Reduced weed growth with different paving constructions

The recent phaseout of herbicide use on public pavements in Flanders has triggered the development of alternative weed control strategies. Besides the search for effective non‐chemical curative methods, there is also a need for strategies that prevent or reduce weed growth on pavements. In this study a paving experiment was set up under a rain shelter to investigate the effects of four construction factors on weed growth: joint filling material, joint width, organic pollution of the joint filling material and type of bedding layer. Paving mini‐plots were oversown with a mixture of dominant, hard‐to‐control weed species found on pavements. The inhibitory effect on weeds was determined by examining initial weed density and weed coverage over a 2‐year period. More weed growth was found in pavings with wide joints and organically polluted joint filling materials. High permeability of the bedding layer resulted in higher weed cover. The coarse‐grained filling materials and the sodium silicate‐enriched sand Dansand^® were associated with less weed cover than the fine‐grained filling materials. Our results show there is potential for preventing weed growth using suitable paving materials and appropriate high‐standard construction and maintenance of pavements.     

栓皮栎软木杂质微观构造及化学成分分析

通过对国产栓皮栎软木杂质的构造观察及其化学成分分析,为栓皮栎软木除杂技术提供理论依据,结果表明:软木夹砂（石细胞）为坚硬、白色、砂粒状,夹杂（褐色杂质）为皮孔通道及褐色填充物组成的皮孔组织;石细胞为厚壁细胞,细胞腔未见。夹砂（石细胞）、夹杂（褐色杂质）与初生软木中各主要化学成分区别在于软木杂质含有较少木栓脂,较多的纤维素,而石细胞灰分含量高于褐色杂质和软木。     

木材吸湿机理及其应用

木材是一种多孔性、吸湿性和各向异性的天然高分子材料,水分影响着木材多方面的性质。文中从木材组分的角度综述了木材对水分的吸湿机理,介绍了木材对水分吸附的基本理论,解释了木材吸湿滞后现象的基本原因;在上述基础上评述了降低木材吸湿性的基本方法及其实现原因,还分析了机理应用方面存在的不足以及测试方法的不统一,并对未来研究趋势进行了展望。     

杨树短轮伐期矮林培育国内外研究进展

短轮伐期矮林作为一种可再生能源原料生产方式,其产品（如生物质成型颗粒燃料、生物乙醇等）可以替代日益匮乏的化石燃料,因此受到广泛关注。文中介绍了国内外杨树短轮伐期矮林培育研究进展情况,主要包括良种选育、营造技术、密度控制、轮伐周期、施肥技术、病虫害防治、收获技术及矮林收获物的化学成分等方面,旨在为今后我国研究和发展杨树短轮伐期矮林提供思路和方法。     

姜花在Cu胁迫下的耐性机理研究

采用模拟湿地盆栽试验,研究了姜花在Cu胁迫下的积累、分布、化学形态和富集能力。结果表明：（1）姜花对Cu的积累能力随Cu处理浓度的增加而增大,但各部位对Cu的积累具有明显的差异性。当Cu处理浓度≤150mg·kg。时,其积累能力表现为根〉叶〉茎;当Cu处理浓度≥200mg·kg。时,其积累能力表现为叶〉根〉茎。（2）Cu在姜花叶片细胞中的分布具有选择性,其主要分布位点为细胞可溶性部分和细胞壁部分,而在细胞器中Cu的含量较低。（3）Cu在姜花根、茎和叶中赋存的化学形态有明显差异。在根部,Cu的化学形态主要以乙醇提取态和水提取态为主;在茎部,Cu均以氯化钠提取态为主;而叶部Cu主要以活性较低的氯化钠提取态、醋酸提取态和盐酸提取态存在。（4）姜花对Cu具有一定的富集能力,但富集能力不强,当Cu浓度达到400mg·kg^-1以上时,姜花植株便出现了较明显的毒害症状并随之死亡,因而姜花尚未达到超富集植物的标准。可见,姜花在Cu胁迫下具有一定的耐受性,分布选择性和富集能力,将其运用于湿地Cu污染修复中,将极大地缓解重金属Cu污染给环境带来的压力。     

基于3S技术的水土流失现状监测研究

以黄土高原与毛乌素沙地线交界处能源重化工基地为研究区域,以2003年9月份的ETM遥感数据为基础数据,在GPS野外定点确定土地利用类型,实测样方内植被盖度及遥感信息与GIS空间信息分析的基础上,分析并确定影响土壤侵蚀的因子,合成了该区水土流失现状专题图.在此基础上对榆林北部6县(区)的各类水土流失类型、面积做了全面清查,并分析了该地的水土流失类型、强度及区域分布的分异特征.     

