整地深松机机械所存在的问题

整地深松机机械是我国农业机械化发展的一个重要方面,因此探析我国在这方面存在的问题就变得非常 必要,同时提出几点建议对探析问题也将是讨论问题同时不可缺少的一部分.     

Site classification of the eastern forest region of Daxing''''an Mountains

StudysiteThestudysiteislocatedintheeasternslopeofDaxing'anMountains(47"25'~49'37'N,119'37'-122"45'E),whichbelongstotheBalinForestryBu-reauofNeiMenggol.ThemaintopographyislowermountainsandhilIs.Thealtitudeis4oo~1ooom.Theannualaccumulativetemperature(>=1oC)isabout1845oC.AnnuaIprecipitationis42omm.Annualaveragetemperatureis-15t.Thefrost-freeperiodis97d.lnthisarea,thezonalsoilisbrownconiferousforestsoil,theothertypeofsoilismeadowsoilandbogsoiI.ThemainfundamentaIrockisgrinite.ThebasaItisse…     

关于皆伐的思考

本文从景观层次上对皆伐的应用进行了分析 ,得出皆伐是森林主伐的一种行之有效的方式。在森林主伐中 ,应根据立地条件和景观格局 ,恰当考虑皆伐的应用。     

黄土高原不同林龄土壤质地和矿质元素差异研究

对黄土高原不同林龄和不同树种条件下土壤的机械组成和矿质元素含量进行了分析研究,结果表明:①成林土壤砂粒、粉粒含量低于中幼林土壤,粘粒含量高于中幼林土壤,且呈显著性差异;②成林土壤Al2O3、Fe2O3、TiO2、MnO2、K2O含量相对于中幼林土壤有不同程度的增加,除MnO2外,差异均为极显著;成林土壤中Al2O3、Fe2O3、TiO2、MnO2在土壤中下层有不同程度的富集,SiO2、CaO含量降低;③矿质元素含量与土壤质地密切相关。     

A target-site mutation is present in a glyphosate-resistant Lolium rigidum population

Annual ryegrass (Lolium rigidum) is the only weed species to have evolved resistance to the broad‐spectrum herbicide glyphosate in Australia. A population that had failed to be controlled by glyphosate was collected from a vineyard in the Adelaide Hills region of South Australia. Dose–response experiments on this population (SLR 77) showed that it was glyphosate resistant, with an LD₅₀ that was 1.9–3.4 times higher than that of a susceptible population (VLR 1). The movement of radiolabelled glyphosate within SLR 77 plants showed that this population did not have the differential glyphosate translocation mechanism of resistance common to several other Australian glyphosate‐resistant populations. Subsequent analysis of shikimic acid accumulation within the plant after glyphosate treatment showed that this population accumulated significantly less shikimic acid than a susceptible population, but more than a glyphosate‐resistant population with the translocation mechanism, indicating the possible involvement of another mechanism of resistance. Sequencing of a portion of the SLR 77 5‐enolpyruvylshikimate‐3‐phosphate synthase gene was carried out and a mutation causing an amino acid change at position 106 from proline to threonine was identified. This mutation is likely to be responsible for glyphosate resistance in this population, as mutations in this position have been found to be responsible for glyphosate resistance in goosegrass (Eleusine indica) from Malaysia. This paper represents the first report of target‐site glyphosate resistance in L. rigidum and provides evidence that this species has at least two mechanisms of glyphosate resistance present in Australia.     

草本植物根系对边坡浅层稳定性影响研究

为研究草本植物根系对边坡浅层稳定性的影响,在假设滑坡体为长方体的条件下,通过对植物根系加固边坡的力学原理进行分析,推导了植物根系对边坡浅层稳定性的安全系数公式,并计算分析了坡度、滑坡体尺寸以及根土面积比对边坡稳定性的影响。结果表明:随着边坡坡度及滑坡体尺寸的增加,边坡的稳定系数将减小。并且,植物护坡的坡体安全系数要大于无防护坡体的安全系数。随着根-土面积比的增大,坡体的稳定系数逐渐增加,说明植物根系能增加边坡的稳定性。     

韩城困难立地造林技术

为了提高造林成活率,作者从选择合适的造林时间和造林树种,选择良种壮苗,因地整地、因势整地,覆盖地膜保温保墒,覆盖油桶保温防风防鼠兔危害等措施入手,使困难立地造林成活率有了显著地提高。     

森林立地分类及质量评价

按植被途径、自然环境途径、综合途径分析和概述了森林立地分类和质量评价研究的发展和现状。详细介绍各学派的形成背景、基本原理和应用条件,并对我国曾采用的各种森林立地分类和质量评价方法及所取得的研究成果进行了评述。提出多因子、多层次、多目标和多功能的森林立地分类和质量评价代表了未来方向。     

不同质量等级食用仙人掌扦插生根试验

对不同质量等级米邦塔食用仙人掌进行扦插生根对比试验,结果表明:质量等级小的掌片生根迅速,质量大的生根缓慢;质量小的掌片根长显著大于质量大的,但质量大的掌片生根的数量、重量和粗度都明显高于质量小的掌片。