内蒙古冷蒿小禾草放牧草原退化与恢复对策研究

对不同围栏年限放牧草原的研究结果表明,冷蒿重要性随着围栏时间的增加呈先增后降的趋势;地上部总干物重、植被总覆盖度、植物平均高度与围栏时间呈负相关变化.在全年性放牧草地中,以上指标均低于围栏放牧草地.植物多样性指数与均匀性指数与围栏时间呈正相关关系.由此提出了遵循生态学原理恢复退化草地的几种措施.     

西藏草业发展战略研究

在介绍西藏草地资源和草业发展现状的基础上,从草地生态保护与植被恢复重建、高寒草地畜牧业、牧草与草坪草种子生产、草坪业和牧草种质资源五方面对西藏草业的发展战略进行了探讨并提出了发展西藏草业的一些对策和措施。     

兰州市桃蚜抗药性监测及治理对策研究

以甘肃省宕昌县桃蚜为敏感种群,测定了兰州、永登等地桃蚜对6种杀虫剂抗药性。结果表明兰州市安宁区桃蚜对溴氰菊酯已产生低水平抗性(6.84倍),对氰戊菊酯则处于耐药力增高或敏感性降低阶段,对灭多威、敌敌畏、氧乐果和乐果已显示出早期抗性;永登县桃蚜对溴氰菊酯和氰戊菊酯处于敏感性降低阶段,对灭多威、敌敌畏、氧乐果和乐果仍属敏感阶段;皋兰县和榆中县桃蚜对上述6种杀虫剂则处于敏感阶段。用酶抑制剂进行增效作用测定结果显示,兰州地区桃蚜的抗药性与羧酸酯酶和多功能氧化酶有关。针对兰州市桃蚜的抗药性现状和抗性机制,提出了以建立抗性监测制度、合理用药为主的抗性治理对策。     

开展校园足球活动的影响因素及对策研究

影响校园足球活动开展的因素众多,采用文献资料法、专家访谈法、实地考察法等,从人、财、物、相关配套政策等方面对影响校园足球开展的相关因素进行梳理。紧紧抓住学生这个活动的主体,从普及、参与和后备人才培养两方面入手,探讨与之相关的影响因素以及存在问题。并提出相应对策：统一认识,理清管理体系;加大经费投入和相关政策的扶持;建立、健全青少年足球四级联赛体系;逐步完善升学机制。     

云南民族竹文化生态旅游研究(英文)

该文在分析云南丰富的旅游观赏竹类资源及其景观价值的基础上 ,从微观形态入手 ,探讨了竹类作为竹文化形成的 5个物质基础性美学特征 ;透过云南独特的观赏竹类及人文景观资源的宏观背景 ,论述了云南竹文化生态旅游的 4大宏观景观资源基础 ;经过对民族生态伦理和文化符号景观的研究 ,总结了作为民族传统生态意识的 3种典型风俗习惯 ,并揭示了作为云南民族竹文化精华的 3个特点 .作者以较宽的学术视野 ,通过借鉴新经济发展理论、创新理论和国内外生态旅游管理的成功经验 ,综合研究了横跨竹类学、民族学、生态学、生态经济学、旅游管理学等多学科的实物性、观念性和符号性民族竹文化景观 ,初步构建了民族竹文化的理论框架 ,简要论述了其独特性 ,并系统分析了民族竹文化与自然资源、其他文化以及生态旅游发展的相关性 ,旨在为生态经济型林业、文化经济学和生态旅游实践奠定坚实的理论基础 ,提供可靠的科学依据 .文中还相应地提出了通过有效保护与合理开发云南丰富多彩的自然及人文景观资源、实现云南生态旅游业可持续发展的 3种首要战略和相关原则     

Resistance gene deployment strategies in cereal hybrids using marker-assisted selection: Gene pyramiding, three-way hybrids, and synthetic parent populations

