共查询到20条相似文献，搜索用时 15 毫秒
1.
通过抗性转育和人工接种鉴定筛选技术,选育出红抗1、2号橘红心大白菜新品种。生育期分别为55-60、75-80d;叶球分别为中桩圆柱状和扣抱圆桶状,外叶深绿,球叶橘黄、经日光照射后呈橘红色;单球重分别为2.1、3.8kg;富含胡萝卜素等多种维生素,营养价值高,生食脆甜,熟食易烂。高抗病毒病,兼抗霜霉病和软腐病。适宜全国大部分地区推广种植。 相似文献
2.
3.
4.
贵州亚热带地区野生秋海棠种质资源及其生境类型 总被引：4，自引：0，他引：4
贵州亚热带地区有野生秋海棠19 种(含新记录种) , 其中1 种仅分布于黔北, 1种仅分布于黔东北, 4 种仅分布于黔东南, 8 种仅分布于黔南。其生境类型可分为灌丛湿地型、森林湿地型和阴湿岩石型, 以阴湿岩石型的种类较多。其按用途可分为观赏型和兼用型,以观赏型种类占多数。粗喙秋海棠、截裂秋海棠、美丽秋海棠、光叶秋海棠和小秋海棠5种处于濒危状态。 相似文献
5.
6.
7.
Trees in the urban environment are subjected to a number of stresses which are very different from those suffered by trees in typical rural conditions. The stresses listed in this paper should be a basis for the selection criteria used in urban tree improvement programs. The basic properties of trees are climatic adaptation, disease resistance and a large phenotypic plasticity. Properties related to the urban situation are related to stresses caused by social factors, the restrictive soil volume and crown space, soil pollution, air pollution, de-icing salt, wind and drought. In addition, aesthetic factors, growth form and growth potential and resistance to breakage of limbs are important selection criteria. The priority ranking of the selection criteria depends on the environment wherein the plants are to be used. The need to broaden the range of species and cultivars planted in Nordic cities should have high priority, and selection programs should, therefore, include new species of urban trees. A practical selection should be made within the four major Nordic climatic regions, which are the northern maritime, northern continental, southern maritime and southern continental regions. The establishment of broad co-operation in the selection of plant materials for urban uses is discussed. 相似文献
8.
Spatially explicit landscape-scale models that predict species distributions, where patches of habitat are shown as having potential to be occupied or unoccupied, are increasingly common. To successfully use such data, one should understand how these predicted distributions are created and how their relative accuracies are assessed. Geographic ranges, defined upon observations (e.g., atlases), literature review, and expert review, are a primary data layer. A map of land cover is created, often from interpretation of satellite imagery or other remotely-sensed data. Species/habitat associations are defined based upon a literature review and expert review, describing associations for habitats derived from the cover map. Included as ancillary associations are how species relate to physical features, where appropriate, such as elevation and hydrography. The three layers of information (range, land cover, and associations) are merged, often using raster-based algebraic statements that exclude unused habitats or patches outside the range of a species. The accuracy of predictions for a suite of species is typically assessed with surveys by comparing the species predicted to occur in an area to the species observed. Omission (i.e., present in species lists but not predicted) and commission (i.e., predicted but not present in lists) errors are reported. Errors may be due to many sources. For example, ranges of species change, cover types may be misidentified, species/habitat associations may be incorrect or change, or species may be rare and unlikely to be seen in surveys and judged in-error even though the species may be present. An example is given of an appropriate use of broad-scale species predicted distributions, in which patterns and threats to Maine terrestrial vertebrate diversity are summarized. 相似文献
9.
Urban landscape sustainability and resilience: the promise and challenges of integrating ecology with urban planning and design 总被引：2，自引：1，他引：1
Jack Ahern 《Landscape Ecology》2013,28(6):1203-1212
The twenty-first century global population will be increasingly urban-focusing the sustainability challenge on cities and raising new challenges to address urban resilience capacity. Landscape ecologists are poised to contribute to this challenge in a transdisciplinary mode in which science and research are integrated with planning policies and design applications. Five strategies to build resilience capacity and transdisciplinary collaboration are proposed: biodiversity; urban ecological networks and connectivity; multifunctionality; redundancy and modularization, adaptive design. Key research questions for landscape ecologists, planners and designers are posed to advance the development of knowledge in an adaptive mode. 相似文献
10.
11.
滇西北悬钩子属植物资源的调查 总被引：7，自引：1，他引：6
滇西北位于喜马拉雅山东坡的横断山区域的南部,是横断山区的中心部分,具有明显的立体气候特征。通过实地调查滇西北16个县和查阅大量标本及有关文献,结果表明,滇西北悬钩子属植物资源极为丰富,分布的种类有66种和20个变种,其中发现新分布种6种1变种,15种和6变种为云南特有种,其中10种和4变种为滇西北特有的分布种类。悬钩子属植物在滇西北广泛分布,从低海拔到高海拔均有分布,从总体水平看,草本类分布种类少,仅有6种2变种,分布高度2300 ~ 4200 m,木本类的分布种类有60种18变种,分布海拔740 ~ 4100 m。提出了10种具有育种潜力或直接利用价值的优良果树种质,为种质资源保存和进一步合理开发利用资源提供依据。 相似文献
12.
