GSH-PX、LPO含量。[结果]接触有机磷农药10年以上的农民体内自由基含量明显增加,但增加量无年限差异。[结论]农民长期接触有机磷农药会引起体内自由基含量增加。  相似文献   

山东寿光蔬菜对土壤中重金属富集的溯源规律及选择性种植   总被引：1，自引：0，他引：1  

陈刚  宋永芬  成世才  马浩宁  亓协全 《江西农业学报》2013,25(4):118-119,123

对山东寿光蔬菜基地土壤及蔬菜中的重金属含量进行了检测分析,研究了蔬菜中重金属富集的可溯源性。结果表明,几种主要重金属在土壤中和蔬菜中含量的高低顺序基本一致。据此提出了蔬菜的选择性种植方法,即在查明区域土壤重金属含量的情况下,按照蔬菜对重金属富集的差异性来选择要种植的蔬菜种类。  相似文献   

含蜡原油管道胶凝形成机理研究进展   总被引：1，自引：0，他引：1  

喻西崇  冯叔初 《油气储运》2000,19(11):6-8

介绍了国内外献中对含蜡原油胶凝形成机理的研究成果。研究结果表明，在含蜡原油管道中，当油温低于浊点时，易在管壁处形成一层类似固体的凝胶物质。含蜡原油管道胶凝的形成主要受热历史和剪切历史的影响，胶凝湿度随冷却速度的减小而降低，随剪切应力的增大而降低，而浊点与冷却速度和剪切应力无关。在环境湿度高于油温的情况下， 即便油温低于浊点湿度，含蜡原油也不会形成胶凝。由于胶凝具有类似固体的机械特性，因此冷却速率越快，石蜡晶体越小，越多，屈服应力也越大，胶凝屈服应力取决于蜡晶的大小和数目。  相似文献