NO在植物体内产生的途径及其作用

近年来的研究表明一氧化氮(nitric oxide,NO)是生物体内的重要的信号分子,参与多种生理功能的调控。文章主要介绍了在植物体内NO的产生途径、信号传导机制、与其他信号分子之间的相互作用及其与植物激素之间的作用。     

蕃茄苗期整形(双干)研究初报

与常规育苗(单干秧苗)比较,双干苗根系发达,根体积增大,活跃吸收面积增加43.7%,根、茎、叶各部的干重均高于单干苗。定植后双干苗生长旺盛,叶面积和全株干重是单干苗的2倍多。同期播种的双干苗前期产量不如单干苗处理,可提前播种15～20天,弥补早熟性不强的缺点,但其总产量极显著地高于单干,双干40cm株距产量比对照(单30)增产59.8%。     

山区乡村森林资源利用方式创新效应及机理分析

在乡村森林资源利用中，正确处理好保护森林资源与获得经济效益之间的关系是一大难题。森林资源利用方式的创新是解决这一问题的有效途径。临安市白沙村以非木质资源和生态旅游为主进行森林资源利用方式创新的实践，使乡村经济收入得到大幅度提高，产业结构得到优化，森林资源和生态环境得到有效保护。这种创新的关键在于对森林资源实行了辨证利用，在经营中以原有的森林副产品作为主产品加以利用，缩短了森林经营利用周期，能够采取有效的措施保护森林资源及其生态环境，并有效地解决了森林经营的外部性问题，从而达到了森林资源生态、经济和社会三大效益之间的协调发展。表3参7     

高职院校学生法制教育的有效途径

法制教育对于高职院校人才培养和自身发展具有重要意义,应法制教育与学生职业培养目标相结合,突出其社会化特点,充分利用校园文化载体,使学生从法制教育的受教者转化为体验者和传播者,才能不断高职院校提高法制教育的效果.     

基因组学发展对传统林木遗传改良的影响

通过对传统林木遗传改良的成就进行概述,分析了基因组研究的发展对传统林木遗传育种的影响,基因组时代的林木遗传改良方法。研究结果表明,传统的林木遗传改良在提高林木生长量和抗性等选育方面取得了显著的成果,单一或者几个树种成为一个国家或地区的主要造林树种成为可能;基因组学的发展从基因的水平对认识林木的遗传本质提供了信息,也丰富了传统遗传改良的方法和手段,必将加速林木遗传育种的进程;基因组学只是辅助传统林木遗传育种的工具,不可能替代传统林木遗传改良理论、方法和技术。     

早熟梨不同整形方式研究

通过开展不同整形方式研究,结果表明:梨幼树不同树形对侧枝生长、树冠形成的影响不同,因此在开花结果早晚、前期产量、效益方面差异较大。以折叠式扇形和Y字形整形提高早期产量效果最为显著。在每667m2栽植110株左右的密度情况下,常常采用折叠式扇形的树形;在栽植密度大于110株/667m2的情况下,采用Y字形树形;栽植密度小于40株/667m2以下的早熟梨采用疏散分层形的树形。根据不同整形方式的方差分析,得出丰产树形结构指标:在栽培密度110株/667m2的条件下,‘翠冠’梨产量控制在3000～4000kg/667m2,枝量30000～40000枝/667m2,一般每20～25cm着生1个结果枝,叶面积系数2.5～3.2,果距保持20～25cm,留果量12000～16000个/667m2,叶果比25～30:1,枝果比2～2.5:1,中短果枝占85%～90%,单株负荷27.5～37.5kg。     

吉林省参地水土保持及可持续利用

人参适宜在土层深厚 ,土壤肥沃的坡地上生长。种植人参采用皆伐林地、清除根茬、顺坡做床的方法 ,从栽培到收获的 6a时间内需换床 1次 ,参后地在 30～ 40a内不能重复利用 ,造成严重水土流失。其整地、晒地期由于土地失去了原有植被的保护 ;管理期间面积占参地 2 0 %～ 2 5 %的作业道要承受整个参地的降水量 ;参后弃地土质疏散、表土裸露 ,在这 3个不同阶段均需采取相应的水土保持措施 ,防止水土流失。     

The effect of recreational disturbance on an upland breeding bird, the golden plover Pluvialis apricaria

The use of the countryside for recreation has increased dramatically in recent years. This has led to concern amongst conservationists about the effects increased human disturbance may have on important wild animal populations. In the UK, recent legislation has widened the level of access to upland habitats, which support internationally important breeding bird populations. Determining the extent to which recreational disturbance affects upland breeding birds is therefore a conservation priority. We used data collected over 13 years to investigate the impact of recreational disturbance on the distribution and reproductive performance of golden plovers breeding in close proximity to the Pennine Way, an intensively used long-distance footpath. Importantly, the Pennine Way was resurfaced in 1994 to prevent further erosion of the surrounding vegetation. We were therefore able to examine if the response of golden plovers to recreational disturbance was influenced by changes in the intensity and extent of human activity resulting from the resurfacing work. Before the Pennine Way was resurfaced, golden plovers avoided areas within 200 m of the footpath during the chick-rearing period. At this time over 30% of people strayed from the footpath and the movement of people across the moorland was therefore widespread and unpredictable. Following resurfacing, over 96% of walkers remained on the Pennine Way, which significantly reduced the impact of recreational disturbance on golden plover distribution; golden plovers only avoided areas within 50 m of the footpath at this time. Despite the clear behavioural responses of golden plovers to the presence of visitors, there was no detectable impact of disturbance on reproductive performance. In many countries, a conflict arises between the use of the countryside for recreational purposes and the protection of habitats or species of high conservation value. However, this study suggests that the implementation of simple measures to influence visitor behaviour can dramatically reduce the impact of recreational disturbance on wild animal populations.     

Comparison of Coleoptera assemblages from a recently burned and unburned black spruce forests of northeastern North America

Several insect groups have adapted to fire cycles in boreal forests, and can efficiently use new habitats created by fire. Our study aimed at producing a first characterization of post-fire Coleoptera assemblages of black spruce forests of eastern North America. For two years, we sampled Coleoptera using flight-interception traps in burned stands of contrasting age and structure in a 5097-ha wildfire and in neighbouring unburned mature stands. More than 40 species were exclusively captured in burned stands. Time elapsed since fire and proximity of unburned forests were the most significant parameters affecting Coleoptera assemblages. Stand age and structure had limited effects on assemblage structure; the Scolytid Polygraphus rufipennis Kirby was the only common species to clearly favor older stands. Fire-associated Coleoptera assemblages found in our study area were clearly distinct from those found in similar unburned stands; we should thus be conservative in our management approach concerning recently burned stands.