我国绿茶由比较优势转化为竞争优势的途径

茶叶是我国的传统出口产品,我国的绿茶在国际市场上具有明显的比较优势,但这种比较优势并没有充分地得以发挥,如何将比较优势转化为竞争优势对于扩大我国绿茶出口规模、增加绿茶出口的经济效益意义重大。进行了从比较优势到竞争优势的理论探讨;分析了我国绿茶比较优势现状及存在问题;提出了将绿茶产品产业的潜在比较优势转化为竞争优势的途径。     

武定鸡早期肉用性能遗传规律的研究

 本文对武定鸡90日龄活重、胸角、龙骨长及屠体性状的遗传规律初步进行了探讨。材料取自我校鸡场1985年1～6月两批出雏的各200只纯繁殖鸡种,测定诸性状的平均数、标准差。遗传分析用单元内半同胞相关法,将不同季节及性别不同资料合并,计算活重遗传力为0.364,龙骨0.1843,胸角0.376,屠体十个性状的遗传力最高是全净膛重0.8748,最低屠体重0.1,此外着重分析活重、龙骨长、胸角度与屠体主要性状的表型相关、遗传相关及环境相关。结果活重与胸角度、龙骨长间存在较高的遗传相关(0.425、0.4652)。而这三个性状,又与屠体诸性状的主要性状间呈较强的正相关。因此通过对活重等三个性状的辅助选择,有可能提高选种的准确性,从而提高遗传改进量。     

Effects of six years of simulated N deposition on gross soil N transformation rates in an old-growth temperate forest

Elevated atmospheric nitrogen(N) deposition has been detected in many regions of China, but its effects on soil N transformation in temperate forest ecosystems are not well known. We therefore simulated N deposition with four levels of N addition rate(N0, N30, N60, and N120) for6 years in an old-growth temperate forest in Xiaoxing'an Mountains in Northeastern China. We measured gross N transformation rates in the laboratory using ~(15)N tracing technology to explore the effects of N deposition on soil gross N transformations taking advantage of N deposition soils. No significant differences in gross soil N transformation rates were observed after 6 years of N deposition with various levels of N addition rate. For all N deposition soils, the gross NH_4~+ immobilization rates were consistently lower than the gross N mineralization rates,leading to net N mineralization. Nitrate(NO_3~-) was primarily produced via oxidation of NH_4~+(i.e., autotrophic nitrification), whereas oxidation of organic N(i.e., heterotrophic nitrification) was negligible. Differences between the quantity of ammonia-oxidizing bacteria and ammonia-oxidizing archaea were not significant for any treatment, which likely explains the lack of a significant effect on gross nitrification rates. Gross nitrification rates were much higher than the total NO_3~- consumption rates,resulting in a build-up of NO_3~-, which highlights the high risk of N losses via NO_3~- leaching or gaseous N emissions from soils. This response is opposite that of typical N-limited temperate forests suffering from N deposition,suggesting that the investigated old-growth temperate forest ecosystem is likely to approach N saturation.     

氯化物催化合成甲,乙,丙酸异戊酯的活性和机理探讨

本文分别用氯化铁，氯化铝和氯化铜催化合成甲、乙、丙酸异戊酯，实验证明氯化铁，氯化铝有较高催化活性，对五个碳以下的有机酸和醇的酯化活性较高，并对其机理进行了的探讨。     

Policy impacts on regulating ecosystem services: looking at the implications of 60 years of landscape change on soil erosion prevention in a Mediterranean silvo-pastoral system

Context

Policy decisions form a major driver of land use change, with important implications for socially and environmentally susceptible regions. It is well known that there can be major unintended consequences, especially where policies are not tailored to regionally specific contexts.

Objectives

In this paper we assess the implications of 60 years of agricultural policies on soil erosion prevention (SEP) by vegetation, an essential regulating ecosystem service in Mediterranean Europe.

