地毯草对铝胁迫响应及临界浓度的研究

以地毯草为研究对象,利用水培法进行耐铝鉴定,初步研究不同铝浓度处理对地毯草坪用质量、叶色和枯黄率的影响。结果表明,不同处理浓度之间存在显著或极显著性差异,中等浓度(0.72、0.96、1.20 mmol/L)铝处理下,地毯草坪用价值明显优于低浓度(0、0.24、0.48 mmol/L)和高浓度的铝处理(1.68、1.92、2.16 mmol/L),呈抛物线形状;0.72 mmol/L铝处理最适宜地毯草的生长。其它高浓度或低浓度都抑制了地毯草的正常生长,从而导致地毯草草坪使用价值下降。通过建立回归方程,以枯黄率下降50%作为地毯草存活临界铝离子浓度,可得地毯草具有50%存活的临界铝离子浓度为2.04 mmol/L。     

大气CO_2倍增条件下冬小麦气体交换对高温干旱及复水过程的响应

探究大气CO_2浓度倍增条件下冬小麦气体交换参数对高温干旱及复水过程的生理响应机制,有助于提高生态过程模型的模拟精度,更加准确地预测全球气候变化对农田生态系统初级生产力及其生态服务功能的影响。利用4个可精准控制CO_2浓度和温度的大型人工气候室,研究了CO_2浓度倍增条件下高温干旱及复水过程对冬小麦气孔特征和气体交换参数的影响。结果表明, CO_2浓度倍增(E)导致冬小麦远轴面气孔密度增加、气孔宽度减小、气孔空间分布规则程度降低,但提高叶片的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和水分利用效率(WUE)。高温干旱(HD)使叶片气孔长度、密度、周长和面积减小,导致叶片气体交换参数均显著下降。然而,高CO_2浓度及高温干旱(EHD)导致气体交换参数下降幅度相对较小,表明高CO_2浓度对高温干旱具有一定的缓解作用。此外,干旱复水后,不同处理条件下冬小麦叶片气体交换参数均有所升高,但高温干旱下叶片的气体交换参数仍未能恢复到对照水平,暗示光合器官可能在高温干旱时遭到损伤和破坏。     

基于风洞平台实验的内浮顶罐油气泄漏扩散数值模拟

研究内浮顶罐油气泄漏扩散规律,对于加强环境污染控制、保障罐区安全具有重要意义。建立风洞实验平台,测试小型内浮顶罐风速及浮盘位置对蒸发损耗速率的影响,并考察了风场、浓度场分布规律。基于CFD数值模拟,使用UDF导入环境风,建立了内浮顶罐油气泄漏扩散的数值模型,并通过风洞实验数据验证其模拟的可行性。重点讨论了内浮顶罐外风场及风压分布规律、风速对内浮顶罐油气流场分布及油气扩散浓度的影响。结果表明:浮盘位置越低、风速越大,蒸发速率越快;罐壁的静压力分布规律为迎风侧最大、背风侧居中、罐两侧最小;不同风速下,罐内油气分布整体呈现对称状态;风速越小,油气质量浓度越高,浮盘缝隙处的油气质量浓度最高,并存在安全和环境污染隐患。研究成果对于内浮顶罐设计及运行维护、环保安全管理具有参考价值。     

Effects of Ozone on Growth of Seven Grass and One Clover Species

Abstract

Seven species of grass and one of red clover were grown at different ozone (O₃) concentrations for about five weeks in growth chambers located in a greenhouse. At an O₃ concentration of 55 compared with 10 nmol mol^?1 during 7 h day^?1 the shoot dry weight decreased by 45% in Phleum pratense, 28% in Dactylis glomerata and Poa pratensis, 23% in Festuca rubra and 16% in Festuca pratensis, while the effects on Agrostis tenuis were not significant. No effect was found at 25 compared with 10 nmol mol^?1O₃. Visible O₃ injury was observed in all six species at 55 nmol mol^?1 and this effect was generally well correlated with the effect on the dry weights. In another experiment no effect was found with O₃ concentrations of up to 62 nmol mol_?1 on Lolium perénne, while the dry weight in Trifolium pratense decreased by 30% at 59 compared with that at 6 nmol mol^?1.     

Genetic dissection of hexanol content in soybean seed through genome-wide association analysis

Hexanol is a major compound contributing to the off-flavors(the bean-like odor) of soybean derived soymilk. The most effective way to reduce the off-flavors of soymilk is the screening and utilization of soybean cultivars with improved hexanol content. However, no genome-wide genetic analysis for this particular trait has been conducted to date. The objective of the present study was to dissect the genetic basis of hexanol content in soybean seed through genome-wide association analysis(GWAS). A total of 105 soybean accessions were analyzed for hexanol content in a three-year experiments and genotyped by sequencing using the specific locus amplified fragment sequencing(SLAF-seq) approach. A total of 25 724 single nucleotide polymorphisms(SNPs) were obtained with minor allele frequencies(MAF)5%. GWAS showed that 25 quantitative trait nucleotides(QTNs) were significantly associated with the hexanol concentration in soybean seed. These identified QTNs distributed on different genomic regions of the 15 chromosomes. A total of 91 genes were predicted as candidate genes underlying the seed hexanol level and six candidates were predicted possibly underlying the seed hexanol by gene based association. In this study, GWAS has been proven to be an effective way to dissect the genetic basis of the hexanol concentration in multiple genetic backgrounds. The identified beneficial alleles and candidate genes might be valuable for the improvement of marker-assisted breeding efficiency for low hexanol level and help to explore possible molecular mechanisms underlying hexanol content in soybean seed.     