Karin K. Peschardt Jasper Schipperijn Ulrika K. Stigsdotter 《Urban Forestry & Urban Greening》2012,11(3):235-244
During recent years, the use of urban green space (UGS) has received increased attention within several research fields, as well as politically, especially in relation to the benefits it provides for human health. Much research on larger green areas has shown that they are beneficial to people's health, physically, socially and mentally. However, because of densification tendencies in cities in Western countries, large green areas are a limited resource and many people live in city areas where the distance to larger green areas reduces the possibility for frequent use. Small Public Urban Green Spaces (SPUGS) in dense city areas might contribute to satisfy the need for everyday experiences of outdoor areas, but research on SPUGS is limited. In this paper, we describe how nine SPUGS in Copenhagen are used by the citizens based on data from 686 respondents who completed on-site questionnaires during their visit. The results show that SPUGS are primarily used for ‘socialising’ and ‘rest and restitution’. Furthermore, they are mainly used by well-educated people between the ages of 30 and 49. For ‘socialising’, SPUGS are primarily used on the way home. For ‘rest and restitution’, SPUGS are primarily used ‘en route’ or on the way home. More than half of the respondents reported living more than 1000 m from the SPUGS, and more than half of the respondents reported that they travel more than 500 m to get to the SPUGS. People aged 50–65 are more likely to visit the SPUGS for ‘rest and restitution’ than the younger age groups. Furthermore the older people are, the less likely they are to visit SPUGS to socialise. These results show that SPUGS are an important asset in citizen's everyday lives, and the results may provide inspiration for landscape architects, city planners and policy makers for the future planning of dense city areas. 相似文献
13.
Shu-Hsien Lee 《Scientia Horticulturae》1982,17(3):201-209
China is one of the oldest centres for vegetable crops. Some of them can still be found in the wild or semi-wild state, but some have already spread to other countries to become world-wide crops. There are many species currently growing that are peculiar to China, including aquatic vegetables, bamboo sprouts and several kinds of beans, gourds, tubers and greens. Quite a number of Brassica varieties are widely grown. Some are considered to have originated in north China (B. pekinensis), and some in central and south China (B. chinensis and B. juncea), and then spread out to Japan and south-eastern Asia. Schemes for the development of different varieties are suggested. 相似文献
14.
研究了宿根性阔叶补血草（ＬｉｍｏｎｉｕｍｌａｔｉｆｏｌｉｕｍＯ．Ｋｕｎｔｚｅ）和里海补血草（Ｌ．ｃａｓｐｉｕｍＧｏｕａｎ）各植株间花粉和柱头的异型性，采用异型授粉方法进行种间杂交，克服了同型杂交不孕的困难，获得了种间杂种。通过染色体组型分析确认了杂种的真实性。入选的里海补血草×阔叶补血草杂种Ｆ１４号株性状优良，可通过组培繁殖形成无性系，作为补血草新类型推广。试验也为我国补血草野生资源的开发利用提供杂交育种技术参考 相似文献
15.
16.
17.
While major urban areas are expanding, becoming more crowded, vegetated lands areshrinking. Built-up densification limits the planning of large urban green spaces,depriving urban dwellers of the benefits provided by such structures. In this context,small public urban green spaces (SPUGS) become of high value for urban landscapes,and their distribution throughout the city should aim to compensate the lack of largergreen areas. The driving forces of SPUGS distribution may be linked to the urbanfunctions they are usually paired with.The current study aimed to determine which are the urban functions that benefit ofhigher amounts of SPUGS in their proximities and to map the distribution and densityof SPUGS within Bucharest, helping us expose the green deprived communities.Results revealed that multi-dwelling residential areas are the ones with higher share ofSPUGS within walking distance. Nevertheless, analysis on SPUGS deprivation withinthe city showed that communist planned residential neighbourhoods are greener thanthe ones developed in the past three decades. Healthcare and commercial functionswithin the city recorded smaller shares of SPUGS in their proximity, highlighting thatvulnerable groups (such as ill people) are exposed to less vegetation, and that publicplanning documents are not encouraging developers to allocate more land for greenfeature development.These results are relevant for projecting the quality of outdoor environmentsthroughout Romania’s capital and for assessing potential future managementchallenges. The outcomes of this research provide local policy makers and plannerswith the vulnerable areas in which immediate action for expanding the greeninfrastructures should take place. At the same time, the methodological approachdescribed in the study proved to be efficient in assessing the distribution of SPUGSthroughout the city and the determinants of this distribution. It can be easily replicatedin other cities by scholars and planners. 相似文献
18.
This paper aims to identify and assess the main decision factors that are relevant for the diffusion of green roof technology in cities of temperate climate in Europe. A mixed design method was applied to identify relevant factors and to structure these along a Strengths, Weaknesses, Opportunities and Threats framework. The factors were subsequently assessed by a sample of green roof experts, using an Analytical Hierarchy Process. The results indicate that prospects for green roofs are in general rather bright, and that dissemination potential is substantial. Green roofs are particularly likely to benefit from climate change and respective counter-strategies, as they are seen as an adaptation and mitigation measure. However, current barriers to adoption need to be carefully considered. Especially the dilemmatic incentive structures, in that building owners bear most of the risks and potential disadvantages, while the public collectively benefits from green roof advantages, could be a major implementation barrier. Without supportive policies, green roofs are thus unlikely to move from niche to regime level in the near future. 相似文献
19.
Ryadg与Rx是分别控制马铃薯对PVY和PVX极端抗性的两个重要基因。利用与两个抗PVY和PVX的基因紧密连锁的标记RYSC3与Rxsp,分别对190份中国马铃薯育成品种进行分子标记分析。结果显示,只含有RYSC3标记的品种15份,占总品种的7.9%|只含有Rxsp标记的品种8份,占总品种的4.2%|既含RYSC3标记也含Rxsp标记的品种7份,占总品种的3.7%。在含有这两种标记的品种中,40%以上为新型栽培种（Neo-tuberosum）和来源于国际马铃薯中心（CIP）的资源育成的品种,50%以上为2001年之后审定的品种。结果表明,目前我国具有抗病毒能力的马铃薯育成品种所占比例仍然较小,但是最近几年来比例在逐渐提高,马铃薯抗病毒育种正在逐渐取得进步。 相似文献