Dendroclimatic signals of pedunculate oak (Quercus robur L.) in Estonia

This study investigates the climate impact on the radial increment of pedunculate oak (Quercus robur L.) in Estonia at the species’ northern distribution limit. Tree-ring width series of 162 living oaks were compiled into three regional chronologies—western (1646–2008), northeastern (1736–2011), and southeastern Estonia (1912–2011). Although these regional growth patterns are similar to each other and even to the growth patterns in adjacent regions, spatial differences in growth responses to climate were established. Thus, oaks growing on shallow soil in western Estonia are positively influenced by summer (June–August) precipitation, and oaks on the deeper soil in northeastern Estonia are favoured by June temperature, while oaks in the southeastern part of the country depend on both July precipitation and temperature. These relationships are pronounced especially in pointer years. However, due to the impact of regional weather fluctuations on tree growth, there is a lack of correspondence between the local and the pan-European pointer years. In addition, our research presents the first tree-ring-based palaeoclimatic reconstruction for the country. Although the created model has relatively low predictive skill describing less than a quarter of the variance in actual summer precipitation in western Estonia, it has passable capacity of detecting past rainfall extremes.     

动物科学专业《饲料学》课程教学方法改革与探索

从教学计划、教学方式、教学内容与实践安排等方面介绍了《饲料学》课程的具体改革与创新措施,旨在通过教学改革提高学生的实践技能,培养学生分析问题和解决问题的能力,启发学生的创新思维,提高学生的综合素质。     

The effects of pure and undersowing green manures on yields of succeeding spring cereals

Abstract

A field experiment was conducted in 2004–2006 to investigate the effect of green manure treatments on the yield of oats and spring barley. In the experiment, different green manure crops with undersowing and pure sowing were compared for amounts of N, C, and organic matter driven into soil and their effect on cereal yield. The spring barley field had a total of 41.7–62.4 kg N ha^?1 and 1.75–2.81 Mg C ha^?1 added to the soil with straw, weed, and roots, depending on the level of fertilisation; with red clover, and both common and hybrid lucerne undersowing, with barley straw and roots, the values were 3.45–3.96 Mg C ha^?1 and 139.9–184.9 kg N ha^?1. Pure sowings of these three leguminous green manure crops had total applications of 3.37–4.14 Mg C ha^?1 and 219.7–236.8 kg N ha^?1. The mixed and pure sowing of bird's-foot trefoil provided considerably less nitrogen and carbon to the soil with the biomass than with the other leguminous crops. Application of biomass with a high C/N ratio reduced the yield of the succeeding spring cereals. Of the green manures, the most effective were red clover and both common and hybrid lucerne, either as undersowing or as pure sowing. Undersowings with barley significantly increased the N supply for the succeeding crop without yield loss of the main crop compared with the unfertilised variant. Compared with ploughing-in of green manure in autumn, spring ploughing gave a 0.2–0.57 Mg ha^?1 larger grain yield.     

Soil compaction effects on soil bulk density and penetration resistance and growth of spring barley (Hordeum vulgare L.)