半干旱退化山区不同土地利用方式土壤理化性质的特征研究

通过对半干旱退化山区不同土地利用方式的土壤理化性质的调查研究.得出不同土地利用措施土壤机械成分表现出一定的差异性,在0-40 cm土层,88542整地和人工草地的粗砂粒平均含量高于天然草地;在0-100 cm土层,最大田间持水量:人工林地＞人工草地＞天然草地;毛管持水量:人工草地＞人工林地＞天然草地;土壤总孔隙度:人工林地＞人工草地＞天然草地;毛管孔隙度:人工草地＞人工林地＞天然草地;土壤的透气性:人工林地＞人工草地＞天然草地.在0-100 cm土层:有机质的含量为:人工林地＞天然草地＞人工草地;土壤碱解氮的含量变化为:人工林地＞人工草地＞天然草地;土壤速效磷的含量变化为:人工林地＞人工草地＞天然草地.结果表明,合理的土地利用方式,改善了土壤结构和肥力,增加土壤的通透性,改变土壤水肥气热状况,其中人工造林整地对土壤容重、持水量、土壤养分的促进作用均优于其它利用方式,有利于植被的快速恢复.     

小麦生理型雄性不育花药中能量相关基因的表达

为揭示小麦(Triticum aestivum L.)生理型雄性不育机理,以化学杂交剂SQ-1为诱导剂,构建了普通小麦西农1376不育和可育生理系,用RT-PCR技术分析了3-磷酸甘油醛脱氢酶(GAPDH)和NFUDP4基因在不同发育时期的不育和可育花药中的表达差异.结果表明,与同期对照相比,GAPDH和NFUDP4基因在不育花药单核期到三核期均下调表达,其中在大量花粉粒败育的单核期,GAPDH下调表达尤为显著.因此,小麦生理型雄性不育花药败育过程中,一方面由于GAPDH基因表达受抑制,使糖酵解受阻导致能量供应不足;另一方面,NFUDP4基因下调表达,可能引起线粒体某一Fe-S族蛋白装配需要的分子骨架减少而使其数量不足,从而可能引起Fe-S族蛋白参与的生化反应减弱,如呼吸链电子传递受阻引起能量供应不足,与小麦生理型雄性不育具有一定关系.     

抚仙湖重金属污染强度、历史及来源的沉积记录

This study focused on the concentration change of heavy metals of sediment cores in heavily polluted north area and less polluted middle area of Fuxian Lake in Southwest China.On the basis of the analysis of Cu,Ni,Ti,V,Pb,Cd,and Zn concentration-depth profiles,the pollution history of heavy metals was studied using ¹³⁷cesium (¹³⁷Cs) dating.The sources of heavy metals were distinguished by normalization of their profiles to aluminum and analysis of heavy metal concentrations of potential source materials.Geoaccumulation index (I_geo) was used to quantify their contamination intensity.The results showed that all the heavy metals found in the Fuxian Lake sediments originated naturally before 1980s.Cu,Ni,Ti,and V were still mainly natural in the north lake after 1980s,Cu,Ni,Ti,V,and Pb were mainly natural in the middle lake at all time,but the concentrations of Pb and Zn in the north lake were influenced by industrial wastes from the phosphorus fertilizer factory and cement plants.In all the lake,the contaminations of Cd and Zn were the results of agricultural cultivation using a large amount of fertilizers and the atmospheric fallouts of dusts from cement plants.At present,the geoaccumulation indices showed that the Fuxian Lake sediments were moderately to strongly polluted by Cd in the middle lake,and unpolluted to moderately polluted by Pb and Zn and strongly polluted by Cd in the north lake.Moreover,the pollution intensities of Cd,Zn,and Pb have been increased since 1980s.     

智能植保机械专题数据库设计技术研究

传统植保机械不仅机械化、自动化、精确化程度不高,而且施药效率较低下,浪费的农药对环境造成了巨大的污染。因此研究智能化植保机械迫在眉睫,以减少防治成本,提高农药使用效率,保护生态环境。在分析植保机械发展现状的基础上,针对智能植保机械分析了建立数据库的必要性,开发完成了包括气象数据库、林木病虫害管理数据库、植保机械数据库、气候条件与喷施农药决策系统、植保机械作业决策系统在内的智能植保机械专题数据库,为科学合理地利用气候条件,提高林木病虫害防治效果提供科学依据和技术支持。