辣椒细菌性果实条斑病菌生物学特性及抑菌药剂筛选

研究辣椒细菌性果实条斑病菌的生物学特性,对病原菌进行室内药剂筛选,旨在为田间病害规律研究和病害防治提供依据。采用紫外分光光度计测定病原菌在不同温度、pH、NaCl浓度下的生长速率。采用滤纸片抑菌圈法对病原菌进行室内药剂筛选试验。结果表明,辣椒细菌性果实条斑病菌最适生长温度为28℃,最适pH 7.0,病原菌的耐盐性为12%。18种供试药剂在药剂推荐使用剂量范围内,四霉素、乙蒜素、77%志信、氯溴异氰尿酸4种药剂对病原菌有抑菌效果,对这4种药剂进行毒力测定,结果表明四霉素的毒力较强,EC₅₀值为11.75 mg/L,毒力强于其他3种试剂,四霉素可作为田间防治药剂的首选。     

池塘内循环流水养殖模式对大口黑鲈生长性能、抗氧化酶、消化酶及消化道组织结构和菌群的影响

为探究养殖过程中池塘内循环流水养殖模式（inner-pond raceway aquaculture, IPRA）对大口黑鲈生长性能、抗氧化酶、消化酶、消化道组织结构及菌落结构的影响。将池塘内循环流水养殖的4条水槽设置为流水组2条和对照组2条，进行为期153 d的养殖实验，分别在养殖中期和末期测量相关生长、生化指标及观察组织形态结构，并采用Illumina Miseq测序平台对消化道中的微生物进行分析。结果显示：①养殖中期，流水组的增重率、特定生长率和肥满度低于对照静水组；至养殖末期，流水组的增重率、特定生长率和肥满度持续下降，但成活率一直高于静水组。②养殖中期，流水组肝脏SOD和CAT显著高于静水组，流水组MDA显著低于静水组，流水组消化酶活性显著高于静水组；至养殖末期，抗氧化酶和消化酶均不同程度下降，但流水组SOD仍显著高于静水组，MDA显著低于静水组。③流水组大口黑鲈肠绒毛高度及密度均明显高于静水组，且养殖中期分泌消化酶较多，运动加强了肠道消化吸收功能。④养殖中期，流水养殖使大口黑鲈肠胃菌群的物种多样性和均匀度明显增高，至养殖末期，流水组的肠胃多样性和均匀度指数不断下降；养殖中期流水组和静水组胃分别为柔膜菌门和蓝细菌，静水组肠主要优势菌依次为变形菌门和厚壁菌门，流水组肠主要优势菌分别为厚壁菌门和变形菌门；至养殖后期时，流水组和静水组胃肠优势菌群均为柔膜菌门；而养殖水体的优势菌为变形菌门和放线菌门。研究表明，IPRA模式下的持续运动会降低其生长指标，但能够提高其成活率，增强其免疫和消化能力，改善肠胃菌群结构，尤其是处于生长期效果更明显，而至养殖末期运动状态可能会打破肠道菌群平衡，引发疾病，应加强养殖管理。     

自动施肥系统开发与性能测试

目的 开发一种适应于以固态水溶肥为原料的自动施肥系统,测试分析自动施肥系统性能。方法 主控机采用ARM9电路控制模块可实现对轮灌编组、预搅拌时长、施肥开始与结束时间、施肥持续时长、施肥量等参数的设置;选择以蠕动泵为注肥装置,通过变频器控制注肥泵电机功率的方式控制注肥速率,控制施肥量。对装置核心部件搅拌器额定功率、计量方式、溶肥搅拌参数、排肥速度及固液相比例等主要参数等进行设计与测试。结果 电感脉冲计量方式标准误差最大值1.26%,误差小、性价比好,确定其为本装置采用的计量方式;搅拌器以1.5 Kw额定功率、38 r/min转速搅拌、肥液浓度在1.1~1.3 g/mL、预搅拌时间30 min时,罐内各液位输出肥液浓度值差异不显著(P< 0.05),达到对肥料浓度均匀性的设计要求。结论 将施肥开始前的预搅拌时间设为30 min、搅拌转速设为38 r/min、肥液浓度不高于1.3 g/mL,输出肥液浓度有较好的均匀性,实现精准施肥。     

马尾松叶表微生物多样性

为发掘对林木生长发育有利的优良微生物资源,并筛选适合叶表微生物的收集方法,以马尾松针叶为试验材料,分别用悬摇法和超声波法收集马尾松叶表微生物,用扩增子高通量测序技术、MUSCLE和Qiime软件研究马尾松叶表微生物的多样性。结果表明:扫描电镜观测结果显示,马尾松针叶表面定殖有大量微生物,包括真菌(菌丝及孢子)和细菌。扩增子高通量测序结果表明,马尾松叶表微生物物种丰富,包含细菌运算分类单位(OTUs)490个,真菌OTUs 1273个。马尾松叶表细菌以未分类的蓝细菌属(unidentified_Cyanobacteria)(36.53%)、未分类的拜叶林克氏菌属(unidentified_Beijerinckia)(28.60%)、鞘氨醇单胞菌属(Sphingomonas)(2.35%)为优势属;叶表真菌以枝孢属(Cladosporium)(2.45%)、拟盘多毛孢属(Pestalotiopsis)(0.92%)、无头孢菌属(Capnobotryella)(0.91%)为优势属。针对叶表细菌多样性的研究表明,悬摇法和超声波法均有较高的物种检出度;在叶表真菌多样性的研究中超声波法优于悬摇法,但超声波法样品间数据变异性较大,测定结果不稳定。     