Methods

To assess these implications we produced and analysed a time series of land cover/use and environmental conditions datasets (from 1951 to 2012) in relation to changing agricultural policies for a specific region in the southern Portugal. A set of indicators related to SEP allowed us to identify that land use intensification as increased soil erosion in the last 60 years.

Results

Particularly in the last 35 years, as a consequence of headage payments for cattle, the agricultural policy had a significant effect in the density and renewal of the tree cover, resulting in drastic effects for the provision of the SEP service. These are more significant after 1986, coinciding with the implementation of several Common Agricultural Policy instruments focused on increasing the modernization and productivity capacity of farm systems.

Conclusions

The results show some unintended effects of agricultural policy mechanisms on ecosystem service provision and highlight the need for context-based policies, tailored to the environmental constrains and potentials of each region.

     

Protective Effect of <Emphasis Type="Italic">Juglans regia</Emphasis> L. Walnut Extract Against Oxidative DNA Damage

Walnuts (Juglans regia L.) are relevant components of the Mediterranean diet providing important macronutrients, micronutrients and other bioactive constituents including unsaturated fatty acids, proteins, fiber, vitamins, minerals, phytosterols and polyphenols. Although the walnut beneficial effects in human health are widely recognized by a lot of epidemiologic studies very little is known regarding its effect on damaged DNA. The aim of the present study was to investigate the effect of Juglans regia L. ethanolic extract from kernel on the induction of DNA strand breaks by thiol/Fe³⁺/O₂ mixed function oxidase, tert-butyl hydroperoxide or UVC radiations in acellular and cellular models. Plasmid DNA cleavage and fast Halo assay were used to monitor oxidative damage to DNA. Both approaches showed protection of oxidatively injured DNA. These results agree with a lot of scientific proofs which recommend walnut as dietary adjunct in health promotion and prevention as well as in treatment of lifestyle-related oxidative diseases.     

Performance of four <Emphasis Type="Italic">Trichogramma</Emphasis> species (Hymenoptera: Trichogrammatidae) as biocontrol agents of <Emphasis Type="Italic">Heliothis virescens</Emphasis> (Lepidoptera: Noctuidae) under various temperature regimes

Trichogramma spp. are major parasitoids of lepidopteran pest eggs, but there is large variation in efficacy toward a given pest among the numerous described Trichogramma species. It is important to select the Trichogramma species that most effectively parasitize and develop in target pest eggs for biological control. In this context, Trichogramma pretiosum, T. exiguum, T. atopovirilia and T. acacioi were studied in Heliothis virescens eggs under different thermal conditions. The parasitoids were reared at constant temperatures of 20, 25 and 30°C and tested at these respective temperatures, while parasitoids reared at 25°C were also tested at 20 and 30°C, for a total of 20 species–temperature combinations. About 30 H. virescens eggs were offered to the parasitoids for 24 h. Among the four species, parasitism rate by T. atopovirilia was highest at all temperature conditions, whereas T. acacioi had the lowest rates of parasitism at 25°C and 25/30°C. Parasitism ranged from 13.8 to 43.8% among all species–temperature combinations. Viability (emerged parasitoids) ranged from 80.8 to 98.4%, and was deemed satisfactory. The emergence rates of T. exiguum and T. acacioi were affected by temperature. Temperature also affected the sex ratio of T. exiguum at 25/30°C, whereas T. pretiosum and T. acacioi produced females predominantly independent of temperature. Overall, the parasitoid T. atopovirilia was the most efficient in parasitizing H. virescens eggs, though the levels of parasitism obtained might not ensure its successful use in biological control programs. The temperature-related differences in biological traits observed in the four Trichogramma species tested hint at the importance of making careful choices regarding climatic conditions where the parasitoid is going to be used when selecting a species for biological control programs.     

Conservation planning with spatially explicit models: a case for horseshoe bats in complex mountain landscapes

Context

Context Bats are considered as an ecological indicator of habitat quality due to their sensitivity to human-induced ecosystem changes. Hence, we will focus the study on two indicator species of bats as a proxy to evaluate structure and composition of the landscape to analyze anthropic pressures driving changes in patterns.

