蔬菜商品苗贮藏运输技术研究进展

随着育苗产业的发展，蔬菜商品苗的贮藏与运输成为幼苗生产必不可少的环节。贮运前商品苗的质量和贮运期间的 管理和调控水平是影响贮运后幼苗质量的两个重要因素。本文就贮运前壮苗的培育和管理技术，以及贮运期间的管理和控制 技术两个方面对贮运商品苗质量保持的相关研究进行了总结，并对现存问题进行了分析。     

An Overview on Exogenous Compounds That Mitigate Heat Stress in Crops

With the global warming and climate change in recent years, heat stress has become one of the major abiotic factors constraining production and productivity of crops in many regions around the world. Although the plants have developed some adaptive behaviors and avoidance mechanisms against heat stress, they wil be hurt under extreme high temperature. Exogenous compounds could enhance plant growth and development, antioxidant enzymes activities, chlorophyl and nutrient contents under stress conditions. Meanwhile, application of exogenous compounds sustains physiological and biochemical process and prevents plants from physiological changes under stress conditions. ln this review, effects of heat stress upon crops, and the functions of hormones in plant adaptation to heat stress are simply stated. Then, we intend to appraise how various phytohomrnones that are related to plant adaptation to heat stress. The role of abscisic acid (ABA), salicylic acid (SA) and polyamines (putrescine and spermine) under heat stress conditions are mainly discussed.     

N-亚硝基化合物的危害性、来源及预防措施

N-亚硝基化合物是一类化学结构多样的化合物。它具有而强烈的致癌毒性,致畸致突变性和对肝脏、肺等许多组织器官的急性毒性。N-亚硝基化合物的前体物质广泛地分布在人类的生活、工作环境及食品中。在参考综合大量文献资料的基础上对N-亚硝基化合物的危害性、来源及预防措施作了简要概括,旨在提高人们对N-亚硝基化合物危害的认识和防范意识,为提高食品的卫生质量提供便利。     

中兽药复方组合与抗生素防治肉鸡呼吸道疾病的协同效应

为探讨中兽药复方组合与抗生素防治肉鸡呼吸道疾病的协同效应,本研究在规模化鸡场两栋鸡舍内分别随机选取100只3日龄白羽肉鸡,分为两组（Ⅰ组和Ⅱ组）：Ⅰ组饮水添加抗生素,Ⅱ组在添加抗生素基础上的不同阶段分别饲喂中兽药玉屏风口服液（3~7 d）、射干地龙颗粒（10~16 d）、双黄连口服液（22~25 d）、麻杏石甘口服液（27~31 d）。分别于8日龄免疫鸡传染性支气管炎活疫苗、新城疫-传染性支气管炎二联活疫苗和新城疫-禽流感二联灭活疫苗,免疫后1、7、14、21、28 d采集血清和气管组织,检测新城疫、禽流感（H9）、传染性支气管炎疫苗的抗体水平,观察气管组织病理变化,计算免疫器官指数和平均日增重。结果显示,Ⅱ组的成活率较Ⅰ组提高了1.23%,Ⅱ组末体重与平均日增重极显著高于Ⅰ组（P<0.01）,分别提高了561.25和16.63 g/d;Ⅱ组病鸡呼吸道症状较Ⅰ组轻,病程短,肝脏和心脏无明显病变,脾脏指数在36 d显著高于Ⅰ组（P<0.05）。免疫后21 d,Ⅱ组新城疫、传染性支气管炎和禽流感（H9）疫苗的抗体水平达到最高,显著高于Ⅰ组（P<0.05）;免疫后28 d,Ⅱ组新城疫抗体水平极显著高于Ⅰ组（P<0.01）。综上所述,4种清热解毒、止咳平喘、清肝利胆的中兽药复方组合使用与抗生素促生长和预防肉鸡呼吸道疾病具有协同效应。     

日粮中紫苏饼、菜籽粕代替豆粕对肉牛养分表观消化率及氮代谢的影响

试验旨在研究日粮中紫苏饼、菜籽粕代替豆粕对肉牛养分表观消化率及氮代谢的影响。选择20头体重相近、健康状况良好的12月龄左右的秦川肉牛（母牛）为试验动物,按照单因素随机区组设计,将20头试验牛分为5组,每组4头牛。不同试验组日粮中分别添加以31%豆粕（对照）、36%菜籽粕、14%紫苏饼+24%菜籽粕、28%紫苏饼+12%菜籽粕和42%紫苏饼为蛋白质原料配制的5种不同的精饲料。试验持续120 d,其中预饲期15 d,正试期105 d。试验期间,测定每头试验牛每天的摄入氮、尿氮及粪氮,测定日粮中干物质（DM）、有机物（OM）、中性洗涤纤维（NDF）和酸性洗涤纤维（ADF）的表观消化率。结果表明：① 42%紫苏饼组摄入氮含量最高,36%菜籽粕组最低,但各组间氮含量差异不显著（P>0.05）;36%菜籽粕组的粪氮显著高于28%和42%紫苏饼组（P<0.05）,且与31%豆粕组和14%紫苏饼组差异不显著（P>0.05）;② 42%紫苏饼组的沉积氮最高,与其他各组均差异显著（P<0.05）,其中31%豆粕组显著高于36%菜籽粕组（P<0.05）;③ 42%紫苏饼组的DM、ADF表观消化率显著高于31%豆粕组和36%菜籽粕组（P<0.05）,14%和28%紫苏饼组的DM、OM和NDF的表观消化率均差异不显著（P>0.05）;④ 14%紫苏饼组尿液中尿素氮含量显著高于31%豆粕组和42%紫苏饼组（P<0.05）,且与36%菜籽粕组和28%紫苏饼组差异不显著（P>0.05）;31%豆粕组尿液中马尿酸氮含量显著高于36%菜籽粕组和42%紫苏饼组（P<0.05）,而这3组均显著高于14%和28%紫苏饼组（P<0.05）;31%豆粕组的尿囊素氮含量显著高于42%紫苏饼组（P<0.05）,与其他3组差异不显著（P>0.05）;各组的肌酸氮、微生物氮预测值、尿素氮/尿氮、肌酸氮/尿氮和嘌呤衍生物氮/尿氮均没有显著差异（P>0.05）。综上,本试验条件下,精料中用42%紫苏饼代替31%豆粕,肉牛氮沉积最高,比对照组高3.65 g/d;DM、OM、NDF、ADF的表观消化率分别比对照组高3.45%、2.22%、6.56%、10.98%。     