中国林产工业集聚水平测度及演进趋势与产业经济增长——基于2003—2016年数据的实证分析

利用产业集聚指数和产业区域集中度测算2003—2016年中国林产工业两位数产业集聚水平，并实证分析林产工业两位数产业集聚与其经济增长的关系。研究表明:1）木材加工业和家具制造业处于中度集聚状态，而造纸与纸制品制造业处于低度集聚状态；2）木材加工业集聚度呈上升趋势，而家具制造业和造纸与纸制品制造业集聚度呈下降趋势；3）中国林产工业主要集聚在经济发达的江苏、广东、山东和浙江等沿海省份，但木材加工业和家具制造业分别在广西和四川有较快增长趋势；4）木材加工业集聚水平与其产业经济增长呈正相关，而家具制造业和造纸与纸制品制造业集聚与其产业经济增长呈负相关。     

Effects of partial replacement of nitrate with different nitrogen forms on the yield,quality and nitrate content of Chinese kale

In this study, the yields, nutritional qualities and nitrate (NO₃) content of Chinese kale were studied with two cultivars, following partial replacement of nitrate (20%) with ammonium (NH₄), urea and glycine in hydroponics. The results showed that, compared with the full nitrate treatment, ammonium replacement increased the fresh weight by 18.1% and 8.0% of ‘Zaobao’ and ‘Lvbao’ cultivars respectively, whereas urea and glycine replacements decreased the biomass significantly. Adding different nitrogen (N) forms significantly improved the contents of vitamin C, soluble sugar, free amino acid, protein, soluble phenol and flavonoids in Chinese kale. Adding the three alternative N forms also reduced nitrate content significantly, in which glycine replacement was the lowest. According to the results obtained, different forms of N replacement could be used for different purposes. Glycine replacement could be the best alternative only to improve qualities, while ammonium replacement could be the best alternative to improve both the yield and qualities.     

高粱绿肥种植密度对设施黄瓜根系生长相关因子的影响

以设施黄瓜为研究对象,在黄瓜定植前40 d分别播撒240、120、60 kg/hm~2不同密度高粱种子,并于黄瓜定植前将高粱植株作为绿肥翻入土壤,研究其对黄瓜结果期生长指标、根际土壤养分含量以及细菌群落结构变化的影响,探讨其影响黄瓜生长指标、根际养分含量和菌群结构变化的内在机制。试验结果表明:240 kg/hm~2种植密度的高梁绿肥可显著提高黄瓜根际土壤有机质质量比31.66%、碱解氮质量比8.75%、速效磷质量比13.89%、速效钾质量比16.86%、脲酶活性6.85%,显著提高结果期黄瓜茎粗12.83%、根系数15.81%、根总体积24.11%、叶片总面积11.43%、单株结瓜数10.97%、总产量9.81%;240 kg/hm~2种植密度的高粱绿肥可明显提高黄瓜根际土壤中变形菌门、放线菌门、厚壁菌门比例而降低酸杆菌门、绿弯菌门、拟杆菌门比例,明显提高鞘脂单胞菌科、黄色单胞菌科、红螺菌科、中华杆菌科、生丝微菌科比例而降低Gp6科、Gp16科、Gp4科比例。该处理主要通过降低根际土壤绿弯菌门和提高鞘脂单胞菌科、中华杆菌科比例而提高脲酶活性,通过提高厚壁菌门、黄色单胞菌科、红螺菌科和降低根际土壤酸杆菌门比例而促进碱解氮质量比、速效磷质量比、茎粗、叶片总面积、根系数、根总体积的提高,最终促进黄瓜生长并提高产量。     

Microbial residues were increased by film mulching with manure amendment in a semiarid agroecosystem

Amino sugars, as a kind of microbial residue, are strongly associated with cycling of microbial-derived soil organic matter. However, responses of amino sugars to agricultural practices on the Loess Plateau in North-western China are poorly known. The objective was to evaluate effects of film mulching (no film mulching + NPK fertilizers, CK; film mulching + NPK fertilizers, PF; film mulching + NPK fertilizers + cow manure, FM) on accumulations of amino sugars in this region. FM significantly increased total amino sugar by 190.46 mg kg^?1 in 0–10 cm layer and 214.66 mg kg^?1 in 10–20 cm layer relative to CK, but PF significantly decreased it by 139.28 mg kg^?1 in 0–10 cm layer. Ratios of glucosamine to muramic acid were markedly decreased by 2.50 in 0–10 cm layer and 2.28 in 10–20 cm layer in FM than CK, suggesting a tendency of microbial residues pool shift towards bacterial residues in this agroecosystem. These results indicated film mulching alone was not benefitial to accumulation of amino sugar while organic manure contributed to the build-up of amino sugar partly due to manure contained microbial residues. The different patterns of amino sugars suggested significant changes in the quality of microbial-derived organic matter.     

星油藤青枯病病原菌鉴定

 星油藤(Plukenetia volubilis L.) 是一种重要的藤本油料植物,在我国华南地区广泛种植。青枯病是近两年在海南星油藤种植区发生的新病害,为探究星油藤青枯病菌的基本特性及种下分化情况,本研究对分离的6株代表菌株进行了相关分析。细菌学鉴定及致病性测定结果表明,该病害是由类茄科雷尔氏菌(Ralstonia pseudosolanacearum)侵染引起。同时,从传统分类及分子生物学不同层面分析了星油藤青枯病菌的遗传分化情况。生理小种及生化变种的测试结果表明,星油藤青枯病菌属于1号生理小种和生化变种Ⅲ;16S rDNA和egl基因部分序列聚类分析显示,星油藤青枯病菌属类茄科雷尔氏菌演化型Ⅰ即亚洲分支菌株,序列变种34。     

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.