Abstract

The weight of the tractor is not the only factor affecting soil compaction. Soil-management practices, such as the use of fertilizers and pesticides, also affect soil properties through an increased number of overriding. The aim of the current study was to investigate compaction effects on soil physical properties, such as dry bulk density and penetration resistance, and the growth of spring barley (Hordeum vulgare L.) as a monoculture. The five-year experiment was conducted on the Estonian University of Life Sciences’ research field at Eerika, near Tartu in 2001–2005. The soil of the experimental site is sandy loam Stagnic Luvisol. The treatments included were no compaction, one pass, three passes, and six passes. All passes were track-by-track. Measurements of soil and plant were made in the earing phase of barley and measurements of yield in the maturity phase of barley. The compaction treatment was conducted using an MTZ-82 tractor (total weight 4.84 Mg). Neither fertilizers nor herbicides were used. 5 years after compaction distinguishable subsoil and topsoil compaction was detected. Soil deformation increases with the number of passes; in the case of six passes soil bulk density increased by 0.15 Mg m^?3 and penetration resistance by 3 MPa. However, there were no significant differences in the soil bulk density and penetration resistance between treatments compacted with one and three passes. The effect of compaction on soil bulk density was higher when the soil was compacted under wet conditions. Compaction decreased the quantity of barley shoots, their phytomass, and grain yield by more than 80%. In the second year of the experiment the dry weight of above ground biomass decreased by almost three times and shoots’ density by 1.5 times, compared with the first year results. In the third year of the experiment the biomass, plant density, and grain yield of barley were stabilized and no further decreases were detected in the following two experimental years. The results from the experiment revealed that even a low weight tractor can induce subsoil compaction and a high decrease of plant productivity by repeated passes over time.     

卡拉库尔羊被毛特性与等级相关性的探讨

本试验对１１０只羔羊的被毛特性和等级进行了相关性分析，结果表明；毛卷类型，毛长，清晰度与等级有较强的相关性，其它一些被毛特性与呈弱相关。     

东北林蛙8个地理种群的形态聚类分析（英文）

[Objective] The research aimed to determine the geographic distribution map of system of Rana dybowskii.[Method] Four morphologic indices(body length,body weight,forelimb length,hindlimb length)of eight geographical populations of R.dybowskii which naturally distribute in Changbai Mountain and Xiaoxing'an Mountain were measured.Measure results were variance analyzed and cluster analyzed.[Result] Variance analysis showed:the genetic branching among the Dongfanghong male population(belongs to Wandashan)and Xiaoxing'an Mountain male population and Changbai Mountain male population were significantly different(P<0.05);the genetic branching between the Hebei female population(belongs to Xiaoxing'an Mountain)and Changbai Mountain female population was significantly different(P<0.05).Cluster analysis showed:male R.dybowskii can be divided into three groups:the first group included Quanyang,Tianbei,Chaoyang and Dakouqin,the second group included Tieli and Anshan,the third group included Dongfanghong;and the female R.dybowskii can be divided into three groups:the first group included Quanyang and Chaoyang,the second group included Tianbei and Dakouqin,the third group included Hebei.[Conclusion] The paper deduced that the Sanjiang Plain was the geographical origin center of R.dybowskii which radiated to Changbai Mountain and Xiaoxing'an Mountain along the adverse current of Songhua River basin,therefore,the current distribution pattern of R.dybowskii was formed.     

一株拮抗棉花枯萎病菌产铁载体内生细菌的筛选(英文)

[目的]以盆栽控病效果良好的一株植物内生细菌为材料,通过对铁载体的研究,探索其对棉花枯萎病的拮抗机制。[方法]通过蔗糖-天冬氨酸(Modified Sugar-Aspartic Acid,MSA)平板初步判断菌株是否产铁载体及其荧光特性;根据特定波长下吸光度值测定各菌株在液体MSA培养基内产铁载体活性;不同铁离子浓度下,比较其铁载体对棉花枯萎病的抑制作用;结合形态、生理生化等特征对其进行初步鉴定。[结果]该内生细菌在MSA培养基中高产的荧光铁载体对棉花枯萎病原真菌——尖孢镰刀菌(Fusarium oxysporum)具有抑制作用,随着铁离子浓度的提高对病原真菌的抑制作用减弱;初步分析确定该内生菌株属于芽孢杆菌属(Bacillus)。[结论]芽孢杆菌可以通过分泌铁载体竞争铁的吸收而抑制尖孢镰刀菌的生长。     

棉酚对多浪羊淋巴细胞凋亡的影响

通过棉酚对多浪羊淋巴细胞的研究,探索棉酚体积分数对淋巴细胞的影响.主要用细胞培养、瑞氏-吉姆萨染色、DNA电泳等方法观察棉酚对多浪羊淋巴细胞的凋亡效应.结果表明:当细胞培养液中棉酚体积分数为0.071mol/L,培养淋巴细胞8h后,可抑制多浪羊淋巴细胞的增殖,并且促进其凋亡.     