AM真菌对植物挥发性物质影响的研究现状与展望

植物挥发性物质在植物与植物及植物与昆虫之间的化学通讯中起着重要作用。由丛枝菌根（arbuscular mycorrhizal,AM）真菌与维管束植物形成的共生体,是自然界中最为广泛的植物-微生物共生体。AM真菌不仅可影响植物养分吸收、生长,调节植物抗逆相关酶和信号物质,同时可通过菌丝桥在不同植物间进行养分、信息交换,促进植物挥发性物质的转化和排放,影响植物对病、虫等生物逆境的响应。本文基于CNKI和Web of Science两个数据库,查阅了1981年1月至2019年12月来AM真菌对植物挥发性有机化合物（biogenic volatile organic compounds,BVOCs）、氧化亚氮（N₂O）、二氧化碳（CO₂）、甲烷（CH₄）等4类挥发性物质影响的研究进展,归纳分析了AM真菌对植物挥发性物质的影响及机理,并对该领域的研究进行了展望。     

A between‐experiment analysis of relationships linking dietary protein intake and post‐weaning diarrhea in weanling pigs under conditions of experimental infection with an enterotoxigenic strain of Escherichia coli

Numerous experiments have demonstrated that feeding a lower protein diet decreases protein fermentation in the gastrointestinal tract (GIT) and reduces the incidence of post‐weaning diarrhea (PWD). However, there is a lack of holistic evidence underpinning the relationship between feeding a lower protein diet and PWD in relation to physiological responses and protein fermentation in the GIT. The scope of this article, therefore, will: (i) focus on the impact of dietary protein levels on selected indices of GIT health in weaned pigs without and with experimental infection with an enterotoxigenic strain of Escherichia coli; and (ii) attempt to conduct regression analysis to examine the relationships between dietary‐origin protein intake, nitrogen fermentation indices, fecal consistency and the incidence of PWD. We used datasets generated from a series of four intensive experiments in weaned pigs. The collective results derived from these datasets indicate that restriction of daily protein intake to less than 60 g through feeding a lower protein diet for as little as 7 days after weaning reduced the incidence of PWD commensurate with a reduction in protein fermentation indices.     

Effects of nitrogen application on flavor compounds of cherry tomato fruits

A pot experiment was conducted to determine the effects of N application on volatile compounds, taste compounds, and firmness of fresh tomato fruits. Each pot was filled with 8 kg of clean sand. The experiment consisted of six nitrogen (N)‐application rates with 0, 2.25, 4.50, 9.00, 18.00, and 36.00 mmol N L^–1 in the nutrient solution. Volatile compounds, soluble sugars, soluble solids, titratable acidity, and firmness of fresh tomato fruits were measured. The results show that increasing N application increased the concentrations of 1‐penten‐3‐one, hexanal, cis‐3‐hexenal, 2‐methyl‐4‐pentenal, trans‐2‐hexenal, 6‐methyl‐5‐hepten‐2‐one, titratable acidity, soluble sugars, and soluble solids. By contrast, increasing N supply decreased the concentration of phenylacetaldehyde and first increased and then decreased the concentrations of 2E–4E‐hexadienal and the firmness of fresh tomato fruits. Close relationships between the concentration of various volatile compounds, titratable acidity, soluble sugars, and soluble solids were found. However, concentrations of these flavor compounds were very poorly correlated with fruit firmness. Based on contributions of these compounds to tomato flavor, we assume that moderate high N supply improves tomato flavor, whereas excessive N supply can deteriorate it.     

几株苯酚类化合物降解菌超微结构的研究

从工业废水中分离到几株苯酚类化合物降解菌 (A1、A2、A3、A4、A5、A6) ,电镜观察各菌的鞭毛特征 ,A2、A3、A4菌无鞭毛 ,A1、A5、A6菌有鞭毛。几株降解菌的外部形态均为短的杆状菌。经JEOL 1 0 0CX透射电镜观察 ,A2、A5菌在不同培养条件下细胞内部结构发生了明显改变。A2菌细胞核中含有的聚 β 羟基丁酸 (PHB) ,具有巨大的应用价值和开发潜力     

苦皮藤内生真菌层出镰刀菌中杀菌成分的结构鉴定

采用红外、质谱、核磁共振氢谱和13C核磁共振谱技术,对苦皮藤韧皮中分离出的1L内生真菌代谢物1L-3,1L-6及1L-8进行了结构鉴定。结果表明,化合物1L-3为enniatinB,化合物1L-6为enniatinB1,化合物1L-8为enniatinA1。