食品防霉剂富马酸二甲酯的合成

以四氯化锡为催化剂,马来酸酐和甲醇为原料,采用"一锅法"催化合成富马酸二甲酯。考察了反应时间、醇酸摩尔比、催化剂的用量对产率的影响,并进行了正交实验设计。结果表明:醇酸摩尔比对产率的影响高度显著,当甲醇与马来酸酐的摩尔比为15∶1,四氯化锡质量分数0.8g,回流反应时间2.5h,产率达88.72%。通过熔点测试和红外光谱分析,确定合成产物即是富马酸二甲酯。     

Fungi isolated from bovine udders,and their possible sources

AIM: To identify fungi isolated from infections of the bovine mammary gland, and establish their possible sources.

METHODS: From a herd of 420 cows, milk samples were collected from all quarters at calving and cultured to detect causative organisms. Quarters identified as infected with fungi were further sampled during early lactation. Samples from feedstuffs, the feed pad and ends of teats were also collected and analysed for the presence of fungi.

RESULTS: Eleven of 420 cows were diagnosed with intramammary infections (IMI) caused by yeasts (nine cows, 10 quarters) and moulds (two cows, three quarters). Six of the yeast species had previously been reported as being responsible for mastitis. Elevated somatic cell counts (SCC) were observed in many quarters, but most infections were eliminated spontaneously. Two of the fungi isolated from milk samples were also isolated from feedstuffs and teat swabs, and seven other fungi isolated from milk samples were not isolated from feed, the feed pad or cows' teats.

CONCLUSIONS: Isolation of fungi from the udder is rarely reported in dairy cows in New Zealand. In this herd, contamination of the end of the teat originating from feedstuffs and possibly exacerbated by the use of a feed pad may have led to the establishment of IMI caused by fungi.

CLINICAL RELEVENCE: Fungi are infrequently if ever reported in mastitis trial data or surveys in New Zealand and are probably of little clinical significance.     

莴笋根茎部病害的病状特征及防治措施

对莴笋灰霉病、腐败病、软腐病这3种常见莴笋根茎部病害的病原、侵染循环、流行规律、危害症状进行了探讨,最后提出相应的综合防治措施。     

放线菌对番茄灰霉病和早疫病的拮抗作用研究

在室内对峙培养的基础上,对接种放线菌F的盆栽番茄植株接种早疫病A1、灰霉病菌B1进行田间抗性鉴定.结果表明:F菌株对2种靶标真菌均有一定的抑制作用.接种F A1、F B1的番茄植株,病情指数要明显低于对照,差异极显著.接种放线茵表现为不同程度的发病症状,且生长势差.接种生防菌真菌F对番茄PPO、POD具有一定诱导作用,在"放线菌-病原菌"双菌体系中对番茄叶片MDA含量有明显的抑制作用,双茵处理的番茄叶片、茎MDA含量明显低于单接番茄病原菌处理.     

番茄叶霉病侵染机制及抗性机理研究进展

番茄叶霉病是由Cladosporium fulvum(Cook)Ciferrd引起的一种世界性病害。自从20世纪80年代以来,随着保护地番茄面积的扩大,该病的危害也越来越严重,成为了番茄生产上的重要叶部病害,严重影响番茄产量和品质。综述了近年来在番茄叶霉病侵染机制、生理小种的分化和抗病性机制方面的研究进展,并对其抗性研究前景进行了展望。     

百合灰霉病发生规律研究

本项研究表明：百合灰霉病的初侵染源主要是随病残体在土壤中越夏越冬的菌核。３月中旬左右百合芽苞出土展叶时,菌核萌发产生孢子,初次侵染植株引起发病。一般温度１５～２７℃、ＲＨ８０％以上的气候条件有利发病;连作、地势低洼、排水不良等情况发病严重。     

