除草剂减量用药对不同生长期反枝苋的防除效果评价

[目的]比较5种除草剂对不同时期反枝苋的防除效果,评价减量用药可行性。[方法]在反枝苋不同生长期喷施除草剂,15 d后测定杂草干重。[结果]反枝苋2叶期时,使用溴苯腈、麦草畏防治,可降低除草剂的使用量。使用厂家推荐剂量甲基磺草酮/特丁津混剂也可有效防治,而特丁津、磺草酮防效不佳。在2叶期喷施5种除草剂,防效均优于4叶期。[结论]在反枝苋2叶期喷施合适除草剂,即使减量用药也能有效防治反枝苋。     

惯性分离装置的性能分析及结构优化

通过搭建惯性分离装置测试平台，结合相关检测设备的数据采集，进行某型惯性除雾器的性能分析。实验发现，两通道折流惯性分离装置的分离效率与液滴直径成正比。对于微小粒径5～10μm的液滴分离效果不佳，风速对分离效率的影响不大。对于30μm以上的液滴分离效果较好，效率整体超过80%。系统进出口压降损失方面，粒径的变化相对于整个装置可以近似忽略，不同粒径条件下压降曲线变化基本相同，风速是压降变化的主要影响变量。为突破小粒径液滴分离效果不佳的限制，分别从板间距、底面高度及板型等方面入手，分析不同尺寸参数条件下分离效率与压降的变化规律。计算结果表明，板间距数值越大，分离效率越低，系统压降越小；底面高度与效率变化并不是总体相关，存在波动并呈现局部相关性；高度增加到30mm时达到最佳，系统压降也较小；通道级数越多，分离效率越高，但压降增加较大；流线型壁面分离效果较好，控制压降的能力也较强。     

Antibacterial Activity of Copper Nanoparticles against Xanthomonas campestris pv. vesicatoria in Tomato Plants

Copper-based bactericides have appeared as a new tool in crop protection and offer an effective solution to combat bacterial resistance. In this work, two copper nanoparticle products that were previously synthesized and evaluated against major bacterial and fungal pathogens were tested on their ability to control the bacterial spot disease of tomato. Growth of Xanthomonas campestris pv. vesicatoria, the causal agent of the disease, was significantly suppressed by both nanoparticles, which had superior function compared to conventional commercial formulations of copper. X-ray fluorescence spectrometry measurements in tomato leaves revealed that bioavailability of copper is superior in the case of nanoparticles compared to conventional formulations and is dependent on synthesis rather than size. This is the first report correlating bioavailability of copper to nanoparticle efficacy.     

Xanthomonas citri pv. citri Pathotypes: LPS Structure and Function as Microbe‐Associated Molecular Patterns

Xanthomonas citri pv. citri is the pathogen responsible for Asiatic citrus canker, one of the most serious citrus diseases worldwide. The lipopolysaccharide (LPS) molecule has been demonstrated to be involved in X. citri pv. citri virulence. Despite enormous progress in investigations of the molecular mechanisms for bacterial pathogenicity, determination of the detailed LPS structure–activity relationship is limited, as the current knowledge is mainly based on structural determination of one X. citri pv. citri strain. As X. citri pv. citri strains are distinguished into three main pathogenicity groups, we characterized the full structure of the LPS from two pathotypes that differ in their host‐range specificity. This revealed an intriguing difference in LPS O‐chain structure. We also tested the LPSs and isolated lipid A moieties for their ability to act as microbe‐associated molecular patterns in Arabidopsis thaliana. Both LPS/lipid As induced ROS accumulation, but no difference was observed between the two pathotypes.