Effects of Grazing Intensity on Soil and Vegetation Properties in a Mediterranean Rangeland

Grazing modifies the aboveground soil and plants of rangeland ecosystems. This study was conducted to determine the effects of various grazing intensity levels on soil bulk density, soil pH, soil electrical conductivity (EC), soil total organic carbon (TOC), aboveground biomass production, plant community richness (N), and vegetation diversity (H) in Gian Rangeland, Hamedan Province, Iran. Soil and vegetation samplings were conducted based on the randomized systematic method. Soil and vegetation samplings were carried out along 100-m-long transects placed at 100, 200, 400, 800, and 1600 m running perpendicular to six sheep corrals. The effects of various grazing intensities on studied parameters were detected by analysis of variance (ANOVA) (at α = 0.05). Results of this study indicated the soil bulk density, EC, TOC, aboveground biomass production, plant community richness, and vegetation diversity values were altered significantly at different distances from the sheep corrals. However, soil pH was not significantly affected by various grazing intensities.     

Single and Interactive Effects of Temperature and Light Quality on Four Canola Cultivars

Combined effects of temperature and light quality on plants have received little attention. We investigated the single and interactive effects of temperature and light quality on growth and physiological characteristics of four canola (Brassica napus) cultivars – Clearfield 46A76 (cv₁), Clearfield 45H72 (cv₂), Roundup Ready 45H24 (cv₃) and Roundup Ready 45H21 (cv₄). Plants were grown under lower (24°/20 °C) and higher (30°/26 °C) temperature regimes at low red/far‐red (R/FR), normal R/FR and high R/FR light ratios in environment‐controlled growth chambers (16 h light/8 h dark). Higher temperature reduced stem height and diameter; leaf number and area; dry matter of all plant parts; and specific leaf weight, but increased leaf area ratio; and chlorophyll (Chl) fluorescence (Y). Low R/FR increased stem height; Y; and ethylene, but decreased stem diameter; F_v/F_m; Chl a; Chl b; and carotenoids. Among cultivars, plants from cv₄ were tallest with thickest stems and greatest dry matter. None of the main factors affected gas exchange. Higher temperature at high R/FR caused cv₃ to be shortest, whereas lower temperature at low R/FR caused cv₄ to be tallest. We conclude that heat and other stress factors will adversely affect sensitive crops, but tolerant genotypes should perform well under future climate.     

冷凝法回收油气的经济性分析

为分析冷凝法回收挥发油气的经济性,结合中国石化长岭分公司在油气装车时检测的由14种气体组成的油气混合物及其组分浓度数据,对采用三级冷凝工艺回收挥发油气的方案进行建模和计算.3级制冷系统分别采用R22、R404A和R508B作为制冷工质,得到各级制冷系统的制冷系数及其能量消耗结果,采用ChemCAD软件获得油气回收效率,通过计算求得制冷系统年平均运行能耗、运行费用、初期投资和收益.分析结果表明：采用冷凝法对油气进行回收时,该工艺系统投运一年内即可完全收回初期投资和当年运行费用,且当处理油气量为40 kg/h时,当年净盈利可以达到4.487 1×104元,年平均净收益远大于年平均总投资.（表5,图1,参4）     

三种荒漠植物叶绿素荧光参数日变化特征

利用Photosynq MultiseQ多功能植物测量仪测定塔克拉玛干沙漠腹地3种主要防护林植物头状沙拐枣、多枝柽柳和梭梭的叶绿素荧光参数日变化,探讨其与环境因子的关系,以揭示3种植物对极端环境的适应策略,为沙漠公路防护林的管护提供理论依据。结果表明：1）3种土壤都呈碱性;0~30 cm土层中的电导率（EC）远高于30 cm以下的土层。1 m内梭梭土层中的含水量高于多枝柽柳高于头状沙拐枣。2）3种植物的光合有效辐射（PAR）、叶片温度和线性电子传递（LEF）及植物周围的大气温度日变化均先升后降,且都在14：00达到最高;而大气湿度、实际光化学效率Y_（II）日变化均呈‘V’型。3）PAR基本上与3种植物的LEF、非光化学淬灭系数（NPQ）、调节性能量耗散量子产量Y_（NPQ）、非调节性能量耗散量子产量Y_（NO）呈显著正相关,与实际光化学效率Y_（II）呈显著负相关;3种植物的Y_（II）与Y_（NPQ）、Y_（NO） 均呈极显著负相关。3种植物的LEF、Y_（II）、Y_（NPQ）的日均值差异不显著,但梭梭与多枝柽柳的NPQ和Y_（NO）日均值差异显著。4）在3种植物的叶绿素荧光参数中,梭梭和头状沙拐枣的LEF、NPQ和Y_（II）要高于多枝柽柳;而多枝柽柳的Y_（NO）要显著高于头状沙拐枣和梭梭。因此,高温和高光均对3种植物造成了不同程度的影响,通过主成分分析表明,3种植物的抗逆性强弱顺序分别为梭梭>头状沙拐枣>多枝柽柳。     

