<i>In-Vivo</i>Management of Purple Blotch of Onion Caused by <i>Alternaria porri</i>(Ellis) Cif. through Fungicides

An experiment was carried out to study the outcome of environmental factors (Temperature, Relative Humidity, Rainfall) and management of the purple blotch disease of onion using five treatments (Rovral + Ridoil gold with 3,4,5,6 sprays and control). The Taherpuri variety was used during the 2015-2016 cropping seasons at BARI, Gazipur, Bangladesh. In the experiment, the purple blotch disease surfaced at the end of January 2016 and was severe in late February to March (PDI 76.12%) due to temperature and RH above 24°C and 95%, respectively. As for the chemical control, the PDI for the treatments ranged from 50.66% to 83.33%. Significantly higher stem height was recorded by T4 (68.06 cm), where six sprays of Rovral + Ridomil were applied. The minimum stem height was recorded in T5 (59.23 cm). The maximum stem number per hill was recorded in T4 (2.30) numerically but differed significantly with T5 (2.00), where fungicides were not applied. The maximum lesion area was measured in T5 (25.26 mm2). Regarding PDI (Percent disease index), there was a significant difference among the treatments. The PDI value on purple blotch of onion ranged from 34.00 to 83.33. The lowest PDI was assessed in T4 (34.00). Statistical analysis revealed that a significant decrease of PDI on purple blotch was recorded under treatments of T1, T2, T3, and T4 (39.20%, 45.60%, 49.59%, and 59.19%) on controlling the disease and giving the optimum yield but all of them significantly differed with T5 (83.33%) where no fungicides were sprayed.

五种茄科糖苷生物碱及其混合物的抗真菌活性研究(英文)

本文研究了五种茄科糖苷生物碱(茄碱、查茄碱、边缘茄碱、澳洲茄碱和番茄碱)对两种植物病原真菌白菜白斑病菌和葱紫斑病菌的抑制活性。结果表明番茄碱的抗真菌活性最强,其后依次是查茄碱、边缘茄碱和澳洲茄碱,茄碱的活性最弱;不同浓度茄碱和查茄碱(马铃薯中的两种糖苷生物碱)的混合物均具有协同抗真菌作用,且低浓度的混合物产生的协同作用效果较大;边缘茄碱和澳洲茄碱(龙葵中的两种糖苷生物碱)的混合物基本没有协同抗真菌作用;边缘茄碱和查茄碱的混合物以及澳洲茄碱和茄碱的混合物(均为来自不同植物的糖苷生物碱的混合物)在抗真菌活性上都呈现了相加关系。

葱紫斑病发生及防治若干问题的初步研究 Ⅰ.分生孢子萌发侵染、潜育显症及杀菌剂筛选

对葱紫斑病菌孢子萌发侵染、潜育显症、杀菌剂筛选等进行了研究。结果表明：葱紫斑病病原菌分生孢子在适温下的清水中3h的萌发率可达到87％，附着胞开始形成，6h后附着胞的形成达到高峰。分生孢子的侵入率和附着胞的形成率呈高度正相关；23—30℃适宜孢子萌发，25℃为孢子萌发的最适温度；萌发后干燥6d后孢子死亡。氮、磷、钾肥均可显著降低葱紫斑病的侵染，且氮、钾肥对大葱抗侵染的效果好于磷肥。葱紫斑病的潜育期为3d，其累积显症率与时间的关系曲线为“倒J”型；百菌清对葱紫斑病菌孢子萌发的抑制效果最好，新万生、大生和杀毒矾的效果次之，而多菌灵、甲基托布津、三唑酮效果较差。

苍耳提取物对大葱紫斑病原孢子和菌丝的影响

以大葱紫斑病原菌为供试菌,采用菌丝生长速率测定法和病原孢子萌发率测定法,对苍耳(Xanthium sibiricum Patr.ex Widd)提取物的抗菌活性进行研究。结果表明,提取物在50、100 mg/mL的浓度下,大葱紫斑病原孢子萌发率低于50%,对菌丝的抑制率大于60%,对大葱紫斑病原菌具有较强的抑制作用。