Objectives

This study develops a spatially-explicit model to highlight key habitat nodes and corridors which are integral for maintaining functional landscape connectivity for bat movement. We focus on a complex mountain landscape and two bat species: greater (Rhinolophus ferrumequinum) and lesser (Rhinolophus hipposideros) horseshoe bats which are known to be sensitive to landscape composition and configuration.

Methods

Species distribution models are used to delineate high-quality foraging habitat for each species using opportunistic ultrasonic bat data. We then performed connectivity analysis combining (modelled) suitable foraging habitat and (known) roost sites. We use graph-theory and the deviation in the probability of connectivity to quantify resilience of the landscape connectivity to perturbations.

Results

Both species were confined to lowlands (<1000 m elevation) and avoided areas with high road densities. Greater horseshoe bats were more generalist than lesser horseshoe bats which tended to be associated with broadleaved and mixed forests.

Conclusions

The spatially-explicit models obtained were proven crucial for prioritizing foraging habitats, roost sites and key corridors for conservation. Hence, our results are being used by key stakeholders to help integrate conservation measures into forest management and conservation planning at the regional level. The approach used can be integrated into conservation initiatives elsewhere.

     

Evaluation of the temporal distribution of <Emphasis Type="Italic">Fusarium graminearum</Emphasis> airborne inoculum above the wheat canopy and its relationship with Fusarium head blight and DON concentration

With the aim of unravelling the role of airborne Fusarium graminearum inoculum in the epidemic of Fusarium head blight (FHB) caused by this species in wheat spikes, a network of Burkard air samplers was set up in five wheat fields distributed in Belgium from 2011 to 2013. Each year from April to July, the daily amounts of F. graminearum inoculum above the wheat canopy were quantified using a newly developed TaqMan qPCR assay. The pattern of spore trapping observed was drastically different per year and per location with a frequency of detection between 9 and 66% and a mean daily concentration between 0.8 and 10.2 conidia-equivalent/m³. In one location, air was sampled for a whole year. Inoculum was frequently detected from the wheat stem elongation stage until the end of the harvesting period, but high inoculum levels were also observed during the fall. Using a window-pane analysis, different periods of time around wheat flowering (varying in length and starting date) were investigated for their importance in the relation between airborne inoculum and FHB parameters (FHB severity, frequency of F. graminearum infection and DON). For almost all the combinations of variables, strong and significant correlations were found for multiple window lengths and starting times. Inoculum quantities trapped around flowering were highly correlated with F. graminearum infection (up to R?=?0.84) and DON (up to R?=?0.9). Frequencies of detection were also well correlated with both of these parameters. DON concentrations at harvest could even be significantly associated with the F. graminearum inoculum trapped during periods finishing before the beginning of the anthesis (R?=?0.77). Overall, these results highlight the key role of the airborne inoculum in F. graminearum epidemics and underline the importance of monitoring it for the development of disease forecasting tools.     

氮磷钾施用量对灌淤土水稻产量及肥料利用率的影响

在宁夏灌淤土上,利用田间试验研究了氮、磷、钾各3个施肥水平对水稻(宁粳28号)产量、养分累积量及籽粒产量构成因素的影响。结果表明,施用氮、钾肥对水稻产量和养分累积有显著影响;水稻当季氮、磷、钾肥利用率都随着施肥量的增加而降低;穗数和每穗粒数随施氮量的增加而增加,而施磷肥有利于穗粒数的形成,过量施用氮肥还会显著降低水稻千粒质量。本试验水稻氮、磷、钾肥最佳经济施肥量分别为N 254.3、P2O5150.8和K2O 145.6 kg/hm2,获得最高产量的最大施肥量组合分别为N 309.3、P2O5253.9和K2O177.6 kg/hm2。