产酶益生素对西门塔尔牛瘤胃液pH及氨态氮浓度的影响

试验选用4头体重(500±20)kg,年龄3.5岁,装有永久性瘤胃瘘管的西门塔尔牛阉牛,采用4×4拉丁方设计,以混合精料和风干玉米秸秆为基础日粮,研究日粮中添加产酶益生素(0、10、20 g/d和30 g/d)对瘤胃液pH及氨态氮浓度的影响。结果表明:日粮添加产酶益生素后,瘤胃pH在采食后3、6 h以及平均值随着添加量的增加有提高的趋势,但差异不显著(P>0.05);20 g/d组和30 g/d组瘤胃液氨态氮浓度显著低于对照组(P<0.05)。以上结果表明,产酶益生素的适宜添加水平为20 g/d。     

Amelioration of salinity on photosynthesis and some characteristics of three rapeseed (Brassica napus) cultivars under increased concentrations of carbon dioxide

This study was done to evaluate the effects of increasing concentrations of CO₂ (CC) on rapeseed. Pot experiments were done with three cultivars (Okapi, Zarfam and RGS003) of rapeseed (Brassica napus) for salinity tolerance. Four levels of salinity (0, 5, 10 and 15 dS m^?1) were tested on the three cultivars at three CC (350, 700 and 1050 mmol L^?1) at the greenhouse of Tarbiat Modares University, Iran, during the crop seasons of 2010 to 2011. Three CCs were considered as three environments and the other two treatments (salinity and cultivar) were tested within these environments in a complete block design arranged as a factorial. Results indicated that photosynthetic rates declined with increasing levels of salinity. Elevated CC significantly increased rates of photosynthesis. The highest CC reduced the impact of salinity on photosynthesis. Increased CC reduced the rate of transpiration, which had the effects of increasing rates of photosynthesis and water use efficiency (WUE); these effects increased vegetative growth and reduced the adverse effects of salinity. Increased CC and salinity reduced harvest index. WUE increased with CC increment, and decreased with salinity elevation.     

农机安全生产管理工作存在的问题及对策

文章重点介绍了那满镇农机安全生产管理过程中存在的问题,并提出了安全生产管理的对策,以期为那满镇农机的安全生产提供技术指导。     

平面SH波入射下深埋圆形组合衬砌洞室的动力反应分析

利用波函数展开法,研究平面SH波入射下,深埋圆形组合衬砌洞室的动力反应问题.利用得到的级数解和数学应用软件MathCAD编写计算机程序,讨论了入射波频率、组合衬砌结构的厚度比、弹性模量、泊松比、密度等因素对围岩和衬砌结构动应力集中系数的影响.结果表明组合衬砌确实能有效地发挥围岩的自承能力,降低衬砌结构的动应力集中,且在低频入射时效果显著.     

Erythropoietin inhibits eryptosis induced by reactive oxygen species

AIM: To observe the influence of erythropoietin (EPO) on eryptosis and production of reactive oxygen species (ROS) in erythrocytes under stimulation of hydrogen peroxide (H₂O₂),and to explore its related mechanism. METHODS: The erythrocyte suspension (1%) was cultured in vitro and divided into 3 groups:control group (C group, the culture medium was PBS), H₂O₂ group (H group, the culture medium was PBS containing H₂O₂ at final concentration of 100 μmol/L) and EPO group (E group, the culture medium was PBS containing H₂O₂ at final concentration of 100 μmol/L and EPO at final concentration of 2×10⁴ U/L). The erythrocytes were collected at 24 h and 60 h. The eryptosis was detected by flow cytometry with Annexin V staining. The production of ROS and intracellular calcium ion concentration ([Ca²⁺]_i) were also analyzed by flow cytometry. RESULTS: The eryptosis in C group was increased as the incubating time extended. The eryptosis in H group was higher than that in C group (P<0.01), while that in E group was lower than that in H group (P<0.01). Meanwhile, ROS production and[Ca²⁺]_i were higher in H group than those in C group (P<0.01), but those were lower in E group than those in H group (P<0.05 or P<0.01). CONCLUSION: EPO inhibits eryptosis induced by H₂O₂ and its mechanism may be related to antioxidant effect and change of[Ca²⁺]_i.