紫斑病菌粗毒素对大蒜幼苗防御酶活性和叶片解剖结构的影响

以抗病品种G087和感病品种G025为试材,研究了大蒜紫斑病菌粗毒素对大蒜幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、苯丙氨酸解氨酶(PAL)活性和丙二醛(MDA)含量及叶片解剖结构的影响。结果表明:在大蒜紫斑病菌粗毒素处理后120h内,抗病品种和感病品种叶片SOD活性呈现一致的变化趋势,均在96h达到峰值,但抗病品种SOD活性始终高于感病品种。随着大蒜紫斑病菌粗毒素处理时间的延长,感病品种叶片POD和PAL活性均呈先持续升高后稍下降的趋势,均有1个峰值;而抗病品种叶片POD和PAL活性均出现2个峰值,POD活性的2个峰值分别出现在48h和96h,PAL活性的2个峰值分别出现48h和120h;抗病品种酶活性的最大峰值高于感病品种。在大蒜紫斑病菌粗毒素处理后的大部分时间内,抗病品种叶片MDA含量低于感病品种。抗病品种叶肉组织结构比感病品种紧密;经大蒜紫斑病菌粗毒素处理后,两个品种叶片栅栏组织及海绵组织的密度都比处理前增加,抗病品种叶肉组织结构比感病品种更加紧密。

Overview of purple blotch disease and understanding its management through chemical, biological and genetic approaches

Purple blotch disease of Allium spp. crops caused by Alternaria porri has remained a major concern in agriculture for both farmers and research fraternity as it severely damages the crops and drastically reduces the yield. The symptoms appear after 1–4 days of infection and bulb rot begin, and eventually turn into dark reddish-purple and then brownish/black lesions. Many factors like season, time of sowing, humidity and temperature, stage of crop, and plant architecture have a huge impact on the progression of purple blotch disease. Many genic markers based on amplification of an Alta1 gene sequence have been designed for identification and differentiation of different Alternaria species groups. Among the most commonly used fungicides, mancozeb, tebuconazole, difenaconazole and azoxystrobin were found to be the ideal for the management of purple blotch disease and increased garlic yield. Many biological approaches such as plant extracts and bio-control agents were found partially effective for controlling the disease. A report on QTL mapping for purple blotch resistance discovered that purple blotch resistance is controlled by a single dominant gene ApR1. To completely understand the purple blotch disease resistance for crop improvement, a study is required at transcriptome level for hunting purple blotch resistant genes by gene annotation and mining. Genetic engineering and genome editing are other approaches that can be done for engineering disease resistance in Allium crops for genetic improvement.

不同生物农药对大葱紫斑病的防治效果

为明确5种生物农药对大葱紫斑病的防治效果,采用田间小区试验方法开展田间防治效果试验。结果表明,10%多抗霉素可湿性粉剂90 g/667m^(2)对大葱紫斑病的防治效果最好,可达78.63%,其次为0.3%四霉素水剂60 ml/667m^(2)防治效果75.4%,两者防治效果略低于化学药剂75%百菌清可湿性粉剂230 g/667m^(2),但三者间无显著差异。两种生物农药在生产上可优先选择。

8种杀菌剂对大葱紫斑病及根腐病的室内毒力测定

以天津地区大葱紫斑病及根腐病病原菌为试验材料,采用菌丝生长速率法,研究了天津地区大葱主产区紫斑病及根腐病病原菌对8种杀菌剂的敏感性,以期为该地区大葱紫斑病及根腐病的防治提供指导。结果表明,吡唑醚菌酯、咪鲜胺、苯醚甲环唑、戊唑醇、咯菌腈对大葱紫斑病和根腐病病原菌均具有较好的抑制作用,其对大葱紫斑病的EC50值分别为0.2627,0.9349,2.1155,0.0088,0.1873μg·mL-1,对大葱根腐病病原菌的EC50值分别为0.7754,0.0018,0.3196,1.6219,1.2359μg·mL-1;95%嘧菌酯对大葱紫斑病抑菌效果较好,但对大葱根腐病抑菌效果较差;95%啶酰菌胺和98%百菌清对两种病原菌抑菌效果较差,生产上不推荐使用。

洋葱紫斑病病原菌鉴定及生物学特性

以黑龙江省3个地区洋葱紫斑病植株为试材,采用组织分离法分离洋葱紫斑病病原菌,对获得菌株进行致病性测定、形态学鉴定以及16srDNA ITS序列分析,并研究其生物学特性。结果表明:该致病菌为葱链格孢菌(Alternaria porri(Ell.)Cifferri),该菌株在以葡萄糖为碳源时产孢量最高,但菌丝生长量最低;在以氯化铵为氮源时菌丝生长量和产孢量都达到最高。32℃,pH 7,光照条件为12h光照/12h黑暗交替培养菌丝生长量最高;24℃,pH 8,连续黑暗条件下产孢量最高。