Stocktake study of current fertilisation recommendations across Europe and discussion towards a more harmonised approach

The European Commission has set targets for a reduction in nutrient losses by at least 50% and a reduction in fertiliser use by at least 20% by 2030 while ensuring no deterioration in soil fertility. Within the mandate of the European Joint Programme EJP Soil ‘Towards climate-smart sustainable management of agricultural soils’, the objective of this study was to assess current fertilisation practices across Europe and discuss the potential for harmonisation of fertilisation methodologies as a strategy to reduce nutrient loss and overall fertiliser use. A stocktake study of current methods of delivering fertilisation advice took place across 23 European countries. The stocktake was in the form of a questionnaire, comprising 46 questions. Information was gathered on a large range of factors, including soil analysis methods, along with soil, crop and climatic factors taken into consideration within fertilisation calculations. The questionnaire was completed by experts, who are involved in compiling fertilisation recommendations within their country. Substantial differences exist in the content, format and delivery of fertilisation guidelines across Europe. The barriers, constraints and potential benefits of a harmonised approach to fertilisation across Europe are discussed. The general consensus from all participating countries was that harmonisation of fertilisation guidelines should be increased, but it was unclear in what format this could be achieved. Shared learning in the delivery and format of fertilisation guidelines and mechanisms to adhere to environmental legislation were viewed as being beneficial. However, it would be very difficult, if not impossible, to harmonise all soil test data and fertilisation methodologies at EU level due to diverse soil types and agro-ecosystem influences. Nevertheless, increased future collaboration, especially between neighbouring countries within the same environmental zone, was seen as potentially very beneficial. This study is unique in providing current detail on fertilisation practices across European countries in a side-by-side comparison. The gathered data can provide a baseline for the development of scientifically based EU policy targets for nutrient loss and soil fertility evaluation.     

Effects of the nitrification inhibitor nitrapyrin and tillage practices on yield-scaled nitrous oxide emission from a maize field in Iran

Nitrification inhibitors can effectively decrease nitrification rates and nitrous oxide(N₂O)emission while increasing crop yield under certain conditions.However,there is no information available on the effects of nitrification inhibitors and tillage practices on N₂O emissions from maize cropping in Iran.To study how tillage practices and nitrapyrin(a nitrification inhibitor)affect N₂O emission,a split factorial experiment using a completely randomized block design with three replications was carried out in Northeast Iran,which has a cold semiarid climate.Two main plots were created with conventional tillage and minimum tillage levels,and two nitrogen(N)fertilizer(urea)management systems(with and without nitrapyrin application)were created as subplots.Tillage level did not have any significant effect on soil ammonium(NH₄⁺)and nitrate(NO₃^-)concentrations,cumulative amount and yield-scaled N₂O emission,and aboveground biomass of maize,whereas nitrapyrin application showed significant effect.Nitrapyrin application significantly reduced the cumulative amount of N₂O emission by 41%and 32%in conventional tillage and minimum tillage practices,respectively.A reduction in soil NO₃^-concentration by nitrapyrin was also observed.The average yield-scaled N₂O emission was 13.6 g N₂O-N kg^-1N uptake in both tillage systems without nitrapyrin application and was significantly reduced to 7.9 and 8.2 g N₂O-N kg^-1N uptake upon the application of nitrapyrin in minimum tillage and conventional tillage practices,respectively.Additionally,nitrapyrin application increased maize biomass yield by 4%and 13%in the minimum tillage and conventional tillage systems,respectively.Our results indicate that nitrapyrin has a potential role in reducing N₂O emission from agricultural systems where urea fertilizers are broadcasted,which is common in Iran due to the practice of traditional farming.