Marker-assisted selection (MAS) for resistance genes (R-genes), identified using molecular markers and quantitative trait loci (QTL) analysis, is now possible in many crops. MAS can be used to pyramid several R-genes into a single host genotype. However, this may not provide durable genetic resistance because the pathogen is exposed to a full homozygous pyramid during hybrid seed production and to a full heterozygous pyramid in the resultant hybrid. Alternative gene deployment strategies that generate genetic variability were analysed, for hybrid cereal cultivars of pearl millet, maize, sorghum and rice, using maintainer lines (B-lines) with two smaller complementary pyramids. An F₁ seed parent, produced on two such B-lines, can be used to produce a three-way hybrid. All target loci are heterozygous for resistance alleles in the F₁ seed parent, and the pathogen is exposed in the hybrid to a host population that is heterogeneous and heterozygous for alleles at the resistance loci targeted by MAS. Alternatively, single-cross hybrids can be made on seed parents that are maintained by two B-lines that differ for the complementary resistance gene pyramids. In a cross-pollinated crop, the B-lines are allowed to intermate to produce a synthetic B-line. In an inbreeding crop, the B-lines are equivalent to a two-component multiline variety. In inbreeding crops, because there is no intermating between the B-line components, the resultant synthetic seed parents have a higher frequency of genotypes with resistance alleles (R-alleles) at several resistance loci. However, in both cross-pollinated and inbreeding crops the genotypic structure in the hybrids is almost the same. All alternatives to a single-cross hybrid having a full pyramid produce hybrid cultivars having lower frequencies of resistance alleles. The frequency of genotypes having R-alleles at several loci increases greatly in both seed parent and hybrid when the overall frequency of R-alleles in the maintainer lines increases. This is simply done by adding a maintainer line that has a full pyramid or by the component lines having overlapping pyramids. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vertical distribution of earthworms in grassland soils of the Colombian Llanos

 The vertical distribution of native earthworm species from natural and disturbed savannas in the Oxisols of the Colombian Llanos was assessed in a native savanna and in a 17-year-old grazed grass-legume pasture during a period of 17 months. Different patterns of vertical stratification were observed for all species with a strong migration of populations to deeper layers in the dry season. The correlation between the size of the earthworms and the average depth at which they were found was not significant (P>0.05), despite the fact that bigger species are located deeper in the soil. The living habits and adaptive strategies of the smallest species, Ocnerodrilidae n. sp., found in both ecosystems studied are responsible for this pattern. This endogeic species is associated with organic pools generated by an anecic species and further studies should assess the role of this species in ecosystem functioning. Mature worms of one anecic species were located deeper than immature ones in the soil (P<0.01). Soil moisture had an important effect on the vertical distribution of earthworms, although differences between immature and mature worms of the anecic Martiodrilus carimaguensis are likely to be of biotic origin. New data on the biology and ecology of these Neotropical species are shown. Received: 24 November 1999     

The FishPath approach for fisheries management in a data- and capacity-limited world

Successful fisheries management systems tend to be underpinned by harvest strategies, specifying formally agreed data collection systems, assessment approaches and management measures used to regulate fishing pressure. While harvest strategies can be effective even in data- and capacity-limited (DCL) situations, their development remains challenging in such contexts. We present a process and decision-support tool, FishPath, to guide the identification of suitable harvest strategy component options given often debilitating conditions: (i) resource limitations and lack of technical management capacity; (ii) ‘uniqueness’ of DCL fisheries; (iii) the concept of harvest strategies is unfamiliar to managers and scientists, and the universe of options is hard to navigate; and (iv) the lack of an effective participatory process to identify solutions tailored to local contexts. These conditions can lead to either management paralysis or generic solutions that may be poor fits to specific conditions. The FishPath Tool uses a diagnostic questionnaire that elicits the key characteristics and specific circumstances of a fishery. It compares these with the requirements of alternative options from an inventory of possible harvest strategy components, identifies where these requirements are met and provides customised, transparent guidance on the appropriateness of component options of a harvest strategy, specific to the fishery of interest and its governance context. The FishPath Process is a facilitated multi-stakeholder, participatory engagement process aimed to set fisheries on the path to develop a harvest strategy. The FishPath Process and Tool combine to ensure a bottom-up, documented, transparent, replicable and efficient process.     

山西杂粮产业化的现状及对策

山西是杂粮栽培历史悠久,素来以品种多、质量优、营养丰富而倍受国内外市场欢迎。经过多年的发展,杂粮已成为山西农业的一大优势产业,但也存在品种退化、产量低、深加工落后等诸多问题,因此,在发展山西产粮产业问题上,必须树立战略思想,加强政府协调,制定配套措施,强化科技力量,建立优质基地,发展龙头企业,才能提高市场竞争力,成为山西农业经济的一大支柱和农业增收的重要途径。