新时期“水土保持工程学”课程教学改革的思考

水土保持工程学;课程改革;教学内容;教材;教学方法;实践教学     

浅析冷铺沥青材料的特性、配制及应用

储存式冷铺沥青混合料,是指平时储存在仓库内,使用对在常温下进行摊铺和压实的材料.文章着重介绍了这种冷铺沥青材料的特性、配制原理及应用技术要求.     

Analysis of root fractal characteristics in remote areas of the Taklimakan desert, China

Fractal geometry is a potential new approach to analyze the root architecture, which may offer improved ways to quantify and summarize root system complexity as well as yield ecological and physiological insights into the functional relevance of specific architectural patterns. Fractal analysis is a sensitive measure of root branching intensity and fractal dimension expresses the ＂space filling＂ properties of a structure. The objective of this study was to find out the fractal characteristics of root systems in a remote area of the Taklimakan desert in China. The entire root system of two naturally occurring species were excavated and exposed with shov- els in 2007. The species were Tamarix taklamakanensis and Calligonum roborovskii. A one-factorial ANOVA with species as factor showed statistically a highly significant difference in fractal dimensions, indicating differences in their pattern of root branching. There was no relationship between root diameter and two parameters of fractal root models a and q, representing general characteris- tics of root systems, for either species （a： the ratio of the sum of root cross-sectional areas after a branching to the cross-sectional area before root division; q： the distribution of the cross-sectional areas after branching）. We have found significant linear relation- ships between the diameter after branching and root length and biomass respectively, because of the self-similarity of root branching. Branching rules are the same for roots of all sizes and lengths. Root biomass for the root systems of entire trees can be estimated by measuring the diameter of each root at the base of the trunk or the diameter after branching. We have shown that the diameter of each root at the base of the trunk and the diameter after branching are effective indices that can be measured easily in order to estimate the root lengths, biomass and other parameters of root architecture.     

广东农林外来有害生物红火蚁入侵历史考察

产自南美洲的红火蚁在国际上被列为最具侵略性和破坏性的有害生物之一。广东地区是红火蚁在中国大陆入侵的首发区,同时也是红火蚁入侵历史较长、分布区域广泛、危害最严重的地区。广东地区红火蚁入侵的历史可分为入侵初期与局部发生时期,蔓延与危害显现时期,危害扩大与综合防控时期等3个阶段。红火蚁的危害主要为攻击人类,破坏生态平衡,危害农业生产以及破坏公共设施。目前红火蚁的防控手段以化学防治为主,生物防治值得重视。     

依兰县林业局森林资源特点及经营措施

论述了依兰县林业局的森林资源现状及森林资源特点,并指明了今后的经营措施和发展方向。     

叶面肥的种类与发展趋势探析

具体阐述了叶面肥的主要特点,并分析了当前叶面肥应用上存在的问题与其发展趋势及前景,以期促进叶面肥的应用与推广。     

2014年中国棉花景气报告 产业发展趋势与政策建议

全文回顾了2013年全国棉花产业经济运行特点——棉花生产呈＂五减一降一平＂特点,纺织品服装内销增幅回落,出口呈现恢复性增长。预测2014年全国棉花产业将呈现＂恢复性＂和＂缩减性＂的分化态势——棉纱产量仍将增长,纺棉恢复性增长,纺织品服装出口增长,原棉进口有望控制,库存减少,面积缩减扩大,棉价理性回落,国内外价差缩小。一号文件指出＂新疆棉花目标价格补贴试点＂和主攻机采棉等有利因素诸多,然而稳定棉花生产难度加大是不利因素。供决策参考。     

水稻病虫害防治技术

一、水稻主要病害防治 1、水稻稻瘟病 稻瘟病俗称“鬼掐颈”,是水稻三大病害之一. 发病特点.苗瘟:病苗基部变黑褐色,上部呈黄褐色或淡红褐色而枯死.潮湿时病苗表面常有灰绿色霉层.叶瘟:病斑呈纺锤形,最外层黄色,内圈褐色,中央灰白色;病斑两端有褐色坏死线向外延伸呈长条状,病斑背面产生灰绿色的霉层.穗颈瘟:发生于穗颈上.病部呈褐色或墨绿色.穗颈发病早的多形成“全白穗”;迟的则谷粒不充实,病穗往往从颈部折下,形成吊颈.     

大豆窄行密植栽培技术

大豆窄行密植栽培,是目前国际上大豆栽培应用面积较大,发展速度较快的一项先进的栽培技术。我省从90年代初期开始,在消化吸收国外技术的基础上,结合我省的自然特点,生产条件,探索出了适合我省生产条件的大豆窄行密植栽培技术。     

影响我国未来粮食安全的隐忧

正我国的改革开放发端于农村土地制度的变革,而实行家庭承包经营制是土地制度变革的主要内容。它确立了农户在农业生产中的主体地位,赋予了农户极大的生产自主权和决定权,从而激发了农民的生产积极性,不仅促进了农村和农业发展,也