放牧对草甸草原土壤水热状况和地上生物量的影响

本文以呼伦贝尔草甸草原为对象,研究了不同放牧强度对草原群落土壤水热状况和地上生物量的影响,旨在揭示二者之间的相互关系。研究结果表明,随着放牧强度的增加,生长季平均土壤温度呈逐渐上升的趋势;放牧对群落3个组份[羊草（Leymus chinensis）、贝加尔针茅（Stipa baicalensis）、杂类草]生物量和相对优势度产生影响。其中,羊草地上生物量和优势度随着放牧强度的增加显著线性降低,而贝加尔针茅和杂类草的生物量与优势度均在中度放牧处理下最高。土壤含水量与羊草生物量显著正相关,与杂类草生物量负相关,而与贝加尔针茅生物量间的关系极弱。本研究为完善放牧优化理论,揭示放牧在草地生态系统功能过程中的梯度效应提供了一个较为重要的研究线索,为草地放牧优化管理制度的确立提供了一定的科学依据。     

绒山羊皮肤毛囊兴盛前期组织形态、chi-miR-107-3p与RHBDF2基因表达分析

为了探究chi-miR-107-3p和菱形家族蛋白2（rhomboid family member 2,RHBDF2）基因在不同品种（系）和光控增绒绒山羊兴盛前期（5~7月份）皮肤毛囊重建时的表达差异,本试验在7月份采集内蒙古阿拉善型绒山羊、敏盖绒山羊和光控增绒技术处理的阿尔巴斯型绒山羊体侧皮肤毛囊组织,采用组织切片技术对组织形态比较分析,实时荧光定量PCR法检测chi-miR-107-3p和RHBDF2基因的表达量。结果显示,在皮肤毛囊兴盛前期,阿拉善型绒山羊次级毛囊正处于重建阶段,敏盖绒山羊和阿尔巴斯型绒山羊（光控增绒）次级毛囊重建已基本完成;在阿拉善型绒山羊皮肤组织中chi-miR-107-3p表达量极显著高于敏盖绒山羊和阿尔巴斯型绒山羊（光控增绒）（P<0.01）,而RHBDF2基因表达量极显著低于其他两品种（系）（P<0.01）,且RHBDF2基因表达量在敏盖绒山羊皮肤组织中显著低于阿尔巴斯型绒山羊（P<0.05）。不同品种（系）和光控增绒绒山羊皮肤毛囊兴盛前期组织显微结构与chi-miR-107-3p、RHBDF2基因在皮肤组织中的表达差异分析结果相一致,次级毛囊重建初期chi-miR-107-3p表达量较高,而RHBDF2基因表达量极低,随着次级毛囊重建完成,chi-miR-107-3p表达量明显降低,RHBDF2基因表达量逐渐增高,且在不同品种（系）内蒙古绒山羊绒毛生长发育过程中的表达机制基本相同。因此,chi-miR-107-3p和RHBDF2基因是绒山羊皮肤毛囊生长发育的重要调控因子。     

荒漠草原主导种群与植物群落地上现存量的关系

以内蒙古锡林郭勒盟苏尼特右旗短花针茅荒漠草原为对象,采用随机区组放牧试验设计,结合对比分析、线性回归分析以及结构方程模型等数据分析方法,探讨荒漠草原主要种群与植物群落地上现存量的关系及在放牧条件下的变化特点。结果表明:随放牧强度增大,短花针茅、无芒隐子草和碱韭主导种群地上现存量占植物群落地上现存量的比例下降,且主导种群与植物群落地上现存量的线性关系减弱;不同年度间主导种群占植物群落地上现存量比例以及线性关系会产生变动;短花针茅种群对荒漠草原植物群落的影响强于无芒隐子草种群和碱韭种群,但无芒隐子草种群在降雨较好年份具有补偿作用。     

浅谈轻烃混空燃气鼓泡制气工艺的物理原理及应用

论述了以C5为主的轻烃液体燃料,采用鼓泡法按比例混入空气的制气工艺,将液态烃置换为优质轻烃混空燃气的物理原理,为设计、制造气化装置提供了理论依据。     

A longitudinal study of oestrous characteristics and conception in tie-stalled and loose-housed Swedish dairy cows

The presence and importance of visual oestrous symptoms and the relation to conception, breed, housing system and milk yield were studied. Data were collected from a Swedish research herd during a 16-year period. Local, secondary and primary oestrous symptoms and an overall oestrus intensity score (OI) were studied. Decreasing trends in oestrous expression and conception rates (CR), and an increase in CR with more intensive oestrus, from 24% at OI score one (very week) to 54% at OI score five (very strong) were observed. The mean interval from first to last observed oestrus symptom was long with a large variation (54?±?SD?=?32?h). Generally, irrespectively of housing system, Swedish Red cows had higher CR, more intensive oestruses and longer oestrus durations compared to Swedish Holstein cows. Local oestrous symptoms, with CR of 24–28%, were most frequently detected, which is why more attention should be paid to local oestrous symptoms.     

路灯照射对大豆生长发育和产量的影响

通过对淮北市五马路沿线2块夏大豆的田间调查分析表明:受路灯照射的影响,夏大豆株高增加,开花期、成熟期推迟,底荚部位上升,单株生产力下降.且距离越近,植株越高,开花、成熟越晚,底荚部位越高,单株生产力越低.