稻田养鱼技术初探

本文全面介绍了稻田养鱼新田间建设模式方法、回形生态鱼塘的开挖方法及鱼、稻养种方法。具有投入少、成本低,见效快,效益高的特点。     

根施阿米西达防治番茄叶霉病效果及对番茄生长的影响

[目的]明确根施阿米西达对番茄叶霉病的防治效果、持效期及对番茄生产的影响。[方法]采用田间试验研究4个根施阿米西达达处理、1个喷施阿米西达对照和1个清水对照对番茄叶霉病的防治效果及对番茄生长的影响。[结果]根施阿米西达超过1 500ml/hm~2,药后75 d对叶霉病的防治效果均超过90%,喷施阿米西达对照的防治效果仅为22.24%,相同用药量持效期较喷雾防治至少高出20 d。阿米西达对番茄植株表现出低浓度促进生长而高浓度抑制生长的特性。[结论]综合考虑,建议春茬番茄(8.10万株/hm~2)根施阿米西达1 500 ml/hm~2预防番茄叶霉病。     

啶酰菌胺与唑胺菌酯混配对灰葡萄孢毒力的增效作用

为明确啶酰菌胺与唑胺菌酯对灰葡萄孢Botrytis cinerea毒力的增效作用,采用菌丝生长速率法测定了啶酰菌胺与唑胺菌酯不同配比混合物对灰葡萄孢菌株DZ3(对多菌灵、乙霉威和嘧霉胺高抗)的毒力,以Wadley公式评价了其协同作用。选取最佳增效组合,采用黄瓜子叶喷雾法测定了其对其他5个菌株的毒力及田间防效。通过测定菌株DZ3分生孢子悬浮液中的溶氧量、电导率和菌丝中丙二醛的含量,研究最佳增效组合的增效机制。结果表明:啶酰菌胺与唑胺菌酯不同质量比(9∶1、7∶1、5∶1、3∶1、1∶1、1∶3、1∶5、1∶7和1∶9)的混合物均对菌株DZ3表现为毒力增效作用,其中质量比为1∶3的组合增效最明显,增效系数达4.76,且对另外5个供试菌株的联合毒力也表现出增效;在使用剂量为有效成分200~300 g/hm2时,质量比为1∶3的组合对番茄灰霉病的防治效果为78.05%~93.96%,同时其对菌株DZ3的呼吸抑制作用与单剂啶酰菌胺相当,但对细胞膜通透性和菌丝膜脂质过氧化的影响均显著高于各单剂。本研究结果表明,啶酰菌胺与唑胺菌酯以质量比1∶3进行混配,可用于番茄灰霉病的防治。     

Low genetic variability in Sclerotinia sclerotiorum populations from common bean fields in Minas Gerais State,Brazil, at regional,local and micro‐scales

Sclerotinia sclerotiorum, causal agent of white mould, is the most destructive and widely distributed soilborne pathogen of common bean during the autumn–winter season in Brazil. Nevertheless, little is known about the genetic structure of the pathogen population. Microsatellite (SSR) markers and mycelial compatibility groups (MCGs) were used to characterize 118 isolates collected from 20 bean fields located in the most important growing regions of Minas Gerais State (MG). Additionally, the genetic variability among 10 isolates obtained from a single sclerotium was investigated in 10 different sclerotia. Seventy SSR haplotypes and 14 MCGs were identified among the 118 isolates. The genetic differences within bean growing areas accounted for most of the genetic variation (72%). Despite the relatively high genotypic diversity, the SSR loci were at linkage disequilibrium. Moreover, 70% of the isolates were assigned to only two MCGs, and haplotypes of a given MCG were closely related. The discriminant analysis of principal components revealed five groups. There was strong genetic differentiation between isolates collected in one municipality in southern MG when compared to other regions. Common bean resistance to white mould should be assessed with representative isolates of the five genetic groups and, if possible, of the different MCGs detected in the present study. One to five haplotypes were detected among the 10 isolates obtained from a single sclerotium. Therefore, in order to ensure genetic identity of an isolate, hyphal tip or monoascosporic isolates should be used.